A Research Study of no Fault Found (NFF) in the Royal Air Force

Hockley, Chris; Lacey, Laura

doi:10.1016/j.procir.2016.09.034

Cited by 8 publications

(1 citation statement)

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“…This problem is indeed topical because according to [39], the average cost of losses due to NFF per aircraft in the US civil aviation was about $200,000 in 2013. Similar losses exist in military aviation [40,41]. So, according to the US Department of Defense, three out of four (75%) weapon systems are subject to NFF-type failures [41].…”

Section: Discussionmentioning

confidence: 99%

Maintenance Model of Digital Avionics

Raza

2018

Aerospace

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Abstract:The cost of avionics maintenance is extremely high for modern aircraft. It can be as high as 30% of the aircraft maintenance cost. A great impact on the cost of avionics maintenance is provided by a high level of No Fault Found events (NFF). Intermittent faults are the leading cause of the NFF appearance in avionics. The NFF rate for avionics systems is between 20% and 50%. The practice of avionics operation and maintenance confirms the relevance of assessing the impact of intermittent faults on the maintenance cost and the choice of such option of the maintenance management, in which the negative impact of the intermittent faults is minimized. In this paper, a new mathematical model of digital avionics maintenance is developed. Key maintenance effectiveness indicators are selected. General mathematical expressions are obtained for the average availability, mean time between unscheduled removals (MTBUR), and expected maintenance cost of single unit and redundant avionics systems, which are subject to permanent failures and intermittent faults. The dependence of the maintenance effectiveness indicators on the rate of permanent failures and intermittent faults is investigated for the case of exponential distribution of time to failures and faults. The dependence of average availability on the number of spare units in the airline's warehouse is also analyzed. On the base of the proposed maintenance model, different options of avionics maintenance management are considered. Numerical examples illustrate how to reduce the expected maintenance cost of avionics systems.

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Section: Discussionmentioning

confidence: 99%