1、No Fault Found: The Search for the Root Cause S. Khan, P. Phillips, C. Hockley and I.K. Jennions No Fault Found: The Search for the Root Cause Khan Phillips Hockley Jennions Today, we are all strongly dependent on the correct functioning of technical systems. They fail, and we become vulnerable. Dis
2、ruptions due to degradation or anomalous behavior can negatively impact safety, operations, and brand name, reducing the pro tability of all elements of the value chain. This can be tolerated if the link between cause and e ect is understood and remedied. Anomalous behavior, which indicates systems
3、or subsystems not acting in accordance with design intent, is a much more serious problem. It includes unwanted system responses and faults whose root cause cant be properly diagnosed, leading to costly, and sometimes unnecessary, component replacements. The title No Fault Found: The Search for The
4、Root Cause was developed to propose solutions to this technical and business challenge, which has become less and less acceptable to the commercial aviation industry globally. Bringing together the areas of systems engineering and quality management, this unique book lists relevant terminology for c
5、onsistent reporting, addresses the importance of “soft” human factors, and deals with aspects of availability and safety, operating policies, tools, diagnostic design, and the use of the right technology. Written by four experts with backgrounds in asset health management, condition monitoring, faul
6、t analysis, and systems failure, No Fault Found: The Search for the Root Cause is a must-read for engineers and managers focused on addressing these complex problems and solving them. About the Authors Dr. Samir Khan is a lecturer of aerospace engineering at Coventry University, with a PhD in Contro
7、l Theory from Loughborough University. He was the leading researcher on the No Fault Found research project between 2011- 2015, at Cran eld University. Dr. Phillips began his career at The University of Manchester, later joining the EPSRC Centre for Through-life Engineering Services at Cran eld Univ
8、ersity. Since 2014, Paul has been the head of advanced projects at UTC Aerospace Systems, Marston, UK. Chris Hockley joined Cran eld University in 2003 after 35 years in the Royal Air Force. He is a chartered engineer and currently the principal investigator at the EPSRC Centre for Innovative Manufa
9、cturing in Through-Life Engineering Services for the NFF project. Ian K. Jennions is the director of the IVHM Centre, Cran eld University, UK, leading its growth since 2008. A mechanical engineer, he previously worked in the gas turbine industry, and holds a PhD in CFD, from Imperial College, London
10、. S. Khan P. Phillips C. Hockley I.K. Jennions No Fault Found: The Search for the Root Cause R-441 ISBN: 978-0-7680-8122-0 AEROSPACENo Fault Found: The Search for the Root Cause R-441_Insides.indb 1 7/28/15 2:53 PMOther SAE books of interest Integrated Vehicle Health Management: The Technology Edite
11、d by Ian K. Jennions (Product Code: R-429) Integrated Vehicle Health Management: Implementation and Lessons Learned Edited by Ian K. Jennions(Product Code: R-438) Counterfeit Electronic Parts and Their Impact on Supply Chains By Kirsten M. Koepsel (Product Code: T-130) For more information or to ord
12、er a book, contact: SAE INTERNATIONAL 400 Commonwealth Drive Warrendale, PA 15096 Phone: +1.877.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S. and Canada) Fax: +1.724.776.0790 Email: CustomerServicesae.org Website: books.sae.org R-441_Insides.indb 2 7/28/15 2:53 PMWarrendale, Penns
13、ylvania, USA By Samir Khan, Paul Phillips, Christopher J. Hockley, and Ian K. Jennions No Fault Found: The Search for the Root Cause R-441_Insides.indb 3 7/28/15 2:53 PM Copyright 2015 SAE International eISBN : 978-0-7680-8227-2 Copyright 2015 SAE International. All rights reserved. No part of this
14、publication may be reproduced, stored in a retrieval system, distributed, or transmitted, in any form or by any means without the prior written permission of SAE International. For permission and licensing requests, contact SAE Permissions, 400 Commonwealth Drive, Warrendale, PA 15096-0001 USA; emai
15、l: copyrightsae.org; phone: +1.724.772.4028; fax: +1.724.772.9765. SAE Order Number R-441 http:/dx.doi.org/10.4271/r-441 Library of Congress Cataloging-in-Publication Data Kahn, Samir.No fault found : the search for the root cause / by Samir Kahn, Paul Phillips, Christopher J. Hockley, and Ian K. Je
16、nnions.pages cmIncludes bibliographical references.ISBN 978-0-7680-8122-01. Fault location (Engineering) 2. Systems engineering. I. Title. TA169.6.K34 2015620.00452-dc232015018194 Information contained in this work has been obtained by SAE International from sources believed to be reliable. However,
17、 neither SAE International nor its authors guarantee the accuracy or completeness of any information published herein and neither SAE International nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the under
