The detection, inspection, and failure analysis of a composite wing skin defect on a tactical aircraft

A routine ultrasonic inspection of a lower wing skin revealed a defect between the titanium alloy stepped-lap joint and composite surface. Since the wing skin passed high-tension loads through to the fuselage, the possible presence of such a defect had the potential to compromise other aircraft with the same construction. Naval Air Station (NAS) Jacksonville personnel took the lead in coordinating the approach to identify, diagnose, and manage the defect by synchronizing efforts between non-destructive testing, metallurgy, and composites experts. The defect was identified as a disbond between the splice plate and bond primer that led to a delamination fatigue crack between composite plies. From these results, staff implemented a novel inspection program to search for similar defects in the fleet.