CR-137585

STRAPDOWN COST TREND STUDY AND FORECAST

By A. J. Eberlein and P. G. Savage

( N A S A-Ck-137585) S T K A P D O t f N COST T H 2 N D S T U D * N 7 5 - 1 7 . 3 2 8A N D F O R E C A S T ( H o n e y w e l l , I n c . )

Unclas^ . . . GJ/.;U 11935

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AMES RESEARCH CENTERNATIONAL AERONAUTICS AND SPACE ADMINISTRATION

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STRAPDOWN COST TREND STUDY AND FORECAST

By A. J. Eberlein and P. G. Savage

Distribution of this report is provided in the interest ofinformation exchange. Responsibility for the contentsresides in the author or organization that prepared it.

Prepared under Contract No. NAS2-8065 by

HONEYWELL INC.Government and Aeronautical Products Division

Minneapolis, Minnesota 55413

For

AMES RESEARCH CENTERNATIONAL AERONAUTICS AND SPACE ADMINISTRATION

CONTENTS

SUMMARY 1INTRODUCTION 3. I SKEWED REDUNDANT STRAPDOWN INERTIAL SYSTEM -

GENERAL CONFIGURATION • 5Strapdown Versus Gimbaled Inertial Navigation Systems ... 5Hexad Skewed Redundant System, Configuration 7Pentad Versus Hexad Configuration 14

Pentad System Description 14Hexad Versus Pentad Configuration 17

Two-Axis Inertial Sensor Assembly (ISA) 19II SYSTEM CONFIGURATIONS INVESTIGATED 24

Kinematic Systems 24Kinematic System K-l 24Kinematic System K-2 24Kinematic System K-3 31

Flight Control Systems 32Flight Control System FC-1 35Flight Control System FC-2 39Flight Control System FC-3 39Flight Control System FC-4 41

Inertial Navigation Systems 43Inertial Navigation System INAV-1 43Inertial Navigation System INAV-2 46Inertial Navigation System INAV-3 46Inertial Navigation System INAV-4 46Inertial Navigation System INAV-5 49

III SYSTEM COST ANALYSES 50Cost of Ownership Formula 50Kinematic Systems Cost Analysis 56

Kinematic System K-l Cost 56Kinematic System K-2 Cost 58Kinematic System K-3 Cost 63

Flight Control Systems Cost Analysis 63Flight Control System FC-1 Cost 63Flight Control System FC-2 Cost 63Flight Control System FC-3 Cost 68Flight Control System FC-4 Cost 68

Inertial Navigation Systems Cost Analysis 70Inertial Navigation System INAV-1 Cost 70Inertial Navigation System INAV-2 Cost 71Inertial Navigation System INAV-3 Cost 71Inertial Navigation System INAV-4 Cost 71Inertial Navigation System INAV-5 Cost 76

Inertial Navigation System Cost Projections 76

111Preceding page blank

IV CONCLUSIONS AND RECOMMENDATIONS 80Summary 80

' Recommendations 89APPENDIX A - HEXAD SKEWED GYRO VOTING AND TRANSFOR-

MATION EQUATIONS 91APPENDIX B - COMPUTER SYNCHRONIZATION 99APPENDIX C - GENERAL SUBSYSTEM REQUIREMENTS FOR

SHORT-HAUL AIRCRAFT 102APPENDIX D - LASER GYRO VERSUS FLOATED GYRO FOR

STRAPDOWN INERTIAL SYSTEMS 107APPENDIX E - COST-OF-OWNERSHIP COMPUTER RUNS 119

IV

ILLUSTRATIONS

Figure Page

1 Honeywell GG1300 Laser Gyro 8

2 General Skewed Redundant Hexad Strapdown SystemConfiguration 10

3 Hexad Mounting Arrangement 11

4 Strapdown Skewed Inertial Computation 13

5 General Skewed Redundant Pentad StrapdownSystem Configuration 15

6 Pentad System Power and Data Strobe Interface 16

7 Pentad Mounting Arrangement 18

8 Two-Axis ISA Functional Block Diagram 20

9 Laser Two-Axis ISA 23

10 Traditional Kinematic System 25

11 K-2 Strapdown Kinematic System 26

12 K-2 System 1C Computer 28

13 K-3 Integrated ISA/Computer Skewed MountingRequirements 33

14 Traditional Commercial Aircraft Flight Control System . . 34

15 Skewed Redundant Commercial Aircraft FlightControl System 36

16 FC-1 System FC Computer 37

17 FC-2 System FC Computer 40

18 FC-4 System 1C/FC Computer 42

19 Typical IC/FC Computer Packaging 44

20 INAV-1 Traditional ARINC 561 Redundant InertialNavigation System 45

21 INAV-2 Strapdown Redundant ARINC 561 InertialNavigation System 47

Figure Page

22 INAV-2 System 1C Computer 48

23 Sample Cost-of-Ownership Computer Run 55

24 Strapdown System Cost-of-Ownership VersusLaser Gyro Reliability 60

25 Laser Strapdown Versus Gimbaled RedundantINS Cost Trends 78

26 Kinematic System Cost Comparisons 81

27 Flight Control System Cost Comparisons 82

28 Inertial Navigation System Cost Comparisons 83

29 Strapdown System Cost-of-Ownership VersusLaser Gyro Reliability 86

30 Laser Strapdown Versus Gimbaled RedundantINS Cost Trends 88

VI

TABLES

Table Page

1 HDO301 Characteristics Summary 29

2 K-l Kinematic System Cost Summary 57

3 System K-2 Line Replaceable Unit (LRU) Cost in Dollars ... 57

4 System K-l Average LRU Parts Cost Per Failure 58

5 K-2 Kinematic System Cost Summary 59

6 Part and Cost Detail for Kinematic System K-2Two Axis ISA 61

7 Part and Cost Detail for Kinematic System K-21C Computer 62

8 K-3 Kinematic System Cost Summary 63

9 Part and Cost Description for Kinematic System K-3Integrated Two-Axis ISA/1C Computer 64

10 FC-1 Flight Control System Cost Summary 65

11 Part and Cost Description for Flight Control SystemFC-1 FC Computer 66

12 FC-2 Flight Control System Cost Summary 67

13 Part and Cost Description for FC-2 System FC Computer . . 67

14 FC-3 Flight Control System Cost Summary 68

15 FC-4 Flight Control System Cost Summary 68

16 Part and Cost Description for Flight Control SystemFC-4 IC/FC Computer 69

17 INAV-1 Inertial Navigation System Cost Summary 70

18 INAV-2 Inertial Navigation System Cost Summary 71

19 Part and Cost Description for Inertial Navigation SystemINAV-2 1C Computer 72

20 INAV-3 Inertial Navigation System Cost Summary 73

vn

Table Page

21 Part and Cost Description for Inertial Navigation SystemINAV-3 Integrated Two-Axis ISA/IC Computer 73

22 INAV-4 Inertial Navigation System Cost Summary. . . . . . . 74

23 Part and Cost Description for Inertial Navigation SystemINAV-4 1C Computer 75

24 INAV-5 Inertial Navigation System Cost Summary 76

25 Part and Cost Description for Inertial Navigation SystemINAV-5 Integrated Two-Axis ISA/IC Computer 77

Vlll

STRAPDOWN COST TREND STUDY AND FORECAST

By A. J. Eberlein and P. G. Savage

SUMMARY

This report summarizes the results of a study performed to ascertain

the potential cost advantages offered by advanced strapdown inertial tech-

nology in future commercial short-haul aircraft. Kinematic systems

(attitude, rate, acceleration sensing) and inertial navigation systems were

investigated in the study. Each type of system was mechanized in the

traditional sense (using conventional sensors), and alternatively, using

advanced strapdown technology (laser gyros and strapdown reference

computers). The initial procurement cost and six year cost-of-ownership,

which includes spares and direct maintenance cost were calculated for each

system investigated such that traditional and strapdown mechanization costs

could be compared.

Each system was mechanized assuming a fail-operational requirement.

For the traditional systems, triple redundant sensors and electronics were

assumed; for the strapdown systems, triple redundant electronics were

assumed with skewed redundant strapdown sensors. In the case of the

kinematic systems, the traditional system sensors were assumed to be

standard flight control grade attitude/rate gyros and accelerometers; the

strapdown sensors and attitude computers were sized for inertial navigation

accuracy.

Cost results for the inertial navigation systems showed that initial

costs and the cost of ownership for traditional triple redundant gimbaled

inertial navigators are three times the cost of the equivalent skewed

redundant strapdown inertial navigator. For the kinematic systems, the

initial procurement cost of the strapdown system is fifty percent higher than

for the traditional system equivalent. However, on an overall cost-of-

ownership basis, the strapdown system cost is twenty percent lower. The

net cost advantage for the strapdown kinematic system is directly attributable

to the fifty percent reduction in sensor count for strapdown compared to

traditional kinematic systems with an associated reduction in sensor failures

and repairs. In addition to the overall cost savings, the strapdown kinematic

system has the added advantage of providing a fail-operational inertial navi-

gation capability for no additional cost due to the use of inertial grade sensors

and attitude reference computers.

INTRODUCTION

This report documents the results of a study performed for NASA Ames

Research Laboratory by Honeywell Incorporated investigating cost compar-

isons and trends between traditional and advanced flight control and navigation

systems in future commercial short-haul aircraft. Prior to this study, a

comprehensive cost-of-ownership study did not exist that compared strapdown

flight control and navigation systems with traditional flight control and navi-

gation systems nor did a comprehensive cost-of-ownership study exist for

comparing strapdown inertial navigation systems with gimbaled inertial navi-

gation systems.

This study was initiated by NASA AMES Research Laboratory to deter-

mine the cost viability of strapdown systems in terms of current producible

hardware and technology. The traditional systems were configured utilizing

conventional sensors (momentum wheel rate gyros, vertical gyros, heading

gyros, and gimbaled platforms); the advanced strapdown systems were con-

figured utilizing strapdown laser gyros for the basic sensing element. Redun-

dancy requirements for the traditional system sensors were implemented

using traditional block level duplication for each aircraft axis independently.

Redundancy requirements for the advanced strapdown systems were imple-

mented using skewed sensor arrays. The computer configurations for the

traditional and advanced strapdown systems were assumed comparable, based

on identical state-of-the-art circuit technology.

Three systems configuration classes were considered in performing the

cost analyses: kinematic systems that provide rate, acceleration, and attitude

signal outputs, flight control systems that contain the kinematic system as an

element and a flight control computer system to operate on the kinematic

signals, and inertial navigation systems. In each case, the systems were

configured to satisfy the fail-operational requirements of commercial short-

haul aircraft.

Section I of the report gives a general description of the skewed redun-

dant strapdown inertial systems and describes more specifically the hexad

(six-axis) skewed sensor assembly and the computer configuration that formed

the basis for the strapdown system mechanizations investigated in the study.

Section II provides a detailed technical description of each of the particular

advanced strapdown system configurations investigated in the study.

Section III described the method used to compute system cost-of-owner-

ship estimates and presents initial procurement cost breakdowns for each

system, resulting cost-of-ownership estimates, and cost comparisons with

the equivalent traditionally mechanized systems. Also included is a projection

of future costs for the advanced and traditional systems showing the impact of

learning and inflation on future system costs. The appendixes contain detailed

information supporting the individual sections of the report including a com-

parison of strapdown systems utilizing laser gyros and conventional floated

rate integrating gyros.

The concluding section of the report summarizes the configurations

investigated and the cost comparisons obtained for the traditional and advanced

strapdown system configurations. A set of recommendations is outlined

to extend the investigations leading to an advanced laser strapdown system

that best satisfies commercial short-haul aircraft dispatch, redundancy,

and cost-of-ownership constraints.

The equipment cost data presented in this document represents engineer-

ing estimates based on past experience for similar components. The cost

figures were prepared for engineering tradeoff comparison purposes only.

SECTION I

SKEWED REDUNDANT STRAPDOWN INERTIAL SYSTEM -

GENERAL CONFIGURATION

Strapdown Versus Gimbaled Inertial Navigation Systems

Inertial navigation systems represent a class of aircraft avionics

equipment that compute position, velocity, and attitude using self-contained

gyros and accelerometers as the primary sensing elements. In general, the

gyros are used to determine the orientation of the accelerometers relative to

earth. Accelerometer outputs are thereby interpreted relative to the earth

referenced coordinates. Integration of the earth referenced acceleration

data in a digital computer provides continuous measurements of aircraft

velocity and position. Attitude data is provided as a by-product of the gyro

reference.

Mechanization of the inertial navigation system is one of the most

exacting electro-mechanical technologies in the aerospace industry. Gyro

reference requirements, in particular, are most demanding. The gyro

reference typically has to be accurate to 0. 01-0. 03 degrees per hour in the

presence of aircraft rates that can be as high as several hundred degrees

per second. This level of performance corresponds to a navigation accuracy

of 1-3 nautical miles per hour, a typical user requirement. In general, two

types of mechanization approaches are possible with inertial navigation

systems: gimbaled and strapdown.

In the gimbaled approach, an orthogonal triad of gyro and accelerom-

eter inertial instruments are mounted on the inner element of a gimbaled

platform. The gimbal assembly contains torque motors about each gimbal

shaft. The gyro outputs are used to command the gimbal torquers, thereby

maintaining the inner element in a space-stable attitude. Commanded

angular rates are applied to the stable inner element (platform) by electri-

cally torquing the gyros. The gyro torquing rates are determined in a

digital computer such that the platform will always be aligned to earth

referenced coordinates (for example, north/east/vertical) as the aircraft

cruises over the earth. The platform torquing rates represent the angular

rate of the aircraft over the surface of the earth and include the effects of

earth rate rotation and vehicle velocity relative to the earth. The torquing

rates are determined in the system computer from vehicle velocity and

position data which is computed by integrating the outputs of the platform

accelerometers. Resolvers on the gimbal shafts provide aircraft attitude

information as a secondary output.

In the strapdown approach, the inertial sensor triad (gyros and

accelerometers) are mounted directly to the airframe. Both the gyro and

accelerometer outputs are input directly to the system computer. The

computer processes the gyro data to continuously determine aircraft attitude

relative to earth referenced coordinates. The attitude data is used with the

aircraft mounted accelerometer signals to compute the equivalent acceler-

ation data in the earth referenced coordinate frame. Thus, the computer

analytically simulates the function of the gimbal assembly in the gimbaled

approach. The remainder of the computation to determine aircraft velocity,

position, and reference torquing commands is identical to the gimbaled

approach. The emergence of the strapdown system as a more practical and

cost-effective system is due to the development of digital computers that are

relatively inexpensive and that have the computational speeds necessary to

perform the strapdown navigation computations rapidly.

The strapdown digital mechanization approach inherently avoids the

problems encountered with gimbaled systems. By eliminating the complex

mechanical gimbal assembly and associated motors, bearings, slip rings,

resolvers, and electronics, strapdown systems offer lower procurement

cost, improved reliability, and reduced maintenance costs. Also, signifi-

cant improvements in reaction time, sensor reliability, and system cost are

achievable because of the recent advent of strapdown laser gyro technology.

The strapdown concept is compatible with recent trends toward large scale

integration of digital avionics functions: the strapdown data format is

. inherently digital, and the total aircraft inertial state vector is available

as a natural output for flight control usage (position, velocity, attitude, rate,

and acceleration). Finally, low cost redundancy is achievable with a strap-

down mechanization through use of skew aligned gyros and accelerometers.

Skewed sensor redundancy is a technique that enables a single inertial

sensor (gyro or accelerometer) to replace any failed sensor regardless of

its input axis orientation. The concept is to mount the sensors such that

their input axes are nonorthogonal (skewed) relative to one another, with

any set of three input axes nonplanar. With this arrangement, any set of

three sensor outputs can be used to derive (in the system computer) the

equivalent output of an orthogonal sensor triad. Thus, four skewed sensors

would be capable of generating complete three-axis orthogonal output data

with up to one sensor failure, and five skewed sensors would be capable of

tolerating two failures. In a conventional redundancy approach, two sets of

orthogonal triads (i. e. , six sensors) would.have the same fail/operational

capability a-s four skewed sensors, and three orthogonal sets (nine sensors)

would be equivalent to five skewed sensors. The hardware savings is sub-

stantial with the skewed approach as the redundancy requirement increases.

Hexad Skewed Redundant System Configuration

The strapdown skewed redundant system configurations investigated in

this study combine six skewed redundant strapdown angular rate sensors

and hexad accelerometers with a set of triple redundant computers pro-

grammed to perform the skewed redundant inertial navigation and attitude

reference function, and for some configurations, to perform aircraft flight

control computations. The hexad angular rate sensor used as a model for

the study was the Honeywell GG1300 Laser Gyro (Figure 1). This advanced

technology inertial component has demonstrated its suitability for precision

inertial applications. The advantages projected for the laser gyro are fast

reaction time, performance insensitivity to acceleration, vibration, and

thermal environments, long term stability," high reliability, and low cost.

' 7

Figure I . - Honeywell GG1300 Lase r Gyro

Figure 2 is a block diagram showing the general configuration of the

hexad/computer system. The internal and external signal, power, and

synchronization interface between the system elements is identified. The

hexad array is formed from three identical ISA's (inertial sensor assemblies),

each containing two gyro/accelerometer pairs. The two angular rate and

acceleration signals from each ISA are transmitted to each computer. Power

supplies are contained in each computer to convert aircraft input power to

regulated voltages for the computer electronics and to power one of the ISA's.

Other computer inputs generally include d-c signals, a-c signals, and

discretes from other aircraft systems for the flight control computations,

and mode control and latitude/longitude initialization data for the inertial

computations from the aircraft control panel. Outputs from each computer,

in general, are a~c, d~c, digital, and discrete outputs to the other aircraft

systems and displays in addition to intercommunications (clock and data

crossfeed) between the redundant computer channels for redundancy manage-

ment.

The orientation of the input axes of one of the gyro/accelerometer

pairs in each inertial sensor assembly box (two-axis ISA), as shown in

Figure 2 is parallel to the long axis of the ISA (normal to the front face).

The second gyro/accelerometer set is mounted with input axes perpendicular

to the first set but skewed 54. 7 degrees (nonorthogonal) relative to the ISA

base. The three two-axis ISA's are mounted to a common base, which is

part of the aircraft rack structure, in precision alignment such that the

long axis of the boxes are skewed relative to one another. This mounting

arrangement is shown in Figure 3.

With the ISA's oriented this way, the gyro/accelerometer sets become

aligned relative to one another such that the input axes of the four sensors

(tetrad) formed from any two of the three sets of two ISA's are non-coplanar

(i. e., they do not lie in a single plane). Under these conditions, software

routines in the computer can operate on any one of the tetrad signal sets to

analytically compute the equivalent roll, pitch, and yaw axis rate/acceler-

ation data for computer operations. In addition, three of the four tetrad

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gyro/accelerometer signals can be combined to analytically derive what the

fourth sensor set is measuring. If the derived signals are unequal to the

fourth set output (within prescribed tolerances), a failure has occurred in

one of the tetrad sensors.

This logic provides the capability for assessing the functional integrity

of each of the three tetrads. A single failure in the hexad (i. e. , in one of

the two-axis ISA's) will cause two tetrads to exhibit failures. The third

tetrad will not exhibit failure, thereby isolating the failed ISA box to the unit

not included in the functioning tetrad. Under these conditions, the identified

functioning tetrad would be used to derive the roll/pitch/yaw axis data in the

computer, thus allowing proper system operation with one failure (single-

fail operational). Multiple failure occurrences can also be identified by this

approach, but without a corresponding failure isolation. Under these con-

ditions, the computer can be shut down safely (fail-safe) and the pilot will be

notified of the shut down by the appropriate failure panel status lamp. Thus,

the hexad geometry provides a single fail-operational/fail-safe capability.

Figure 4 illustrates the inertial computations in the system computers

showing the hexad redundancy management and inertial calculations data

flow. The ICS first compensates the input data from the three two-axis

skewed gyro/accelerometer sets for known systematic errors in each instru-

ment such as bias, scale factor, and misalignment. The compensated

skewed gyro/accelerometer signals are then compared in the skewed voting

algorithms for failure detection, isolation, and computation of equivalent

three-axis orthogonal axis data (roll, pitch, yaw axis rate and acceleration)

from a selected functional tetrad. In Appendix A the derivation of a repre-

sentative set of skewed redundancy gyro voting equations and skew-to-

orthogonal transformation equations that would be programmed into the

system computer is given. Skewed accelerometer equations would be

similar to those for the gyros in Appendix A./

The roll/pitch/yaw angular rate derived from the skewed gyro voting

logic is then used in,a three-axis attitude integration algorithm to compute

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the attitude of the aircraft (more specifically, the accelerometer assembly)

relative to local vertical/azimuth coordinates. The angular rate of the air-

craft over the surface of the earth (due to earth's rotation and aircraft

velocity) is included in this computation to account for the rotation rate of

the local vertical.

