A Marine Corps helicopter crash was investigated. Efforts were directed to the failure of one of the main rotor blades that had apparently separated in the air. The apparent failure of a blade integrity monitor (BIM) system was also considered. The rotor blade comprised a long, hollow 6061-T651 aluminum alloy extrusion and 26 fiberglass “pockets” that provided the trailing-edge airfoil shape. Visual examination of the fracture surface of the aluminum extrusion indicated fatigue crack growth followed by ductile overload separation. Examination of the fatigue fracture region revealed several pits that appeared to have acted as fracture origin sites. Time...
Lawrence Kashar, Failure of a Helicopter Main Rotor Blade, Handbook of Case Histories in Failure Analysis, Vol 1, Edited By Khlefa A. Esaklul, ASM International, 1992, p 20–24, https://doi.org/10.31399/asm.fach.v01.c9001024
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