4 thrust revers

Created by Rafik Chabou ENGINE CF6-80E1 General Familiarization

１０２

44 --Thrust Reverser System

Thrust Reverser System

Objectives

Given an objective exercise, you will be able to:

Identify the location of the components of the thrust reversersystem

Identify the components of the thrust reverser system Identify the purpose of the components of the thrust reverser

system Identify the purpose of the thrust reverser system Identify the operation of the thrust reverser system

Overview

The thrust reverser system consists of the following components:

Thrust reverser Thrust reverser cowl opening actuator Translating cowls Blocker doors Cascade vanes Thrust reverser pressurizing valve Directional pilot valve and pressure switch Center drive unit (CDU) Thrust reverser position switches Thrust reverser (RVDT) sensor Flexible drive shafts Angle gearbox and ballscrew actuators Thrust reverser electro-mechanical brake Thrust reverser junction box

In this lesson, you will learn about the location, identification, and purposeof the components, and the operation of the thrust reverser system.


１０３

Location Left Side ViewThe components of the thrust reverser are identified below.

The thrust reverser assembly is installed aft of the aft fan case.The top of the assembly is hinged to the pylon.

The engine has two thrust reverser cowl opening actuators, one foreach reverser half. Each actuator is installed between the pylon andthe thrust reverser cowl door.

There are two translating cowls. Each cowl is installed on the outersurface of the thrust reverser assembly.

The blocker doors are installed on the inner surface of thetranslating cowl.


１０４

The cascade vanes are installed on the fixed structure of the thrustreverser. When the thrust reverser is in the stowed position, thetranslating cowls hide the cascade vanes.

The directional pilot valve (DPV) and pressure switch (PS) areinstalled at the 10 o'clock position on the thrust reverser supportstructure on the thrust reverser half.

The thrust reverser position switches are on the CDU on eachthrust reverser half.


１０５

The center drive unit (CDU) is installed on the forward bulkheadstructure of the thrust reverser at the horizontal centerline. Thereare two CDUs per engine: one at the 3 o'clock position, and theother at the 9 o'clock position.

The thrust reverser rotary variable differential transducer (RVDT)is installed on a drive pad on top of the CDU.

The flexible drive shafts or flexshafts are splined to the CDUfeedback unit at one end, and to the ballscrew actuators at theother end.


１０６

The angle gearbox and ballscrew actuators are attached to thetorque box. The torque box is, in turn, attached to the forward faceof the thrust reverser bulkhead.

The thrust reverser electro-mechanical brake is installed on thethrust reverser support structure just above the upper anglegearbox and ballscrew actuator on each thrust reverser half.

The thrust reverser junction box is on the aft fan case at the 10o'clock position.


１０７

Location Right Side ViewThe components of the thrust reverser systemare listed below.

The thrust reverser pressurizingvalve (TRPV) is installed on the HPCcase at the 2 o'clock position.

Purpose

The thrust reverser system deflects and redirects the fan dischargeairflow, and helps to slow down the aircraft on landing. This reduces thedistance that an aircraft needs to stop safely and efficiently.

Operation

To deploy the thrust reverser, the thrust lever is moved up. The electrical

current from the ECU energizes the TRPV and the TRDV relays.

Pressurized air from the TRPV flows through the directional pilot valve

(DPV) and enters the CDUs.


１０８

The DPV sets the directional valves in the CDUs to the deploy position.

The translating cowls start to move towards the deploy position. The

thrust reverser position switches on each CDU send signals to the ECU

that the two translating cowls are no longer in the stowed position.

At the end of travel of translating cowls, the thrust reverser position

switches transmit an indication to the ECU that the thrust reverser is

fully deployed. The ECU terminates the electrical current to the TRPV,

which in turn stops the air supply to the CDUs. The movement of the

translating cowls positions the blocker doors into the fan discharge

airflow path, and redirects the air in the forward direction, over the

cascade vanes.

To stow the thrust reverser, the thrust lever is moved down. An electrical

signal is sent to the ECU. The ECU energizes the TRPV and shuts down the

power to the DPV. Pressurized air from the TRPV goes to the CDUs.

However, the air does not enter the DPVs. This causes the spring-loaded

DPVs to move into the stowed position. With the TRPV in the open position,

the translating cowls move towards the stowed position.

The thrust reverser position switches send signals to the ECU that the

translating cowls are moving towards the stowed position. The end-of-

travel position of the cowls is sent to the ECU when the thrust reverser is

in fully stowed condition. The blocker doors are now positioned away from

the fan discharge airflow, and sit flush with the inside surface of the

translating cowl.


１０９

Thrust Reverser

Location: The thrust reverser assembly is installed aft of the aft fancase. The top of the assembly is hinged to the pylon.

Identification: The thrust reverser

assembly consists of two hinged

halves that are latched together at

the bottom split line.

Purpose: The thrust reverser

assembly reduces the speed of the

aircraft on landing, and decreases the

distance that the aircraft has to travel before safely coming to a stop.

Thrust Reverser Cowl Opening Actuator

Location: Each thrust reverser cowl opening actuator is installed betweenthe pylon and the thrust reverser cowl door.

Identification: The engine has twothrust reverser cowl opening actuators,one for each reverser half. Eachactuator consists of the followingcomponents:

Hydraulic actuator Inlet fitting Pylon mount Cowl-opening actuator support


１１０

Purpose: The thrust reverser cowl opening actuators help to open the

thrust reverser halves and provide access to the engine system and

components in the engine cold section.

Translating Cowls

Location: There are two translating cowls. Each cowl is installed on theouter surface of the thrust reverser assembly.

