In-service inspection strategies for the case of unexpected detection of fatigue cracks in a fleet of aircraft

For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatigue cracks unexpectedly detected in a fleet of aircraft within a. warranty period (prior to the first inspection). The paper examines this case and proposes a technique to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and decision-making. Numerical example is provided to illustrate the procedure.