On attempting to start the engine for a post-maintenance ground run, the propeller turned through approximately three blades then stopped. Propeller was difficult to rotate forward or backward. Inspection of the starters Bendix drive shaft revealed cracks in the gear running parallel to the teeth, causing the gear not to properly mesh with the flywheel.
Multiple aircraft components, including pressure pumps, turbochargers, alternators, and magnetos, experienced failures due to sheared, worn, or cracked drive shafts.
These failures led to significant operational issues such as loss of instrument pressure, engine power during flight, or the inability to start the engine.
Many incidents occurred at relatively low component operating hours, with some failures having no immediate obvious cause.
One severe incident highlighted an installation error where an unengaged set screw allowed a prop governor idler shaft to cause total oil loss.
During a VFR instrument training flight, the instructor noted there was no instrument pressure from either engine. Inspection revealed both engine-driven pressure pumps had sheared their drive shafts. Technicians could not find any obvious reason for both shafts to fail.
Part total time: 88.6 hours
CREATE A FREE ACCOUNT
Sign up to keep reading
Create a free account to continue. Already a member? Sign in below.