The aircraft attitude data is used to resolve the roll/pitch/yaw aircraft

axis acceleration vector data from the skewed accelerometer voting logic

into the local vertical/azimuth coordinate frame. The computed horizontal/

vertical acceleration components are then integrated in an inertial velocity/

position computation algorithm to calculate aircraft horizontal velocity and

latitude/longitude position. Barometric altitude is used in the inertial com-

putation to stabilize the vertical channel.

Pentad Versus Hexad Configuration

The skewed sensor configuration chosen for the study uses a hexad

(six-axis) sensor array to achieve fail-operational performance in general,

and limited fail-operational performance. Theoretically, a pentad (five-

axis) array could meet the fail-operational requirement with one less sensor

and, therefore, less cost, but, as explained later in the report, this is not

the case.

Pentad system description. - Figures 5 and 6 are block diagrams of a

skewed redundant pentad inertial system showing the internal and external

signal, power, and synchronization interface between the system assemblies.

Each of the five ISA's in Figure 5 contains one skewed gyro/accelerometer

pair. The angular rate and acceleration signals from each ISA are trans-

mitted to each of the three redundant computers. Power supplies are con-

tained in each computer to convert aircraft input power to regulated voltages

for the computer electronics and to power three of the ISA's. Figure 6

defines the power interface.

14

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The orientation of the input axes of the gyro/accelerometer pair in

each inertial sensor assembly box (single-axis ISA) in Figure 5 is parallel

to the front face of the ISA but skewed 54. 7 degrees relative to the ISA base.

The five single-axis ISA's are mounted to a common base in precision align-

ment such that the long axis of the boxes are skewed relative to one another.

Figure 7 illustrates the mounting orientation of the five ISAs.

With the ISA's oriented this way, the gyro/accelerometer sets become

aligned to one another such that the input axes of the four sensors formed

from any of the four sets of five ISAs are non-coplanar. Under these con-

ditions, software routines in the computer can operate on any one of the

tetrad signal sets to analytically compute the equivalent roll, pitch, and yaw

axis rate/acceleration data for computer operations. In addition, three of

the four tetrad gyro/accelerometer signals can be combined to analytically

derive what the fourth sensor set is measuring. If the derived signals are

unequal to the fourth sensor set output (within prescribed tolerances), a

failure has occurred in one of the tetrad sensors.

With this logic the functional integrity of each of the five tetrads can

be assessed. A single failure in the pentad will cause four tetrads to exhibit

failures. The fifth tetrad will not exhibit failure, thereby isolating the failed

ISA box to the unit not included in the functioning tetrad. Under these con-

ditions, the identified functioning tetrad would be used to derive the roll/

pitch/yaw axis data in the computer, thereby allowing proper system oper-

ation with one failure. Multiple failure occurrences can also be identified

by this approach, but without a corresponding failure isolation. Under these

conditions, the computer can be shut down safely and the pilot will be notified

of the failure by the appropriate failure status panel lamp. Thus, the pentad

geometry provides single fail-operational/fail-safe capability.

Hexad versus pentad configuration. - The six-axis array was chosen

for the study because the sensors can be divided into three two-axis packages

with the hexad asropposed to five single-axis packages for the pentad.

Decreased chassis costs result. Three ISA assemblies in the hexad provides

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a simple, single interface between any one ISA and one computer for power

and data strobe (Figure 2). For the five ISA boxes in the pentad, the equiva-

lent interface in each ISA requires redundancy voting on power and data

strobe signals from the three computers (Figure 6). The skewed redundancy

logic software for the hexad requires voting between three tetrads; the pentad

software requires voting between five tetrads. These combined effects tend

to nullify the cost penalty for one additional sensor set for the hexad as com-

pared to the pentad.

The hexad has three technical advantages over the pentad. First, for

the hexad, each ISA has one of its sensor axes in the horizontal plane normal

to the front face; therefore, each of the three tetrads have two accelerometers

nonaligned in the horizontal plane. The horizontal plane acceleration data

for each tetrad (the most critical for the inertial computations), therefore,

tends to be insensitive to accelerometer scale factor error (low level g's are

input on the average in the horizontal plane). Performance is thereby

improved for the hexad because not.all of its axes are out of the horizontal

plane and are not continuously exposed to nearly 1 g. The second advan-

tage is the added redundancy provided by the hexad, which allows system

operation with multiple failures in any one ISA. The third advantage is in

the physical installation of the ISA boxes. As can be seen in Figure 3, the

three interchangeable two-axis ISA boxes for the hexad can be easily installed

or removed from one side of a side-wall mount. For the pentad (Figure 7),

such an arrangement is not possible if the five single-axis ISA's are to be

identical (interchangeable). The mounting arrangement for the pentad ISA's

would require installation from all sides (or from the top) of a floor mount.

Such an installation is very inconvenient.

Two-Axis Inertial Sensor Assembly (ISA)

Figure 8 is a functional block diagram of one of the three identical

two-axis ISA's used in the hexad sensor array showing the data flow to the

interface with the three redundant computers. Each ISA contains two

19

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Honeywell GG1300 laser gyros, two accelerometer modules, pulse accumu-

lator electronics for each channel, and computer interface electronics. Bias

power for the ISA is provided by one of the three redundant computers (See

Figure 2).

The laser gyros and accelerometer modules identified in Figure 8 are

identical single-unit assemblies that are physically interchangeable in each

of the two ISA axis channels and between ISA's. The output from the accel-

erometer contained in the accelerometer module is an electrical current

proportional to sensed input axis linear acceleration. This signal is input

to digitizer electronics within the accelerometer module to quantize the

continuous analog electrical signal into digital incremental pulses. Each

pulse represents the accumulation of a fixed increment of integrated linear

acceleration. The output signals from the laser gyro are in a similar digital

pulse format, each representing the accumulation of a fixed increment of

integrated input axis angular rate.

Calibration data (fixed bias, scale factor error, and alignment errors)

are included in each laser gyro and accelerometer module in a Programmable

Read Only Memory (PROM) element for sensor input data compensation in

the computer (See Figure 4). The PROM calibration data is read into each

of the three redundant computers as part of normal preflight alignment pro-

cedures. Also read into each computer is calibration data from one of the

three triple redundant PROM's attached to the hexad mounting plate containing

known misalignments for the three ISA mounts. The PROM calibration con-

cept provides a complete module interchangeable capability without accompa-

nying software changes and without requiring sensors to be dedicated to

particular mounting blocks or ISA's.

The pulses from each sensor are accumulated in an up-down counter

for each channel. All counters are simultaneously strobed/cleared into

holding registers at regular intervals by one of three redundant system

computers (See Figure 2). Under computer clock control, the sensor'-*?£C;v,

address and control electronics then serially transmit the pulse counts

21

from each sensor holding register into each of the three redundant computers

simultaneously. The data transfer is repeated three times and completed

before the next data strobe pulse is provided by the computer. During the

data transfer period, sensor pulse counters accumulate data for the next

data transfer to be initiated by the next computer strobe pulse. The three

sequential transmissions are provided such that each of the three redundant

computers can read the data from each of the three ISA's sequentially.

Figure 9 is a cutaway drawing illustrating the overall packaging

arrangement for the two-axis ISA. The ISA consists of two GG1300 laser

gyros, two accelerometer modules, a sensor module mounting block, a

plug-in card assembly, and a chassis with associated wiring. The accel-

erometer module contains one accelerometer, and that portion of the digitizer

electronics (Figure 8) that is performance calibrated to the particular

accelerometer in that module. Estimated weight for the two-axis ISA is

35 pounds.

The laser gyros do not require temperature control,and perform

satisfactorily mounted to the main mounting block structure. The accel-

erometer is chosen for compatibility with the laser gyro to perform, within

required inertial navigation accuracy specifications over the anticipated

range of operating temperatures without temperature controls. Thus, the

ISA does not require heaters, and warm-up delays normally associated with

inertial systems are, thereby, eliminated. The low power (28 watts) dissi-

pation within the ISA will permit satisfactory operation in commercial air-

craft maximum temperature ambient environments (130°F) without special

cooling provisions.

The ISA counter, holding register, address and control, and nonper-

formance critical accelerometer digitizer electronics (Figure 8) are

mounted on plug-in cards. The interface wiring for the plug-in cards is

through a wire-wrap baseplate.

22

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SECTION U

SYSTEM CONFIGURATIONS INVESTIGATED

Kinematic Systems

Kinematic System K-l. - The traditional kinematic system, K-l,

investigated in the study supplies triple redundant heading, attitude (pitch

and roll), orthogonal body rates (roll, pitch, and yaw), and orthogonal body

acceleration signals to multiple flight control electronic packages and cockpit

instruments. Figure 10 is a block diagram and pictorial drawing of System

K-l. This system is considered to be generally applicable to short-haul

aircraft.

The K-l system contains triple redundant attitude gyros for pitch/roll

attitude, compass systems (flux gate, directional gyro, and compass coupler)

for heading, three-axis (roll, pitch, and yaw) rate gyros, and three-axis

(longitudinal, lateral, and lift) accelerometers. The K-l system in con-

junction with a comparison voter located in the redundant aircraft flight

control equipment, which is supplied with K-l outputs, can be considered

capable of satisfying a fail-operational/fail-safe redundancy requirement.

Kinematic System K-2. - The traditional fail-operational/fail-safe

K-l system can be replaced by a laser strapdown hexad (three two-axis

ISA's) and three inertial calculation (1C) computers. This K-2 system

supplies the same output signals (heading, attitude, body rate, and body

acceleration) as does the traditional kinematic system, but the strapdown

signals from K-2 are more accurate than those supplied by the traditional

kinematic system. Also,aircraft velocity and position information is avail-

able, if desired, for navigational outputs.~r •,

Figure 11 is a general block diagram and pictorial drawing of the K-2

strapdown kinematic system. The details of hexad strapdown systems and

their internal ISA/computer interfaces were described in Section I. The

24

3 AXISRATE PACKAGE

DIRECTIONAL GYRO ANDCOMPASS COUPLER

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Figure 10. - Traditional Kinematic System

25

TWO-AXIS ISA'S

1C COMPUTERS

-\ DIGITAL»; INTERFACE

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Figure 11. - K-2 Strapdown Kinematic System

26 ORIGINAL PAGE*OF TOOK

particular strapdown K-2 System output interface to aircraft flight control

systems is serial digital.

System K-2 computer: A functional block diagram of the System K-2 .inertial calculations (1C) computer is given in Figure 12. The processingsection of the computer was assumed to be mechanized with state-of-the-artMOS LSIC circuit technology; the Honeywell HDC-301 central processor unitand associated MOS semiconductor memory was used as a model for theprocessing section. One HDC-301 processor with 4000 words of memory(two HDC-301 memory cards) can perform the inertial computation functionfor System K-2. (Computation details were given in Section I. )

The Honeywell HDC-301 is a general purpose, medium speed, MOS

LSIC digital processor designed for aircraft application. It is composed of16 LSIC and 21 standard logic electronic piece parts mounted on a single6. 45-inch, plug-in, multilayer printed circuit board. Table 1 summarizesthe salient characteristics of the HDC-301.

The principal I/O device for the System K-2 computer is a serialdigital interface module that takes in serial data from the three two-axisISA's under computer control. The computer ISA data control functionprovides a 200-Hz data sample strobe pulse and a 125-kHz clock to oneof the three ISA's for serial data word transmission (see Figure 11). Theserial digital interface module contains the logic to receive the data setsfrom each of the three ISA's (transmitted three times in succession), decodeeach sensor word for each ISA for one of the transmission times, and enterthe word in memory. An additional function of the serial digital interface is

to provide an interface with the pilot control panel for mode selection.

A timing and synchronization module is provided for overall I/Ocontrol/synchronization and for generating a 25-Hz real time clock for

the computer. This clock is voted against similar clocks from the othertwo redundant computers to obtain a synchronized 25-Hz computation cycleclock, and 200-Hz arid 125-kHz clocks are generated for the ISA interfacesynchronized to the 25-Hz synchronous clock.

27

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TABLE 1. - HDC-301 CHARACTERISTICS SUMMARY

Organization • General purpose, stored program

• 16 bit, parallel

• Double precision arithmetic

• 47 Instructions

• One hardware index register

Circuits Custom two-phase dynamic P-MOSlarge scale integrated circuits (LSIC's)

Operational speeds • 1 -megahertz clock

• Add - 5 microseconds

• Multiply - 21 microseconds

• Divide - 65 microseconds

• Double precision add - 10 microseconds

• Two-phase clocking

Input/ output • 16-bit parallel input

• 16-bit parallel output

• Discrete inputs and outputs

• 1 system interrupt bus

• 1 power recovery interrupt

29

An output module is provided to convert the computer digital outputs

from a 16-bit parallel word to a 16-bit serial word for transmission to other

devices over a minimum number of wires. A power supply consisting of a

transformer module, power card, and regulator card converts aircraft

unregulated input power to regulated voltages which are required by the

computer electronics. The computer supply also provides regulated power

to one of the three ISA's.

BITE (Built-In-Test-Equipment) circuitry is provided in the 1C

computer to verify proper operation of computer functional elements through

measured responses to stimuli applied to the I/O and through HDC-301

processor/memory operation checks.

The computer electronics circuits are packaged on plug-in circuit

cards and/or on modules and are mounted in a standard one-half long ATR

chassis. Each of the three redundant 1C computers are identical and are

interchangeable. System differences in the ISA interface would be imple-

mented through the ISA/computer interface wiring. Each computer chassis

contains 12 circuit cards and a power supply module.

System K-2 redundancy management concept: To provide the equiva-

lent fail-operational/fail-safe redundancy capability as System K-l, System

K-2 incorporates a redundancy management approach that encompasses

three elements: power supply redundancy, ISA input data synchronization,

and computation cycle synchronization.

The power supply redundancy management scheme is straightforward

for the hexad configuration. The power supply in each computer also powers

one of the two-axis ISA's. Therefore, a single power supply failure would

affect one ISA and one computer, and the resulting degraded computer output

would be detected and isolated by comparison monitors in the aircraft flight

control equipment. The remaining two computers would still read all three

ISA's, but would flag an ISA failure, reject the data from the failed ISA, and

use the remaining two two-axis ISA's. A second power supply failure would

30

affect a second ISA and computer channel. This would be detected by the

flight control comparison monitor allowing safe shut-down of the flight

control system.

Input data from the skew redundant sensor configuration is synchro-

nized to ensure that each computer receives identical data. This allows

each computer to make identical failure decisions, to select identical inputs

for the inertial computations, and to provide identical outputs. All of the

ISA output data is strobed into each computer at 200-Hz via a 125-kHz clock

that is derived from a 2-Mhz oscillator located in each computer. The

200-kHz and 125-kHz clocks are synchronized between computers by means

of their derivation from a 25-Hz clock that is vote synchronized between

computers (See Appendix B for details).

Each computer strobes one ISA. When the ISA receives the 200-Hz

data request strobe, it transmits its data three times to all three computers

(at a 125-kHz bit transfer rate). Each computer, then, serially receives the

data from the three ISA's sequentially during the three transmission periods.

Because each computer inputs data from all three ISA's, identical data is

received from the ISA's by each computer. The voted 25-Hz clock is used

to synchronize the 200-Hz and 125-kHz data transfer pulse generators to

prevent a continuing divergence between the 200-Hz data request strobes

in each ISA.

Computer computation cycle synchronization consists of simultaneously

restarting each computer at the 25-Hz computation cycle rate from a "halt"

condition entered at the end of the previous computation cycle, using the

25-Hz synchronous clock.

Kinematic System K-3. - Kinematic System K-3 is functionally identi-

cal to System K-2; the only difference is in packaging. In System K-3, each

computer and one of the two-axis ISA's is packaged in a single housing as

opposed to separate housings as in System K-2. The interface is simplified

and three ATR housings are eliminated.

31

A standard, long ATR chassis is required to house each of the System

K-3 triple redundant two-axis ISA/IC computer assemblies. Figure 13

shows the resulting growth in mounting area that is required for the K-3

skewed orientation compared to the System K-2 skewed ISA's. The 19. 56-

inch installation dimension shown for the K-2 system ISA's is the maximum

ATR chassis length and typical installation mounting depth permitted by

ARINC. The 30-inch installation dimension shown for the K-3 system would

require special mounting shelves. To maintain alignment between the two-

axis ISA's, the skewed assemblies must remain rigid relative to each other.

This is more difficult for the large System K-3 mounting area.

If the 19. 56-inch maximum ARINC length standards are followed for

the ATR installation racks, the height of each System K-3 chassis must be

made larger to accommodate the required length decrease. This appears

to be a more reasonable approach as the modification to the standard size

electronic racks would, thereby, be minimized. Alternately, a vertical

stacking mount could possibly be used with the 19. 56-inch size K-3 assem-

blies to remain within a 19. 56-inch installation mounting depth constraint.

Further study is required to define configuration options and installation/

packaging penalties associated with System. K-3 compared to System K-2.

The cost benefits (given in Section III) for System K-3 compared to K-2

must be weighed against these packaging penalties before a recommendation

of the preferred configuration could be made.

Flight Control Systems

Figure 14 depicts the configuration of the traditional short-haul

commercial aircraft flight control system assumed for the study. The

dotted line outlines the System FC-1 flight control hardware assemblies

analyzed in the study for cost comparisons to the equivalent strapdown

mechanization. Items outside the dotted line are common to both alterna-

tives. The System FC-1 configuration in Figure 14 interfaces a traditional

K-l kinematic system with a triple redundant flight control computer.

32

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Figure 13. - K-3 Integrated ISA/Computer SkewedMounting Requirements

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Figure 15 shows the same basic flight control system using a strap-

down skewed redundant mechanization for the outlined items. The system

in Figure 15 contains a hexad ISA and associated triple redundant inertial

computation (1C) computers to provide the required signals to the flight

control computers. Three different versions (Systems FC-2, FC-3, and

FC-4) of the outlined assemblies in Figure 15 were analyzed in the cost

comparison to System FO1. These three versions differ in where the

inertial computations computer is housed: separately, with the flight control

computer, or with the ISA's.

At present, there is no requirement for inertial navigation equipment

on short-haul aircraft. The navigation function is normally handled by the

radio-navigation computer and/or its related sensors. It should be noted,

however, that inertial velocity and position information is available in the

1C computer as part of normal attitude reference calculations and this infor-

mation can be used, if desired, as an aid or, possibly, as a replacement for

the R-Nav computer.

Flight control system FC-1. - The area within the dotted lines of

Figure 14 is a hardware block diagram of the traditional flight control system

FC-1 showing the signal interface between the system assemblies and exter-

nal aircraft systems. The. traditional kinematic system, K-l, is included

as the sensing assembly in System FC-1.

System FC-1 computer: A functional block diagram of the FC-1 flight

control (FC) computer is presented in Figure 16. Computer inputs are d~c

signals, a~c signals, and discretes from the system sensors and other air-

craft systems. Outputs from, each computer are d-c control signals and.

discretes to other aircraft systems plus intercommunications (clock and

data crossfeed) between the redundant computer channels for redundancy.

The redundancy management functions implemented in each computer

are identical and..ar,e, designed to ensure that each computer operates simul-.;'..'"•• " ""%

taneously on the same set, of data. Deviations in the redundant computer

35

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outputs can, thereby, be clearly identified as computer failures. This is

achieved by transferring the flight control signals from each computer to all

computers and voting between these signals in each computer using a common

voting law. An additional function of the redundancy management routine is

to identify failures in redundant input signals by redundancy voting for output

to the failure status panel.

The computer uses a Honeywell HDC-301 central processor with a

MOS semiconductor memory. The flight control computations require

approximately 8000 words of memory, which is approximately four HDC-301

memory cards.

Actual FC computer interface requirements will vary from aircraft

to aircraft. An arbitrary group of input/output (I/O) modules have been

assumed for costing purposes. These modules consist of a d-c input multi-

plexer, an a-c input module, and a discrete multiplexer for aircraft and

sensor/computer input signals. For computer/aircraft output signals, they

consist of a d-c multiplexer and sample hold, and a discrete multiplexer.

These I/O devices all interface with the HDC-301 either directly or through

an analog-to-digital-to-analog (A/D/A) converter module. The remaining

I/O device is an external data transfer module that allows the exchange of

data, taken in through I/O, between computer channels for redundancy voting

(See Figure 16).

