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Aerospace Actuators 3

Series Editor Jean-Paul Bourriegraveres

Aerospace Actuators 3

European Commercial Aircraft and Tiltrotor Aircraft

Jean-Charles Mareacute

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley amp Sons Inc

Apart from any fair dealing for the purposes of research or private study or criticism or review as permitted under the Copyright Designs and Patents Act 1988 this publication may only be reproduced stored or transmitted in any form or by any means with the prior permission in writing of the publishers or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address

ISTE Ltd John Wiley amp Sons Inc 27-37 St Georgersquos Road 111 River Street London SW19 4EU Hoboken NJ 07030 UK USA

wwwistecouk wwwwileycom

copy ISTE Ltd 2018 The rights of Jean-Charles Mareacute to be identified as the author of this work have been asserted by him in accordance with the Copyright Designs and Patents Act 1988

Library of Congress Control Number 2017959463 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-84821-943-4

Contents

Introduction ix

List of Acronyms xiii

Chapter 1 European Commercial Aircraft before the Airbus A320 1

11 Introduction 1 12 The Caravelle and irreversible primary flight servocontrols 2

121 Servodyne servocontrol 4 122 Artificial feel of load 9 123 Hydraulic power generation 11

13 The Concorde and flight controls with analog electrical signals and controllers 14

131 General architecture of flight controls 16 132 Operation modes 19 133 Closed-loop analog electrical control 20 134 Relay jack and PFCU 22 135 Artificial feel 25 136 Hydraulic power generation 28

Chapter 2 Airbus A320 and Electrically Signaled Actuators 31

21 Airbus A320 or Signal-by-Wire with digital computers 31 22 Flight controls 32

221 General concepts 33 222 Architectures and redundancies 34 223 Actuators 38

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Aerospace Actuators 3

Series Editor Jean-Paul Bourriegraveres

Aerospace Actuators 3

European Commercial Aircraft and Tiltrotor Aircraft

Jean-Charles Mareacute

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley amp Sons Inc

Apart from any fair dealing for the purposes of research or private study or criticism or review as permitted under the Copyright Designs and Patents Act 1988 this publication may only be reproduced stored or transmitted in any form or by any means with the prior permission in writing of the publishers or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address

ISTE Ltd John Wiley amp Sons Inc 27-37 St Georgersquos Road 111 River Street London SW19 4EU Hoboken NJ 07030 UK USA

wwwistecouk wwwwileycom

copy ISTE Ltd 2018 The rights of Jean-Charles Mareacute to be identified as the author of this work have been asserted by him in accordance with the Copyright Designs and Patents Act 1988

Library of Congress Control Number 2017959463 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-84821-943-4

Contents

Introduction ix

List of Acronyms xiii

Chapter 1 European Commercial Aircraft before the Airbus A320 1

11 Introduction 1 12 The Caravelle and irreversible primary flight servocontrols 2

121 Servodyne servocontrol 4 122 Artificial feel of load 9 123 Hydraulic power generation 11

13 The Concorde and flight controls with analog electrical signals and controllers 14

131 General architecture of flight controls 16 132 Operation modes 19 133 Closed-loop analog electrical control 20 134 Relay jack and PFCU 22 135 Artificial feel 25 136 Hydraulic power generation 28

Chapter 2 Airbus A320 and Electrically Signaled Actuators 31

21 Airbus A320 or Signal-by-Wire with digital computers 31 22 Flight controls 32

221 General concepts 33 222 Architectures and redundancies 34 223 Actuators 38

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Series Editor Jean-Paul Bourriegraveres

Aerospace Actuators 3

European Commercial Aircraft and Tiltrotor Aircraft

Jean-Charles Mareacute

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley amp Sons Inc

Apart from any fair dealing for the purposes of research or private study or criticism or review as permitted under the Copyright Designs and Patents Act 1988 this publication may only be reproduced stored or transmitted in any form or by any means with the prior permission in writing of the publishers or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address

