The development of the book was sponsored by Shanghai Jiaotong University Press Commercial Aircraft Hydraulic Systems Shanghai Jiao Tong University Press Aerospace Series Shaoping Wang Department of Mechatronic Engineering Beihang University, China Mileta Tomovic Batten College of Engineering and Technology Old Dominion University, USA Hong Liu AVIC The first Aircraft Institute AMSTERDAM l BOSTON l HEIDELBERG l LONDON NEW YORK l OXFORD l PARIS l SAN DIEGO SAN FRANCISCO l SINGAPORE l SYDNEY l TOKYO Academic Press is an imprint of Elsevier Academic Press is an imprint of Elsevier 225 Wyman Street, Waltham, MA 02451, USA The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK Copyright Ó 2016 Shanghai Jiao Tong University Press Published by Elsevier Inc All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein) Notices Knowledge and best practice in this field are constantly changing As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein ISBN: 978-0-12-419972-9 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress For information on all Academic Press publications visit our website at http://store.elsevier.com/ Typeset by TNQ Books and Journals www.tnq.co.in Printed and bound in the United States of America Foreword In general, the flight control system is the critical system of an aircraft The aircraft hydraulic actuation system and its power supply system are very important, related systems that directly influence aircraft flight performance and flight safety Over the past several decades, aircraft system design focused predominantly on the design principle itself without considering the related system effects The hydraulic power supply system provides high-pressure fluid to the actuation system; therefore, its characteristics and performance could influence the actuation system performance On the other hand, the actuation system utilizes hydraulic power to drive the surfaces, the performance of which not only depends on the displacement control strategy but also on the power supply performance This book focuses on the aircraft flight control system, including the interface between the hydraulic power supply system and actuation system, and it provides the corresponding design principle and presents the latest research advances used in aircraft design The aircraft hydraulic system evolved with the flight control system Early flight control systems were purely mechanical systems in which the pilot controlled the aircraft surfaces through mechanical lines and movable hinge mechanisms With the increase in aircraft velocity, the hinge moments and required actuation forces increased significantly to the point at which pilots had difficulty manipulating control surfaces The hydraulic booster appeared to give extra power to drive the surfaces With the increasing expansion of flight range and duration of flight, it became necessary to develop and implement an automatic control system to improve the flight performance and avoid pilot fatigue Then, the electrically signaled (also known as fly-by-wire (FBW)), hydraulic powered actuator emerged to drive the aircraft control surfaces Introduction of the FBW system greatly improved aircraft flight performance However, the use of many electrical devices along with the flutter influence of the hydraulic servo actuation system led to a reliability problem This resulted in wide implementation of redundancy technology to ensure high reliability of the FBW system Increasing the number of redundant channels will potentially increase degree of fault To achieve high reliability and maintainability, a monitoring and fault diagnosis device is integrated in the redundant hydraulic power supply system and redundant actuation system Modern aircraft design strives to increase the fuel economy and reduction in environmental impacts; therefore, the high-pressure hydraulic power supply ix x Foreword system, variable-pressure hydraulic system, and increasingly electrical system are emerging to achieve the requirements of green flight This book consists of four chapters Chapter presents an overview of the development of the hydraulic system for flight control along with the interface between the flight control system and the hydraulic system The chapter also introduces different types of actuation systems and provides the requirements of the flight control system for specification and design of the required hydraulic system Chapter introduces the basic structure of aircraft hydraulic power