Outfield Reliability Evaluation Method for Aeronautical Equipment Considering Production Side Risk
When the aeronautical equipment has a short time of field test flight or a small number of faults,the lower confidence limit of MTBF is determined according to the general practice that the user risk is 20% .At this time,the fluctuation of the interval estimation is large.If the product evaluation reliability is not qualified,it will delay the finalize work of the entire aircraft.This paper draws on the practice of the US military standard,receives the probability formula from the environmental stress screening to further support the shortest test time;determines the minimum number of faults of the interval estimation from the perspective of the discrimination ratio and the risk of both sides,making the field test evaluation more fair and scientific.Generally,according to the user risk of 20%,according to the manufacturer's risk can not be less than 20% but not more than 40% to calculate the minimum number of faults,otherwise only point estimation can be carried out.Then the"factory and repair"data are preprocessed,including determining whether the minimum average working time per unit is reached and whether the fault data meet the exponential distribution.Finally,the unilateral confidence limit of MTBF index is quantitatively evaluated through the quantile of the chi-square distribution,and whether the MTBF specified value is judged.
goodness of fitconfidencepoint estimationinterval estimationproducer side risks
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