ISTE Ltd John Wiley amp Sons Inc 27-37 St Georgersquos Road 111 River Street London SW19 4EU Hoboken NJ 07030 UK USA

wwwistecouk wwwwileycom

copy ISTE Ltd 2018 The rights of Jean-Charles Mareacute to be identified as the author of this work have been asserted by him in accordance with the Copyright Designs and Patents Act 1988

Library of Congress Control Number 2017959463 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-84821-943-4

Contents

Introduction ix

List of Acronyms xiii

Chapter 1 European Commercial Aircraft before the Airbus A320 1

11 Introduction 1 12 The Caravelle and irreversible primary flight servocontrols 2

121 Servodyne servocontrol 4 122 Artificial feel of load 9 123 Hydraulic power generation 11

13 The Concorde and flight controls with analog electrical signals and controllers 14

131 General architecture of flight controls 16 132 Operation modes 19 133 Closed-loop analog electrical control 20 134 Relay jack and PFCU 22 135 Artificial feel 25 136 Hydraulic power generation 28

Chapter 2 Airbus A320 and Electrically Signaled Actuators 31

21 Airbus A320 or Signal-by-Wire with digital computers 31 22 Flight controls 32

221 General concepts 33 222 Architectures and redundancies 34 223 Actuators 38

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley amp Sons Inc

Apart from any fair dealing for the purposes of research or private study or criticism or review as permitted under the Copyright Designs and Patents Act 1988 this publication may only be reproduced stored or transmitted in any form or by any means with the prior permission in writing of the publishers or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address

ISTE Ltd John Wiley amp Sons Inc 27-37 St Georgersquos Road 111 River Street London SW19 4EU Hoboken NJ 07030 UK USA

wwwistecouk wwwwileycom

copy ISTE Ltd 2018 The rights of Jean-Charles Mareacute to be identified as the author of this work have been asserted by him in accordance with the Copyright Designs and Patents Act 1988

Library of Congress Control Number 2017959463 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-84821-943-4

Contents

Introduction ix

List of Acronyms xiii

Chapter 1 European Commercial Aircraft before the Airbus A320 1

11 Introduction 1 12 The Caravelle and irreversible primary flight servocontrols 2

121 Servodyne servocontrol 4 122 Artificial feel of load 9 123 Hydraulic power generation 11

13 The Concorde and flight controls with analog electrical signals and controllers 14

131 General architecture of flight controls 16 132 Operation modes 19 133 Closed-loop analog electrical control 20 134 Relay jack and PFCU 22 135 Artificial feel 25 136 Hydraulic power generation 28

Chapter 2 Airbus A320 and Electrically Signaled Actuators 31

21 Airbus A320 or Signal-by-Wire with digital computers 31 22 Flight controls 32

221 General concepts 33 222 Architectures and redundancies 34 223 Actuators 38

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Contents

Introduction ix

List of Acronyms xiii

Chapter 1 European Commercial Aircraft before the Airbus A320 1

11 Introduction 1 12 The Caravelle and irreversible primary flight servocontrols 2

121 Servodyne servocontrol 4 122 Artificial feel of load 9 123 Hydraulic power generation 11

13 The Concorde and flight controls with analog electrical signals and controllers 14

131 General architecture of flight controls 16 132 Operation modes 19 133 Closed-loop analog electrical control 20 134 Relay jack and PFCU 22 135 Artificial feel 25 136 Hydraulic power generation 28

Chapter 2 Airbus A320 and Electrically Signaled Actuators 31

21 Airbus A320 or Signal-by-Wire with digital computers 31 22 Flight controls 32

221 General concepts 33 222 Architectures and redundancies 34 223 Actuators 38

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

vi Aerospace Actuators 3

23 Landing gears 59 231 Braking 59 232 Auxiliary landing gear steering 63

24 Hydraulic system architecture 66 25 Hydraulic pumps 69

251 Engine-driven pump (EDP) 73 252 Electric motor pump (EMP) 76 253 Reversible power transfer unit (PTU) 77 254 Ram air turbine (RAT) 78