Identification: The translating cowl, also called

the transcowl, is a composite structure with a

honeycomb core. Each translating cowl has three

panels for access to the CDU and to the

installation pins on the ballscrew actuators. The

axial movement of the translating cowl is guided

by a Teflon-coated, T-track arrangement.

Purpose:

Provides a smooth, aerodynamic outer surface when in the stowedposition

Provides space for the cascade vanes and the actuation systemcomponents

Blocker Doors

Location: The blocker doors are installed on the inner surface of thetranslating cowl.


１１１

Identification: There are six blocker

doors for every thrust reverser half.

Each blocker door is hinged on its

forward edge to the translating cowl and

to the blocker door link arm near the aft

edge. The blocker doors are made of

acoustic material.

Purpose: The blocker doors deflect the

fan duct airflow over the cascade vanes.

Cascade Vanes

Location: The cascade vanes are installed on the fixed structure of the

thrust reverser. When the thrust reverser is in the stowed position, the

translating cowls hide the cascade vanes.

Identification: There are

16 cascade vanes in each

thrust reverser half. Each

cascade vane is bolted to

the thrust reverser

structure and to the

adjoining vane. There are

four different configurations of cascade vanes:


１１２

Straight 45° left-hand deflection 45° right-hand deflection Blocked

The straight cascade vanes are made of composite materials. The othercascade vanes are made of aluminum.

Purpose: The cascade vanes allow the reversed airflow to escape into the

atmosphere without interfering with the aircraft control surfaces. The

vanes also prevent ingestion of debris into the engine.

Thrust Reverser Pressurizing Valve

Location: The thrust reverser pressurizing valve (TRPV) is installed on theHPC case at the 2 o'clock position.

Identification: The TRPV

consists of a valve, a

pressure regulator actuator,

an electrical solenoid, three

air inlets, and a discharge

port. The three air inlets

bring bleed air from the

following HPC stages: 14th

stage, regulated 8th/14th

stage, and the ECS. The discharge port provides air at a constant

pressure to the CDUs.

Purpose: The TRPV provides regulated airflow to the thrust reverser

system.


１１３

Directional Pilot Valve and Pressure Switch

Location: The directional pilot valve (DPV) and pressure switch (PS) are

installed at the 10 o'clock position on

the thrust reverser support structure

on the left-hand thrust reverser half.

Identification: The DPV is a solenoid-

operated valve. The PS is an electrical

switch. Both the components have

individual electrical connectors.

Purpose: The PS is used to monitor the

air pressure in the thrust reverser system, and to provide feedback to

the ECU. The DPV provides an air signal to the CDU, thus releasing the

CDU brake and repositioning the directional valve.

Center Drive Unit

Location: The center drive unit (CDU) is

installed on the forward bulkhead structure

of the thrust reverser at the horizontal

centerline. There are two CDUs per engine:

one at the 3 o'clock position, and the other

at the 9 o'clock position.

Identification: There is a separate CDU for

each thrust reverser half. Each CDU consists


１１４

of the following components:

Air motor Angle gearbox Directional valve Brake assembly Integral ballscrew actuator Feedback unit Rig indicator

Purpose: The CDU provides rotational torque force to move the

translating cowl to deploy or stow positions, thus causing the blocker

doors to extend or retract.

Thrust Reverser Position Switches

Location: The thrust reverser position switches are on the CDU on eachthrust reverser half.

Identification: The thrust reverser position

switches can be replaced as a unit from the CDU and

do not require any rigging cables.

Purpose: The thrust reverser position switches

provide end-of-travel information about the

translating cowl to the ECU.

Thrust Reverser RVDT Sensor

Location: The thrust reverser rotary variable differential transducer

(RVDT) is installed on a drive pad on top of the CDU.


１１５

Identification: The RVDT is

an electronic position

feedback sensor and contains

a reduction gearbox assembly

that is attached to dual

variable transducers. The

sensor is rigged to the CDU.

Purpose: The RVDT sensor

continuously provides the ECU

with information about the position of the translating cowl.

Flexible Drive Shafts

Location: The flexible drive shafts or flexshafts are splined to the CDU

feedback unit at one end, and to the ballscrew actuators at

the other end.

Identification: There are two flexible drive shafts for each

thrust reverser half. The shafts rotate inside a protective

sheath when driven by the CDU.

Purpose: The flexible drive shafts are used to transmit

mechanical force from the CDU to the upper and lower angle

gearbox and ballscrew actuators.


１１６

Angle Gearbox and Ballscrew Actuators

Location: The angle gearbox and ballscrew actuators

are attached to the torque box. The torque box is, in

turn, attached to the forward face of the thrust

reverser bulkhead.

Identification: There are two angle gearbox and

ballscrew actuators for every thrust reverser half.

The angle gearbox and ballscrew actuators are

subassemblies that are attached together.

Purpose: The angle gearbox and ballscrew actuatorsassist the CDU in driving the translating cowl duringthe thrust reverser operation.

Thrust Reverser Electro-mechanical Brake

Location: The thrust reverser electro-mechanical brake is installed on

the thrust reverser support structure just

above the upper angle gearbox and ballscrew

actuator on each thrust reverser half.

Identification: The thrust reverser brake is

an electro-mechanical, solenoid-actuated,

disk-type brake assembly.

Purpose: The thrust reverser electro-

mechanical brake is used to lock the thrust

reverser in the stowed position.


１１７

Thrust Reverser Junction Box

Location: The thrust reverser junction box is on the aft fan case at the10 o'clock position.

Identification: The thrust reverser junction box is a prefabricated unit

containing electrical connections that connect

it to channels "A" and "B" of the ECU.

Purpose: The thrust reverser junction box

transmits control and feedback signals

between the ECU and the thrust reverser

components.

4 thrust revers

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