Nondestructive Inspection of Piper PA25 Forward Spar Fittings

摘要

The Federal Aviation Administration's (FAA's) Aging Aircraft NDI Validation Center (AANC) at Sandia National Laboratories applied two nondestructive inspection (NDI) techniques to inspect a forward spar fuselage attachment fitting. The techniques used were based on radiography and ultrasonic test methods. The combination of these techniques did reveal material thinning of two spar fittings from Piper PA25 aircraft. However, crack detection near a notch design feature could not be performed. Based on the results of these experiments, an ultrasonic test procedure was subsequently developed for the material thinning. The procedure has since been incorporated by the FAA into a revision of Airworthiness Directive 93-21-12.