The Impact of No Fault Found (NFF) on Through Life Engineering Services

Hockley, Christopher J.

doi:10.1007/978-3-319-12111-6_4

Cited by 3 publications

(5 citation statements)

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“…This system has a maximum of n inputs and n outputs. There is no disturbances, and the e ect of a single fault f i (t) depends on the choice of K i in (2). Here y (t) is the term defining the sensor fault f s (t) of the form 0 sin(t) and the intermittent fault is of the form (20).…”

Section: Simulation Conditionsmentioning

confidence: 99%

“…This therefore poses an ever increasing challenge in the maintenance of electronic, mechanical and hydraulic equipment. A substantial portion of malfunctions attributed to intermittent faults as tested healthy and may be categorized as No Fault Found (NFF) [2]. When the fault is not intermittent and the fault symptoms are consistent (hard fault), it is not di cult to isolate and repair.…”

Section: Introductionmentioning

confidence: 99%

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The Performance of Observer-based Residuals for Detecting Intermittent Faults: The Limitations

2014

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In this paper a broad nonlinear system is considered. Attention is focused upon both performance of a high-gain observer-based residual and the investigation of residual e ectiveness for detecting faults in actuators components. Residual performances for di erent fault positions and various system complexities are compared. Both qualitative and quantitative evidence for selected fault positions indicated the performance and the e ectiveness of the residuals decrease by ascending the system complexity. The poor performance of residuals in the more complex system may cause No Fault Found (NFF). The methods may be extended to the more general class of nonlinear systems and di erent observers. E ciency of the proposed approach is demonstrated through the intermittent failure case in a vehicle suspension system.

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Section: Simulation Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Performance of Observer-based Residuals for Detecting Intermittent Faults: The Limitations

2014

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“…Hence, the intermittent fault acts an ever-increasing dispute in the maintenance of electronic, mechanical and hydraulic equipment. An ample fraction of breakdowns associated to the intermittent faults will test well and will be classified as ''No Fault Found'' (NFF) [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Feed-forward observer-based intermittent fault detection

Sedighi

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Sydor

2017

CIRP Journal of Manufacturing Science and Technology

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“…Thus faults of this nature raise many concerns in the realm of throughlife engineering of products [2]. A substantial portion of malfunctions attributed to intermittent faults will test "OK" and will be categorized as No Fault Found (NFF) [3]. A much simplified maintenance process within an organization can be observed in Figure 1, which separates the rectification process into three key levels within an organization.…”

Section: Introductionmentioning

confidence: 99%

“…However, when bench test do not reveal any reported faults perfectly working components are replaced and tagged as "NFF", Figure 1. There may be various reasons that contribute to this overall process, however, recent publications have highlight intermittent faults within the system to be a major cause, [3]. This highlights the need for revisiting testability requirement that are capable of detecting an intermittent fault.…”

Section: Introductionmentioning

confidence: 99%

Intermittent fault detection on an experimental aircraft fuel rig: Reduce the No Fault Found rate

Sedighi

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Khan

2015

2015 4th International Conference on Systems and Control (ICSC)

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Abstract-In the context of aircraft engineering and maintenance, No Fault Found (NFF) is a chain of events that develops from a pilot experiencing a system malfunction with postflight maintenance failing to reproduce the reported symptoms. Without any repair being undertaken, the malfunction may be experienced again on subsequent flights. This present significant cost impacts to the industry that includes financial, reduced operational achievement, airworthiness challenges and potential flight safety issues. One of the major causes identified for NFF occurrence within electronic, mechanical and hydraulic products are faults that are intermittent in nature. This makes it difficult to use systematic fault detection techniques effectively, as system are subject to unknown disturbances and model uncertainties. The philosophy behind this criterion is that the designed model-based Fault Detection (FD) observer should be robust to disturbances but sensitive to intermittent faults where the occupance of intermittent faults can be alarmed by the use of an adaptive threshold. The aim of this paper is to demonstrate the development of such methodologies and to examine its performance in a real-world test bed. The test bed consists of an aircraft fuel system simulation rig which simulates by hardware the components of an aircraft fuel system.

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The Impact of No Fault Found (NFF) on Through Life Engineering Services

Cited by 3 publications

References 0 publications

The Performance of Observer-based Residuals for Detecting Intermittent Faults: The Limitations

The Performance of Observer-based Residuals for Detecting Intermittent Faults: The Limitations

Feed-forward observer-based intermittent fault detection

Intermittent fault detection on an experimental aircraft fuel rig: Reduce the No Fault Found rate

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