supply systems, provides the design principle of the main hydraulic components, and provides some typical hydraulic system constructions in current commercial aircraft Chapter introduces the reliability design method of electrical and mechanical components in the hydraulic system The chapter provides comprehensive reliability evaluation based on reliability, maintainability, and testability and gives the reliability evaluation of the aircraft hydraulic power supply and actuation system Chapter introduces new technologies used in modern aircraft, including the high-pressure hydraulic power supply system, variable-pressure hydraulic power supply system, and new types of hydraulic actuators We thank all of the committee members of a large aircraft flight control series editorial board and all of the editors of Shanghai Jiaotong Press for their help and assistance in successfully completing this book The authors are also grateful to Ms Hong Liu, Mr Zhenshui Li, and Mr Yisong Tian, who reviewed the book outline and contributed to the writing of this book We are indebted to their comments We should also mention that some of the general theory and structure composition were drawn from related references in this book; therefore, we would like to express our gratitude to their authors for providing outstanding contributions in the related fields Finally, we hope that the readers will find the material presented in this book to be beneficial to their work Shaoping Wang Mileta Tomovic Hong Liu July 2015 Preface Aircraft design covers various disciplines, domains, and applications Different viewpoints have different related knowledge The aircraft flight control series focus on the fields that are related to the aircraft flight control system and provide the design principle, corresponding technology, and some professional techniques Commercial Aircraft Hydraulic Systems aims to provide the practical knowledge of aircraft requirements for the hydraulic power supply system and hydraulic actuation system; give the typical system structure and design principle; introduce some technology that can guarantee the system reliability, maintainability, and safety; and discuss technologies used in current aircraft The intention is to provide a source of relevant information that will be of interest and benefit to all of those people working in this area xi Chapter Requirements for the Hydraulic System of a Flight Control System Chapter Outline 1.1 The Development of the Hydraulic System Related to the Flight Control System 1.2 The Interface between the FCS and Hydraulic System 1.3 Actuation Systems 1.4 Requirement of the FCS to the Hydraulic System 1.5 Conclusions References 13 33 50 51 1.1 THE DEVELOPMENT OF THE HYDRAULIC SYSTEM RELATED TO THE FLIGHT CONTROL SYSTEM [1] The flight control system (FCS) is a mechanical/electrical system that transmits the control signal and drives the surface to realize the scheduled flight according to the pilot’s command FCSs include components required to transmit flight control commands from the pilot or other sources to the appropriate actuators, generating forces and torques Flight control needs to realize the control of aircraft flight path, altitude, airspeed, aerodynamic configuration, ride, and structural modes Because the performance of the FCS directly influences aircraft performance and reliability, it can be considered as one of the most important systems in an aircraft A conventional fixed-wing aircraft control system, shown in Figure 1.1, consists of cockpit controls, connecting linkages, control surfaces, and the necessary operating mechanisms to control an aircraft’s movement The cockpit controls include the control column and rudder pedal The connecting linkage includes a pushepull control rod system and cable/pulley system Flight control surfaces include the elevators, ailerons, and rudder Flight control includes the longitudinal, lateral-directional, lift, drag, and variable geometry control system Since the first heavier-than-air aircraft was born, it is the pilot who drives the corresponding surfaces through the mechanical system to control the aircraft, which is called the manual flight control system (MFCS) without Commercial Aircraft Hydraulic Systems http://dx.doi.org/10.1016/B978-0-12-419972-9.00001-2 Copyright © 2016 Shanghai Jiao Tong University Press Published by Elsevier Inc All rights reserved Commercial Aircraft Hydraulic Systems FIGURE 1.1 Structure of the initial FCS power A very