18、standing that SAE International and its authors are supplying information, but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. ISBN-Print 978-0-7680-8122-0 ISBN-PDF 978-0-7680-8227
19、-2 ISBN-epub 978-0-7680-8229-6 ISBN-prc 978-0-7680-8228-9 To purchase bulk quantities, please contact: SAE Customer Service E-mail: CustomerServicesae.org Phone: +1.877.606.7323 (inside USA and Canada)+1.724.776.4970 (outside USA) Fax: +1.724.776.0790 Visit the SAE International Bookstore at BOOKS.S
20、AE.ORG 400 Commonwealth Drive Warrendale, PA 15096 E-mail: CustomerServicesae.org Phone: +1.877.606.7323 (inside USA and Canada)+1.724.776.4970 (outside USA) Fax: +1.724.776.0790 R-441_Insides.indb 4 7/28/15 2:53 PMv Acknowledgments .ix Chapter 1: Introduction . 1 1.1 Background 1 1.1.1 Maintenance
21、and NFFHistorical Perspective 3 1.1.2 The Growth of NFF within Aerospace 4 1.1.3 NFF Related Literature .8 1.2 The NFF Phenomena 9 1.3 The Cost of NFF 13 1.4 Scope of This Book 14 1.5 References 15 Chapter 2: Basics and Clarification of Terminology 17 2.1 Introduction .17 2.2 Systems Basics .18 2.3
22、Failure and Types of Failure 19 2.4 Fault and Types of Fault.20 2.5 Maintenance and Related Terms.21 2.6 No Fault Found Terminology 23 2.6.1 NFF Classification 23 2.6.2 Case StudyThe Impact of Inconsistent Terminology 30 2.6.3 Other Related Terms 31 2.7 Nomenclature 33 2.8 Conclusion .36 2.9 Referen
23、ces 36 Chapter 3: The Human Influence . 39 3.1 Introduction .39 3.2 The Human Element 40 3.2.1 Organizational Context .40 3.2.2 Communication .42 3.2.3 Human Factors Impacting NFF .44 3.3 The Maintenance Engineer and System Interactions 46 3.3.1 Typical Maintenance Processes in Civil Aircraft .46 3.
24、3.2 Hardware Interactions 47 3.3.3 Software Interactions.48 3.3.4 Environment Interactions .49 3.4 Human Factors Survey 49 3.4.1 Introduction 49 3.4.2 Aircraft Testing Resources .50 3.4.3 Aircraft Maintenance Manuals 52 3.4.4 Organizational Pressures 53 3.4.5 Maintenance Engineer: Competence and Tra
25、ining .55 Table of Contents R-441_Insides.indb 5 7/28/15 2:53 PMvi 3.5 Best Practice Guidelines .58 3.6 Conclusion .59 3.7 References 60 Chapter 4: Availability in Context 61 4.1 Introduction .61 4.2 Aerospace Maintenance Practice 62 4.3 The Quality of Maintenance Systems .64 4.4 Design for Maintena
26、nce and System Effectiveness .66 4.5 Availability .67 4.5.1 The Multiple Facets of Availability .67 4.5.2 Design Requirements for RAM .71 4.6 The Impact of NFF on Availability .73 4.7 A Process for Improvement .77 4.7.1 Overview .77 4.7.2 A Methodology for Monitoring NFF In-Service .80 4.7.3 Unit Re
27、moval Datasheets .80 4.8 Conclusion .82 4.9 References 82 Chapter 5: Safety Perceptions . 85 5.1 Introduction .85 5.2 Faults and SafetySome Perceptions 86 5.3 A Conceptual Discussion .87 5.4 The Regulatory Issues in the Air Environment 89 5.5 Faults and the Link with Maintenance Errors 91 5.5.1 The
28、Maintenance Contribution 91 5.5.2 Operational Pressure .92 5.5.3 The Human Factors Contribution .93 5.5.4 Diagnostic Maintenance Success .96 5.6 NFF and Air SafetyA Case Study .97 5.7 Conclusion .98 5.8 References 99 Chapter 6: Operating Policies for Management Guidance . 101 6.1 Introduction .101 6
29、.2 Through-Life Engineering Services Context .102 6.3 Policy Requirements .108 6.4 The NFF Control Process . 111 6.5 Application Example 122 6.5.1 Introduction 122 6.5.2 Implementation Prerequisites 122 6.5.3 Application .123 6.6 Conclusion .125 6.7 References 126 R-441_Insides.indb 6 7/28/15 2:53 P
30、Mvii Chapter 7: A Benchmark Tool for NFF . 127 7.1 Introduction .127 7.2 Benefits of NFF Management 127 7.3 Challenges of Investigating NFF 130 7.3.1 Technical Challenges .131 7.3.2 Commercial Challenges 131 7.4 A Proposed Tool for Managing NFF 132 7.4.1 The Benchmark Tool 132 7.4.2 A NFF Maturity M
31、odel .133 7.5 Deployment of the Tool 143 7.5.1 Stage 1 143 7.5.2 Stage 2 143 7.5.3 Stage 3 144 7.5.4 Stage 4 144 7.6 Summary of the Tool 144 7.7 References 144 Chapter 8: Improving System and Diagnostic Design 145 8.1 Introduction .145 8.2 Diagnostics Design and NFF .146 8.2.1 In-Service Feedback Ac
32、tivities .147 8.2.2 Diagnostic Design Activities 148 8.3 System Design and System Integrity .149 8.4 Testability .150 8.4.1 Testability Standards .151 8.5 Design for Diagnosis 152 8.6 Information Feedback to Diagnostic Design 153 8.7 Level of Training .154 8.8 User-Interaction and System Design 155
33、8.9 Conclusion .155 8.10 References 156 R-441_Insides.indb 7 7/28/15 2:53 PMviii Chapter 9: Technologies for Reducing No Fault Found 159 9.1 Introduction .159 9.2 Advanced Diagnostics .160 9.2.1 Health and Usage Monitoring of Electrical Systems 160 9.2.2 Built-In Test .160 9.2.3 Monitoring and Reaso