An I/O control module is included in the FC computer for overall I/O

control and synchronization. A timing and synchronization module is pro-

vided for generating a 25-Hz real time clock for the computer and for voting

this clock against similar clocks from the other two redundant computers to

obtain a synchronized 25-Hz clock (See Appendix B for details). The 25-Hz

synchronized clock is used through the I/O control module for initiating each

25-Hz computation iteration cycle. In this manner, all redundant computers

are synchronized to the same time base every 40 /itsec.

38

A power supply consisting of a transformer module, power card, and

regulator card converts aircraft unregulated input power to regulated voltages

which are required by the computer electronics. Built-in test equipment

(BITE) circuitry is provided in the FC computer to verify proper operation

of computer functional elements through measured responses to stimuli

applied to the I/O and through HDC-301 processor/memory operation checks.

The FC computer electronics circuits are packaged on plug-in circuit

cards and/or modules and are mounted in a standard three-fourths long ATR

chassis. Each of the three redundant FC computers is identical and inter-

changeable. Each computer chassis has space for approximately 30 circuit

cards plus a power supply module. The FC computer uses 22 circuit cards.

Flight Control System FC-2. - The FC-2 flight control system consists

of a K-2 strapdown kinematic system interfaced with triple redundant flight

control computers. The FC-2 flight control computer is almost identical to

the computer in the FC-1 system. The difference is the added serial digital

interface I/O in the FC-2 system, which takes in the digital kinematic sensor

data, and the elimination of the a-c and d-c input signals previously assigned

for traditional kinematic sensor inputs. Figure 17 depicts the FC-2 system

FC computer.

Flight Control System FC-3. - System FC-3 is a packaging variation

of System FC-2. For this configuration, each 1C computer in the kinematic

system has been packaged with one of the two-axis ISA's as described pre-

viously for System K-3. The flight control computer is identical to the

computer used in System FC-2. Thus, System FC-3 is composed of a K-3

kinematic system in conjunction with triple redundant FC-2 flight control

computers.

As discussed in the subsection on the K-3 kinematic system, the cost

benefits of combining the 1C computers and two-axis ISA's would have to be

weighed against the problems associated with the resulting larger skewed

assemblies before a recommendation could be made between the FC-2 and

FC-3 flight control configurations.

39

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Flight Control System FC-4. - System FC-4 is another packaging

variation of System FC-2. In FC-4, each 1C computer in the kinematic

system is housed in a common chassis with one of the flight control com-

puters. The hexad ISA's used with the integrated inertial calculations /flight

control (IC/FC) computers are identical to the K-2 kinematic system ISA

assemblies.

Kinematic systems are "dispatch critical"; that is, they must be

operating to dispatch the aircraft. (Appendix C gives a definition of dispatch

critical assignments for all flight control equipment considered in the study. )

Flight control computers alone are not dispatch critical; however, they

become dispatch critical when combined with the dispatch critical 1C com-

puters. Further cost studies would have to be made to determine if the cost

savings for the FC-4 configuration compared to the FC-2 or FC-3 configu-

rations is offset by delay costs incurred in servicing the dispatch critical

IC/FC computer during normal flight operations.

System FC-4 computer: A functional block diagram of the integrated

IC/FC computer used in System FC-4 is presented in Figure 18. The FC-4

computer is essentially a superposition of the FC-2 flight control (FC) com-

puter (Figure 17) and the K-2 inertial calculations (1C) computer (Figure 12).

The FC-4 computer utilizes two Honeywell HDC-301 central processors,

each with individually dedicated MOS semiconductor memories. A data

transfer card is included between the 301 processors to enable interprocessor

communications as an internal I/O function. One of the 301 processors is

dedicated to the hexad inertial computation section (ICS) functions; the

other 301 processor comprises the flight control computation section (FCCS).

I/O and memory modules are dedicated to each of the 301 processors shown

in Figure 18 to perform the ICS and FCCS functions.

The I/O control module for the integrated IC/FC computer provides

the overall I/O control and synchronization for both the IGS and FCCS. The

I/O, memory timing, and synchronization implementation for the ICS and

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FCCS are identical to those functions described previously for the K-2

computer (for the 1CS) and for the FC-2 night control computer (for the

FCCS). A single power supply consisting of a transformer module, power

card, and regulator card converts aircraft unregulated input power to regu-

lated voltages, which is required by all computer electronics. Thus, com-

bining the 1C and FC computers in a common housing eliminates one power

supply. The computer supply also provides regulated power to one of the

three ISA's.

BITE circuitry is provided in the IC/FC computer to verify proper

operation of ICS and FCCS computer functional elements through measured

responses to stimuli applied to the I/O and through the HDC-301 processor/

memory operation checks.

.Figure 19 is a cutaway drawing of a typical packaging arrangement for

the IC/FC computer showing its construction and relative location of functions.

The IC/FC computer electronics circuits are packaged on plug-in circuit

cards and/or modules and are mounted in a standard full long ATR chassis.

Each of the three redundant IC/FC computers are identical and interchange-

able. System differences in the ISA interface would be implemented through

the ISA/computer interface wiring. Each computer chassis has space for

approximately 30 circuit cards plus a power supply module. The IC/FC

computer uses 28 circuit cards.

Inertial Navigation Systems

Inertial Navigation System INAV-1. - An ARINC 561 gimbaled INS

such as the CAROUSEL IV was selected as representative of a traditional

commercial aircraft inertial navigation system. For the study, a triple

redundant, fail-operational/fail-safe ARINC 561 INS configuration was

investigated. Figure 20 summarizes its form factor, power, and weight.

43

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Inertial Navigation System INAV-2. - System INAV-2 is a strapdown

equivalent of System INAV-1. It consists of a hexad inertial sensor assembly

(three two-axis ISA's) and three 1C computers with ARINC 561 I/O. Figure

21 summarizes the INAV-2 system form factor, weight, and power. The

INAV-2 computer consists of 20 cards and a power supply module housed in

a standard three-fourths long ATR chassis.

The INAV-2 computer, shown in the block diagram of Figure 22, is

similar to the K-2 kinematic system computer described previously, differing

only in the ARINC 561 I/O addition. The ARINC 561 I/O consists of nine

interface cards (eight ARINC signal cards and one INS display interface card).

The INS display interface card acts as the digital interface between the pilot

display unit and the computer for system initialization and readout. The

other seven cards are used to generate and/or receive synchro signals,

discrete signals, d~c signals, and digital signals to meet the ARINC 561

output format.

Inertial Navigation System INAV-3. - System INAV-3 is functionally

identical to the INAV-2 system.; it differs in the combined packaging of each

computer with one of the ISA's in a single standard full high long ATR chassis.

The resulting larger skewed sensor assemblies present the same

mounting problems as described previously for the K-3 system. The advan-

tage of the K-3 system over the INAV-2 system is reduced cost.

Inertial Navigation System INAV-4. - The INAV-4 system is the same

as the K-2 kinematic system except for the addition of an INS display inter-

face card and a digital serial-to-parallel I/O card for air data altitude inputs.

The addition of these two cards converts the K-2 kinematic system into a full

inertial navigator. The INAV-4 system was configured to show the cost

benefits of an all-digital format for the .strapdown navigator compared to the

INAV-.2 configuration with the more complex ARINC 561 interface.

46

TWO-AXIS ISA'S

HEXAD

1CCOMPUTER

1CCOMPUTER

1CCOMPUTER

ARINC 561

TWO-AXIS ISA'S (3)

1C COMPUTERS (3)

TOTALS

WEIGHTPOUNDS

128.5

80.1

208.6**

POWER*WATTS

84

379

463

* NO WARM-UP REQUIRED** INCLUDES 25 POUNDS FOR ADDITIONAL AIRCRAFT

HEXAD INSTALLATION STRUCTURE

Figure 21. - INAV-2 Strapdown Redundant ARINC 561Inertial Navigation System

47

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Inertial Navigation System INAV-5. - The INAV-5 system is the same

as the K-2 kinematic system except for the addition of an INS display inter-

face and digital serial-to-parallel I/O card. The resulting navigation system

can be compared to System LNAV-3 to assess the cost advantages of a digital

interface compared to a standard ARINC 561 interface.

49

SECTION III

SYSTEM COST ANALYSES

In this section is described the method utilized to calculate cost of

ownership in the study, and the cost results for the system configurations

described in Section II are summarized. The detailed cost of ownership

calculation computer run printouts for each system are contained in

Appendix E. The cost of ownership calculations are based on an assumed

150 airplane fleet and a six-year amortization of initial hardware costs.

The cost figures presented represent engineering estimates based on past

experience for similar equipment assuming 1973-1974 labor and material

rates. For the computer and strapdown hexad items, costs were based on

the estimated average for an initial 500 system production run. The cost

data shown was prepared for engineering tradeoff comparison purposes only.

Cost of Ownership Formula

The formula used to calculate system cost of ownership in the study

was obtained by Honeywell from Boeing Commercial Airplane Co. and sub-

sequently incorporated into a computer program. The cost of ownership

formula is summarized below.

Cost of Ownership (CQ ~ dollars/1000 flight'hours).

C = C + C +o SP UI

50

where:

CTP = amortized initial hardware cost

Cj = amortized hardware spares cost

GC, = added fuel costr

CM = hardware direct maintenance cost

Amortized initial hardware cost (CT^)

B x a x (C + CIN) x N x Y x 1000CIP • ims

where:

B = borrowed money cost factor (B = 1.1)

a = amortization factor computed by fixed rate method. Based

on six-year operation and 10-percent scrap value of C after

six years (a = . 15)

C = hardware purchase cost per unit

CTN = unit installation cost

N = quantity of units per airplane

Y = annual parts pool cost factor (Y = 1. 0)

H = average daily flight hours per airplane (H = 9)

D = airplane operating days per year (D = 365)

Amortized spares cost (CT)

,-, _ C x a x B x y x Q x 1000C I " A x H x D

n = A x N x H x K x T f A x N x H x K x T *" MTBF x K r XV

51

where:

Q = quantity of hardware units required to replace those

removed during the repair turn-around period

A = number of airplanes in fleet (A = 150)

K - ratio of hardware operating hours per flight hour (K = 1. 5)

T = average repair turn-around time (T = 7 days)

MTBF = hardware unit mean time between failures

Kp ;R = hardware failure/removal ratio ( K p , R = 0. 5)

r = risk factor (r = 2)

Added fuel cost (C^)

P^ x R,.,,. x W x N x 1000F / t v F

where:

PF = fuel purchase price per gallon (Pp = $0. 42)

Yp = pounds per gallon of fuel (YF = 6. 7)

R p / , = ratio of added fuel per flight hour to added aircraft

operating empty weight (Rp/ t = 0. 133)

W = hardware unit weight

Direct maintenance cost (C,J

= M R N + C L

52

where:

MRN = failed module repair or replacement cost

CT = line maintenance cost

Co = shop repair cost

CT-, = burden costr>

Failed module repair (or replacement) and checkout cost

N x K x C x 1000MRN MTBF

where:

Cp = average parts cost per failure

Line maintenance cost (CT )

N x K x tT x LT x 1000= ±i id

L MTBF x KF ,R

where:

tj = average line maintenance time per removal (t^ = 0. 5 hours)

LT = line maintenance labor rate (LT = $9. 52/hr)j_i LI

Shop repair cost (C^)

N x K x t x L x 1000C =S MTBF x Kp ,R

53

where:

t = average shop repair hours per removal. Includes failedo

module replacement cost but not module repair (or new

module purchase).

L = shop labor rate (L = $8. 14/hr)s s

Burden cost (Cg)

/-i _ / 1 i -D-tv \ __ / f~^ i /-i \

where:

BR = burden rate (BR = 100%)

Figure 23 is a sample printout of a cost-of-ownership computer run

that is representative of the equivalent runs for each system configuration

contained in Appendix E.

The second line of the printout identifies the run number and computer

run. In this case it was "RUN 1. 2. 3, 3 TWO-AXIS ISA'S LASER LIFE =

15, 000 HOURS". The next eight lines list 16 cost-of-ownership variables

given constant values for this study. The values used for these variables

were supplied by Boeing as representative of typical commercial aircraft

experience (except for the values included in "Line Hours Per Removal",

'"Fuel Costs", and "Average Turn-Around Time", which were Honeywell

estimates).

The four lines beginning with the word "Enter" show the values given

to the eight cost-of-ownership variables that were free to vary during the

study. The fail-removal ratio variable was not allowed to vary but was set

at 0. 5 for all configurations.

54

DESCRIBE LIMIT

! RUM 1.£.'3 3 TOn-RXIS ISR'S LRSER LIFE = 15.000 MRS

HMDPIZR TI DM FPCTOP 0.15PRPTS PDDL COST 1.00DP. HRS TD FLT MRS 1.50RISK FRCTDR £.00

HP F'RTE FOP LINE 9.5£LINE ri='S PEP REWOVRL 0.50LES PEP GRL FUEL 6.70S-L PUPBEM PER CENT 100.00

BORROWED MOMEY COST 1.10DfllLY FLIGHT HOURS 9.00FUEL PRICE PER GfiLLDN 0.4£DP. DRYS PER YERR 365.00

HP RRTE FDR SHOP 3.14DRYS TO PEPfllR 7. 00RRTIO RDDEP FUEL 0.1333HO. QF RIPPLRNES 150.00

EMTEP LIMIT PRICE- IM'-TrlLLRTIDM PRICE! 17410.- 655.

ENTER HPS BETI.IEEM FRILUPE- SHOP HPS PEP PEMDVRL! 3861. » ',

EMTEP LIMITS PEP RIRPLriME. UMIT WEIGHT! 3.- 34.5

EMTER RV. PRPTS COST PER FRILUPE- FRIL-REMGVRL RRTID! 361.

DIRECT MRIMTEMRMCE CDST» MEW MODULES OR REPflIP 49447£.87 3296.49

» LIME MRIMTEyflMCE 5467.34 36.45* SHOP MODULE PEPLftCEMT 65447.30 436.3£» BURDEM-SHDP ftHD LIME 70914.64 472.76

TDTRL CDST DF OWNERSHIP £494030.50 16626.87

.5

SYSTEM C3STMO. OF SPRPE LIMITS

flr-iriUflL FLEET PEMDVRI. SHMM'JRL PLRME PEMDVRL SREMDVRLS PER 1000 FLIGHT HRS

riMDPTIZED IMITIRL COST

AMORTIZED SPflRE COSTS

FUEL COST

5£'230. 0031.41

1 148.607.66£.33

RMMURLFLEETCOSTS

1341356. 00

90843.61

4£6153.87

RMMURLPLRMECOSTS

8942. 17

601.6?

£841. 06

1000FLT HRS

COSTS

£7££. 12

183. 14

864 . 86

1003.50

11. 10132.82143.92

5061.45

• DIRECT MfiPMT CDST 636302. 1£ 4242.01 1291.33

Figure 23. - Sample Cost-of-Ownership Computer Run

ORIGINAL PAGE ISOF POOB QUAlilg 55

The output from the computer run begins below the dotted line.

System cost is, equal to the unit' price multiplied by the number of units.

The assumed number of spare units refers to the total system spares

required to service an assumed 150 airplane fleet for the seven day shop

turn-around period required for failed line replaceable unit (LRU) repairs.

The next three lines list the probable LRU removals per fleet (150 planes)

per year, per plane year, and per 1, 000 flight hours.

Computed costs are shown in the printout on the basis of annual fleet

costs, annual plane costs, and costs per 1, 000 flight hours. Direct mainte-

nance costs are a part of the total cost of ownership but are also shown

separately on the last line.

Kinematic Systems Cost Analysis

Kinematic System K-l cost. - Table 2 summarizes the direct mainte-

nance and ownership costs for the K-l kinematic system and line replaceable

units (LRU's ) as obtained in the study from the cost-of-ownership computer

program. The detailed computer run printouts for the data are contained in

Appendix E (Runs 1.1.1- 1. 1. 6).

Table 3 identifies three sources of cost information for the K-l equip-

ment and the actual costs that were used for the study in the cost-of-owner-

ship computer program. These costs are considered representative of the

1973-1974 costs for this class of equipment.

The wiring installation prices used in the computer runs were supplied

by Boeing with the exception of the rate gyro. The rate gyro is usually

packaged with the flight controls. A one-hundred dollar wiring price was

arbitrarily .allocated for the rate gyro.

The MTBF data utilized in the computer runs were obtained from a

Battelle Report (NAS2-6889). This data was collected from July, 1971 to

56

TABLE 2. - K-l KINEMATIC SYSTEM COST SUMMARY

K-l system LRU's

3 vertical gyros

9 rate gyros

9 accelerometers

3 compass couplers

3 directional gyros

3 flux gates

K-l system total

MTBF(hrs)

1, 000

711

10, 787

2,834

2, 566

60, 000

307

Initialcost

(dollars)

18, 600

9, 000

9, 000

12,600

11,400

1,800

62,400

Directmaintenance

cost(dollars /flight hr)

2.84

. 86

. 06

. 29

. 77

. 02

4. 84

Cost ofownership

(dollars /flight hr)

4. 60

1. 50

.83

1. 38

1. 73

.29

10. 33

TABLE 3. - SYSTEM K-2 LINE REPLACEABLE UNIT (LRU)COST IN DOLLARS

LRU

Rate gyro

Accelerometer

Compass coupler

Flux gate

Directional gyro

Vertical gyro

Boeing

600-1, 200

700

4, 200

600

10, 000

Batteilea

1, 000

1, 000

4, 200

600

3, 500

6, 000

Honeywell

1, 000

1,000

3,800

6,200

Cost usedin study

1, 000

1, 000

4,200

600

3,800

6, 200

Listed as replacement or spares cost in Battelle Report prepared underContract No. NAS2-6889.

57

June, 1973 on Air California aircraft. The average number of hours

required to verify a failure in the shop is an estimate based on Honeywell

experience. The assumed weights are typical for this type of equipment.

The average parts costs per failure used in the study were based on a

percentage of initial cost as listed in Table 4.

TABLE 4. - SYSTEM K-l AVERAGE LRU PARTSCOST PER FAILURE

LRU Cost basis

Vertical gyro . .

Rate gyro . . . .

Accelerometer .

Compass coupler

Directional gyro

Flux gate . . . .

29% of initial cost

34% of initial cost

34% of initial cost

$500 (cost of a typical card)

34% of initial cost

100% of initial costa

The 180, 000 MTBF and low cost ($600) makes this item a throw-away unit.

Kinematic System K-2 cost. - Table 5 summarizes the K-2 kinematic

system cost-of-ownership data detailed in the Appendix E Computer Runs

1. 2. 3 and 1. 2. 7. Tables 6 and 7 provide detailed breakouts of unit cost,

MTBF, and average parts cost per failure for the two LRU's utilized in

System K-2, which form the basis for equivalent data entries in the com-

puter runs.

Wiring installation costs used in the computer runs for System K-2

LRU's are estimates obtained from Boeing. The shop hours per removal

are Honeywell estimates and were made assuming that automatic test equip-

ment will be used. Automatic test equipment enables the identification and

replacement of an electronic assembly card in one-half hour. A seven-hour

figure (considered conservative) was assumed for identification, replacement,

58

TABLE 5. - K-2 KINEMATIC SYSTEM COST SUMMARY

K-2 systemLRU's

3 two-axis ISA's

3 1C computers

K-2 system total

MTBFhrs

1287

1873

763

Initialcost

(dollars)

52, 230

43, 440

95, 670

Directmaintenance

cost(dollars /night hr)

1. 29

. 38

1. 67

Cost ofownership

(dollars /flight hr)

5. 06

3. 43

8. 49

and checkout of assemblies containing laser gyros and accelerometers.

Weight estimates were generated by Honeywell and are considered conserva-

tive.

An arbitrary fail-removal ratio of 0. 5 was assigned to all equipment.

The 0. 5 ratio is considered realistic based on current airline experience.

Strapdown digital configurations have the potential for a much higher ratio

because of BITE and related failure identification.

The 15, 000-hour MTBF figure used for the laser gyros is a reliability

estimate based on limited gyro test data, accelerated life tests, and experi-

enced electronic piece-part failure rates (discussed in Appendix D). While

it it felt that the 15, 000-hour MTBF figure is a realistic estimate, it is

also recognized that a degree of uncertainty exists because of the limited

amount of reliability data available on laser gyros utilizing current tech-

nology. Figure 24 was prepared to illustrate the sensitivity of the K-2

system cost of ownership to variations in laser gyro MTBF and is also

representative of variations in cost of ownership for the general class of

laser gyro strapdown systems investigated during the study. The data of

Figure 24 is a plot of the Appendix E computer run printouts for System K-2

varying laser gyro MTBF as a parameter (Runs 1. 2. 1 - 1. 2. 6). Also shown

in Figure 24 is the cost of ownership for traditional Kinematic System K-l,

which indicates a lower cost for the strapdown system even for laser gyro

MTBF's as low as. 5, 000 hour, which is considered extremely pessimistic.