early aircraft used a system of wing warping in which no conventionally hinged control surfaces were used on the wing A MFCS uses a collection of mechanical parts such as pushrods, tension cables, pulleys, counterweights, and sometimes chains to directly transmit the forces applied at the cockpit controls to the control surfaces Figure 1.1 shows the aircraft’s purely mechanical manipulating system, in which a steel cable or rod is used to drive the surfaces If the pilot wants to move the flaps on a plane, then he would pull the control column, which would physically pull the flaps in the direction that the pilot desired In this period, the designer focuses on the friction, clearance, and elastic deformation of the transmission system so as to achieve good performance With the increase of size, weight, and flight speed of aircraft, it became increasingly difficult for a pilot to move the control surfaces against the aerodynamic forces The aircraft designers recognized that the additional power sources are necessary to assist the pilot in controlling the aircraft The hydraulic booster, shown in Figure 1.2(a), appeared at the end of the 1940s, dividing the control surface forces between the pilot and the boosting mechanism The hydraulic booster utilizes the hydraulic power with high pressure to drive the aircraft surfaces according to the pilot’s command As an auxiliary component, the hydraulic booster can increase the force exerted on the aircraft surface instead of the pilot directly changing the rotary or flaps As the earliest hydraulic component that is FIGURE 1.2 Evolution of the aircraft FCS (a) Mechanical manipulating system with booster, (b) irreversible booster control system, (c) reversible booster control system, (d) stability augmentation control system, and (e) FBW systems [2] Commercial Aircraft Hydraulic Systems related to the aircraft FCS, the hydraulic booster changed the surface maneuver from mechanical power to hydraulic power and resisted the hinge moment of surfaces without the direct connection between the control rod and surfaces There are two kinds of hydraulic booster: reversible booster and irreversible booster In the case of the irreversible booster control system shown in Figure 1.2(b), there is no direct connection between the control rod and the surface The pilot controls the hydraulic booster to change the control surface without feeling of the flight state The advantages of hydraulically powered control surfaces are that (aerodynamic load on the control surfaces) drag is reduced and control surface effectiveness is increased Therefore, the reversible booster control system emerged through installing the sensing device to provide the artificial force feeling to the pilot, shown in Figure 1.2(c) The reversible booster control system includes the spring, damper, and additional weight to provide the feedback (feeling) so that a pilot could not pull too hard or too suddenly and damage the aircraft In this kind of aircraft, the characteristics of booster (maximum output force, distance, and velocity) should satisfy the flight control performance In general, the center of gravity is designed forward of center of lift for positive stability Modern fly-by-wire (FBW) aircraft is designed with a relaxed stability design principle This kind of design requires smaller surfaces and forces, low trim loads, reduced aerodynamic airframe stability, and more control loop augmentation This kind of aircraft operates with augmentation under subsonic speed When the aircraft operates at supersonic speed, the aircraft focus moves backward, and the longitudinal static stability torque rapidly increases At this time, it needs enough manipulating torque to meet the requirements of aircraft maneuverability However, the supersonic area in the tail blocks the disturbance propagation forward, and the elevator control effectiveness is greatly reduced Hence, it is necessary to add signals from stability augmentation systems and the autopilot to the basic manual control circuit As we know, a good aircraft should have good stability and good maneuverability The unstable aircraft is not easy to control Because the supersonic aircraft’s flight envelope expands, its aerodynamics are difficult to meet the requirements at low-altitude/low-speed and high-altitude/high-speed In the high-altitude supersonic flight, the aircraft longitudinal static stability dramatically increases whereas its inherent damping reduces, then the short