Aircraft Systems Mechanical, electrical, and avionics subsystems integration, potx

Aircraft Systems: Mechanical, electrical, and avionics subsystems integration, Third Edition.. Ian Aircraft systems : mechanical, electrical, and avionics subsystems integration / Ian Mo

Aircraft Systems: Mechanical, electrical, and avionics subsystems integration, Third Edition Ian Moir and Allan Seabridge

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Library of Congress Cataloging in Publication Data

Moir, I (Ian)

Aircraft systems : mechanical, electrical, and avionics subsystems integration / Ian Moir,

Allan Seabridge.

p cm.

Includes bibliographical references and index.

ISBN 978-0-470-05996-8 (cloth : alk paper)

1 Aeronautics—Systems engineering 2 Airplanes, Military—Design and construction.

3 Airplanes—Equipment and supplies I Seabridge, A G (Allan G.) II Title.

TL671.M59 2008

629.135—dc22

2008001330

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 978-0-470-05996-8

Typeset in 10.5/12.5pt Palatino by Integra Software Services Pvt Ltd, Pondicherry, India

Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire

This book is printed on acid-free paper.

Professor of Systems Engineering

at Loughborough University

An inspiration to all systems engineers

and sadly missed

Contents

1.10.3 Multiple Redundancy Actuation 22

3.4 Fuel Quantity Measurement 94

4.11 Hydraulic Reservoir 152

5.9.5 Heating 213

9 Rotary Wing Systems 319

10.3 Integrated Flight and Propulsion

10.5.4 More-Electric Environmental Control

10.6 More-Electric Actuation 388

The Aerospace and Defence industry has been at the forefront of systemsengineering for many decades The imperatives of commercial success and / ormilitary need have compelled those in the Industry to seize the opportunitiesoffered by taking a systems engineering approach to solve a variety of complexproblems

The insights offered by use of computer based modelling techniques, whichhave the capacity to represent multiple complex systems, their interdependen-cies, interactions and their inputs and outputs have propelled the exploitation

of systems engineering by those in Aerospace and Defence The approach isnot confined to those mechanical and electrical systems for which stand alonesystems models can be constructed Rather, it is put to its best use when consid-ering a major product or service as a system made up of many subsystems Forexample, the optimisation of aircraft layout involving trade-offs between struc-tural aspects, aerodynamic design, electronic and mechanical system perfor-mance as well as integrity can be achieved Carried out in a balanced way, thiscan be the most powerful tool used by the Engineering teams in the process ofdefining a light, cheap to manufacture, reliable and high performance aircraft

In stark terms, success or failure in the Aerospace and Defence sector is mined by the approach taken in the development of systems and how well orotherwise the systems or their interactions are modelled, understood and opti-mised The most obvious output from such a process is the resulting systemperformance, for example how fast your aircraft can fly and what it can seeusing its radar In addition however, the dimensions of cost and elapsed time

deter-to develop and build a system, deter-together with its inherent reliability throughoutits life, are also all critically dependent on effective systems engineering fromthe outset Projects, and sometimes entire businesses, will succeed or flounder

on the basis of how well the systems engineering approach has informed sion making relating to the definition of responsibilities between, for example,customers and suppliers, industrial partners or members of an alliance or team.Effective systems engineering will help to expose where the natural bound-aries are between areas of activity which in turn informs the definition ofsuitable contractual boundaries and terms and conditions of a contract Theultimate benefit of this approach is more effective assignment of responsibili-ties, enduring contracts and, most importantly, safer systems

deci-The ultimate consequence of having a culture within an organisation thatcentres on Systems Engineering is that the inherent approach spills over intoother aspects of the activity across the enterprise involved Obvious benefits inmanufacturing process optimisation sit alongside the creation of business infor-mation management systems and other tools each playing a part in the questfor an organisation to make the best use of its resources, skills and funding.All of this contributes to the drive for predictable business performance andbusiness success.

