An oil scavenge pump was found to have failed when a protective shear neck fractured during the start of a jet engine. Visual inspection revealed that the driven gear in one of the bearing compartments was frozen as was the corresponding drive gear. Spacer wear and thermal discoloration (particularly on the driven gear) were also observed. The gears were made from 32Cr-Mo-V13 steel, hardened and nitrided to 750 to 950 HV. Micrographic inspection of the gear teeth revealed microstructural changes that, in context, appear to be the result of friction heating. The spacers consist of Cu alloy (AMS4845) bushings...
L.D. Cologna, Investigation of Jet Engine Oil Scavenge Pump Failure, ASM Failure Analysis Case Histories: Air and Spacecraft, ASM International, 2019, https://doi.org/10.31399/asm.fach.aero.c9001575
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