On July 5, 1985, a Stinson 108-2 (registration N9306K) was involved in an aviation accident near Hastings, MI. Investigators recorded the probable cause as: Crankshaft gear failed due to high cycle fatigue. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an engine break-in flight, the pilot heard a clank and lost power. Unable to find an open field, the aircraft struck trees in a stalled attitude and came to rest 10 feet above ground. Investigation found the crankshaft gear had failed due to high cycle fatigue.
Flight Purpose
The flight was conducted to break in a newly overhauled engine.
Narrative
The pilot reported flying locally for about 25 minutes when a clank was heard and the engine lost complete power. With no open field available for a forced landing, the pilot anticipated a tree landing. The aircraft struck trees in a nose-high, wings-level, stalled attitude and came to rest approximately 10 feet above ground in a tree.
Engine Examination
Disassembly of the engine revealed that the crankshaft gear had failed. A metallurgical examination determined the failure was caused by high cycle fatigue.
Findings
The engine failure was attributed to the crankshaft gear failure due to high cycle fatigue, resulting in a complete loss of engine power.