Probability of Detection of Flaws in a Gas Turbine Engine Component Using Electric Current Perturbation

In an exploratory development program, the Electric Current Perturbation (ECP) method was optimized for inspection of typical F-100 gas turbine engine components (disks and seals).1,2 A primary objective was to achieve high reliability for the detection of flaws (fatigue cracks) at the retirement-for-cause (RFC) target flaw size of 0.010 in. long x 0.005 in. deep. Probability of detection (POD) data for surface flaws in blade slots of an F-100 first stage fan disk were estimated from experimentally determined probability density functions (PDF’s) for background and flaw signals. The POD as a function of flaw size was estimated from these data.