Lycoming; I0-540 K1G5; Failed Oil Pump; ATA 8550

“The driven oil pump gear (P/N 61298) which was aluminum and not changed at overhaul lost a tooth. The broken tooth jammed into the drive gear (P/N 61297) which broke two teeth off the oil pump drive (P/N LW10318). This (oil pump drive) is the only part involved that was replaced at overhaul. The idler gear (P/N LW10284) had one broken tooth, and the crankshaft gear (P/N LW10297) had one tooth broken as well.

Why this model engine is exempt from ADs (affecting similar parts in other engines) I don’t know….” A search of the FAA Service Difficulty Reporting System data base revealed one other report of this same engine model having lost teeth on the oil pump drive gear.

Part Total Time: 1,747.0 hours.