What happened
During the flight, the pilot and a passenger observed a sudden loss of engine power accompanied by a distinct metallic sound. Following this mechanical failure, the crew executed a wheels-up forced landing in a plowed field.
The investigation
A teardown of the engine revealed that the crankshaft, part number 54297-1, had failed due to fatigue. A metallurgical examination determined that the fatigue crack originated at a machine groove normally associated with the overhaul process of the crankshaft. At the time of the incident, the crankshaft had accumulated only 130 flight hours since it was reconditioned by an FAA-approved repair station.
Findings
The failure was attributed to fatigue of the engine crankshaft. Contributing factors included a metallic sound preceding the power loss and the specific origin of the crack at a machine groove related to the overhaul procedure. The aircraft sustained significant damage, and the pilot executed a forced landing in an agricultural field.
Safety message
This incident highlights the critical importance of quality assurance in engine overhaul processes. Proper inspection of crankshafts for machining defects is essential to prevent premature fatigue failures, even when components have been serviced by FAA-approved repair stations.