periodic oscillation in the longitudinal and transverse direction appear that greatly influences the aircraft maneuverability To maintain stability of the supersonic aircraft, it is necessary to install the stability augmentation system shown in Figure 1.2(d) Because the stability augmentation system can keep the aircraft stable even in static instability design, the automatic flight control system (AFCS) appeared The AFCS consists of electrical, mechanical, and 248 Commercial Aircraft Hydraulic Systems Phase F01 (t ) Onboard PHM F14 (t ) Onboard PHM fault F12 (t ) Data chain link F03 (t ) Phase Phase Ground repair system F25 (t ) Data chain link fault Without repair FIGURE 4.70 Markov state transfer diagram of aircraft connection among onboard PHM, data chain, and the ground maintenance center, the state transfer diagram of 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knowledge based systems, Energy 29 (12) (2004) 2553e2572 Z Yang, J Guo, et al., Multi-scale support vector machine for regression estimation, Adv Neural Networks 3971 (2006) 1031e1037 Lecture Notes in Computer Science C Chen, Wavelet energy entropy as a new feature extractor for face recognition, in: The 4th International Conference on Imagine and Graphics, 2007, pp 616e619 M.J Romer, J Ge, A Liberson, Autonomous impact damage detection and isolation prediction for aerospace structure, in: Aerospace Conference, 2005, pp 1e9 E Crow, Automatic Logistics Supporting Tactical Combat Vehicles in the MAGTF, Penn State University, 2009 Bochao Huang Study on key techniques of aircraft intelligent variable pressure hydraulic system (PhD thesis), Beihang University, 2012 (in Chinese) S Wang, Reliability engineering, Beijing University of Aeronautics and Astronautics Press, 2000 (in Chinese) Abbreviations 2H/2E 2H ACMP ACT ADP ALS BIT CA CALCE CBIT CCA EBHA EDP EHA EMA EMD EMI FBW FMEA FMECA FO FPVM FS FT FTA HA HUMS IVHM LVDT MA MCS MTBF MTTF MTTR NRV PHM PTU RAT RBD Two hydraulic power supply and two electrical power supply systems Two hydraulic power supply system Alternating current motor pump Active control technique Air turbine-driven pump Autonomous logistics support Built-in-test Criticality analysis Center for advanced life cycle engineering Continuous built-in-test Common cause analysis Electro-backup hydraulic actuator Engine driven pump Electro-hydrostatic actuators Electromechanical actuator Empirical mode decomposition method Electromagnetic inference Fly-By-Wire Failure mode and effect analysis Failure mode effect and critical analysis Failure operation Fixed pump displacement and variable motor speed Failure safe Fault tree Fault tree analysis Hydraulically powered actuator Health and usage monitoring system Integrated vehicle health management Linear variable differential transformer Markov analysis Minimal cut set Mean time between failure Mean time to failure Mean time to repair Non-return valve Prognostics and health management Power transfer unit Rotary air turbine Reliability block diagram 253 254 Abbreviations SNR SOV SV SVM VPFM VPVM Signal-to-noise ratio Shutoff valve Servo valve Support vector machines Variable pump displacement and fixed motor speed Variable pump displacement and variable motor speed Notation and Symbols A Ac Ae Ah AS Be Bm Bpe Bph C C Csh Cel Cele Celi Cpl Cst D D Df d dz Ee Ey Fe Fh Fmax f0 fe fh Gv ðSÞ H I i ie iv isv Jc Jm K1 The piston area Piston area of cylinder Effective area of piston Piston area Axial sum of relative power The viscous damping coefficient of cylinder Total load damping coefficient of motor-pump module Viscous damping coefficient of EHA Viscous damping coefficient Repair cost Initial laminar correction coefficient Total leakage coefficient Total leakage coefficient External leakage coefficient Inner leakage coefficient Total leakage coefficient The leakage coefficient of cylinder Fault location condition Probability distribution of system parameters The diameter of piston distribution in cylinder barrel Piston diameter The diameter of piston Bulk modulus of elasticity Equivalent volume elastic modulus Output force Output force of HA Maximum force of actuator Basic axial frequency of pump Damping force Friction between piston and cylinder Transfer function of servo system controller Material hardness Rotor moment of inertia The input current to servo valve Motor current Input of servo valve Current in servo valve Moment of inertial of swash plate variable mechanism Total moment of inertia of