Estimation of Warranty Period for Fatigue-sensitive Aircraft Structure Components

One of the most important problems in the fatigue analysis and design of aircraft structures is the prediction of the fatigue crack growth in service. Available in-service inspection data for various types of aircraft indicate that the fatigue crack damage accumulation in service involves considerable statistical variability. In this paper, we consider the problem of estimating the minimum time to crack initiation (or warranty period) for a number of aircraft structure components, before which no cracks (that may be detected) in materials occur, based on the results of previous warranty period tests on the structure components in question. This problem is a special case of a general class of problems concerned with the analysis of the fatigue crack damage accumulation in aircraft service. The technique proposed here for solving the above problem emphasizes pivotal quantities relevant for obtaining ancillary statistics. Attention is restricted to invariant families of distributions. The numerical examples are given.