59

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TRADITIONAL KINEMATICSYSTEM K-l COST-OF OWNERSHIP"?

K-2 BASELINE

10,000 20,000 30,000

LASER GYRO MTBF (HOURS)

40,000

Figure 24. - Strapdown System Cost-of-Owner ship VersusLaser Gyro Reliability

60

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Kinematic System K-3 cost. - Table 8 is a cost summary for the K-3

kinematic system obtained from the corresponding Appendix E detailed Com-

puter Run 1. 3. 1. Table 9 presents'the detail for the overall cost, MTBF,

and parts repair cost used in the computer run for the integrated two-axis

ISA/IC computer, the only LRU in the K-3 system. The rationale for the

other variables in the computer run is the same as for the K-2 system.

TABLE 8. - K-3 KINEMATIC SYSTEM COST SUMMARY

K-3 system LRU's

3 two-axis ISA/IC computers

K-3 system total

MTBF(hrs)

819

819

Initialcost

(dollars)

86, 700

86, 700

Directmaintenance

cost(dollars/flight hr)

1. 76

1. 76

Cost ofownership

(dollars /flight hr)

7. 88

7. 88

Flight Control Systems Cost Analysis

Flight Control System FC-1 cost. - Table 10 summarizes the FC-1

flight control system cost data detailed in the Appendix E Computer Runs

1. 1. 1 - 1. 1. 6 and 2. 1. 1. Table 11 provides the back-up detail for overall

cost, MTBF, and parts repair cost utilized in the computer for the FC-1

FC computer (Run 2. 1. 1). The rationale for the remaining input variables

for Run 2. 1. 1 parallels that described for the K-2 system. The remaining

assembly in FC-1 is the K-l traditional kinematic system (Appendix E Runs

1. 1. 1 - 1. 1. 6); cost elements for this system have been described previously.

Flight Control System FC-2 cost. - Table 12 summarizes the FC-2

flight control system cost data detailed in Appendix E Computer Runs 1. 2. 3,

1. 2. 7, and 2. 2. 1. Table 13 details the overall cost, MTBF, and parts

repair costs for the FC computer in FC-2 used in the corresponding Appendix

E Computer Run 2. 2. 1. The rationale for the remaining input variables for

Run 2. 2. 1 parallels that described for the K-2 system. The remaining

assembly in FC-2 is the K-2 kinematic system (Runs 1. 2. 3 and 1. 2. 7); cost

elements for this system have been described previously.

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64 *»**'*' ^ ^^_W

POOR QUAIOT

'ABLE 10. - FC-1 FLIGHT CONTROL SYSTEM COST SUMMARY

FC-l system LRU's -

3 vertical gyros

9 rate gyros

9 accelerometers

3 compass couplers

3 directional gyros

3 flux gates

3 FC computers

FC-1 system total

MTBF(hrs)

1, 000

711

10, 787

2,834

2, 566

60,000

899

299

Initialcost

(dollars)

18, 600

9,000

9,000

12,600

11,400

1, 800

65, 700

128, 100

Directmaintenance

cost(dollars /flight hr)

2.84

.86

.06

. 29

. 77

. 02

. 76

5.60

Cost ofownership

(dollars/flight hr)

4. 60

1. 50

.83

1. 38

1. 73

.29

5. 32

15.65

65

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66

TABLE 12. - FC-2 FLIGHT CONTROL SYSTEM COST SUMMARY

FC-2 systemLRU ' s

3 two-axis ISA's

3 1C computers

3 FC computers

FC-2 system total

MTBF(hrs)

1287

1873

866

406

Initialcost

(dollars)

52, 230

43, 440

67,380

163,050

Directmaintenance

cost(dollars/night hr)

1. 29

. 38

. 78

2. 45

Cost ofownership

(dollars/flight hr)

5. 06

3. 43

5. 48

13. 97

TABLE 13. - PART AND COST DESCRIPTION FOR FC-2 SYSTEMFC COMPUTER

LKL' part

IIDC-301 CPU

HDC-301 memory

301 buf fe r card

I/O control

Data transfer card

A/J J /A converter

Timing and sync card

AC analog input

DC input multiplexer

Discrete input multiplexer

Discrete output

Analog output

Serial digital interface

Bite

Power supply regulator

Power supply components

Power supply transformer

Chassis and mother board

Assemble and test

itemcost

dollars

3500

2000

280

340

280

360

340

530

380

260

340

350

280

320

310

1250

90

3400

700

iSo.items

1

4

1

2

1

1

1

2

1

1

3.

1

2

2

1

1

1

LRU total -"*>..

Costtotal

dollars

3500

8000

280

680

280

360

340

1060

380

260

340

350

560

320

310

1250

90

3400

700

22,460

Failure rate, %per 1, 000 hr

2. 7

2. 0

. 70

. 8

. 70

1. 50

1. 50

2. 8

. 82

3. 0

. 85 .

2. 9

. 7

1. 00

1I 3. 2

I1. 3

Totalfailure rate, %pur 1, 000 hr

2. 7

8. 0

. 7

1. 6

. 70

1. 50

1. 50

5. G

. 82

3. 0

2. 55

2. 9

1. 4

1. 00

3. 2

1. 3

38. 47

Partscost

dollars

1000

400

280

340

380

360

340

530

380

260

340

350

280

320

350

300

3418

Partscost per

hr

0. 0270

. 0320

. 2202

. 0054

. oo iy

. 0054

. 0051

. 0297

. 0031

. 0078

. 0087

. 0105

. . 0039

. 0032

. 0112

. 0039

0. 1608

a Average parts cost per failure is calculated by dividing part costs per hour by failures per hour

ORIGINAL PAGE ISOF POOR QUAUTSf ,

67

Flight Control System FC-3 cost. - Flight Control System FO3 costs

are the combination of the costs for Kinematic System K-3 (Appendix E

Computer Run 1. 3. 1) and the FC-2 FC computer (Run 2. 1. 1). Table 14

summarizes the FC-3 System cost data.

TABLE 14. - FC-3 FLIGHT CONTROL SYSTEM COST SUMMARY

FC-3 system LRU's

3 two-axis ISA/IC computers

3 FC computers

FC-3 system total

MTBF(hrs)

819

866

421

Initialcost

(dollars)

86, 700

67, 380

154, 080

Directmaintenance

cost(dollars/night hr)

1. 76

. 78

2.54

Cost ofownership

(dollars /flight hr)

7.88

5. 48

13. 36

Flight Control System FC-4 cost. - Table 15 summarizes the FC-4

flight control system cost data detailed in Appendix E Computer Runs 1. 2. 3

and 2. 4. 1. Table 16 details the overall cost, MTBF, and parts repair costs

for the IC/FC computer in System FC-4 used in the corresponding Appendix

E Computer Run 2. 4. 1. The rationale for the remaining input variables for

Run 2. 4. 1 parallels that described for System. K-2. The remaining assembly

in FC-4 is the hexad (three two-axis ISA's) utilized in the K-2 kinematic

system; cost elements for this system have been described previously.

TABLE 15. - FC-4 FLIGHT CONTROL SYSTEM COST SUMMARY

FC-4 systemLRU's

3 two-axis ISA's

3 IC/FC computers

FC-4 system total^"^•^"Criv,

MTBF(hrs)

1287

715

460

Initialcost

(dollars)

52, 230

93, 030

145, 260

Directmaintenance

cost(dollars /flight hr)

1.29

. 98

2. 27

Cost ofownership

(dollars /flight hr)

5. 06

7. 42

12. 48

68

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0BIGINALQF POOR QUAIZTgf

69

Inertial Navigation Systems Cost Analysis

Inertial Navigation System INAV-1 cost. - Table 17 summarizes the

INAV-1 traditional ARINC 561 gimbaled inertial navigation system cost data

detailed in the Appendix E Computer Run 3. 1. 1. The rationale for the input

variables to the cost-of-ownership computer run is outlined below.

TABLE 17. - INAV-1 INERTIAL NAVIGATION SYSTEM COST SUMMARY

3 gimbaled ARINC 561nav units

INAV-1 system total

MTBF(hrs)

600

600

Initialcost

(dollars)

285, 000

285, 000

Directmaintenance

cost(dollars /flight hr)

7. 50

7. 50

Cost ofownership

(dollars/ flight hr)

25. 39

25. 39

An ARINC 561 gimbaled navigation unit, such as the Carousel IV, is

estimated to cost $95, 000 in terms of 1973-1974 dollars. The weight of the

Carousel IV navigation unit, which is 53 pounds, was used in the study for

the INAV-1 LRU weight. The $2, 000 cost assumed for wiring installation is

an estimate supplied by Boeing and was identical for all I-Nav Systems in the

study.

At the Joint Services Data Exchange for Inertial Systems (August 19-21,

1974), it was reported that the Delco Carousel IV Navigation Unit was achieving

an 1, 800-hour MTBF with a 0. 5 failure-to-removal ratio (Jack Raia - Pan

American) and that the Litton LTN-51 system was achieving an 1, 881-hour

MTBF (Ed Overxharper - Overseas National Airways). An 1, 800-hour MTBF

and a 0. 5 failure-to-removal ratio was used in the study for the INAV-1

system gimbaled navigation unit.

The Battelle report gives the direct maintenance costs per installed

INS as being $2. 50 to $3. 00 per hour. The 14- shop hours and $2, 525 parts

70

cost per failure were selected in the study to produce a $2. 50 per flight hour

direct maintenance cost per LRU in the computer run.

Inertial Navigation System INAV-2 cost. - Table 18 summarizes the

cost-of-ownership data for the INAV-2 inertial navigation system detailed in

Appendix E Computer Runs 1. 2. 3 and 3. 2. 1. Details supporting the overall

cost, MTBF, and parts cost for the INAV-2 1C computer (Run 3. 2. 1) are pre-

sented in Table 19. Rationale for the input variables for Run 3. 2. 1 parallel

those for the K-2 kinematic system. The two-axis ISA utilized in INAV-2 is

identical to the equivalent unit used in the K-2 kinematic system (Computer

Run 1. 2. 3); cost detail for this system has been presented previously.

TABLE 18. - INAV-2 INERTIAL NAVIGATION SYSTEM COST SUMMARY

INAV-2 systemLRU's

3 two-axis ISA's

3 1C computers

INAV-2 system total

MTBF(hrs)

1287

1019

569

Initialcost

(dollars)

52, 230

58, 440

110,670

Directmaintenance

cost(dollars/ flight hr)

1. 29

.68

1.97

Cost ofownership

(dollars/flight hr)

5. 06

4.82

9.88

Inertial Navigation System INAV-3 cost. - Table 20 summarizes the

cost of ownership for the INAV-3 inertial navigation system detailed in

Appendix E Computer Run 3. 3. 1. Table 21 provides the overall cost,

MTBF, and parts cost detail utilized in Run 3. 3. 1 for the only LRU in

INAV-3, the integrated two-axis ISA/IC computer. Rationale for the other

input variables for Run 3. 3. 1 parallels that for the K-2 kinematic system

described previously.

Inertial Navigation System INAV-4 cost. - Table 22 summarizes the

cost-of-ownership data for the INAV-4 system detailed in Appendix E, Runs

1. 2. 3 and 3. 4. 1. Cost detail for the 1C computer (Run 3. 4. 1) for INAV-4 is

presented in Table 23. Cost detail for the INAV-4 two-axis ISA (Run 1. 2. 3)^

71

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72

TABLE 20. INAV-3 INERTIAL NAVIGATION SYSTEM COST SUMMARY

3 two-axis ISA/IC computers

INAV-3 system total

MTBF(hrs)

600

600

Initialcost

(dollars)

101, 460

101, 460

Directmaintenance

cost(dollars/ flight hr)

2. 20

2. 20

Cost ofownership

(dollars/ flight hr)

9. 60

9. 60

TABLE 21. - PART AND COST DESCRIPTION FOR INERTIAL NAVIGATIONSYSTEM INAV-3 INTEGRATED TWO-AXIS ISA/IC COMPUTER

I . K l part

II DC :i01 (.'PL

IIJJC 301 memory

301 but' far card

Timing module

Hue card

1I\S display interface card

A U I N f

Digital /synchro

HC'U and binary serial

.Synchro/digital

Serial/ parallel

Digital/analog converter

I 'p-down counter and storage cards

\cceleromettjr pulse logic card

I/O control

Accelerometer block

Laser gyro block

Accelerometc;r and module electronics

Laser gyros

Power supply regulator

Power supply

Power transformer

Chassis (wir ing connectors, etc. )

Assemble and test

Itemcost

dollars

:i500

2000

280

310

320

240

430

290

430

200

450

380

230

340

330

330

1870

4000

310

1250

90

3300

2000

No.items

1

2

1

1

1

1

7

1

1

1

1

2

1

2

1

1

2

2

1

1

1

1

1

I . K U total

Costtotal

dollars

3500

4000

280

310

320

240

3010

290

430

200

450

SCO

230

680

330

330

3620

8000

310

1250

90

3300

2000

33,820

Failure rate,%per 1, 000 hr

2. 7

2. 0

. 70

1. 5

1.0

• ™

1. 5

. 7

1. 5

. 7

1.5

.80

.80 '

.80

--

--

4. 06. 7

3. 2

1. 5

Totalfailure rate, %per 1, 000 hr

2. 74. 0

. 7

1. 5

1. 0

. 7

10. 5

. 7

1. 5

. 7

1. 5

1.6

.80

1.6

--

--

8.0

13.4

3. 2

1. 5

55. 6

Partscost

dollars

1000

400

280

310

320

240

430

290

430

290

450

280

230

340

--

--

625

1200

350

300

3634

Partscost per

hr

0. 0270

. 0160

. 0019

. 0047

. 0032

. 0017

. 0452

. 0020

. 0065

. 0020

. 0068

. 0045

. 0018

. 0054

--

--

. 0484

. 1608

. 0112

. 0045

0. 3536

1'arts cost per failure is calculated by dividing part costs per hour by failures per hour

ORIGINAL<* QUALEnl

73

TABLE 22. - INAV-4 INERTIAL NAVIGATION SYSTEM COST SUMMARY

INAV-4 systemLRU's

3 two-axis ISA's

3 1C computers

INAV-4 system total

MTBF(hrs)

1287

1736

739

Initialcost

(dollars)

52,230

45,030

97, 260

Directmaintenance

cost(dollars /flight hr)

1.29

.40

1.69

Cost ofownership

(dollars /flight hr)

5.06

3. 56

8.62

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75

is identical to that presented for the K-2 kinematic system. Rationale for the

computer run input variables for INAV-4 parallels that for the K-2 kinematic

system discussed previously.

Inertial Navigation System INAV-5 cost. - Table 24 summarizes the

cost of ownership for the INAV-5 inertial navigation system detailed in

Appendix E Computer Run 3. 5. 1. Table 25 provides the overall cost, •

MTBF, and part cost detail for the only LRU in INAV-5, the integrated two-

axis ISA/IC computer. Rationale for the other input variables for Run 3. 5. 1

parallels that for the K-2 kinematic system described previously.

TABLE 24. - INAV-5 INERTIAL NAVIGATION SYSTEM COST SUMMARY

INAV-5 systemLRU's

3 two-axisISA/IC computers

INAV-5 system total

MTBF(hrs)

756

756

Initial cost(dollars/ flight hr)

89, 250

89, 250

Directmaintenance

cost(dollars/flight hr)

1.82

1.82

Cost ofownership

(dollars /night hr)

8. 15

8. 15

Inertial Navigation System Cost Projections

Figure 25 illustrates the effect of inflation and learning on the gimbaled

INAV-1 and strapdown INAV-2 inertial navigation systems from 1974 to 1975.

The curve illustrates the impact of inflation on a mature inertial technology,

INAV-1, compared to a new technology, INAV-2/ Because INAV-1 is a

mature production program, high learning rates have already been experi-

enced and, therefore, there is no great potential for learning. For INAV-2,

however, a new technology just entering production, high learning rates will

be experienced between 1974 and 1978. The net effect is that the INAV-2

learning should offset the inflationary spiral between 1974 and 1985, while

INAV-1 costs should rise at the inflation rate. This results in a widening of

the cost advantage projected for strapdown over gimbaled systems during the

next ten years. The plotted points of Figure 25 represent the average cost of

120 systems for the year shown.

76

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600,000-

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WITHOUT INFLATION

TRIPLE REDUNDANTGIMBALEDINS COSTS

FAIL-OPERATIONALFAIL-SAFE LASERHEXAD INS COSTS

WITHOUT INFLATION

1974 1976 1978 1980YEAR

1982 1984

Figure 25. - Laser Strapdown Versus Gimbaled Redundant INS Cost Trends

78

Some assumptions applicable to the system cost projections were made.

The production rate was assumed to be 10 systems (strapdown or gimbaled)

per month over the 1974-1985 time period. The costs projected for the strap-

down system are based on an average cost of $110, 670 per system for the

first 500 systems (INAV-2 system cost) and a 90-percent learning curve.

The costs projected for the gimbaled system are based on the cost of the

2, 000th unit in 1974 being $95, 000 ($285, 000 system cost). A 90-percent

learning curve is assumed and cost projections begin with the 2, 001st (667th

system). This experience factor was selected as conservatively representa-

tive of current gimbaled navigation experience. As examples, Singer Kearfott

has produced over 2, 000 gimbaled KT-70 inertial navigation units, and Litton

has produced over 10, 000 gimbaled navigation units. Also, inflation rates of

6 percent and 10 percent per year were assumed.

79

SECTION IV

CONCLUSIONS AND RECOMMENDATIONS

Summary

Figures 26, 27,and 28 summarize the various kinematic, flight control,

and inertial navigation systems investigated in the study, comparing the initial

procurement cost, direct maintenance cost, and cost-of-ownership of these

systems to the equivalent traditionally mechanized and strapdown laser gyro

system configurations. The cost-of-ownership and direct maintenance cost

formulas to derive the cost figures in Figures 26, 27, and 28 were based

for the most part on inputs from Boeing Commercial Airplane Company.

The initial costs for the laser systems are the estimated average prices

for 500 systems assuming 1973-1974 labor and material rates and a 500 sys-

tem initial buy; initial costs for the traditional systems were based on 1973-

1974 prices for this equipment. Direct maintenance costs were based on an

assumed fleet of 150 airplanes with nine flight hours per day per airplane,

calculated or known failure rates and maintenance/repair costs. The cost of

ownership figure includes the direct maintenance cost, a six-year amortization

of the initial system procurement and aircraft installation cost including a

borrowed money cost factor of 1. 1, and aircraft fuel costs associated with

the equipment weight.

Throughout Figures 26, 27, and 28, the direct maintenance cost and

cost of ownership for the laser strapdown systems are notably lower than the

equivalent set of traditional equipment. For the kinematic and flight control

systems (Figures 26 and 27), the strapdown cost savings results from the

significant reduction in the number of inertial components per system

(reduced from 24 in the traditional system to 12 in the stre.pdown system).

For the inertial navigation systems (Figure 28), the savings results primarily

from the elimination of the gimbal assemblies in the traditional systems.

80

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83

The traditional kinematic system for commercial aircraft (System K-l) ,

as shown in Figure 26, consists of triple redundant attitude gyros, compass

systems (heading gyro with flux valve), rate gyro triads (three orthogonal

axes), and accelerometer triads. The equivalent redundant laser system

(K-2 or K-3 in Figure 26) contains a skewed redundant hexad (ISA) inertial

sensor assembly (three identical two-axis ISA's each containing two laser

gyros and two accelerometers), and triple redundant inertial computation

(1C) computers. The 1C computers are separate assemblies, as in System

K-2, or are individually integrated with each two-axis ISA, as in System. K-3.

The tradeoff between strapdown configurations K-2 and K-3 is lower cost for

System K-2 versus a longer skewed ATR chassis in System K-3 and, hence,

a more difficult skewed installation.

A cost comparison between the traditional and strapdown kinematic

systems in Figure 26 shows a 20-percent cost-of-ownership savings for the

strapdown system. A more significant fact is that the laser gyro strapdown

kinematic system computer is mechanized assuming an INS attitude reference

implementation. As such, the K-2 and K-3 system computers generate navi-

gational position and velocity data as a normal part of the attitude reference

calculations. Because the laser gyros utilized have INS accuracy capabilities,

the additional navigation signals available in the triple redundant computers

can be used to provide triple redundant inertial navigation outputs. The

additional cost per system, to utilize this capability is $1, 500 for additional

I/O electronics.