motor-pump module Leakage coefficient of the pump 255 256 Notation and Symbols Kc Ke Ke Kf Km Kt Kq Ks Ksv Ku Kv k kq L L Le L0 Mf me md mph mpe N n n P P1 P1 P2 Pa Pb Pe p p pf ph pL pn ps Q1 Qe Qil QL jQL j Qh Qt q q1 Flow-pressure coefficient Total pressure-flow coefficient Opposing electromotive force coefficient The feedback gain Electromagnetic torque constant Connection stiffness of surface Flow amplification coefficient Abrasive wear coefficient The servo valve gain The gain of electrical amplifier Gain of amplifier Wearing coefficient under specified operating conditions Flow gain Distance between variable cylinder axis to the center of swash plate Travel distance of piston Armature inductance Sliding distance The equivalent mass Equivalent inertia Equivalent mass Piston mass Mass of EHA Gear reducer ratio Number of repairs Number actuation cycles Related to the variable maintenance resources Volume loss of pump Inlet pressure of cylinder Outlet pressure of cylinder Outlet pressure Inlet pressure Load pressure Crew pitch Friction surface pressure Load pressure Load pressure Load pressure Designed parameters Outlet pressure of pump Flow loss of hydraulic pump Load flow rate The internal leakage Load flow rate Flow that load take from the pump Load flow Flow rate of pump Relative speed of friction surface Inlet flow rate of cylinder Notation and Symbols q2 qt RS Re Ri RT r S s0 T Te Ti Tm Tm Tsv t ti ue ue V Vc Ve Vi Vp VS Vt Vth Vmax W X jXðf Þj jXðf Þj2 Xmax Xt xe xh xh xt xv Y Z aj be bj g xh xv 2h Outlet flow rate of cylinder Angular displacement Radial sum of relative power Armature resistance Failure area Components reliability Ratio of wear The piston stroke Stress Life of item Output torque of motor Life of the ith component Torque of motor Repair time The time constant of servo valve Operational time Operational time between failures of repairable product Control voltage Motor control voltage Displacement of pump Total volume of variable cylinder Total volume of cylinder Performance parameter Coefficient of pressure disturbance torque Volume of pump outlet The volume of cylinder Total volume of HA Maximum speed of actuator Normal load System parameters set Amplitude spectrum Power spectral density Maximum displacement of actuator The piston displacement Displacement of piston Displacement of cylinder Displacement of Surface displacement Spool displacement of servo valve in swash plate variable mechanism System performance The number of pistons Failure mode ratio Fluid equivalent modulus of elasticity Conditional probability of mission loss Angle of swash plate Relative damping coefficient of swash plate variable mechanism Damping coefficient of servo valve The hydraulic damping coefficient 257 258 Notation and Symbols ue uh ui um uS uv m m m ms my md s ss sy sd s2 h hv G d d d0 l lV U D DP Dpi Dpu DV DVi Motor speed Inherent frequency of swash plate variable mechanism Weight of Ri Motor speed Volume lag tuning frequency Characteristic frequency of servo valve Repairable rate Mean or expectation of the distribution Fluid dynamic viscosity Mean value of of stress s Mean value of random variable y Mean value of strength d Standard deviation Standard deviation of stress s Standard deviation of random variable y Standard deviation of strength d Variance Characteristic life described by Weibull distribution The volumetric efficiency Gamma function Strength Single slit height Initial slit height Failure rate of component Failure rate of voting machine Performance threshold Leakage flow rate Pressure difference between two chamber Variance of the ith design parameter Pressure drop of servo valve Wear volume Variance of Vi Index Note: Page numbers followed by “f” and “t” indicate figures and tables, respectively A C AC motor-driven pump, 78e81, 80f, 82f, 145 Accumulator, 49, 57e59, 65, 206e207 hydraulic, 73f, 90e91 Active control technique, 34, 117 Actuation systems, 13e33, 54, 63f, 66e67, 69, 94, 110e111, 143, 143f commercial aircraft implementation, 27e33, 27fe31f, 32t, 33f hydraulic, dissimilar redundant, 211e212, 212f hydraulic, reliability evaluation of, 159e168, 160f, 162fe163f, 165f, 166t, 167f performance criteria, 38e46, 40fe45f, 47f powered by centralized hydraulic supply, 14e23, 14fe23f powered by electrical supply, 24e26, 24fe26f, 26t Aerodynamic centering, 19e21 drag, 1e2 load, 1e2, 18, 23, 53, 71, 159e160 Ailerons, 10, 12, 27, 30e31, 66e67 Aircraft control surfaces, 8e11, 9f, 64f hydraulic pump, 72e83, 