Chapter 3 Airbus A380 79

31 Introduction 79 311 A need for high-capacity long-range aircraft 80 312 Actuation need 81 313 Innovative architectures and technologies 83

32 Data transmission and processing 85 33 Power generation and distribution 89

331 2H-2E architecture 89 332 Hydraulic power generation 91

34 Flight controls 96 341 Topology 96 342 Displacement control for the actuators of slats and flaps 102 343 Electrohydrostatic actuators 107 344 Trimmable horizontal stabilizer actuator 111

35 Landing gears 116 351 Topology 116 352 Signal considerations 117 353 Power considerations 117 354 Extensionretraction 119 355 Steering 119 356 Braking 123

36 Thrust reversers 126 361 Locking in stowed configuration 129

37 Subsequent programs 130

Chapter 4 V-22 and AW609 Tiltrotors 133

41 V-22 Osprey military tiltrotor 134 411 Overall architecture of flight controls 135 412 Hydraulic power generation architecture 139 413 Control architecture of flight control actuators 140 414 Control surface actuators 141

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Contents vii

415 Swashplate actuators 143 416 Pylon conversion actuators 146

42 AW609 civil tiltrotor 161 421 Overall architecture of flight controls 162 422 Hydraulic power architecture 164 423 Power architecture of electrohydraulic actuators 165 424 Pylon conversion actuators 171

43 Comparison of the pylon conversion actuator approaches for the V-22 and AW609 182

Bibliography 185

Index 193

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Introduction

This book is the third in a series of volumes that cover the topic of aerospace actuators The first volume Aerospace Actuators 1 focuses on aerospace actuation needs concepts of reliability and redundancy and hydraulically-powered actuation solutions The second volume Aerospace Actuators 2 focuses exclusively on more electric solutions with regard to both signal (Signal-by-Wire or SbW) and power (Power-by-Wire or PbW) This third volume of the series Aerospace Actuators 3 is entirely about the detailed analysis of operational applications Rather than putting together the most exhaustive possible catalog of implemented solutions the objective is to rely on generic solutions that have been presented in the first 2 volumes from an architectural and functional perspective in order to highlight the constraints and opportunities offered by the technologies used A particular aim is to provide by means of examples a matrix view that covers various applications in an aircraft (power generation primary and secondary flight controls landing gears and engines) and various types of aircraft (fixed wing and rotor wing) at the same time This book is structured into chapters dedicated to aircraft types or families The chapters cover various actuation-related applications The first 3 chapters cover the evolution of actuation for European commercial aircraft focusing on aircraft representing the technological breakthroughs of each decade The first chapter relates to the Caravelle which introduced irreversible hydraulically-powered flight controls with no mechanical backup for 3 axes and to the supersonic Concorde of the 1970s which introduced analog flight controls with mechanical backup Chapter 2 deals with the Airbus A320 from the

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

x Aerospace Actuators 3

1980sndash1990s which introduced electrically-signaled and digitally-controlled flight control systems with mechanical signaling as backup for 2 axes Chapter 3 addresses the Airbus A380 from the 2000s which introduced disruptive innovations concerning more electric actuation particularly with the introduction of Electrohydrostatic Actuators (EHA) Chapter 4 provides an opportunity to analyze and compare architectural design and technological solutions that have been implemented for the Boeing-Bell V-22 tiltrotor military aircraft and the Agusta Westland AW609 tiltrotor civil aircraft Particular attention has been given to linear screw jacks developed for the tilting of nacelles ensuring the transition between plane and helicopter modes Although hydraulically powered these highly critical actuators use rotary hydraulic motors to generate output translational motion Consequently the power transmission solutions implemented and particularly those for secondary functions and reliability present an interest as similar preoccupations relate to Electromechanical Actuators (EMA) which are on their way to replacing Hydraulic Servo Actuators (HSA) also known as Servo-Hydraulic Actuators (SHA) for high power All chapters cover hydraulic power generation which is quasi-exclusively related to actuation functions On the contrary none of the chapters cover electric power generation The reason for this is twofold it is not specific to actuation and it is very well described by many references some of which are mentioned below