The traditional flight control system in Figure 27 (System FC-1) con- .

sists of a triple redundant kinematic system interfaced with triple redundant

fail-operational/fail-safe flight control computers. Three equivalent fail-

operational/ fail-safe strapdown laser flight control systems are shown in

Figure 27. The FC-2 and FC-3 configurations interface the K-2 and K-3

kinematic systems with a triple redundant flight control computer; in the

FC-4 configuration,the 1C computer is integrated into the same housing as

the FC computer. The tradeoff between the FC-2 and FC-3 configurations

is similar to that between K-2 and K-3. The tradeoff between FC-4 and

84

FC-2 or FC-3 is lower cost versus the imposition of a dispatch critical

requirement on the FC computer. The kinematic system is dispatch critical

for commercial applications, the flight control computer normally is not.

Incorporating part of the kinematic system into the FC computer makes this

also a dispatch critical item.

A cost comparison between the traditional and strapdown flight control

systems in Figure 27 shows the strapdown systems (FC-2 and FC-3) to have

13-percent lower cost of ownership. In the case of the FC-4 configuration,

20-percent savings results. In addition, triple redundant inertial navigation

data can be obtained from either of the strapdown configurations for an added

system cost of $1, 500, as for the kinematic systems in Figure 26.

The traditional inertial navigation system shown in Figure 28, (System

INAV-1) consists of a triple redundant ARINC 561 gimbaled INS. Four strap-

down system types of equivalent redundancy level are illustrated in Figure 28:

configurations INAV-2 and INAV-3 have the identical ARINC interface as

INAV-1 but differ in where the 1C computer is housed; configurations INAV-4

and INAV-5 are similar to INAV-2 and INAV-3 except that the ARINC inter-

face is replaced by a simpler digital interface. The tradeoff between INAV-2

and INAV-4 and INAV-3 and INAV-5 is cost versus added skewed ATR length

and associated installation constraints.

A comparison between the cost of ownership for the traditional and for

the strapdown INS configuration in Figure 28 shows a dramatic 62-percent

cost reduction for the strapdown systems with standard ARINC interface.

For the strapdown systems with the simpler digital interface, the cost savings

is 67 percent.

The strapdown system cost data summarized in Figures 26, 27, and 28

is based on an assumed laser gyro MTBF of 15, 000 hours. Although this is

considered to be a realistic estimate at the present time, it contains a degree

of uncertainty because of the limited amount of reliability data currently

available on recent technology laser gyros. Figure 29 illustrates the

85

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TRADITIONAL KINEMATICSYSTEM K-l COST-OF OWNERSHIP^?

t —

10,000 20,000 30,000

LASER GYRO MTBF (HOURS)

40,000

Figure 29. - Strapdown System Cost-of-Ownership versusLaser Gyro Reliability

86

sensitivity of the cost-of-ownership of strapdown system K-2, which is

representative of the sensitivity of all strapdown systems evaluated in the

study, to variations in laser gyro MTBF. Figure 29 shows that the strap-

down system cost advantage over the traditional system, System K-l, is

retained for laser gyro MTBF's as low as 5, 000 hours, and this is con-

sidered unreasonably pessimistic.

Figure 30 illustrates the impact of six- and ten-percent inflation and

90-percent learning between 1974 and 1985 on initial procurement cost for

redundant gimbaled (INAV-1 system) and strapdown (INAV-2 system) inertial

navigation systems assuming a 10 system per month production rate. The

curves show a widening of the strapdown cost advantage with time because of

production learning. .High rates of learning for the new strapdown technology

are still to be experienced; mature gimbaled technology has been in production

for several years and high learning rate periods are in the past. The new

learning slope for the strapdown technology is steep enough between 1975 and

1978 to offset the effect of inflation. Because of the shallower learning slope

for the gimbaled system, no such cancellation occurs and inflation results

in an ever increasing procurement price.

From the study results it can be concluded that laser skewed redundant

strapdown systems can provide significant advantages for future commercial

aircraft in the areas of cost reduction and added performance capabilities.

For basic redundant flight control systems and sensors, the strapdown

approach is not only 15 to 20 percent lower in cost than traditional systems,

but also can provide triple redundant inertial navigation data as an additional

output for virtually no cost penalty. In the case of triple redundant inertial

navigation systems, the strapdown skewed redundant system is one third the

cost of the equivalent ARINC gimbaled triple redundant INS. If inflation and

learning is taken into account, the strapdown INS cost advantage is even more

dramatic. Strapdown systems are new and there is much to be learned about

their production. The resulting steep learning slope for the strapdown tech-

nology over the next ten years will offset inflationary cost increases. For

mature gimbaled technology, high learning rate periods are in the past, and

87

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coo

co

co>_io:

LJ

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QL

600,000-

500,000-

400,000-

300,000-

200,000-

100,000'

WITHOUT INFLATION

TRIPLE REDUNDANTGIMBALEDINS COSTS

FAIL-OPERATIONALFAIL-SAFE LASERHEXAD INS COSTS

WITHOUT INFLATIONO

= 0

/&,• ' .-

£.:1 1 1 1 1

1974 1976 1978 1980 1982 1984i5v/obq,6'i;:ia sriJ *io* eqola gnkriBsI q$£&Rgciilh)s~3i eiiT .noi:tDjjbo-iq ii

Figure^SO.;, +- ,Laser,.Str,apdow(n..y.ersus.Gimbaled^Redwndante.k\&e.HiylXiU J«20-j V.-i-bflu^^lU,'. -VC^K;Li^'^ ts J-Joav. wal J A ^ U »«j AO"iNBACost-TrendsJa-jsq eri^ nl SIB sboiiaq 3i«?i "gnia'xssl rigid v^

p§oJondoo^ b9lsdm.tg a-:

inflation over the next ten years will result in continually increasing costs at

the inflation rate.

Recommendations

For the study summarized in this report, several traditional and

advanced strapdown configurations of kinematic, flight control, and inertial

navigation systems were investigated for comparison on a cost-of-ownership

basis. The study results have demonstrated that the strapdown skewed redun-

dant configuration has significant cost and performance benefits over the

equivalent traditional system. As a potential follow-on study, it is recom-

mended that a strapdown configuration tradeoff be performed to define a

single strapdown configuration that best satisfies overall requirements for

commercial aircraft.

First, alternate system configurations would be defined for tradeoff

evaluation. A kinematic system that includes the air data computation

function interfaced with a set of remote air data transducers might be one

configuration. Because air data is dispatch critical as is the kinematic

system, this would be a logical combination of functions. Integrating the

air data computation in the kinematic system computer would eliminate the

air data computer ATR assembly normally contained in traditional flight

control systems and it could then be replaced with a simpler, low cost

remote transducer.

Tradeoff analyses would then be performed, entailing a review of all

configurations investigated and the formulation of cost assumptions with

commercial airline companies and aircraft manufacturers. Comments and

recommendations would be solicited for preferences, changes, and config-

uration alternates. Questions concerning skewed ATR installation constraints

that arose during this study would be answered. An additional question to be

addressed would be how skewed ISA LRU's should be mounted in an aircraft

such that necessary high alignment accuracies can be achieved between ISA's

without requiring special installation alignment procedures.

89

The new configurations would then be costed and compared against

the equivalent traditional system in the same manner as performed under

the current study. In addition, a parameter variation study would be per-

formed to assess the sensitivity of the system costs to uncertainties in the

cost-of-owner ship computer program input data. This was performed for

the laser gyro MTBF in the current study, and could be performed for all

other variables in the cost-of-ownership formula. The results could then

be correlated with expected variations in the input parameters.

90

C _

APPENDIX A

HEXAD SKEWED GYRO VOTING AND TRANSFORMATION EQUATIONS

Gyro Error Detection Equations

The derivation of a typical set of error equations to be used in the gyro

error detection/isolation routines for the hexad system will be described in

this subsection. It must be assumed that the three sets of orthogonal two-axis

ISA's are placed such that each ISA has one input axis in the p and q (roll and

pitch) plane, and the other axis rotated through an angle a with respect to the

p and q plane as shown in Figure A-l. The p, q, and r (roll, pitch, yaw)

coordinate frame was selected as the orthogonal reference triad. Figure A-2

shows the projection of the hexad input axes on the p and q plane.

The hexad input axes can be expressed in terms of the reference triad

and configuration geometry by inspection as:

"V"2a)3

^4

"S

uu_6

=

1 0 0

0 - C a Sa

CB SB °

C a C A - CaSA Sa

/CB / - SB 0

1

-CaCA - CaSA Sa

P

q

r

91

-p

Figure A-l. - Hexad Geometry

A -p

-q

Figure A-2. - Projection of Hexad Input Axesinto the q, p Plane

92

WhereUK = angular rate sensed by hexad gyro i

p, q, r = roll, pitch, yaw rates

a = 45°

B = 60°

A = 30°

C = Cosine

S = Sine

The three sets of orthonormal two-axis ISA outputs are defined by u>uu, u'o» i«4, ID,-, and u)fi. These sets, taken two at a time, result in threetetrad combinations:

1.

3.

«V a)2' V U16

The associated error equations for each tetrad are sufficient to isolatea first failure to one two-axis ISA and to detect a second failure.

The tetrad error equations are derived by selecting pairs of triads fromeach of the tetrad combinations, such as:

3.

2. < ID,, u)0,1' 2' W5

and

and

and < uu, , IDO, ID,

, ID-, «)„5 6

93

and solving for p, q, and r in terms of the three rowed submatrix inverses

associated with each pair of triads. That is, for the selected pair of triads

from the first tetrad,

""l"u>2

J°3_

-u-

u>3

_"4_

=

=

~ 1 0 0

0 -Ca -Sa

CB SB 0

~1 0 0

CB -Ca -Sa

CACa -SACa Sa

P

qr

P

qr

the second tetrad

i

a)1

u,2

_*5_

~«>rtt>2

UU /i6

=

=

1 0 0

0 -Ca Sa

CB -SB 0

~1 0 0

0 -Ca Sa

-CaCA -CaSA Sa_ . _

P

qr

P

q

r

and the third tetrad,

"im4

_<v~W3~

^5

•"6

=

=

=

CB SB 0

CaCA -CaSA Sa

CB -SB 0

~CB SB 0

CB -SB 0

-CaCA -CaSA Sa

P

qr

P

qr

94

Taking inverses obtains for the first pair

p

qr

=

1 0 0

-CotB 0 Csc(B)

-CotaCotE Csca CotaCsc(B)

"l

U'2

"3

and

P

qr

=

1 0 0

-TanA SecA 0

-Cota SecA TanACota. Csca

u'l

U'2

U!4

for the second pair,

P

qr

1

CotB

Cota CotB

and for the third

pi

q = 2r

1CB1

SBCa SA CASa SB'CB"

0

0

C a

pair,

0

0

2

0

-CscB

-CotaC

and

1CB1

SBCa

CB SB Sa

l"3

"4

*5

and

^

q1

1CB1CR

CaCBSI

C-B

-k °. Ca_ SA CA 2

Sa SB " "CB Sa

In an ideal system, subtracting any two of the expressions for p, q, or

r in each tetrad should yield zero. Nonzero values are indications of gyro

(ID.) failures. The difference equations can, therefore, be identified as error

equations used to evaluate tetrad functional integrity. Subtracting the r terms

for each tetrad yield the following equations:

E- = Cota SecA (1-SinA) (tUo + w - , ) Csca (uu - u u . )

= Cota CscB

, = CotaCosASecB ((!)„ + u ) K ) +C adii. - u)c)o o b 4 b

Identical equations would be obtained (within a constant scale factor) if thep or q terms were subtracted and a nontrivial solution was produced (i. e. ,not a zero identity).

95

And for the angles as previously specified,

~El = 0. 58 (u^ + u ) g ) +0 .707 (uu2 - u»4)

E2 = -1.15 (iu1 + c u 5 ) + 1 . 4 1 4 («)2 - u j g )

E3 = -1.73 fog + a > 5 ) + 0 . 7 0 7 (u)4 - (i)g)

To minimize the software requirements, the equations would be scaled

such that one of the coefficients in each error equation would become unity.

To be capable of discriminating low-level (soft) failures from normal

input random noise, the E. equations are first integrated and squared before

comparison with an error tolerance equation for error detection. The error

tolerance equation is a second-order polynomial and its coefficients repre-

sent statistical sensor output error tolerances. The tolerance equations are

of the form:

T. = A. +B. t + C.t2

1 1 1 1

where,

A = constant, based on the covariance of the

scale factor and misalignment calibration

uncertainties, input axis geometry, and

worst case rates.

B = function of input axis geometry and

random walk bias covariance.

C = function of input axis geometry and con-

stant bias covariance.

If the inequality

E — r r T71, — 1 1 T J .1 J 1

t „A. +B. t + C.t

o - 1 1 1

exists, a failure is indicated in tetrad i.

96

These E. error equations are sufficient to isolate a first failure to one

of the three sets of two-axis ISA boxes and to detect a second failure to enablei i

subsystem shut-down. For example, if ui1 or U)0 failed, E1 and E wouldl i & i &exceed the precomputed tolerance level, and EQ would remain within tolerance.

•jThis isolates the failure to the [ID. , UIQ] ISA. An additional failure would cause1 ^all three error equations to exceed their tolerance levels.

When a sensor failure is indicated, the appropriate error flag is set for

use by the error response/action routine in the computer.

Gyro Selection and Orthogonal Computations

Two of the three two-axis ISA's are selected from which to compute a

best estimate of the components along the referenced triad (p, q, r). That is,

the tetrad is selected based on the error flag status as determined in the

error detection/isolation routine. If no failures are indicated, the tetrad

formed by ui.., iw , and ui_ , ui is selected for processing. This approach

minimizes the software memory and time requirements due to the resulting

consistent form of the equations.

Assuming the variance of each gyro is the same and given four measure-

ments, it can be shown that the best estimate of the reference triad compo-

nents (p, q, r) can be found by assuming measurements oh, uu , ui~, u) are forthis example,

p

qr

U)

where A is a constant matrix defined by the geometry of the hexad configura^tion. For this case,

97

A =

1

0

CB

CaCA

0

-Ca

SB

-CaSA

0

Sa

0

Sa

If the indicated matrix operations are carried out, equations of the

following form result:

p

q

r

K(3x4)

" f f l l

U12

U!3

U14

The matrix K is computed for each of the three selected tetrads and are

stored in constant memory. Selecting the corresponding four a> measurements

results in three sets of equations for p, q, and r. The failure flags determine

which set is to be used, and a subroutine is used to do the computations.

98

.

APPENDIX B

COMPUTER SYNCHRONIZATION

Figure B-l is a block diagram of the computer hardware synchronization

concept assumed for the study. A 2-MHz oscillator in each computer is

used to generate a 125-kHz ISA data transfer pulse rate signal, a 200-Hz data

strobe ISA input cycle pulse, and a 40-msec (25 Hz) clock pulse. The 40-msec

clock pulse is compared with the equivalent clock pulses from the other com-

puter channels to derive a 40-msec sync pulse used to synchronize the com-

puters, to reset and start the ISA input data timing counters (200-Hz and 125-

Hz clocks), and start the next 40-msec clock time count.

The 40-msec clock pulses are transferred between channels and sub-

jected to the clock sync generator and failure detection logic shown in Figure

B-2. This logic generates a valid sync pulse when two or three pulses from

the individual 40-msec clocks occur within a prescribed time interval (r),

which is derived from the 2-MHz oscillators, and reset each time a pulse is

received. If the time difference between the occurrence of the first and second

or second and third pulse is greater than T, failure discrete F. is generated.

If no two pulses occur during time T, two failure discretes (F1 and F?) are

issued. In either case, a 40-msec clock sync pulse is generated that syn-

chronizies the computers by releasing them from a "halt" condition entered at

the end of each 25 - Hz computation cycle. The derived 40-msec clock sync

pulse also synchronizes the 125- kHz, 200-Hz ISA data transfer timing signals

and resets/starts the 40-msec clock timer to generate the next 40-msec pulse.

The above operations occur simultaneously in each computer such that

all become synchronized to the same 40-msec clock.

99

CONTROL

TRAN'SI.;n • TRANSMITLOGIC REGISTER

|

. _ _ _.

HtXAU |Ct.,ELY

SERIALD A T A ^

•

12S *H.

200 «.

TWO AXIS- IMK1IAL SENSOK A c

r,,TA CONTROL1R?NS*.|T , AND''c'1 — ««|SMn

' t

SLI'.!I5LY

SLidAL

200 H.-

TV'.'O AXIS- INERTIAL SENSOR AS

naTA CONTROL

TRANSMIT » 1P.AAD..ITLOUL iUCISH.-R

" T

SEMSLY

SERIALDATA

»»

125 kH/

200 H^

n nrK ^

-CLOCK 1

^CLOCK 1

J

COMPUTER *

SERIALDIGITALINTERFACE

ik 1

1

1

-0 iMSEC

— 1 125

""

Hz

kHz

F,

-

1-

40 .-.SEC cCLOCK SYNC h2 ^AND HAILURt *DETECTOR - •-•»

RESET

PROCESSORAND

MEMORY

2 MHzOSC

1

COMPUTER •

SERIALDIGITALINTERFACE

i . i

1

P.

40raSEC LCLOCK p —

— 1 125

Hz

kHz h-

40 mSEC f

CLOCK SYNC 2 _ANU KAILUKt •

RESET

PROCESSORAND

MEMORY

2 MHzOSC

1

COMPUTER =3

SERIALDIGITALINTERFACE

140 miLCCLOCK

J 200

— | 125

Hz

(Hz

->

4 —

4

"x

^30 mSEC FTCLOCK SYNC ' fcAND FAILURE *

RESET

PROCESSORAND

MEMORY

2 MHzOSC

1

Figure B-l. - Computer Synchronization Concept

100

COUNTER RECEIVESCLOCK SYNCAND IS STOPPED

COUNTEIS RESET ANDSTARTS WITH

FIRSTPULSE

COUNTER RECEIVESSECOND PULSECOUNTER RECEIVES

SECOND PULSE

COUNTERIS RESET AND

STARTED

COUNTERIS RESET AND

STARTED

COUNTER RECEIVESTHIRD PULSE

COUNTER RECEIVESTHIRD PULSE

GENERATE FAILURES Fl AND F2IF NO CLK SYNC PRESENT(ANALOG BACK-UP)

INTERNAL I/O LOGIC

STARTS COMPUTATIONAL FRAME(HALT EXIT TO COMPUTER)

STARTS 40 mSEC CLOCK

NOTE - COUNTER IS DRIVERBY 2 MHz OSC

Figure B-2. - Sync Generator and Failure Detection Logic

ORIGINALOF POOR SJ0AIOTL

101

APPENDIX C

GENERAL SUBSYSTEM REQUIREMENTS FOR SHORT-HAUL AIRCRAFT

An operational requirement does not exist for inertia! navigation (I-Nav)

systems on short-haul aircraft because traditional attitude and area navigation

(R-Nav) equipment will be satisfactory. I-Nav systems would have to be cost

competitive with traditional attitude systems to be considered for short-haul

aircraft. The cost of ownership of conventional gimbaled I-Nav systems has

kept the I-Nav function from being seriously considered for short-haul appli-

cations even though there are realizable benefits in enroute and terminal navi-

gation. Figure C-l is a matrix relating general sensor output requirements

for short-haul aircraft to the traditional computational boxes that use the

sensor data and indicators for data display. The numbers shown in the

matrix indicate redundancy levels required for boxes and indicators. The

flight control mechanizations developed for the study as described in Section

III were based on the Figure C-l requirement summary.

Dispatch critical equipment refers to equipment that must be operating

before the aircraft can leave. Airlines have multipage procedures governing

the conditions for determining whether a particular piece of equipment is

dispatch critical for a given flight. These procedures vary from airline to

airline.

It is not believed that short-haul aircraft will be dispatched to a termi-

nal at a time when landings must be under Category II or Category III weather

conditions. Table C-l shows probable dispatch critical assignments for tra-

ditional flight control equipment of the type described in Section III (Figure

14). Table C-2 shows probable dispatch critical assignments for a strap-

down skewed redundant laser flight control system (Figure 15 of Section III).

It should be note'd-that the hexad that replaces the three-axis accelerometer

packages, flux gates, compass couplers, direction gyros, vertical gyros, and

three-axis rate packages is considered a di'spatch critical item as is most of

the equipment it replaces.

102

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OBIGINAIJ PAGE EJOF POOR QUALITV!

