Case Studies of three fatigue failure evaluations in aircraft

Three cases of aircraft accidents are described that involved failure by fatigue. All of them relate to components, rather than to the main structure of the aircraft. None of the accidents involved loss of life. The items involved were landing gear, an engine bearing and a blade from a gas producer turbine wheel. The landing gear failure was found to have resulted from prior cracking; the engine bearing failure was caused by fatigue of the roller bearing cage; and the helicopter turbine blade failure was a result of large brittle precipitates at the surface of the cast structure of the blade/disc combination from which a fatigue crack had grown.