Abstract
The condition of no fault found (NFF) has been accepted by engineers and operators for many years. Whilst there are known general reasons for NFF one of the areas that is overlooked is the importance of the test equipment, whether built-in test equipment or automatic test equipment, and specifically the effectiveness of the test. How much of a system or component is actually being test by the test equipment? This paper explores the system or component fault coverage effectiveness and the impact on NFF. In doing so a module is proposed to establish the relationship between NFF and test coverage effectiveness for different reliabilities. As the component or system reliability improves along with the test effectiveness the percentage of NFF occurrences decreases. Another consideration is the assumed number of random failures that the design engineers include during the development phases. This is usually an underestimate and the combination of this and the ineffective fault coverage have a negative impact on the operational availability.
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Abbreviations
- E:
-
Effectiveness fault coverage of the test
- MT:
-
Maintenance test
- NFF:
-
No fault found
- R:
-
Reliability of system/component before the test
- RE :
-
Reliability of the tested part of the system/component before test
- R(1−E) :
-
Reliability of the NOT tested system/component
- RL :
-
Reliability of the whole system/component after testing
- RT :
-
Reliability of system/component after test
- α:
-
Probability of a FAIL-FALSE
- β:
-
Probability of a FAIL-PASS
References
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Jones JV (2006) Integrated logistic support handbook, 3rd edn. New York Sole Logistics Press, McGraw-Hill
Thompson J (1994) Mathematics of FRACAS, advances in logistics, Thesis. University of Exeter MIRCE research centre
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© 2017 Springer International Publishing AG
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Thompson, J., Lacey, L. (2017). Insights into the Maintenance Test Effectiveness. In: Redding, L., Roy, R., Shaw, A. (eds) Advances in Through-life Engineering Services. Decision Engineering. Springer, Cham. https://doi.org/10.1007/978-3-319-49938-3_16
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DOI: https://doi.org/10.1007/978-3-319-49938-3_16
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