103

TABLE C-l. - TRADITIONAL FLIGHT CONTROL SYSTEMDISPATCH CRITICAL ASSIGNMENTS

No. of sensors

3

2

3

3

3

3

3

2

2

3

1i3

No. ofcomputational boxes

2

3

2

2

2

No. of displays

2

2

2

2

2

2

2

2

2

Type of Sensor

Central air data computers

Angle of attack sensors

3-axis accelerometer package

Flux gates

Compass couplers

Directional gyros

Vertical gyros

3-axis rate packages

• 3 yaw rate sensors

• 3 roll rate sensors

• 3 pitch rate sensors

VHH omni-directional radio

Distance measuring equipment

Instrument landing systems

Automatic direction finder

Radio altimeters

Type of computation box

High-speed yaw dampers

Flight control system electronics

Auto-throttle

Mach trim - auto trim

R-NAV computers

Type of Display

Airspeed

Total air temp

Mach

Altitude & h indicators

Horizontal situation indicators

Attitude director indicators

DME indicators

Radio Magnetic Indicators

R-NAV Displays

Dispatch critical

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

No

Yes

No

Dispatch critical

Yes

' No

No

No

Route dependent

Dispatch critical

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Route dependent

104

TABLE C-2. - STRAPDOWN LASER SKEWED REDUNDANT -DISPATCHCRITICAL ASSIGNMENTS

No. of sensors

3

2

1

2

2

3

1

3

No. ofcomputational boxes

2

3

2

2

2

No. of displays

2

2

2

2

2

2

2

2

2

Type of sensor

Central air data computers

Angle of attack sensors

Hexad

VHH omni- directional radio

Distance measuring equipment

Instrument landing systems

Automatic direction finder

Radio altimeters

Type of computational box

High-speed yaw dampers

Flight control system electronics

Auto throttle

Mach trim auto trim

R-NAV computers

Type of display

Airspeed

Total air temp.

Mach

Altitude and h indicators

Horizontal situation indicators

Attitude director indicators

DME indicators

Radio magnetic indicators

R-NAV displays

Dispatch critical

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Dispatch critical

YesaYes

No

No

Route dependent

Dispatch critical

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Route dependent

Those functions that are supplied to flight critical displays and the high-speed yawdamper are classified flight critical.

105

Airplane manufacturers are giving considerable attention to subsystem

groupings to determine whether these groupings make sense from a dispatch

critical point of view. For instance, the computer that is needed for the

I-Nav calculations could also perform the air data calculations as both func-

tions are dispatch critical.

106

APPENDIX D

LASER GYRO VERSUS FLOATED GYRO FORSTRAPDOWN INERTIAL SYSTEMS

Laser Gyro Versus Floated Gyro Performance

Figures D-l depicts the Honeywell GG1300 laser gyro and Figure D-2

depicts the Honeywell GG1009H strapdown floated rate integrating gyro. Table

D-l summarizes their relative performance characteristics. The laser gyro

has reaction time advantages because of its capability to achieve required per-

formance levels without temperature control or frequent calibrations. For

strapdown application, the performances of the floated gyro are marginal in

scale factor accuracy; as such, its maneuver and flight path envelope is

limited. The high scale factor accuracy capability of the laser gyro imposes

no such restriction.

Laser Gyro Reliability Versus Floated Gyro Reliability

The MTBF for the laser gyro and its built-in electronics is projected at

15, 000 hours while the MTBF for the floated gyro and its support electronics

is projected at 5, 700 hours.

The maintenance philosophy of airlines seldom provides for replacement

and preventive maintenance on electronic equipment. Equipment is repaired

and replaced only when it fails.

Figure D-3 shows a typical plot of device failure rate versus operating

time. The shape of the plot is based upon both laboratory conducted tests and

field observations. The curve is divided into three sections. Section A repre-

sents the failure rate during the infant mortality period. Infant morality fail-

ures are eliminated from operational considerations by burn-in tests. Section

B of the curve is essentially flat representing a period where the failure rate

is approximately constant. It is generally desired that this constant failure

107

SIGNAL & MONITORCONNECTOR

READOUT PWBASSEMBLY

HERMETIC SEALSURFACE

INPUT POWER CONNECTOR

CURRENT CONTROLAND DITHERPWB ASSEMBLY

LENGTH CONTROL' PWB ASSEMBLY

LASER BLOCKASSEMBLY

HOUSING

SIZE:

7 BY 8 BY 2 INCHES

WEIGHT:6.5 POUNDS

POWER:6.0 WATTS NOMINAL, 8.0 WATTS MAX.

MAXIMUM'INPUT RATE:± 400 DEG/SEC

SCALE FACTOR:

2 ll RAD/PULSE 1.574 ARC-SEC/PULSE

PATH LENGTH:43.13 CM (TOTAL); 5.66 INCHES PER LEG

NE LASER TRANSITION:0.6328 MICRON

LOCK-IN COMPENSATION:CAVITY ROTATIONAL DITHER

Figure D-l. - Honeywell GG1300 Laser Gyro Characteristics

108

oro

OCUDc•H

oStfT5(D

OTD

02oo<— (OO

4)S5O

IN

QQJ

6JO•H

En

OF POOR QUALM 109

TABLE D-l. - LASER AND FLOATED GYRO STRAPDOWNPERFORMANCE SUMMARIES

Parameter GG1300Laser gyro

GG1009HFloated gyro

Bias

Scale factor error

Operating temp.

Warm-up time

Calibration time

Alignment time

0. 01-0. 03 deg/hr

0. 001%

-65°F to 160°F

0 i

0

2-5 min

0. 01-0. 03 deg/hr

0. 01%

Controlled at180°F

10 min

5 min

2 min

110

portion of the curve be as long as possible. Section C of the curve represents

long term wear-out phenomena of the device.

B

OPERATING TIME

Figure D-3. - Device Failure Rate Versus Operating Time

Both the floated gyro and the laser gyro have a wear-out mechanism.

The wear-out mechanism for the floated gyro centers on the ball bearings and

results in a mean wear-out life of approximately 11, 000 hours. The wear-out

mechanism that limits lifetime in the laser gyro is the gas pumping action of

the cathode. To sustain the laser gas discharge, positive ions collide to pro-

vide electron emission. Some ions are trapped during this process and other

gas atoms are buried by the sputtered cathode material. Thus, when the dis-

charge is run, a small amount of helium and neon is pumped by the cathode.

Over a period of time, this results in reduced gas pressure and eventual gyro

failure. Based on accelerated life test results, estimates for the wear-out

life due to cathode pumping of recent technology gyros is 30, 000 hours.

As both gyros have long term wear-out mechanisms, the Curve C failure

rates shown in Tables D-2 and D-3 are applicable for the floated and laser

gyros respectively.

I l l

TABLE D-2. - FLOATED GYRO FAILURE RATES

1 floated gyro

1 gyro digitizer

1 temp, control

1 gyro loop electronics

Applicable fail rate

Failure rate, %/l, 000 hrs

Section B

5.0

2.8

1. 0

2. 0

10.8

Section C

11. 8

2.8

1.0

2.0

17. 6

TABLE D-3. - LASER GYRO FAILURE RATES

•

1 laser gryo and electronics

Applicable failure rate

Failure rate, %/l, 000 hrs

Section B

5. 1

5. 1

Section C

6. 66

6. 66

112

An approximate equivalent MTBF for equipment having both a random

and wear-out (normal) failure distribution can be computed using the following

equation:

(MTBF) equivalent =-T(1"e " '

where

^ = random failure rate (Curve B)

T = mean in hours of wear-out distribution

Using 5 percent per 1, 000 hours (random failure rate) and 11, 000 hours

(mean life) for the floated gyro yields the 11. 8 percent per 1, 000 hours failure

rate for Section C (Table D-2). The floated gyro electronics are treated

separately in Figure D-4.

Using 5. 1 percent per 1, 000 hours (random) and 30, 000 hours (mean

life) for the laser gyro yields the 6. 66 percent per 1, 000 hour failure rate for

Curve C (Table D-3). The laser gyro electronics shown in Figure D-5 are

included as part of the gyro.

If the gyros were replaced before they reached Section C of Figure D-3

(not normal airline maintenance philosophy), the Section B failures of Table

D-2 and D-3 would apply.

Laser Gyro ISA Costs Compared To Floated Gyro ISA Costs

The cost of ownership of a hexad ISA mechanized with laser gyros is

projected at 58 percent of the cost of a hexad ISA mechanized with floated gyros.

The direct maintenance cost of a laser hexad ISA is 34 percent of the cost of a

floated gyro hexad ISA.

113

BALANCED CURRENTHI- VOLTAGEEXCITATION

GYRO I j

DITHER I"DRIVE LH

D C S

TlPATHLENGTHCONTROL

.-- fe PRFAMP -* READOUT h

ANHIF

PULSES

Figure D-4. - Laser Gyro Self-Contained Electronics

114

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Tables D-4 and D-5 show how the MTBF and initial cost figures are cal-

culated for laser and floated gyro two-axis ISA's. Table D-6 shows a cost

summary for the two configirations based on Appendix E cost-of-owner ship

Computer Runs 4. 1 and 1. 2. 3.

116

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118

APPENDIX E

COST-OF-OWNERSHIP COMPUTER RUNS

1. 0 Kinematic System Computer Runs

1. 1 Kinematic System K-l

Run 1. 1. 1: 9 rate gyros

Run 1.1.2: 9 accelerorneters

Run 1.1.3: 3 vertical gyros

Run 1. 1. 4: 3 directional gyros

Run 1. 1. 5: 3 compass couplers

Run 1. 1. 6: 3 flux gates

1. 2 Kinematic System K-2

Run 1. 2. 1: 3 two-axis ISA's (laser life = 5, 000 hours)

Run 1. 2. 2: 3 two-axis ISA's (laser life = 10, 000 hours)

Run 1. 2. 3: 3 two-axis ISA's (laser life = 15, 000 hours)

Run 1. 2. 4: 3 two-axis ISA's (laser life = 20, 000 hours)

Run 1. 2. 5: 3 two-axis ISA's (laser life = 30, 000 hours)

Run 1. 2. 6: 3 two-axis ISA's (laser life = 40, 000 hours)

Run 1. 2. 7: 3 1C computers (kinematic-digital)

1. 3 Kinematic System K-3

Run 1. 3. 1: 3 two-axis ISA/IC's (kinematic-digital)

2. 0 Flight Control System Computer Runs

2. 1 Flight Control System FC-1

Run 2. 1. 1: 3 FC computers (analog input)

Ref run: K-l kinematic system (Runs 1. 1. 1 through 1. 1. 6)

2. 2 Flight Control System FC-2

Run 2. 2. 1: 3 FC computers (digital input)

Ref run: 1. 2. 3 (3 two-axis-ISA's)

Ref run: 1. 2. 7 (3 1C computers)

2. 3 Flight Control System FC-3

Ref run: 1. 3. 1 (3 two-axis ISA/IC's)

Ref*r,un: 2. 1. 1 (3 FC computers)

119

2. 4 Flight Control System FC-4

Run 2. 4. 1: 3 IC/FC computers

Ref run: 1. 2. 3 (3 two-axis ISA's)

3. 0 Inertial Navigation System Computer Runs

3. 1 INAV-1 system

Run 3. 1. 1: 3 gimbaled navigation boxes

3. 2 INAV-2 system

Run 3. 2. 1: 3 1C computers (INAV-ARINC)

Ref run: . 1. 2. 3 (3 two-axis ISA's)

3. 3 INAV-3 system

Run 3. 3. 1: 3 two-axis ISA/IC's (INAV-ARINC)

3. 4 INAV-4 system

Run 3. 4. 1: 3 1C computers (INAV-digital)

Ref run: 1. 2. 3 (3 two-axis ISA's)

3. 5 INAV-5 system

Run 3. 5. 1: 3 two-axis ISA/1C (INAV-digital)

4. 0 Hexad Inertial Sensor Assembly (Floated Gyros) Computer Run

4. 1 3 two-axis ISA's (floated gyros)

120

DESCRIBE UMIT

! RUN 1.1.1 9 RRTE GYROS'

nMGRIZRTION FRCTOPPRRTS POOL COSTOP. MRS TO FLT HRSRISK FHCTOR

0. 151. 0 01.502. 00

HR RRTE FOR LIME 9.52LIME HRS PER REMOVRL 0.50LES PER GRL FUEL 6.70S-L EURDEM P'ER CEMT 100.00

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DRYS PER YEftR 365.00

HR RRTE FOR SHOP 8.14DRYS TO REPRIR 7.00RRTIO RDDED FUEL 0.1333MO. OF RIRPLRNES 150.00

ENTER UNIT PRICE- IMSTRLLRTIDM PRICE! 1000., 100.

ENTER HRS BETWEEN FR1LUPE, SHOP HRS PER REMOVflL! 6400.- 1.5

ENTER LIMITS PER RIRPLRNE* LIMIT WEIGHT! 9., 1.67

ENTER RV. PRRTS COST PER FRILURE. FRIL-REMOVRL RRTIO! 340., .5

SYSTEM COSTNO. OF SPRRE LIMITS

RMMI.iRL. FLEET REMDVRLSRNNURL PLRNE PEMOVRLSREMOVRLS PER 1000 FLIGHT HRS

H-'PPTIZED IMITIRL COST

AMORTIZED SPRRE COSTS

FUEL COST

9000. 0052 . 5 0

2078.7913. 864.22

RMMI.IRLPLEETCOSTS

245024.97

3661.72

61335.66

RMNURLPLRNECOSTS

1633.50

57.74

412.57

1000FLT HRS

COSTS

497.26

17.58

125.59

DIRECT MRIMTEMRMCE COST* NEW MODULES OR REPRIR

* LIME MHIMTEMRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP RMD LIM.E

353394.12

..,.TOTRL.,..GOSt OF '-0WMERSH I P

* DIRECT MR INT COST

2355.96 717.19

9395. 0425332. 0135277. 05

739520.62

423943.25

65.97169.21235. 18

4930. 14

2826.. 32

20. 0851.5171.59

1500.80

360.37

^ORIGINAL PAGE ISOF POOR 121

DESCRIBE LIMIT

• RUN 1.1.2 9 RCCELERCMETERS

o. 151.001.502. 00

9.520.506.70

100.00

FRCTORPfiRTS POOL COSTDP. MRS TO FLT- MRSRISK FfiCTDR

MR RRTE FDR LI HELINE MRS PER PEMOVRLLBS PEP GRL FUELS-L BURDEN PEP CENT

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLDN 0.42OP. DfiYS PER YERP 365.00

HP *RTt FOR SHOP . 9.14DRYS TO PEPRIR 7.00RRTIO RDOEB FUEL U.I333HO. OF RIRPLRNES 150.00

ENTER HRS BETWEEN FRIL.UPE. SHOP HRS PEP REMOVRL! 96700.. 1.5

ENTER UNITS PEP RIPFLRNE. UNIT WEIGHT! 9.r .5

ENTER RV. PRPTS COST PER FRILURE- FRIL-REMQVRL RRTID! 340..

SYSTEM COST •3 f i o n . n nNO. DF SPRRE UNITS 5.39

HNNURL FLEET REMOVRLS 137.53rlHNLIRL PLRNE REMOVRLS 0.92REMOVRLS PEP 1000 FLIGHT HRS 0.23

RNHURLFLEET

RMOPTI

RMORTI

FUEL C

ZED INITIRL COST

ZED SPRPE COSTS

OST

COSTS

36196-3. 69

971.41

13528.65

RNNURLPLRNECOSTS

2413. 12

6 . 43

133.52

J OOfiFLT HRS

COS

734.

1.

-' f m

TS

59

97

60

DIRECT MRINTENRNCE COST* NEW MDInJLES OP REPRIR

* LI HE -,P1H INTENRHCF* SHOP' T1DPULE REPLRCEMT* BURDEN-SHOP RND LINE

rOTriL COST DF OWNERSHIP

DIRECT MR I NT COST

23339. OT 155.93 47.47

654.1679.2354.

409527.

23053.

393973

25

or.

4.11.15.

£730.

137.

3720 ..57

16

06

1.3.4.

331 .

5-.

334174

11

94

122

urnr

• RUN 1.1.3 3 VERTICflL GYRO

RHDRIZflTION FfiCTOR 0.15PftRTS POOL CDST 1. 00DP. MRS TO FLT HRS 1.50RISK FflCTDP £. 00

HP PflTE FDR LINE 9.5£LIME HRS PEP REMOVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 1 0 0 . 0 0

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DRYS PER YERR 365.00

HR RRTE FOR SHOP 3. 14DRYS TO REPRIP 7. 00RRTIO RDDED FUEL 0.1333NO. OF RIPPLRNES 150.00

ENTER UNIT PRICE? INSTRLLRTIDH PRICE! 6200., 1620.

ENTER HRS BETWEEN FRILURE. SHOP HRS PER REMOVRL! 3000.. £.

ENTER UNITS PER RIRPLRNE. UNIT WEIGHT! 3., £0.

ENTER RV. PRRTS COST PEP FRILURE. FRIL-REMOVRL RRTID! 1311.- .5

SYSTEM COSTNO. OF SPRRE UNITS

RNNURL FLEET REMOVRLSRNNURL PLRNE REMOVRLSREMOVRLS PER 1000 FLIGHT HRS

RMDRTIZED INITIRL CDST

AMORTIZED SPRRE COSTS

FUEL COST

lob UU. UU39. 00

14 78. £59.353.00

RNNURLFLEETCOSTS

530634.37

39395.91

£47048.69

RNNUfiLPLRNECOSTS

3370.90

£65. ? 7

1646. 99

1 0 0 0FLT HRS

COSTS

1173. 36

30.97

501.37

DIRECT MRINTENRNCE CDST* NEW ilDDULES DP PEPRIP 1333555.50

» LINE MRINTENRNCE 7036.47* SHOP MODULE PEPLRCEMT £4065.91» BURDEN-SMBP RND LINE 31102.38

TOTRL CDST OF OWNERSHIP ££68340.00

46.91160.44£07.35

151££.£7

£716.50

14. £343.8463. 1£

4603.43

DIREG^'-MRINT COST 1400760.£5 9333.40 £84£.74

123

DESCRIBE UNIT

! RUM 1.1.4 3 DIRECT IGNrlL GYROS

HriQRIZRTIDN FRCTOP 0.15PRRTS PDDL COST 1.00OP. MRS TD FLT HRS 1.50RISK FRCTPP £. 00

MR RRTE FDR LIME 9.52LIME MRS PEP REMDVRL 0.50LFS PER GRL FUEL 6. 70S-L EURDEM PEP CENT 100.00

BORROWED MONEY COST i. i oDRILY FLIGHT HGURS 9.00FUEL PRICE PEP GRLLON 0.42DP. DRY'S PER YERP 365. 00

HP RRTE FDR SHOP 3.14DHYS TD PEPRIR 7.00RRTID RDDED FUEL 0. 13.53f-iQ. OF RIRPLRNES 150.00

ENTER UNIT PRICE- INSTRLLRTIDN PRICE! 3300.- 50.

ENTER MRS BETWEEN FRILURE. SHOP HRS PER REMDVRL! 7700.- 3.

ENTER UNITS PER RIPPLRNE- UNIT I..JEIGNT! 3.. 14.

ENTER RV. PRRTS CDST PER FRILURE. FRIL-REMQVRL RRTID! Id36..

SYSTEM LOSTNO. uP SPRRE UNITS

RNNURL FLEET REMDVPLSRNNURL PLRNE REMDVRLSREMDVRLS PER lOnO FLIGHT HR::

1140i

RMOPTIZED INITIRL CDST

RMORTIZED SPRPE COSTS

FUEL CDST

DIRECT MRINTENRNCE CDST* NEW MODULES DP REPRIR

* L INE MRINTENRNCE* SHOP MODULE PEPLRCEWT*'BURDEN-SHOP RND LINE

TOTRL CDST DF OWNERSHIP

17. 69

3.341.17

•-

1

HNN'JRLFLEETCOSTS

85862.44

11093. 13

7 £93 4. 00

RNNURLPLRNECOSTS

1905.75

73 . 95

1152.89

1 0 0 0FLT HPS

COSTS

530. 14

££.51

350. 96

355931.87

£741.439376.33

1 £117.81

850057.1£

£372.88

18. £86£.5130.79

5667.05

7££.34

19. 03£4.59

1725. 13

DIRECT MRINT CDST 330167.50 £534.45 771.52

124

DESCRIBE UNIT

• RUM 1.1.-5 3 CDMPflSS COUPLERS:

RMOPIIRTION FftCTDR ' 0.15PRRTS POOL COST 1.00OP. HRS TO FLT HPS 1.50RISK FRCTOR 2.00

HR PRTE FOR LIME 9.5£LIME HRS PER REMOVRL 0.50LES PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER 6RLLOM 0.4,?QP. DflYS PER YERR 365.00

HR RRTE FOR SHOP 8. 14DRYS TO PEPRIP 7. 00RRTID RDDED FUEL 0.1333MO. OF RIRPLRNES 150.00

ENTER UNIT PRICE* INSTRLLRTIDM PRICE! 4£00., 1415.

