Primary finding
Probable cause
The failure of the number 3 cylinder intake valve stem. A factor in the degree of damage the aircraft sustained in the mishap was attributable to the off airport emergency landing on show covered tundra.
Investigator assessment
Analysis narrative
The non scheduled air taxi cargo flight, conducted under 14 CFR part 135, experienced a loss of engine power while in cruise flight. The pilot made an emergency landing on snow covered tundra. A post accident examination of the powerplant by a federal aviation administration aviation safety inspector revealed that the number 3 cylinder intake valve stem failed, causing the valve to pass through the piston, resulting in extensive internal damage to the engine.
Source record
Factual narrative
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