The effect of flaw size distribution on the estimation of POD

Damage tolerance-based operation and maintenance of aircraft components requires the estimation of probability of detection (POD) of non-destructive inspection (NDI) techniques. The standard approach to estimate POD of an NDI process is to perform demonstration tests on simulated or real components. To generate a realistic POD, it has been suggested that flaw sizes should be uniformly distributed on a log scale covering the transition region of the POD on the interval [ln(a_1%), ln(a_99%)].

This paper presents an alternative approach that is based on a Rayleigh distribution of flaw sizes on a log scale covering the whole range of flaws of potential interest. The use of this approach can increase the accuracy of the POD estimate by optimally distributing flaw sizes in the range of minimum and maximum flaw sizes.