Primary finding
Probable cause
A complete loss of engine power which resulted from two stuck exhaust valves.
Investigator assessment
Analysis narrative
Reportedly, the pilot refueled the airplane after it had been parked on the ramp several days. After completing the preflight inspection, the pilot took off, and five minutes into the flight the engine lost power; the pilot made a forced landing in a field. The post accident engine examination discovered that two exhaust valves were stuck in the open position. Both valves were forcibly removed from the engine. The valve examination further disclosed that the valve stems were coated with a layer of carbon, which prevented normal valve movement. The pilot used automotive fuel in the airplane, and both oil and fuel additives were used routinely.
Source record
Factual narrative
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