This book exemplifies the need to apply a systems engineering approach tothe aircraft systems as well as the avionics systems deployed by the aircraftand weapons systems in the performance of its military role The performanceand inter-relationship of all systems are paramount in meeting the air vehiclespecification requirements, which in many future offensive air vehicles will

be unmanned The authors have described the Aircraft Systems that emergefrom the application of Systems Engineering to show the benefits to individualsystems performance and whole aircraft design and integration Examples ofsolutions in commercial and military aircraft are given, which complement thesystems described in companion volumes

The forthcoming More-Electric Aircraft and More-Electric Engine gies as described in various places within this text herald the approach ofinnovative and highly integrated technologies for many of the aircraft systemsthat will serve both civil and military applications in the future The bookhas much to recommend it as a place mark in time in relation to the ultimatematurity and application of these technologies

technolo-Nigel Whitehead, Group Managing Director – Military Air Solutions, BAE SYSTEMS

Series Preface

The field of aerospace is wide ranging and covers a variety of products,disciplines and domains, not merely in engineering but in many relatedsupporting activities These combine to enable the aerospace industry toproduce exciting and technologically challenging products A wealth of knowl-edge is contained by practitioners and professionals in the aerospace fieldsthat is of benefit to other practitioners in the industry, and to those enteringthe industry from University

The Aerospace Series aims to be a practical and topical series of books aimed

at engineering professionals, operators, users and allied professions such ascommercial and legal executives with in the aerospace industry The range oftopics spans design and development, manufacture, operation and support ofaircraft as well as infrastructure operations, and developments in research andtechnology The intention is to provide a source of relevant information thatwill be of interest and benefit to all those people working in aerospace

About the Authors

went on to Smiths Industries in the UK where he was involved in a number

of advanced projects Since retiring from Smiths he is now in demand as ahighly respected consultant Ian has a broad and detailed experience working

in aircraft avionics systems in both military and civil aircraft From the RAFTornado and Apache helicopter to the Boeing 777, Ian’s work has kept him atthe forefront of new system developments and integrated systems in the areas

of more-electric technology and system implementations He has a specialinterest in fostering training and education in aerospace engineering

SYSTEMS at Warton in Lancashire in the UK In over 30 years in the aerospaceindustry his work has latterly included the avionics systems on the NimrodMRA 4 and Lockheed Martin Lightning II (Joint Strike Fighter) as well as athe development of a range of flight and avionics systems on a wide range

of fast jets, training aircraft and ground and maritime surveillance projects.Spending much of his time between Europe and the US, Allan is fully aware

of systems developments worldwide He is also keen to encourage a furtherunderstanding of integrated engineering systems An interest in engineeringeducation continues with the design and delivery of systems and engineeringcourses at a number of UK universities at undergraduate and postgraduatelevel

This book has taken a long time to prepare and we would not have completed

it without the help and support of colleagues and organisations who willinglygave their time and provided information with enthusiasm

We would especially like to thank Gordon Leishman who reviewed therotorcraft chapter and Geoff Poole, Dr Craig Lawson and Roy Langton whoreviewed the entire manuscript We are indebted to their valuable comments.The following organisations kindly provided information and images:

DoD photograph by TSGT Edward

Boyce

Rolls Royce/Turbomeca

Engineering Arresting Systems Corp US Air Force

Senior Airman Darnall Cannady

We would like to thank the staff at John Wiley who took on this project from

a previous publisher and guided us to a satisfactory conclusion

List of Abbreviations

AIAA American Institute of Aeronautics & Astronautics

ASM Air Separation Module

AS/PCU Air Supply/Pressurisation Control Unit (B777)

CANbus Commercial-Off-The-Shelf data bus (originally designed by

Bosch for automobile applications)

CBLTM Control-By-LightTM (Raytheon proprietary fibre optic bus)

IMA)

CSAS Control Stability Augmentation System

ECAM Electronic Crew Alerting & Monitoring

E2PROM Electrically Erasable Programmable Read Only Memory

EICAS Engine Indication & Crew Alerting System

EPMS Electrical Power Management System (AH-64C/D Apache)

EUROCAE European Organisation for Civil Aviation Equipment

Conference (1998)

FMEA Failure Modes & Effects Analysis

(A330/A340)FMQGS Fuel Management & Quantity Gauging System (Global

Express)

FSEU Flap Slats Electronics Unit (B777)

