Primary finding
Probable cause
The partial loss of engine power due to a stuck exhaust valve on the number two cylinder and the pilot's inability to climb the aircraft above the trees surrounding the airport. A factor in the accident was the effects of the high density altitude on the aircraft climb performance.
Investigator assessment
Analysis narrative
The pilot, the pilot rated passengers and a mechanic ground witness reported that the aircraft used the entire length of the runway to become airborne. The aircraft would not climb, and, while flying in ground effect, collided with a tree about one mile off the end of the runway. The density altitude was computed to be just over 7,000 feet. The mechanic witness said the engine sounded like the carburetor heat was on during the takeoff ground roll. Detailed examination of the engine revealed that the exhaust valve on the number two cylinder was stuck in the open position. A engine overhaul facility reported that the valve was stuck due to 'a considerable amount of carbon' in the valve guide.
Source record
Factual narrative
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