73fe75f, 76t, 78fe80f, 82f, 84f, 207 hydraulic system, 1e252 Antiskid brake system, 53, 116 Antivibration design, 128e129 Autonomous logistics support (ALS), 245e246 Cabin and cargo doors, 63e65 Cable design, 66e67 Centralized hydraulic power system, 49f, 56f, 97, 145e146, 146fe147f, 148te149t, 156e158, 157f, 158t, 172e197, 173f, 174t, 175f, 177fe182f, 182t, 184fe185f, 187fe191f, 192t, 193f, 194t, 195f, 198f, 200fe202f supply, 14e23, 14fe23f Check valve, 89, 90f Cockpit control, Common cause analysis, 36, 59, 156 Comprehensive reliability, 115e170 definition of, 117e118 design of, 126e145 development of, 116e117 evaluation of, 156e168 maintainability design, 145e147 system assessment methods, 150e156 theory, 118e126 Conditional probability, 120, 123, 125, 150e151 Connecting linkage, Constant pressure variable pump, 173e174, 179e183, 180fe181f, 185f, 187f, 189e190 Contact stress, 136 Control valve, 88, 153fe154f Control augmentation, 4e6, 117, 197e200 signal, 188e191, 195 surface, 8e11, 9f, 64f Critical surfaces, 158e159 Criticality analysis, 23, 59, 150e151, 151t Cumulative probability of failure, 119e120, 120f B Bathtub curve, 120e121, 121f Boolean algebra, 158 259 260 Index D Design standard, 127t Dual pressure pump, 181e182, 182f redundant hydraulic system, 58e59 Dynamic design, 72 performance requirements, 48e49 stiffness, 45e46 E Early failure, 120, 121f Economics, 115, 116f Electric power, 36, 59, 142, 200e205, 212f Electrical component, 127, 129f power transmission, 24, 197e200 Electro-backup hydraulic actuator (EBHA), 30e31, 67, 197e200 Electro-hydrostatic actuators (EHA), 11e12, 66e67, 159, 197e200 key technologies of, 206e207 principle, 200e208 Electromechanical actuator (EMA), 11e12, 25e26, 212 Elevator, 1, 8, 9f, 27fe29f, 64f aileron computer, 12, 28 pitch control, 10 Emergency generators, 12, 65 Energy management techniques, 177 Engine-driven pump (EDP), 72e78, 145 Enhanced cross correction, 223 Environmental temperature, 128 Evolution without after-effects, 125 Exponential distribution, 123e125, 124f F Failure characteristics, 127t, 227t criticality, 36, 59, 127t detection, 55e56, 139, 145e146, 146fe147f, 150, 152t, 217e219 distribution, 116e117, 119e120, 123e124 mode, 150e151 mode and effect analysis (FMEA), 227t mode effect and critical analysis (FMECA), 23, 59, 150e151, 151t rate, 120e121 record, 139 transients, 46, 47f, 105e108 Failure-free performance, 118 Fatigue reliability of cylinder barrel, 131e133 of piston, 133e136 Fault diagnosis, 225fe226f, 230, 237e240 feature extraction, 219e220, 221f, 225fe226f monitoring, 109 prediction, 240e245 tree analysis (FTA), 36, 59, 116e117, 151e155 tolerance capability, 138e139 transient, 110, 139 Fixed-wing aircraft, Flap, 1e4, 8, 9f, 13f, 64f, 146f control, 10 Flight control computer, 12, 12f, 16e17, 22, 27, 29e30, 190e191, 191f, 192t, 210, 211f control system, 1e8 profile, 71e72, 181, 183e184, 191, 193f Fluid cooling system, 94 flow rate, 40, 71e72 temperature, 71 Fly-by-wire (FBW), 4e5, 59 Force coupling, 41, 109 Force voting, 111 Fuzzy logic, 224e227 diagnosis, 226f H Hierarchical intelligent reasoning, 220e223 High-lift devices, 29, 33f High pressure hydraulic power supply Hydraulic accumulator, 73f, 90e91 actuator, 35, 41e42 driven generator, 55 filter, 92e93, 92f fluid, 14, 69 network, 172, 197e200 pipes, 72 power package, 55 power supply system, 12f, 15e16, 56f, 97, 146fe147f, 148te149t, 156e158, 157f power transmission, 197e200 powered actuator, 11e12, 18, 26, 197e200 Index pressure, 70 pump design, 81e83 reservoir, 93e94 servo system, 54, 183e188 system, 1e12, 33e50, 69e111, 126e145, 156e168, 215e248 transmission system, 183 Horizontal stabilizer, 8, 11e12, 23, 28f, 67 Hydraulically powered actuator, 69, 197e200 I Independent processes, 125 Intelligent hydraulic power supply system, 181e197, 184f pump controller, 183e188, 190e197, 191f, 194t variable pressure hydraulic system, 188e189 Internal failure, 118 Irreversible booster control system, 2e4, 3f, 18 J Jump resonance, 104e105, 106f K k/n(G) Voting System, 122, 142, 142f L Landing gear, 53, 61e62, 64f, 112f, 227e228 Laplace transform, 161 Leakage coefficient, 98, 161e163 external, 78, 208 internal, 78, 208 total, 196, 208 Level of risk, 118 Load sensing pump, 180e181, 180fe181f sharing, 110 M Maintainability design, 145e147 Maintenance management, 215, 217e219, 246f Maneuverability, 4e5, 53, 116e117, 172, 175, 188 Manual flight control system (MFCS), 1e2 Manufacturing process, 116e117 Material parameters, 