Similar to previous volumes further bibliographic references are recommended as sources of valuable information referring to aerospace actuation

ndash books focusing on hydraulic actuation for aerospace [NEE 91 RAY 93]

ndash books covering all aircraft systems in English [MOI 08 ROS 00 USF 12 WIL 08] or in French [DAN 17 LAL 02 SAU 09]

ndash state-of-the-art reviews (Aerospace Information Report or AIR) by the Society of Automotive Engineers (SAE) [SOC 12 SOC 16]

ndash conference proceedings particularly those exclusively focusing on aerospace actuators (Recent Advances in Aerospace Actuation Systems and Components INSA Toulouse 2001 2004 2007 2010 2012 2014 2016)

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

Introduction xi

Some of these references provide the reader with information related to other types of aircraft besides those covered in this volume such as the Boeing B737 and B747 models or the US military aircraft models F-15 F-16 F-18 and B2

These references will also provide the reader with information on the actuation of aircraft models covered in this volume However this is most often exclusively presented as descriptive information By contrast throughout the following chapters significant effort has been put into analyzing the adopted solutions in terms of architecture design and technology Various aspects of these solutions are discussed (power capacity reliabilityredundancy control and monitoring maintenance and operation etc) as part of the generic solutions presented in the first 2 volumes The difference in terms of objective and targeted audience also explains why the diagrams in this volume are not presented in a form that is similar to that used by aircraft manufacturers As in the previous volumes the diagrams in this volume distinguish between the signal view (full arrow) and the energy or power view (half-arrow) The direction of signal arrows represents the direction of information flow As for power transmission the half-arrow indicates only the functional direction however in the case of reversible elements it is possible for power to flow in the opposite direction (which is for example the case of an aiding load) Finally while technological aspects are only to a certain extent covered in this volume to the benefit of architectural aspects it is not because they are considered unimportant On the contrary it should be kept in mind that it is often due to technological imperfections that the industrial interest in certain architectural solutions is limited at a given time