ENTER HRS BETWEEN FRILUPE- SHOP HPS PER REMOVRL! 85GO.. 1.

ENTER UNITS PER RIRPLRNE. UNIT WEIGHT! 3.• 3.6

ENTER RV. PRPTS COST PER FRILUPE? FRIL-REMOVRL PRTID! 500..

SYSTEM COSTNO. DF SPRRE UNITS

RNNURL FLEET REMOVRL SRHNURL PLRNE PEMOVRLSREMOVRLS PEP 1000 FLIGHT HPS

RMOPTIZED INITIRL COST

RMOPTIZED SPRRE COSTS

FUEL COST

1 £ i-. i'i f 1 . fl i'i

5£1.743 . 431 . 06

RNNURLFLEETCOSTS

416913.69

11313.23

1 06230. 39

RNNURL. 1000PLRNE FLT HRSCOSTS COSTS

£779.42 346.10

75.46 ££.97

708.21 £15.59

DIRECT MRINTENRNCE COST* NEW MODULES .QP PEPRIR

* LINE MRINTENRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP RND LIME

TOTRL COST OF OWNERSHIP

0433.

£433.4246.6730.

31

4692J '•-•

369.

16.23.44.

56

563137

264.

5.C''— ' .

13.

71

046266

673357.50 45££.3S 1376.68

DIRECT MR INT COST 143394.59 95'r1. 30 £9£.0£

PAGE ISPOOR

125

DESCRIBE UhlT

• RUN 1.1.6 3 FLUX GRTES

RMORIZRTIDN FfiCTDR 0.15PRRTS POOL COST 1.00DP. HRS TD FLT HRS 1.50RISK FRCTOP £.00

HR PRTE FOP LIME 9.52LINE HRS PER REMOVAL 0.50LES PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.4£DP. BRYS PER YEftR 365.00

HR RRTE FOR SHOP 8.14DRYS TD REPRIR 7. 00RRTIO RDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE, INSTRLLfiTION PRICE! 600., 900.

ENTER HPS BETWEEN FRILUPE, SHOP HRS PEP REMOVRL! 180000.. .5

ENTER UNITS PEP RIRPLRNE, UNIT WEIGHT! 3., £.

ENTER RV. PRPTS COST PEP FRILURE, FRIL-REHDVRL RRTIO! 600.,

SYSTEM COSTNO. OF SPRRE UNITS

.RNNURL FLEET. PFMOV'RLSRNNURL PLRNE REMOVRLSREMDVRLS PER 1000 FLIGHT HRS

RMDRTIZED INITIRL COST

AMORTIZED SPRPE COSTS

FUEL COST

laOO. 001 . 35

£4 . 640. 160. 05

RNNURLFLEETCOSTS

111374.93

13 £.3 3

£4704.86

RNNURLPLRNECOSTS

742.50

!.££

164.70

1000FLT HRS

COSTS

££6. 03

0.37

50. 14

DIRECT MRINTENRNCE COST* NEW MODULES DP PEPRIR

* LINE MRINTENRNCE» SHOP MODULE REPLRCEHT* BURDEN-SHOP RND LINE

TOTRL COST OF OWNERSHIP

7391. £5

11 7. £7100. £7£17.55

144039.09

49. £7

0. 730. 671.45

960.59

15. 00

U.£40. £' 00.44

£9£.4£

DIRECT MRINT COST 73£6.35 5£. 18 15.38

126

DESCRIBE UNIT

! PUN 1.2.1 3 TWO-RXIS ISR'S LRSER LIFE = 5« 000 MRS

RMDRIZRTIDIS FflCTDP 0.15 BORROWED MONEY COST 1.10PRRTS POOL COST i.oo DRILY FLIGHT HOURS 9.00DP. HRS TO FLT HRS 1.50 FUEL PRICE PER GRLLOh 0.4£RISK FRCTOR £.00 DP. DRYS PER YERR 365.00

HR PriTE FOP LINE 9.5£ HR RRTE FDR SHOP 3.14LIME HRS PER PEMOVRL 0.50 DRYS TD REPRIR 7.00L£S PER GRL FUEL 6.70 RRTIO RDDED FUEL 0.1333S-L BURDEN PEP CENT 100.00 MO. OF RIRPLRMES

FNTF.P UNIT PRI-CF. INSTRLLRT10H PRICE! 17410.) 655.

EfiTEP HPS BETWEEN FRILURF* SHOP HRS PER REMQVRL! 1904. , 7.

ENTER UNITS PEP RIRPLRNE- UNIT WEIGHT! 3.» 34.5

ENTER RV. PRPTS COST PER FRILURE, FRIL-REMDVRL RRTIO! 1033..

SYSTEM COSTND. OF SPRPE UNITS

riNNURL FLFET PFMDVRLSHNNURL PLRNE PENOVRLSREMDVRLS PEP 1000 FLIGHT HRS

RMDRTIZED INITIHL COST

RMORTIZED SPRPE CDSTS

FUEL COST

3££>;0. 0053. 04

£3-29. 1315.534. 73

RNNURLFLEETCOSTS

1341356. 00

166717.41

4£6153.87

RNNURLPLRNECOSTS

8942. 17

1 1 1 1 . 45

£341. 06

1000FLT HRS

COSTS

£7££. 1£

333.34

364 . 86

DIRECT MRIHTENRNCE CHST» NE!.i MODULES OP PEPRIP 1£03019.00 8020.13 £441.44

* LINE MHlNTENPMCE 11086.87 73.91 ££.50» SHOP MODULE REPLRCEMT 13£716.4i 334.73 £69.34* EUPDEH-SHOP RHD LINE 143803.£8 958.69 £91.34

TOTRL COST OF OWNERSHIP 3424828.0-0 £2832.19 6950.44

» DIRECT MR TNT COST 1490625.50 9937.50 3055.12

OEIGINAL PAGE ISPOOR QUALITY 127

DESCRIBE UNIT

! RUN !.•£.£• 3 TWO-RXIS ISR'S

rtflGPTZRTION FRCTDR 0.15PRRTS POOL COST 1.00np. HPS TD FLT MRS 1.50RISK PRCTDR 2. 00

HP RRTE FDP LINE 9.53L I N E H P S PER R E h C V RL 0. 3 0LBS PER bHL FUEL 6.70S - L B U P D E H P E R C E N T 1 0 0. 0 0

LHStK! LIt-E - 10; HPS

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER' GRLLOH 0.4,3DP. DRYS PEP YERR 365.00

HP PRTE FOR SHOP 3.14DRY'S TO RE PR IP 7. 00RRTIQ RDDED FUEL 0.13?3NO. OF RIRPLRHES 150.00

ENTER HRS BETWEEN FRILUPE- SHOP HRS PER REMOVRL! 3077. . 7.

ENTER UNITS PEP RIRPLRNE. UNIT WEIGHT! 3.. 34.5

ENTER RV. PRPTi' COST PER FRILURE- FRIL-PEMOVRL RRTIO! 930..

SYSTEM COSTNO. OF SPRPE UNITS

RNNURL FLEET REMDVRLS^NNURL. PLRNE PEMOVRLSREMDVRLS PEP 1000 FLIGHT HP::

RMOPTIZED INITIRl. COST

Rr^aRTIZED SPHPE COSTS

FUEL COST

DIRECT M ft IN T E N RhCE C0S T» NEW MOLULES DR PEPHlR

* LINE riRINTENhf-iCE» SHOP MODULE REPLRCEMT* BURDEN-SHOP RND LINE

TDTRL COST'OF OWNERSHIP

5£'c'-:0. 0033. 16

H-NNIJRL

FLEETCOS

1341336.

1 09607 .

436153.

TS

0 0

14

.-, -7

HNNURLPLRNECOSTS

3942.17

730.71

£341. 06

1 0 0 0.-L.T HRS

COSTS

37£3. 13

333. 44

364 . 36

4467.90

45. 74547.49

1360.09

DIRECT flHTNT COST 343151.37 5654.34

128

DESCRIBE UNIT

! PUN 1.£.3 3 T;...in-RXIS ISR'S

HMDRIZRTION FhCTGRFRRTS POOL COSTOP. HPS. TG FIT HPSRISK FKCTDR

HR P.RTE FGP LINELIME HPS PEP PEMPVRLLES PEP oRL FUELS-L BURDEN PEP CENT

0.151 . 001.50£. 00

SEP LIF£ = 000 HP I:

DRILY FLI-5HT HOURS 9.00FUEL PRICE PER GRLLQN 0.42OP. DRY'S PEP YERR 365.00

HP RRTE FOP SHOP 3.14DRYS TO PEPRIR 7. 00SRTID nDDED FUEL. 0.1333N,l, ijF RIPPLRNES 150.00

•ENTER UNIT PRICE. I h ":THL LHTIOM PRICE! 17410. « 655.

ENTER HPS EETi.iEEN FRILURE- SHOP HPS PER REMOVRL! 3>:t l.j 7.

ENTER UNITS PER RIRPLHNE. UNIT HEIGHT! 3.-. 34.5

ENTER PV. PRRTS COST PER FHILURF. FHIL-PEMDVRL PRTID! 361..

SYSTEM C3STND. DF SPRPE UNITS

Rr-iMUflL FLEET PEMDVRL SRNMURL PLRNE REMDVRLSPEMDVHLS PER 1000 FLIGHT HP

5c'?:30. 00

rif1DRTI?EB INITIRL COST

drinPTIZEP SPRRE- COSTS

FUEL COST

DIRECT MRINTENRNCE COST* NEW MODULES OP REPRIR

* LINE MRIhTENRMCE* SHOP MODULE PEPLflCEWT* BURDEM-SHOP RMD LIME

TOTHL COST OF OWNERSHIP

31.41

1143.60

RNMURLFLEET-COSTS

1341336. 00

•90343.61

436158.37

RNrjURLPLRNECOSTS

3943. 17

6 0 1 . 63

3841 . 06

1 0 0 0FLT HPS

COSTS

2723. 13

1 3'3 . 1 4

864. 36

4-94472. 87

5467.3465447.307 0914.64

2494030.50

3296.49

36.45436.32472.76

16626.87

1 00--:. 50

11.10132.32143.92

5061.45

* DIRECT MR I NT COST 636302.12 ;. 01

129

DESCRIBE UNIT

RUN 1 . £. 4 3 TWO-RXIS ISR'S LRSER LIFE = £0? 000

RMOPIZRTION FflCTDP 0.15PRRTS POOL COST 1.00QP. MRS TD FLT HPS 1.50RISK FRCTOP £.00

HP RRTE FOP LINE 9.5£LINE HPS PER REMDVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER 6R|_LON 0.4£DP. DRYS PER YERR 365.00

HR RRTE CDR SHOP 3.14DRYS TD REPRIR 7.00RRTIO RDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE- INSTRLLRTION PRICE! 17410.. 655.

ENTER HRS BETWEEN FRILUREj SHOP HRS PER REMOVRL! 4444.. 7.

ENTER UNITS PER RIRPLRNE* UNIT WEIGHT! 3.- ?4.5

ENTER RV. PRRTS COST PER FRILUPE* FRIL-REMOVRL RRTIO! 809..

DIRECT MRINTENRNCE COST» NEW MODULES OR REPRIR 403658.06

» LINE MRINTENRNCE 4750.09+ SHOP MODULE REPLRCEMT 56861.40«• BURDEN-SHOP RND LINE ' 61611.49

TDTRL COST OF OWNERSHIP £374477.50

£691.05

31.673T9.03410. 74

15829.85

.5

SYSTEM COSTNO. OF SPRRE UNITS

RNNURL FLEET PEMOVRLSRNNURL PLRME PEMOVRLSREMDVRLS PER 1000 FLIGHT HPS

RMDPTIZED INITIRL COST

RMDRTIZEIi SPRRE COSTS

FUEL COST

5££30. 00£7.89

997.9£6.65£. 03

RNNURLFLEETCOSTS

13413£6. 00

30111.31

4£6158. 87

RNNURLPLRNECOSTS

894£. 17

534. 03

£34 1 . 06

1 0 0 0FLT HRS

COSTS

£7££. 1£

16£.5S

864.36

319.19

9.641 15.401£5.04

4318.33

» DIRECT HfllhT COST 526881.00 3512.54 1069.£7

130

DESCRI BE UNIT

! RUN 1.2.5 3 TWO-RXIS ISR'S

RMDRIZflTION FRCTOP 0.15PRRTS POOL CDST 1.00OP. HRS TO FLT HRS 1.50RISK FflCTDR 2.00

HR RRTE FDR LINE 9.52LINE HRS PER PEMDVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 100.UU

LRxEK LlFh = 30-000 HRX

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DRY'S PER YERR 365.00

HP RRTE FOR SHOP 3.14DRYS TO REPRIR 7.00RRTID HDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE- INSTflLLRTIGN..PRICE! 17410.- 655.

ENTER HPS BETWEEN FRILUPE, SHDP MRS PER REMDVRL! 5203.- 7.

ENTER UNITS PEP RIPPLRNE. UHTT HEIGHT! 3.j 34.5

ENTER RV. PRRTS COST PEP FRILUPE. FfilL-PEMDVRL RRTIO! 742.- .5

SYSTEM COSTNO. DF SPRRE UNITS

RNNURL FLEET PEMDVflL SRNNURL PLRNE REMOVRuSREriDVRLS PER 1000 FLIGHT HRS

AMORTIZED INITIRL CDST

RMDRTIZED SPRPE COSTS

FUEL COST

52230. 0024.41

351.535. 631.73

RNNURLFLEETCOSTS

1341326. 00

70129. 66

4:26153.37

RNNLIfiLPLRNECOSTS

3942. 17

467.53

2341. 06

1000FLT HRS

COSTS

2722. 12

142.32

364.36

DIRECT MRINTENRNCE COST* NEW NODULES OR REPRIR 315916.31

* LINE MRINTENRNCE 4053.27* SHOP MODULE PEPLRCEMT 43519.93» BURDEN-SHOP fiND LINE 52573.24

TOTRL COST OF OWNERSHIP 2258677.50

21 06. 11

27. 02323.47350.49

15057.35

3.2393.47106.69

4533.32

» DIRECT MR I NT COST 421062.31 2307.09 354.52

131

DESCRIBE UNIT

• RUN 1.2.6 3 TWO-RXIS ISR-'x

RMDRIZRTIDN FRCTDR 0.15PRRTS PDDL COST 1.00DP. HPS TD PLT HPS 1.50RISK FRCTOR £.00

HP PflTE FDR LINE 9.52LINE HPS PEP PEMDVRL 0.501_BS PEP GRL FUEL 6.70S-L BURDEN PEP CENT 100.00

LRSER LIFE = 40?000 MRS

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLDN - 0.42OP. DRYS PER YERR 365.00

HR RRTE FDR SHOP 8.14DRYS TO REPRIR 7. 00RRTID RDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE? INSTRLLRTION PRICE! 17410.? 655.

ENTER HPS BETWEEN FRILURE? SHOP HRS PER REMOVRL! 5714.j 7.

ENTER UNITS PEP RIPPLhNE? UNIT WEIGHT! 3.> 34.5

ENTER RV. PRRTS COST PER FRILURE- FRIL-REMOVRL RRTID! 693.. .5

SYSTEM COSTNO. OF SPRPE UNITS

hNNURL FLEET REMOVRL SHNNURL PLRNE REMOVRLSREMOVRL S PER 1000 FLIGHT HRS

RMOPTIZED TNITIRL COST .

AMORTIZED SPRPE COSTS

FUEL COST

52230. 00££.60

776. 125.171 . 58

HNNURLFLEETCOSTS

1341326. 00

64923. 54

426158.87

••

HNNURLPLRNECOSTS

8942. 17

432.82

2841 . 06

1 0 00FL T HRS

COSTS

2722. 12

131.76

864 . 86

DIRECT MhlNTENRNCE COST* NEW MODULES OR PEPRIR

* LINE MRINTENRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP RND LINE

TjTRL COST QF OWNERSHIP

3694.3344223.3147917.64

2199109.50

1805.77

£4.63294.3£319.45

14660.73

549.70

7.5039 . 75

4462 . 93

* DIRECT MR I NT COST 366701.19 £444.67 744. 19

132

DESCRIBE UNIT

! RUN 1.2.7 3 1C COMPUTERS

HMDRIZRTION FRCTDP 0.15PRRTS POOL CDST 1.00DP. HPS TD FLT HRS 1.50RISK FRCTDR 2.00

HR RRTE FDR LINE 9.52LINE HRS PER REMOVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

CKINEMRTIC-DIGITRL.:'

BORROWED MONEY CDST 1.10DRILY FLIGHT HOURS 3.00FUEL PRICE PEP GRLLON h.42DP. DRYS PER YERR 365.00

HR RRTE FOR SHOP 8.14DRYS TO REPRIR 7.onPRTID RDDED FUEL • 0.1333NO. QF RIPPLRNES 150,00

ENTER UNIT PRICE? INSTRLLRTION PRICE! 14430.? 2000.

ENTER HPS BETWFFN FRILURE? SHDP HRS PER PEMDVRL! 56£0.? .5

ENTER UNITS PER RIRPLRNE? UNIT WEIGHT! 3.? 13.

ENTER RV. PRRTS CDST PER FRILURE? FRIL-REMOVRL RRTID! 440.?

SYSTEM CDSTNO. OF SPRPE UNITS

HNNURL FLEET PEMDVRLSRNNURL PLRNE PEMOVRLSREMOVRLS PEP 1000 FLIGHT HRS

RMDPTIZED INITIRL CDST

RMOPTIZED SPRRE CDSTS

FUEL CDST

43440. 0022 . 9 1

739. 105.261.60

RNNURLFLEETCDSTS

liu:-:639. 75

54745.63

2,22343. 31

RNNURL 1000PLRNE FLT HRSCDSTS COSTS

8157.60 2433.29

364.97 11) . 10

1432.29 451.23

DIRECT MRINTENRNCE CDST* NEW MODULES OP REPRIR 173602.£3

» LINE MRINTENRNCE 3756.12» SHDP MODULE REPLRCEMT 3211.64* BURDEN-SHOP RND LINE 6967.76

TOTRL COST OF OWNERSHIP 1633267.00

1157.35

25. 04£1.4146.45

11255.11

352.31

7. 626.5214. 14

3426.21

* DIRECT MRINT CDST 1250.25 330.59

ORIGINAL PAGE ISPOOB 133

DESCRIBE LIMIT

2 RUN 1.3.1 3 TWD-flXIS ISR/IC'S (KINEMflTIC-DIGITRL)

RMDRIZflTIDN FflCTORPRPTS PDDL COSTDP. MRS TD FLT MRSRISK FflCTDR

HP PRTE FOP LINELINE MRS PER REMOVRLLBS PEP GRL FUELS-L BURDEN PEP CENT

0.15 BORROWED MONEY COST1.00 DRILY FLIGHT HOURS1.50 FUEL PRICE PEP GflLLOM2.00 DP. DflYS PER YEfiR

9.52 HR RRTE FOR SHOP0.50 DRYS TO REPflIP6.70 RRTIO RDDED FUEL

100.00 NO. DF RIRPLRNES

1. 109. 000.42

365. 00

8. 147.00

0. 1333150. 00

ENTER UNIT PRICE, INSTALLATION PRICE! £3900., 2000.

ENTER MRS BETWEEN FfllLUPE

ENTER UNITS PER RIPPLR^E,

ENTER RV. PRPTS COST PEP

SYSTEM COSTND. DF SPRRE UNITS

RNNURL FLEET REMDVRLSRNNURL PLRNE PEMOVRLSREMDVRLS PER 1000 FLIGHT

RMORTIZED INITIRL COST

AMORTIZED SPRPE COSTS

FUEL COST

DIRECT MRINTENRNCE COST* NEW MODULES DP PEPfilR

* LINE MRINTENRNCE+ SHDP MODULE PEPLRCEMT* BURDEN-SHOP RND LI HE

, SHDP HRS PER PEMOVftL! 2457., 7.