G&C Guidance & Control

IDEA Integrated Digital Electric Airplane

IEEE Institute of Electrical & Electronic Engineers

IET Institute of Engineering & Technology (formerly IEE)

IFPC Integrated Flight & Propulsion Control

IMechE Institution of Mechanical Engineers

IR Infra Red

J/IST Joint Strike Fighter/Integrated Subsystems Technology

MEE More-Electric Engine

NH or N2 Speed of rotation of engine HP shaft

HL or N1 Speed of rotation of engine LP shaft

PCU Power Control Unit

PEPDC Primary Electrical Power Distribution Centre (A380)

R & D Research & Development

SCR Silicon Controlled Rectifier (Thyristor)

SEPDB Secondary Electrical Power Distribution Box (A380)

SEPDC Secondary Electrical Power Distribution Centre (A380)

SFENA Société Française d’Equipments pour la Navigation Aerienne

TADS Target Acquisition & Designator System (Apache)

Systems

TRU or TR Transformer Rectifier Unit

V/STOL Vertical/Short Take-Off & Landing

VTOL Vertical Take-Off & Landing

Since the Second Edition of Aircraft Systems was published six years ago a few

but not many major new aircraft projects have emerged At the time of writing,the Airbus A380 is approaching certification and entry into service (the firstaircraft being delivered to Singapore Airlines in October 2007), the LockheedMartin F-35 Lightning II (previously known as JSF) is well established on itsflight test programme and the Boeing 787 is months away from first flight andthe Airbus A350XWB final design is emerging However, with the development

of these new aircraft the introduction of new technologies abounds and theuse of avionics technology to integrate systems at the aircraft and subsystemslevel has gained considerable pace

The use of Commercial-of-the-Shelf (COTS) digital data buses is increasinglybeing adopted; 100 Mbits/sec AFDX/ARINC 664 is used as the aircraft leveldata bus on both A380 and B787; JSF uses 800 Mbits/sec IEEE 1394b as theintegration data bus for the Vehicle Management System (VMS) Ethernetbuses of 10 Mbits/sec and CANbus commercial derivatives up to 1 Mbits/seccan be found in many aircraft systems Often these buses are employed in adeterministic form, that is, their performance is constrained so that it alwaysresponds in a repeatable fashion and no optimisation is permitted

Many More-Electric Aircraft (MEA) features and technologies are found

in these three major programmes and significant research, development anddemonstration programmes are underway to drive the technology furtherforward for both aircraft and engine applications In a real sense some of thesedevelopments are challenging the way that aircraft systems are engineered forthe first time since World War II A key enabler in many of these developments

is the advent of high power, reliable power electronics Indeed so influential arethese developments, and their effect upon systems integration so widespread,that a new section has been provided in Chapter 10 – Advanced Systems – toprovide the reader with an overview of the new technology involved

The emergence of Unmanned Air Vehicles or Unmanned Air Systems hasresulted in at least 600 different platforms from 250 companies in 42 nations atthe time of writing [1,2] The continuing development of unmanned air systemswill pose challenges in both military and commercial markets for effectivesolutions for sensors and general systems The question of autonomous opera-tion and certification for use in controlled air space will continue to tax peoplefor some time

It will be noted that this edition contains descriptions of legacy aircraftsystems This is intentional because many of these aircraft types, and much

of this technology, remains in service today and will for some time to come

It also serves as a useful historical source of the development of systems

It should also be noted that the lifetime of aircraft is increasing, while thelifecycle of technology is reducing This means that obsolescence is an issuethat will need to be considered in modern developments, especially those usingcommercial off the shelf systems driven predominantly by commercial anddomestic technology

There has been an increased awareness of environmental issues, both in theuse of materials and in the emission of contaminants and pollution Theseissues are being addressed by international agreements and protocols, and bymeasures by industry to reduce the use of banned and restricted materials.This poses some interesting issues when the platforms in service today are duefor removal from service or when accidents occur – there will inevitably becontamination from ‘heritage’ materials The issue has been addressed to someextent in this edition, although not fully It has been left to emerging legislation

to provide authoritative guidelines It is the duty of the competent systemsengineer to become familiar with Safety, Health & Environmental legislationand the impact on system design

