LME induced failure of a combat aircraft gun

Premature catastrophic failures of gun barrel casings of a combat aircraft were reported. Magnetic particle fluorescent (MPF) and die penetrant inspections of in-service casings indicated cracks in various locations. Further investigations unveiled them to be multiple initiation fatigue cracks.The fracture surface of the failed casings showed chevron marks pointing towards the crack origin, where Pb, Cu and Zn were present in high concentrations. The finding construed that the failures were anticipated by liquid metal embrittlement.