131e132 Mathematical expectation, 123 Markov process, 155 state transfer method, 116e117 Maximum rate capability, 38e40 Maximum stroke, 38e39, 40f Mean life, 121 Mean time between failure (MTBF), 121e122 Mean time to failure (MTTF), 121e122 Mechanical component, 129 Memorylessness, 125 Mission profile, 119, 191, 191f, 192t Model based reasoning, 223f N Nonrepairable system, 118e122 reliability theory of, 122e123 Non-effective power increase by high power, 176e181 increase by high pressure, 176 Nonlinear parameters influence, 101 Normal deviation, 125 distribution, 125 O Operation basic, 56e57 continued, 17 full, 34 normal, 38, 224, 227e228 system, 39e40, 168 Operational environment, 116e117 Operational state, 122 Optimized sensor layout, 232f P Parallel system, 139, 141f Performance degradation, 118, 139, 163e164, 166, 168, 216e219, 222e223, 240, 243e245 Power generation, 49, 216 loss, 176e183 matching circuit, 177 spectral density, 235, 236f transfer unit (PTU), 55, 83e87, 145 261 262 Index Power-by-wire, 8t, 23, 30e31, 200e205 Pressure pulsation, 72, 201f ripple, 75, 78, 82, 91, 179, 179f Primary flight controls, 9e10, 9f, 17, 30e31, 34, 69, 87 Priority valve, 87e88 Probability density function, 123e126, 129 of occurrence, 127t Product design phase, 116 lifecycle, 117, 120e124 quality, 115e116 Prognostics and health management (PHM), 215e248 development, 215e217 evaluation, 246e248, 247fe248f fault prediction, 240e245, 241t, 242f, 244fe245f hierarchical intelligent fault diagnosis algorithm, 220e240, 221fe223f, 225fe226f, 227t, 228f, 229t, 230fe236f, 238f, 239t information acquisition, 219e220, 220f maintenance of, 245e246, 246f structure, 217e219, 218f Proof test, 111e112 Propulsion diagnostics, 216 Q Quantitative flight safety, 7e8 FCS requirement, 7t R Ramps, 46e47, 108 Random factors, 120e121 failure, 120e121, 121f Redundancy configuration, 139 management strategy, 139 Redundant hydraulic actuators, 123e124 Reliability block diagram, 116e117, 246e248 design, 126e145 evaluation, 150, 156e168 Repair technician, 116e117 time, 116e117, 122e123, 163, 215e216, 245 Repairable product, 121e122, 121f rate, 123 system, 122e123 time, 123 Requirement of airworthiness, 36e38 element design, 36e37 system design, 37 tests, 37e38 Reservoir, 5, 49, 55, 58f, 61, 93e94 Resources recovery, 139 Rudder, 1, 8, 13f, 23, 27, 27fe29f, 64f S Safety assessment tools, 36, 59 Safety assessment methods failure modes, effects, and criticality analysis, 150e151 fault tree analysis, 151e155 Markov analysis, 155e156 Saturation analysis, 103e105, 104f Secondary flight controls, 10e11, 33e34, 69 Segmentation control surface technology, 159 Servo valve, 97f, 166t, 211f determination, 97, 97f, 144 model, 160 reliability, 144 Single hydraulic system, 55e57, 127t Slat, 9f, 10 Spoiler, 9f, 10e11 Stability augmentation, 3f, 4e5, 117, 197e200 Stall load, 38e41, 159 Static stability design method, 117 Statistical distribution, 123e124 Standard deviation, 125, 130e131, 133 of equivalent stress, 136e137 of operational stress, 135 of piston fatigue limit, 135 of piston strength, 135 due to radial force, 134 of tensile strength, 131e133 Steering, 64f nose wheel steering, 67, 87, 146f Strength distribution fatigue, 133 piston, 135 Stress concentration, 133 distribution, 132e135, 132f, 134f strength interference curve, 130f Index Supportability, 115e116, 116f, 118, 129f, 215e217, 246 maintenance supportability, 246 System reconfiguration, 139 reliability design, 138e145, 168 safety requirements, 34e36, 59 stability, 117, 179e180 T Testability, 115e118, 116f Thermal design, 128e129, 129f 263 Thrust reversers, 35, 59, 61e62, 64f, 66, 213 Tolerance design, 128, 129f Transfer function, 46e47, 99e101, 160e161, 164, 197, 208 Trimmable horizontal stabilizer, 8, 12, 28f, 67 W Water proof design, 129f Wear reliability, 136e138 Wear-out failure, 120e121 Weibull distribution, 123e124, 126 ... system, and (e) FBW systems [2] 4 Commercial Aircraft Hydraulic Systems related to the aircraft FCS, the hydraulic booster changed the surface maneuver from mechanical power to hydraulic power and... control and hydraulic systems 12 Commercial Aircraft Hydraulic Systems Flight control computer Control surfaces Electric motor, solenoids Actuator Hydraulic power supply system Hydraulic power... controls of commercial aircraft 10 Commercial Aircraft Hydraulic Systems control is critical to safety, and loss of control in one or more primary flight control axis is hazardous to the aircraft