Event Summary
On the day of the accident, maintenance was performed on the number one cylinder to dislodge a stuck valve. After the maintenance, the pilot refueled the airplane and taxied for departure. The flight proceeded without difficulty during the climb to a cruise altitude of 3,500 feet msl.
Engine Failure and Forced Landing
Approximately 45 minutes into the flight, the engine started running rough. The pilot diverted and attempted a precautionary landing. Before the landing could be completed, there was a total loss of engine power. The airplane subsequently crashed into trees.
Engine Performance Indicators
Prior to the engine running rough, the exhaust gas temperature (EGT) was indicating normal. After the engine started running rough, the EGT dropped to below normal. The EGT sensor was located on the number one cylinder.
Post-Accident Examination
Examination of the engine after the accident revealed no anomalies except for a broken intake valve rocker-arm on the number one cylinder. Inspection of the rocker-arm showed no evidence of fatigue or any other form of progressive crack growth.