Fatigue and fracture in an aircraft engine pylon

This paper summarises the events leading to a catastrophic aircraft accident near Amsterdam in October 1992. The aircraft, a Boeing 747-200, lost both of the engines and pylons from its right wing. Subsequently it became uncontrollable and crashed into an apartment block. The accident resulted in one of the most thorough investigations in aviation history. Many organisations and technical disciplines were involved. The paper concentrates on the NLR's examination of the mid-spar components of the #3 engine pylon-to-wing connections. This examination, which found fatigue failure of a so-called fuse pin, proved essential in determining the most probable cause and sequence of damage leading to loss of the #3 engine and pylon. This engine then hit the #4 engine, causing it and its pylon also to separate from the right wing. The paper concludes with a summary of the remedial actions taken by the aircraft manufacturer after the accident and investigation.