Unraveling the Cannot Duplicate and Retest OK problems by utilizing physics in testing and diagnoses

Reliability Engineering & System Safety

Phillips

Jennions

et al. 2014

This paper reviews the literature dealing with the nature and characteristics of no-fault found events within maintenance lines. Increasing systems complexities have seen a rise in the number of unknown faults that are being reported during operational service. Units tagged as 'No-Fault Found' are evidence that a serviceable component was removed, and attempts to troubleshoot the root cause have been unsuccessful. This scenario worsens when faults occurring at the component level are intermittent in nature. Here, the paper describes the prominent issues that have persisted across a variety of industrial applications and processes for decades. Some recent developments including standards, financial implications and safety concerns are highlighted.

Section: Organizational Procedures and Administrationmentioning

confidence: 91%

Section: Fill In Technical Logbookmentioning

confidence: 99%

No Fault Found events in maintenance engineering Part 1: Current trends, implications and organizational practices

Reliability Engineering & System Safety

Phillips

Jennions

et al. 2014

“…As more sophistication is added to electronic systems, the ability to maintain them is becoming ever more difficult and costly. Standard testing using Automatic Test Equipment (ATE) usually includes features such as timing, signal strength, duplicating the operating environment, loading, fanout and properly interconnecting the Unit Under Test (UUT) [60,79,80,81,82]. The idea of ATE is to force the UUT to fail without actually injecting faults.…”

Section: Improvements In Test Abilitiesmentioning

confidence: 99%

“…When it is suspected that NFF occurs due to a lack of fault coverage by the ATE (or BITE), there comes the requirement to use additional tools which are capable of identifying the root cause of the problem. Ungar and Kirkland (2003) [79] argue that to achieve this, an understanding of the Physics-of-Failures (PoF) 15 within the operating environment is needed. Once this is known, appropriate test equipment can be selected to support the ATE which through interpretation of the physics, for example, of circuits under the test environment to be used as fault locators; a capability often beyond that of standard ATE.…”

Section: Detecting Blind Spotsmentioning

confidence: 99%

No Fault Found events in maintenance engineering Part 2: Root causes, technical developments and future research

Reliability Engineering & System Safety

Phillips

Hockley

et al. 2014

This is the second half of a two paper series cover aspects of the NFF phenomenon, which is highly challenging and is becoming even more important due to increasing complexity and criticality of technical systems. Part 1 introduced the fundamental concept of unknown failures from an organizational, behavioral and cultural stand point. It also reported an industrial outlook to the problem, recent procedural standards, whilst discussing the financial implications and safety concerns. In this issue, the authors examine the technical aspects, reviewing the common causes of NFF failures in electronic, software and mechanical systems. This is followed by a survey on technological techniques actively being used to reduce the consequence of such instances. After discussing improvements in testability, the article identifies gaps in literature and points out the core areas that should be focused in the future. Special attention is paid to the recent trends on knowledge sharing and troubleshooting tools; with potential research on technical diagnosis being enumerated.

“…The global interest on the topic of hidden failures is evident from the increasing number of recent publications within the area (Söderholm, 2007;James et al, 2003;Ungar and Kirkland, 2008;Hockley and Phillips, 2012). Since the key enabler for their resolution is the availability of competent technicians, engineers and senior management, educational institutions have a responsibility to develop relevant high-quality modules and training material to support further progress in the field.…”

Section: Introductionmentioning

confidence: 99%

Research study from industry-university collaboration on “No Fault Found” events

Journal of Quality in Maintenance Engineering

2015

Purpose -The purpose of this paper is to present the successes and barriers from an industry-university partnership on studying the impact of No Fault Found (NFF) events. As a consequence, various opportunities are explored to engage with industry to investigate the problem. A comprehensive training is also outlined to ensure that experience and troubleshooting techniques can be disseminated as guidelines across businesses. Design/methodology/approach -The study was performed by Cranfield University in collaboration with industrial partners on identifying the impact of the NFF problem within engineering services. This includes discussions with maintenance engineers, outcomes from a symposium organised specifically on NFF and the authors' own experiences with the issue. Findings -The paper discusses the continuing serious problem with NFF events found at various maintenance echelons, and suggests a need for formal postgraduate training to be taught within the field of maintenance management. This includes not just technical issues, but also encompassing organisational structures, cultures and behaviours. Since focusing only on one issue at a time does not suffice in dealing with the NFF problem, an integrated approach is required for modern maintenance services and operations. Research limitations/implications -Higher education learning outcomes have been outlined for competent engineering personnel, to broaden their understanding on the subject area. This is based on discussions with industrial collaborators and recently published material. Practical implications -This paper emphasises the importance of the breath of interaction channels and demonstrates the opportunities for effective knowledge exchange by using the activities at Cranfield University to demonstrate their usefulness. The arguments clearly lead to the necessity of academia in this type of industrial problem. However, the presence of a university in this case is not as the sole problem solver, but the rather to act as a collaborative medium between various other outlets. Further ideas proposed, such as constructing guidelines for industries in handling NFF problems and benchmarking tools, can serve as real products that can be benefit industries. The study also aims to promote best practice in the field of maintenance management and outlines the foundations for NFF training material. Originality/value -The originality of the paper is that it presents a structured methodology for engaging with industry. It also outlines a curriculum for NFF training. It essentially serves as a road-map for research and offers a detailed account of areas that need to be taken into account in order to reduce the likely event of NFF.