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

List of Acronyms

ABCU Alternate Braking Control Unit

ADC Air Data Computer

ADCN Avionics Data Communication Network

ADIRU Air Data and Inertial Reference Unit

AFCS Automatic Flight Control System

AFDX Avionics Full DupleX switched ethernet

APPU Asymmetry Position Pick-off Unit

APU Auxiliary Power Unit

BCM Backup Control Module

BCS Brake Control System

BFWS Blade Folding and Wing Stowing

BHB Backup Hydraulic Brake

BHPDU Backup Hydraulic Power Drive Unit

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

xiv Aerospace Actuators 3

BLG Body Landing Gear

BPS Backup Power Supply

BSCU Braking and Steering Control Unit

BTV Brake To Vacate

BWS Body Wheel Steering

CCQ Cross Crew Qualification

CFRP Carbon Fiber-Reinforced Polymer

CPIOM Core Processing InputOutput Module

CSMG Constant Speed Motor Generator

DDV Direct Drive Valve

EBCU Emergency Brake Control Unit

EBHA Electrical Backup Hydraulic Actuator

ECAM Electronic Centralized Aircraft Monitoring

ECU Electronic Control Unit

EDP Engine-Driven Pump

EEC Electric Engine Control

EFCS Electrical Flight Control System

EHA Electrohydrostatic Actuator

EIS Entry Into Service

ELAC Elevator and Aileron Computer

EMA Electromechanical Actuator

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

List of Acronyms xv

EMI Electromagnetic Interference

EMP Electric Motor Pump

EMS Elastic Mode Suppression

EPDU Electric Power Drive Unit

ETRAC Electric Thrust Reverser Actuator Controller

ETRAS Electric Thrust Reverser Actuation System

FbW Fly-by-Wire

FAC Flight Augmentation Computer

FADEC Full Authority Digital Engine Control

FCDC Flight Control Data Concentrator

FCGC Flight Control and Guidance Computer

FCPC Flight Control Primary Computer

FCRM Flight Control Remote Module

FCS Flight Control System

FCSC Flight Control Secondary Computer

FFCM Free Fall Control Module

FHS Fluide Hydraulique Standard

FOD Foreign Object Debris

FPPU Feedback Position Pick-up Unit

GDO Ground Door Opening

HIRF High-Intensity Radiated Field

HPDU Hydraulic Power Drive Unit

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

xvi Aerospace Actuators 3

HSA Hydraulic Servo Actuator

HSTA Horizontal Stabilizer Trim Actuator

IDT Interconnect Drive Train

IMA Integrated Modular Avionics

IOM InputOutput Module

IPPU Instrumentation Position Pick-up Unit

ITFV Integrated Three Function Valve

LAF Load Alleviation Function

LEHGS Local Electrohydraulic Generation System

LGCIS Landing Gear Control and Indication System

LGCIU Landing Gear ControlInterface Unit

LGERS Landing Gear Extension and Retraction System

LRM Line Replaceable Module

LRU Line Replaceable Unit

LVDT Linear Variable Differential Transformer

MCE Motor Control Electronics

MCPU Motor Control and Protection Unit

MDE Motor Drive Electronics

MLC Maneuver Load Control

MLG Main Landing Gear

MPD Motor Power Drive

MPE Motor Power Electronics

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

List of Acronyms xvii

MSU Motor Switching Unit

MTBF Mean Time Between Failure

MTBFCF Mean Time Between Flight Critical Failure

MTOW Maximum Take-Off Weight

MWGB Mid-Wing Gear Box

neo New Engine Option

NLG Nose Landing Gear

NWS Nose Wheel Steering

PbW Power-by-Wire

PCA Pylon Conversion Actuator

PCS Pylon Conversion System

PCU Power Control Unit

PDU Power Drive Unit

PFBIT Pre-Flight Built-In Test

PFCS Primary Flight Control System

PFCU Powered Flying Control Unit

PHB Primary Hydraulic Brake

PHPDU Primary Hydraulic Power Drive Unit

PLS Primary Lock System

POB Pressure-Off Brake

PTU Power Transfer Unit

RAT Ram Air Turbine

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

xviii Aerospace Actuators 3

RCCB Remote Current Circuit Breaker

RDC Remote Data Concentrator

RJ Relay Jack

RPK Revenue Passenger Kilometer

RVDT Rotary Variable Differential Transformer

SAE Society of Automotive Engineers

SAR Search and Rescue

SbW Signal-by-Wire

SFCC Secondary Flight Control Computer

or Slat and Flap Control Computer

SEC Spoiler and Elevator Computer

SHA Servo-Hydraulic Actuator

THS Trimmable Horizontal Stabilizer

THSA Trimmable Horizontal Stabilizer Actuator

TLS Tertiary Lock System

TRPU Thrust Reverse Power Unit

UAV Unmanned Aerial Vehicle

VFG Variable-Frequency Generator

VSTOL VerticalShort Take-Off and Landing

WLG Wing Landing Gear

WTB Wing-Tip Brake

ZFW Zero Fuel Weight

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

1

European Commercial Aircraft before the Airbus A320

11 Introduction

European industry abounds in examples that highlight the 4 major stages of the evolution of commercial aircraft actuation

ndash the Caravelle (Sud Aviation) the first shortmedium-range jetliner that used from the end of the 1950s irreversible servocontrols without the possibility for human-powered control1 of the 3 axes of primary flight controls (roll pitch and yaw)

ndash the Concorde (Sud Aviation and British Aircraft Corporation) the only supersonic commercial jetliner which by the mid-1970s introduced electrically-signaled flight controls driven by analog electric controllers

ndash the Airbus A320 that introduced by the mid-1980s electrically-signaled flight controls with digital computers which are often called Fly-by-Wire (FbW)

ndash the Airbus A380 that by the mid-2000s introduced electrically-powered actuators and electrically-powered local hydraulic power generation used as backup

