A stochastic approach to determine lifetimes and inspection schemes for aircraft components

This paper describes a stochastic methodology for predicting aircraft component fatigue lifetimes and optimum inspection intervals. An introduction covers some basics in design philosophies and the main aspects of deterministic and stochastic analysis. Then a stochastic life approach (SLAP) is presented. This consists of three steps: (1) determining the failure distribution; (2) reverse crack growth analyses from the failure distribution to obtain the initial inspection time and corresponding crack length distribution; and (3) forward crack growth analyses to determine a schedule for repeated inspections. The SLAP methodology is illustrated using in-service inspection data from an actual aircraft component and comparing the results with a deterministic analysis. Concluding remarks summarise the findings and address open issues.