Systems Integration

It is the integration of major aircraft systems and the increased interrelationshipand interdependence between them that is driving the increasing adoption ofhigh-speed digital data buses Figures 0.1, 0.2 and 0.3 illustrate at a top levelthe power generation (hydraulic and electrical), environmental control and fuelsystems of a modern combat aircraft These are complex systems within them-selves; however, it is the interrelationship between them that gives the vehicleits fighting edge, as well as causing many of the development headaches.Digital data buses greatly facilitate the interchange of data and control thatcharacterises the functional integration of these systems; on more recent aircraftthese data buses also carry a significant amount of health monitoring andmaintenance data The ease with which component and subsystem perfor-mance information can be gathered and transmitted to a central or distributedcomputing centre has led to the emergence of prognostics and health moni-toring systems that do much more than simply record failures They nowexamine trends in system performance to look for degradation and incipientfailures in order to schedule cost-effective maintenance operations This is

an important aspect of improvement in the maintenance of aircraft systems,reducing the incidence of No Fault Found component replacement actions.The engines of the typical military fast jet accessory drive shafts that powerAircraft Mounted Accessory Drives (AMADs) are mounted within the airframe

as shown in Figure 0.1 In the simplest implementation these accessory drivespower Engine Driven Pumps (EDPs) to pressurise the aircraft centralised

LEFT AMAD RIGHT AMAD

Hyd System

1

Hyd System 2

LEFT ENGINE

RIGHT ENGINE

Electrical Power System

RAT E

H

H

Airframe Engine

E

Engine

Start

Engine Start

T S

T S

Key :

H Hydraulic Power

E Electrical Power Temperature Speed T S

LEFT ENGINE

RIGHT ENGINE

Airframe Engine

Key :

Temperature Pressure T

P

Primary

Heat Ex

Primary Heat Ex

Secondary

Heat Ex

Secondary Heat Ex Bypass

Valve

Bypass Valve

powered by high-pressure air Most aircraft also possess an emergency powerunit or Ram Air Turbine (RAT) to provide emergency supplies of electricaland hydraulic power.

Once started, the engine provides bleed air for the aircraft systems as well asprimary thrust to maintain the aircraft in flight (see Figure 0.2) The generation

of electric and hydraulic power has already been described One of the primaryfunctions of the bleed air extracted from the engine is to provide the means

by which the aircraft Environmental Control System (ECS) is driven Bleed airtaken from the engine compressor is reduced in pressure and cooled though aseries of heat exchangers and an air cycle machine to provide cool air for thecockpit and the avionics cooling system Suitably conditioned bleed air is used

to pressurise the cockpit to keep the combat crew in a comfortable environmentand may also be used to pressurise hydraulic reservoirs and aircraft fuel tanks,among other aircraft systems

B

B B

DUMP

LEFT LP COCK

RIGHT LP COCK

UNDER

WING

TANK

UNDER WING TANK

IN-FLIGHT REFUELLING PROBE

The aircraft fuel system as shown in Figure 0.3 is fundamental to supplyfuel to the engines to maintain thrust and powered flight Fuel feed to theengines is pressurised by using electrically powered booster pumps to preventfuel cavitation – this is usually an engine HP pump-related problem associatedwith inadequate feed pressure which is manifest particularly at high altitude.Electrical power is used to operate the transfer pumps and fuel valves thatenable the fuel management system to transfer fuel around the aircraft duringvarious phases of flight In some cases, bleed air, again suitably conditioned,

is used to pressurise the external fuel tanks, facilitating fuel transfer inboard

to the fuselage tank groups

Since the Second Edition was published one of the major developments infuel systems has been the establishment of fuel tank inerting systems as acommon requirement for ensuring fuel tank safety of civil aircraft Boeing isinstalling Nitrogen Generation Systems (NGS) on all of its current produc-tion aircraft and the issues associated with these new requirements are fullydescribed in Chapter 3 – Fuel Systems

