Primary finding
Probable cause
The fatigue failure of the no. 1 exhaust valve for undetermined reasons, and the lack of suitable terrain for the forced landing.
Investigator assessment
Analysis narrative
The airplane was in cruise flight at 3,000 when the engine began to run rough and vibrate. The engine then failed and the pilot executed a forced landing to rough terrain below. The airplane struck trees and came to rest. The engine was examined and the no. 1 cylinder exhaust valve was found failed at the valve stem in fatigue. The outside diameter of the valve stem exhibited excessive wear.
Source record
Factual narrative
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