1 The Caravelle used some equipment concepts and operating experience feedback provided by the Comet (De Havilland) the first commercial jetliner put in service 7 years earlier and whose first versions had a difficult career start

Aerospace Actuators 3 European Commercial Aircraft and Tiltrotor Aircraft First Edition Jean-Charles Mareacute copy ISTE Ltd 2018 Published by ISTE Ltd and John Wiley amp Sons Inc

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

2 Aerospace Actuators 3

This chapter focuses only on the first 2 examples the Airbus A320 and A380 being dealt with in their own specific chapters

12 The Caravelle and irreversible primary flight servocontrols

At the end of the 1930s several planes were already using hydraulic actuators for end-stop to end-stop positioning functions (extensionretraction of landing gear deploymentretraction of wing flaps openingclosure of engine cowling flaps) or functions of force transmission for wheel braking (see Figure 17 in Volume 1 [MAR 16b]) For primary flight controls hydraulic actuators were also installed along with cable controls that transmitted pilot actions to mobile surfaces This allowed for the imposition of the flight control surface position setpoints by the automatic pilot when this was engaged (see Figure 18 of Volume 1 [MAR 16b]) Due to the increase in aircraft size speed and flight duration the need to reduce the level of force generated by the pilot for primary flight controls rapidly became essential The introduction of tabs deflected in the direction opposite to that intended for flight control surface deflection provided assistance to the pilotrsquos efforts without using an airborne power source being subjected to aerodynamic forces the tab produces a deflection moment that orients the flight control surface in the intended direction of movement The application of this concept has led to several variants [LAL 02 ROS 00]

ndash the servo tab (Figure 11(a)) for which the pilot acts only on the tab (if the assistance is insufficient the bell crank arrives at end-stop and then the pilot acts directly on the flight control surface)

ndash the auto tab (Figure 11(b)) for which the pilot acts only on the flight control surface (tab deflection results from the flight control surface movement relative to the fixed surface)

ndash the spring tab (Figure 11(c)) for which the tab generates assistance only beyond a certain value of the maneuvering force which allows for the improvement of control accuracy at small deflections

ndash the servo tab with compensation panel (Figure 11(d)) which increases the servo tab aid rate due to the moment produced by a panel subjected to the difference in pressure between the lower surface and the upper surface of the wing profile

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram

European Commercial Aircraft before the Airbus A320 3

Figure 11 Aerodynamic assistance concepts For a color version of this figure see wwwistecoukmareaerospace3zip

This form of assistance still used today on low-capacity and low-cruising-speed aircraft has the advantage of simplicity as the assistance is generated by aerodynamic forces On the contrary its field of application and interest are limited by several drawbacks The assistance rate strongly depends on the speed relative to the air flight control surface deflection and aircraft behavior Consequently it is ill-suited to large aircraft and high speed Its setup which necessarily involves kinematic modifications after flight tests is lengthy and tedious

A further solution involves the insertion of a hydraulic actuator in series with the mobile surfaces mechanical actuation chain The irreversible Jacottey-Leduc servocontrol presented in Figure 110 of Volume 1 [MAR 16b] was for example fitted in line with a control linkage on the Armagnac commercial aircraft (SNCASE SE-2010) that made its first flight in 1949 and was commissioned in 1952 The level of forces to be generated was such that it allowed for manually resuming its control in case of failure of servocontrol whose output ram was then functionally connected with the input ram