UNIT WEIGHT! 3. , 40.5

FRILUPE, FRIL-REMOVftL RflTIO! 716.,

36700. 0046.33

1804.95'l2. 03

HRS 3 . 66

RNNURL - RNNURLFLEET PLRNECOSTS COSTS

2294324.50 15295.50

221174.16 1474.49

500273.56 3335.16

646170.37 4307.80

8591.54 57.28102845.77 685.64111437.30 742.92

.5

1000FLT HPS

COSTS

4656. 16

448.86

1015.27

1311.36

17.44£03. 72226. 15

TDTRL COST DF OWNERSHIP

+- DIRECT MR INT COST

3334817.50

869045.00

25898.79

5793.63

7883.95

1763.66

134

DESCRIBE UNIT

• RUM 3 FC COMPUTERS

RMOPIZPTION FPCTOP 0.15PRRTS POOL COST 1.00OP. HPS TO FLT HRS 1.50RISK FRCTOR £.00

HR RRTE FDR LINE 9.52LINE HRS PER REMOVRL 0.50LBS PER GPL FUEL 6.70S-L BURDEN PEP CENT 100.00

<RNRL06 INPUTS.)

BORROWED MONEY COST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DRYS PEP YERR 365.00

HR RRTE FOR SHOP 8.14DRYS TO REPRIP 7.00RRTID RDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE. INSTRLLPTION PRICE! £1900.. £100.

FNTER HRS BETWEEN FBILURE- SHOP HRS PER REMDVRL! £693.? .5

ENTER UNITS PEP PIRPLRNE. UNIT WEIGHT! 3.. £5.

ENTER RV. PRPTS COST PER FRILURE, FRIL-REMOVRL RPTID! 4£3.-.

SYSTEM COSTNO. OF SPRPE UNITS

RNNUPL FLEET PEMOVRLSHNNUPL PLPNE REMOVRLSREMDVPLS PEP 1000 FLIGHT HPS

HfluRTIZED INITIRL COST

RMOPTIZED SPRPE COSTS

FUEL COST

65700. 004£.75

1643.7210.963 . .34

RNNUhLFLEETCOSTS

1781999.75

154486. 06

303810.75

flNNURLPLRNECOSTS

1 1830. 00

1029.91

£058.74

1000FLT HRS

COSTS

3616.44

313.52

6£6.71

DIRECT MRINTENPNCE COST* NEW MODULES OP REPPIR 347646.£5

«• LINE MPINTENRNCE 73£4.09* SHOP MODULE REPLRCEMT 6689.93» BURDEN-SHOP PND LINE 14514.03

TOTPL COST OF OWNERSHIP 2621971.00

£317.64

52. 1644. 6 096.76

17479.31

705.52

15.3313.58£9.46

5321.10

DIRECT MRINT COST 576674.31 £511.16 764.43

135

DESCRIBE LIMIT

! RUN 2.2.1 3 FC COMPUTERS v'DIGITRL INPUT.?

RMDRIZRTION FRCTDP 0.15PRRTS POOL COST 1.00DP. MRS TO FLT MRS 1.50RISK FRCTOR £. 00

HP PRTE FDR LINE 9.52LINE HRS PER REMDVRL 0.50LBS PER GRL FUEL 6.70S-L EUPHEN PEP CENT 100.00

ENTER UNIT PRICE. TNSTRLLRTIDN

ENTER HRS BETWEEN FBI LURE, SHOP

ENTER UNITS PER RIPPLRNE, UNIT

BORROWED MONEY COSTDRILY FLIGHT HOURSFUEL PRICE PEP GRLLONDP. DRYS PEP YERR

HR RRTE FOP SHOPDRY'S TO REPRIRRRTIO PDHED FUELNO. OF RIPPLRNES

PRICE! ££460.? £100.

HPS PER REMOVRL! £599., .5

WEIGHT! 3.» £6.5

ENTER RV. PRPTS COST PER FRILURE, FRIL-REMOVRL RRTID! 413..

SYSTEM COSTNO. OF SPRPE I,INITS

RNNLIRL FLEET PEMOVRLSRNNURL PLRNE REMOVRL SREMOVALS PEP 1000 FLIGHT HRS

RMORTIZED INITIRL COST 1

RMORTIZED SPRPE COSTS

FUEL COST

DIRECT MRINTENRNCE COST* NEW MODULES OR REPflIP

» LINE MPINTENRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP PND LINE

67380. 0044. 17

1706.331 1 . 333 . 4 6

RNNURL RNNURLFLEET PLRNECOSTS COSTS

823579 . 75 1 £ 1 57 . £ 0

163671.50 1091.14

327339.50 2132.26

356622.87 £377.49

31 ££.13 54.156944.76 46.3015066.39 100.45

1.109. 000.4£

365. 00

8. 147. 00

0. 1333150. 00

.5

1 0 0 0FLT HPS

COSTS

3700

332

664

723

161430

.32

. 16

. 31

.74

. 43

. 09

. 53

TOTRL COST OF OWNERSHIP £701348.00 18 008.99 5482. 19

* DIRECT MR INT COST 336756.62 £573.38 734.35

136

DESCRIBE UNIT

• RUN £.4.1 3 IC.''FC COMPUTERS

RrtORIZRTICN FRCTOR 0.15PRRTS PDDL COST 1.00DP. HRS TO FLT MRS 1.50RISK FfiCTDP 2.00

HP RRTE FDR LINE 9.5£LINE HRS PER REMDVRL 0.50LES PER GRL- FUEL 6.70S-L BURDEN PER CENT 100.00

BORROWED MONEY COST 1. 1 0DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42DP. DRYS PER YEflP 365.00

HR RRTE FDR SHOP 3.14DRYS TO REPRIR 7. 00RRTID RDDED FUEL 0.1333ND. DF RIPPLRNES 150.00

ENTER UNIT PRICE? IHSTRLLRTION PRICE! 31010.? 3000.

ENTER MRS BETWEEN FRILURE, SHOP HRS PEP REMOVRL! £146., .5

ENTER UNITS PER RIPPLRNE» UNIT WEIGHT! 3.> 30.5

ENTER RV. PRRTS COST PEP FRILURE. FRIL-REMOVRL RRTIO! 434.,

SYSTEM CDSTND. DF SPRRE UNITS

RHNURL FLEET PEMDVRl SRNNURL PLRNE REMDVRL SREMDVRLS PER 1000 FLIGHT HRS

RMOPTIZED INITIRL CDST

RNDRTIZED SPRPE COSTS

FUEL CDST

93030. 00er -. -i •-,•-'!_• C C

£ 066.521 3 . 784.19

RNNURLFLEETCOSTS

£5£5£4£. 00

£67£04.94

376749. 19

RNNURLPLRNECOSTS

16834.95

1731.37

£511.66

1 0 0 0FLT HRS

COSTS

51 £4. 79

542.27

764.58

DIRECT MRINTENRNCE COST

* NEW MODULES DP REPRIR

* LINE MRINTENPNCE* SHOP r-IDDULE REPLRCEMT* EURDEN-SHDP RND LINE

TDTRL COST DF OWNERSHIP

448434.6£

9836.638410.7318247.36

36541£5.00

£989.56

65.5356. 07121.65

£4360.83

910. 07

19. 9617. 0737. 03

7415.78

DIRECT MRINT COST 484929.37 3232.86 984.13

137

DESCRIBE UNIT

! RUN 3.1.1 3 GIMBRLLED NRVISRTION BOXES

HP10RIZRTIDN FfiCTDR 0.15PRRTS POOL COST 1.00DP. HRS TD FLT MRS 1.50RISK FRCTOR £.00

HR RRTE FDR LINE 9.5£LINE HRS PER REMOVRL 0.50LBS PER GRL FUEL €..70S-L BURDEN PER CENT 100.00

BORROWED MONEY COST 1. 1 0DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DRYS PER YERR 365.00

HR RRTE FDR SHOP S.14DRYS TD REPRIR 7.00RRTIO RDDED FUEL 0.1333NO. OF RIRPLRNES 150.00

ENTER UNIT PRICE. INSTRLLRTIDN PRICE! 95000.. £000.

ENTER HPS BETWEEN FRILURE* SHOP HRS PER REMOVRL! 1300., 14.

ENTER UNITS PER RIRPLRNE. UNIT WEIGHT! 3.> 53.

ENTER RV. PfiRTS COST PER FRILURE. FRIL-REMDVRL RRTIO! £525.>

DIRECT MRINTEMftNCE COST* NEW MODULES OP REPfllR

* LINE MRINTEIWfCE* SHOP NODULE REPLRCEHT* BURfcEN-SHDP flND LINE

TOTflL COST OF OWNERSHIP

»i«rcT COST

3110484.50

11727.45£80768.94£93496.37

12503544.00

3695477.50

£0736.56

78. 181371.791949.98

83390.30

24636.92

.5

SYSTEM COSTNO. OF SPRRE UNITS

RNNIJRL FLEET REMOVRLSRNNIJRL PLRNE REMOVALSREMOVRLS PER 1000 FLIGHT HRS

RMORTIZED INITIRL COST

RMOPTI2ED SPRRE COSTS

FUEL COST

£85000. 0061.00

£463.7516. 4£5.00

RNNIJRLFLEETCOSTS

7£0££49. 00

956139.15

654679. 00

RNNIJRLPLRNECOSTS

48014.99

6374. £6

4364.53

1000FLT HRS

COSTS

14616.44

1940.41

13£8.6£

6312.50

£3.80569.80593.60

£5385.18

7499.70

138

s-.

DESCKIK UH1T

! RUN 3.2.1 3 1C COMPUTERS <INRV-ftRINC>

RMORIZftTIOM FflCTOR 0.15PRRTS POOL COST 1.00DP. HRS TO PUT HRS 1.50RISK FRCTOR 2. 00

HR RRTE FOR LIME 9.52LINE HRS PER REMOVAL 0.50LBS PER 6RL FUEL 6.70S-L BURDEN PER CENT 100. 00

BORROWED HOMEY COSTDRILY FLIGHT HOURSFUEL PRICE PER 6RLLOMOP. DftYS PER YEflR

HR RRTE rOK SHOP \J

DRYS TO REPRIRRftTIO ftDBCD FUEL:''ND. -OF-

' IvlO9v00O.M2

3&5Str6'

' 7.00,' ,0. 1333

ENTER UNIT PRICE. INSTflLLRTIOtt PRICE! 19480.. 2000.

ENTER HRS BETWEEN FfllLURE. SHOP HRS PER REflOVflL* 3058.. .5

ENTER UNITS PER RIRPLRNE* UNIT WEIGHT! 3.." 26.

ENTER ftV. PRRTS COST PER FRILURE, FRIL-REMOVRL RflTIO! 429.,

DIRECT MftlNTENftNCE COST* NEW MODULES DR REPRIR 311070.62

» LINE MRINTENRNCE 6903.01* SHOP MODULE REPLRCEHT 5902.36* BURDEN-SHOP RND LINE 12805.37

TOTRL COST OF OWNERSHIP 2376030.50

2073.80

46. 0239.3585.37

15340.?!

.5

SYSTEM COSTNO. OF SPRRE UNITS

HHNUflL FLEET REMOVRLSRNNURL PLRNE REMOVRLSREMDVRLS PER 1000 FLIGHT HPS

AMORTIZED INITIRL COST

AMORTIZED SPRPE COSTS

FUEL COST

58440. 0038.36

1450.21• 9/672.94

RNNURLFLEETCOSTS

1594889.75

123295.95

321163.25

RNNURLPLRNECOSTS

10632.60

321.97

2141.09

1000FLT HRS

COSTS

3236.71

250.22

651.78

631.30

14.0111.9825.99

4821.98

DIRECT MRINT COST 336681.37 2244.54 683.27

139

DESCRIBE UNIT

RUM 3 TWO-RXIS ISR/IC'S aNflV-RRINC)

RMOPIZRTIDN FflCTOP 0.15PRPTS PDDL COST 1. 00DP. HRS TD FLT MRS 1.50RISK FRCTOR 2. 00

HP RRTE FDP LINE 9.52LINE HRS PER REMOVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

ENTER UNIT PRICE. INSTRLLRTION

ENTER HPS BETWEEN FRILUPE. SHOP

ENTER UNITS PEP RIPPLRNE. UNIT

BORROWED MONEY COSTDRILY FLIGHT HOURS-FUEL PRICE PER GflLLOhOP. DRYS PER YERR

HP RRTE FDR SHOPDRYS TO REPFtIRRRTIO RDDED FUELNO. OF RIRPLRNES

PRICE! 33820. , £000.

HRS PER PEMOVRL! 1799. , 7.

WEIGHT! 3.» 5£.

ENTER RV. PRPTS COST PER FRILURE. FRIL-REMOVRL RRTID! 634. »

SYSTEM CCSTNO. OF SPRRE UNITS

RNNURL FLEET PEMDVRLSRNNURL PLRNE REMDVRLSPEMDVRLS PER 1000 FLIGHT HRS

RMGRTIZEIi INITIRL COST £

RMDRTIZED SPRPE COSTS

FUEL CDST

DIRECT MRINTENRNCE COST* NEW MODULES OR PEPRIP

* LINE MRINTENRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP RND LIME

1 01460. 006 1 . 03

£465. 1£16.435. 00

RNNURL RNNURLFLEET PLRNECOSTS COSTS

659634.50 17730.90

340553.44 ££70.36

64£3£6 . 5 0 4£3£ . 1 8

78144£.87 5£09.6£

11733.97 78. £314046£.50 936.42152196.47 1014.64

1.109.000.4£

365. 00

3. 147. 00

0. 1333150. 00

.5

1000FLT HRS

COSTS

5397.53

691. 13

1303.55

1 585 . 38

£3.31£35. 06303.37

TOTPL COST OF OWNERSHIP

DIRECT MRINT COST

4723350.00

1085335.75

'31522.33

7238.91

9595.34

2203.62

140

DESCRIBE UhlT

! RUM 3.4.1 3 1C COMPUTERS <INRV-DIGITRLJ

RMORIZRTION FRCTDRPORTS POOL COSTDP. MRS TO FLT HRSRISK FRCTDR

HP R~RTE FDR LINELINE HRS PER PEMOVflLLBS PEP GftL FUELS-L BURDEN PER CENT

0.15 BORROWED MONEY CDST1.00 DRILY FLIGHT HOURS1.50 FUEL PRICE PER GRLLON£.00 DP. DRYS PER YERR

9.5£ HR RRTE FDR SHDP0.50 DRYS TO REPRIP6.70 RRTID RDDED FUEL

100.00 ND. DF RIRPLRNES

1.109. 000.4£

365. 00

3. 147. 00

0. 1333150. 00

ENTER UNIT PRICE* INSTRLLRTIDN PRICE! 15010., £000.

ENTER HRS BETMEEN FRILURE

ENTER UNITS PEP RIRPLRNE.

ENTER RV. PRRTS COST PEP

SYSTEM CDSTND. DF SPPPE UNITS

RNNURL FLEET 'REMDVRLSRNNURL PLRNE REMDVRLSREMDVRLS PER 1000 FLIGHT

RMORTIZED INITIRL CDST

RMDPTIZED SPRRE CHSTS

FUEL CDST

DIRECT MRINTENRNCE CDST* NEW MODULES DR REPRIP

* LINE MRINTENRNCE* SHOP MODULE REPLRCEMT* BURDEN-SHOP RND LINE

. SHDP HRS PER REMOVRL! 5203. » .5

UNIT WEIGHT! 3. » 19.

FRILUPE, FRIL-REMDVRL RRTIO! 427.,

45030. 00£4.41

351.535.68

HRS 1 . 73

RNNURL RNNURLFLEET PLRNECOSTS COSTS

1 £6£99£ . £5 34 1 9 . 95

60462. 16 403. 03

£34696. £5 1564.64

131800.91 1£1£.01

4053.27 £7.0£3465.71 £3.107518.93 50.13

.5

1 0 0 0FLT HPS

COSTS

£563. 15

122.70

476.30

368.95

3. £37. 03

1 5 . £6

TDTRL COST DF OWNERSHIP

DIRECT MRINT COST

1754989.75

196833.37

11699.93

1312.26

3561.62

399.47

141

DESCRIBE UNIT

• RUN 3.5.1 3 TWD-RXIS ISfl/IC'S

RMOPIZRTION FRCTDP 0.15PRPTS POOL CDST 1.00DP. HPS TO FLT HRS 1.50RISK FRCTOR £.00

HP RRTE FOP LINE 9.52-LINE HPS PER PEMOVRL 0.50LBS PER GRL FUEL 6.70S-L BURDEN PER CENT 100.00

BORROWED MONEY CDST 1.10DRILY FLIGHT HOURS 9.00FUEL PRICE PER GRLLON 0.42OP. DfiYS PER YEPR 365.00

HP PRTE FOR SHOP S.14DRYS TO PEPRIR 7.00RRTID RDDED FUEL 0.1333ND. OF HIPPLRNES 150.00

ENTER UNIT PRICE* INSTRL.LRTIPN PRICE! £9750.. £000.

ENTER HPS BETWEEN FfllLURE. SHOP HRS PER REMOVRL! ££67.? 7.

ENTER UNITS PEP RIRPLRNE? UNIT WEIGHT! 3.? 4£.

ENTER RV. PRRTS CDST PEP FRILUPE? FRIL-PEMDVRL RRTID! 670.,

DIRECT MRINTENRNCE COST» NEW MODULES DP REPRIP 655333.50

» LINE MRINTENRNCE 9311.60* SHOP MODULE PEPLRCEMT 111465.39* BURDEN-SHOP RND LINE 1£0777.00

TDTRL COST OF OWNERSHIP 4017413.50

DIRECT fWINT COST 396887.50

4368.89

62. 03743.10305.18

£678£.79

5979.£5

. 5

SYSTEM COSTNO. OF SPRPE UNITS

RNNURL FLEET REMDVRLSRNNURL PLRNE REMDVRLSREMOVRLS PER 1000 FLIGHT HPS

AMORTIZED INITIRL CDST

RMDPTIZED SPRRE COSTS

FUEL CDST

8925 0 . 0 049.77

1956.2213. 043.97

RNNURLFLEETCOSTS

£357437. 00

£44£9£. 16

518802. 12

HNNURLPLRNECOSTS

157 16. £5

1628.61

3453.68

1000FLT HRS

COSTS

4734.25

495.77

1052.37

1329.95

18. 9 0£26.21£45.11

3153.06

, 1820.17

142

DESCRIBE UNIT

• RUM 4.1 3 TWO-RXIS ISfi'S (FLDRTEB GYROS)

RMDRIZRTIDN FRCTORPRPTS POOL COSTDP. HRS TD FLT HRSRISK FfiCTOP

HP RRTE FOP LINELINE HRS PER REMOVRLLBS PER GflL FUELS-L BURDEN PEP CENT

0.15 BDRROWED MONEY COST1.00 DRILY FLIGHT HOURS1.50 FUEL PRICE PEP GRLLDN£-.00 DP. DRYS PEP YERP

9.52 HP RRTE FDR SHDP0.50 DRYS TD PEPRIR6.70 RRTID RDDED FUEL

100.00 NO. DF RIRPLRNES

1.109. 000.42

365. 00

3.147. 00

0. 1333150. 00

ENTER UNIT PRICE. INSTRLLRTIDN PRICE! 23710.? 655.

ENTER HRS BETWEEN FBI LURE

ENTER UNITS PEP RIPPLRNE.

ENTER RV. PRRTS COST PER

SYSTEM COSTNO. OF SPRRE UNITS

PNNURL FLEET REHOVRLSRNNURL PLRNE RCflDVflLSREMOVRLS PEP 1060 FLI6HT

. . . • ...,.--.,

RMORTIZED IMITtftt COST

RHOR-TIZED SWWE CBSTS'*- • '

:- FUEL COST - :

jf " J* » P^t w- 1 * tTT t F » • t ir' t t "• tU^ IJf ^ »'• ",- ' - imm ' i - m t. ^ • •

i|w'-. **'-••• -•::- . - !*" ' ^ - - 1 • T MC MA T M Wft MM C » v-;( t% .1-''™ L* A r*c> n A r» rEd vv K-

. SHOP HRS PEP. REMOVRL! 2096. » 10.

UNIT WEIGHT! 3. . 34.5

FPILURE. FRIL-REMDVRL RRTID! 1423..

71130. 0053.32

2115.8214. 11

HRS 4.29

RNNURL RNNURLFLEET PLRNECOSTS COSTS

1809101.00 12060.67

208585.44 1390.57

426158.87 2841.06

1505403.00 10036.02

10071.23 67.14»->. 1-72227.37 1148.18

•- - •' 182298'.*66 1215.32

.5

1000FLT HRS

COSTS

3671.44

423.31

864.86

3055. 10

20.44349.52369.96

43 13846. 00 28758.97

12444.67

8754.63

3799.«3

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