Fibr e C ha nnel Fibre Channel Avionics

Hyd System 1

Hyd System 2 Electrical Power System

RAT E

T

T T

&

HYDRAULICS

FUEL

From the very short, almost superficial, description of how these majorsystems interact, it is not difficult to understand how complex modern aircraftsystems have become to satisfy the aircraft overall performance requirements

If one system fails to perform to specification then the aircraft as a whole willnot perform correctly Figure 0.4 illustrates in a very simple fashion how thesesystems functionally interrelate

deter-A less obvious example of significant interaction between systems is howvarious systems operate together to reject waste heat from the aircraft Heat isgenerated when fluids are compressed and also by energy conversion processesthat are not totally efficient Figure 0.5 depicts the interaction of several majorsystems – this time within the context of a civil aircraft The diagram illustrateshow a total of eight heat exchangers across a range of systems use the aircraftfuel and ambient ram air as heat sinks into which waste heat may be dumped.

Fan

Casing

Elec Hyd

Air/

Air Air/

Key:

Ram Air Bleed Air Fuel Hydraulics Electrical Power Engine Oil Fan/Cabin Air HYDRAULIC POWER

ELECTRICAL POWER

Fuel Air/

Warm

Cold 1

Hyd

system (See Colour Plate 1)

Starting with the engine:

1 Air extracted from the engine fan casing is used to cool bleed air tappedoff the intermediate or high pressure compressor (depending upon enginetype) – Chapter 7, Environmental Control Systems

2 Air is used to cool engine oil in a primary oil cooler heat exchanger –Chapter 2, Engine Systems

3 Fuel is used to cool engine oil in a secondary oil cooler heat exchanger –Chapter 7 Engine Systems

4 The electrical Integrated Drive Generator (IDG) oil is cooled by air –Chapter 5, Electrical Systems

5 The hydraulic return line fluid is cooled by fuel before being returned tothe reservoir – Chapter 4, Hydraulic Systems

6 Aircraft fuel is cooled by an air/fuel heat exchanger – Chapter 3, FuelSystems

7 Ram air is used in primary heat exchangers in the air conditioning pack

to cool entry bleed air prior to entering the secondary heat exchangers –Chapter 7, Environmental Control Systems

8 Secondary heat exchangers further cool the air down to temperatures able for mixing with warm air prior to delivery to the cabin – Chapter 7,Environmental Control Systems

suit-A new chapter has also been introduced to examine the environmental tions that the aircraft and its systems will be subject to in service This chapterprovides some guidance on how to specify systems to operate in differentclimatic and environmental contamination conditions and how to ensure thattesting is conducted to gather evidence to qualify the systems This is increas-ingly important since military aircraft are being deployed to theatres of opera-tion with very different conditions to their home base, and commercial aircraftare flying long routes that may have widely differing conditions at the desti-nation to those prevailing at departure

condi-The authors hope that this edition has brought together technologies thathave emerged since the previous editions and our sincere aim is that readerswill practise systems engineering principles in pursing their system analysisand design The interconnectedness of systems in the modern aircraft meansthat systems do not stand alone: their performance must be considered in thelight of interaction with other systems, and as making a contribution to theperformance of the aircraft as a whole

References

[1] Hughes, David, Aviation Week & Space Technology, 12 Feb 2007.

[2] Unmanned Air Vehicles and Drones Survey, Aviation Week & Space Technology, 15 Jan 2007.

Casing

Elec Hyd

Air/

Air Air/

Ram Air Bleed Air Fuel Hydraulics Electrical Power Engine Oil Fan/Cabin Air HYDRAULIC POWER

Warm

Cold 1

Hyd

system (See Figure 0.5)

Aircraft Systems: Mechanical, electrical, and avionics subsystems integration, Third Edition Ian Moir and Allan Seabridge

F2 Centre Fuselage F3 Engina Feed Tank (F3L & F3R)

F5 Aft Fuselage (F5L & F5R)

F5L F4L

WL Left Wing Box

WR Right Wing Box F4 Wing carry-Throught (F4L & F4R)

Figure 3.10)

Derby (Courtesy of the Royal Aero Club)

Aircraft Systems: Mechanical, electrical, and avionics subsystems integration, Third Edition Ian Moir and Allan Seabridge