34、ning of Failure Precursors .163 9.2.4 Monitoring Life-Cycle Loads .165 9.3 Improvements to Testing Abilities .166 9.3.1 Testability as a Design Variable .166 9.3.2 Functional and Integrity Testing .167 9.3.3 Testing Under Environmental Conditions .169 9.3.4 Management of the Test Station .170 9.3.5
35、Tracking Spare Part Units .171 9.4 Conclusion .172 9.5 References 173 Chapter 10: Summary and Ideas for Future Work . 175 Index .181 About the Authors .191 R-441_Insides.indb 8 7/28/15 2:53 PMix Acknowledgments The authors wish to acknowledge the support and opportunity provided by the EPSRC Centre
36、for Innovative Manufacturing in Through-Life Engineering Services in the preparation of this book. The Centre was set up by the EPSRC in June 2011 as a partnership between Cranfield and Durham Universities with 5 main projects, research into NFF being one of those. Initial research established that
37、there was very little knowledge and information available in the public domain about NFF. What information that did exist seemed to be in specialist publications or only readily available to limited groups or industries. An early aspiration of the project therefore was to redress this deficiency wit
38、h a book that would provide a foundation in the subject for engineers and managers alike. The research and knowledge gained during the NFF project within the Centre has provided both the material, and certainly the inspiration, for this book. We are most grateful to the Centre Director, Professor Ra
39、j Roy for his encouragement and to the SAE for the opportunity. In particular we would like to thank Monica Nogueira at SAE who has helped us achieve our aspirations. We trust that you the reader will find this a useful book in your efforts to understand and hopefully reduce the occurrence of NFF in
40、 your area of responsibility. R-441_Insides.indb 9 7/28/15 2:53 PMx R-441_Insides.indb 10 7/28/15 2:53 PM1 Chapter 1 Introduction 1.1 Background In todays society we are all strongly dependent on the correct functioning of technical systems, and this dependence has made us vulnerable to their failur
41、e. Any disruption, due to degradation or anomalous behavior, is of major concern, not only to us (the user) but also to the manufacturers, suppliers, operators, and maintainers of the equipment. It can have adverse effects on safety, operation, and brand name, and it can directly reduce the profitab
42、ility of all elements of the value chain. Such disruption can come in various forms. Slow degradation, giving enough time to source and fit a new part, is a relatively minor inconvenience. A part that breaks (rapid degradation) is somewhat more annoying, as the ability of the equipment to perform it
43、s function is lost until the part is replaced. It is, nonetheless, tolerated, as the link between cause and effect can be understood and easily remedied. Neither of these is as troublesome as anomalous behavior, in which systems or subsystems do not act in accordance with design intent. In this cate
44、gory, one can include emergent behaviors in which, principally due to the complexity of subsystem interaction, a system can demonstrate a response with action that was unintended. Another area in the same category is that of faults where the root-cause diagnosis cannot be identified. In such cases,
45、a suspect component is replaced only for it to be found that the fault has not gone away, and when the component is tested on a bench, it is found to be working normally. This area has been given the name No Fault Found (NFF) and is the subject of this book. When NFF occurs, other components are rep
46、laced until functionality returns, without a clear idea as to why. Due to our inability to diagnose such problems, the cost incurred, until recently, has become part of “the cost of doing business.” However, with all companies now operating much more efficiently than one or two decades ago, this (la
47、rge) overhead can no longer be tolerated, and the constituents of the problem have to be examined. 1 R-441_Insides.indb 1 7/28/15 2:53 PMFigure 1.1 shows a generic operating environment that can be found across many different sectors (e.g., aerospace, rail, and energy), which operate expensive, comp
48、lex equipment. The original equipment manufacturer (OEM) supplies an asset to an operator who is going to use it as part of a business to make a profit. The operator needs the equipment to be regularly maintained, and the maintainer will have access to the OEMs supply chain for spare parts. This is
49、all done with a respect for standards, and certification in some industries. Altogether, this picture is much more complicated in real life, but it serves the purpose here of exposing all of the areas where NFF could have an effect, and that therefore have to be explored to reduce the (significant) cost of this effect. All of the areas shown are covered, to some degree, in this book. Operational Schedule Availability Profit Turnaround time Asset tracking Cost of NFF warranty Obsolescence Safety Diagnostics Maintenance the OEM has beco
