Primary finding
Probable cause
The collision with a road sign during a forced landing. Contributing to the accident was the total loss of engine power due to fatigue failure of the crankshaft.
Investigator assessment
Analysis narrative
During cruise flight, the engine experienced a partial loss of power. During the descent for a precautionary landing, the engine quit and the propeller stopped. The pilot performed a forced landing on a road, and during the landing roll the right wing collided with a road sign. The airplane veered to the right, collided with a fence then came to rest. Examination of the engine revealed that the crankshaft failed near the rear counterweight. Metallurgical examination revealed that it failed due to fatigue which emanated from a subsurface origin. Review of the engine logbooks revealed that the crankshaft was the original when the engine was manufactured on april 14, 1961. The engine had accumulated 4,032 hours total time, and had been overhauled two times, the latest occurring in 1986. At that time the crankshaft was magnafluxed. The engine had accumulated 1,032 hours since the latest overhaul.
Source record
Factual narrative
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