Primary finding
Probable cause
Separation of the number 3 cylinder exhaust valve head and overloading of the nose gear strut. A factor contributing to the accident was the uneven terrain.
Investigator assessment
Analysis narrative
While in cruise the engine began running rough and vibrating. The pilot, unable to maintain altitude due to the power loss, executed a forced landing onto an uneven field during which the nose gear strut folded aft due to overload and the aircraft nosed over. Subsequent disassembly of the engine revealed that the number 3 cylinder exhaust valve had separated at the neck just beneath the base of the valve head.
Source record
Factual narrative
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