Primary finding
Probable cause
The partial loss of engine power during the initial climb out on a night flight.
Investigator assessment
Analysis narrative
The pilot stated shortly after takeoff, the airplane '...lost the ability to climb/maintain altitude.' emergency procedures were unsuccessful, and the airplane settled into the tree tops. Postaccident examination revealed no evidence of preimpact propeller assembly failure. An engine teardown revealed the top piston ring in the #1 cylinder was broken, with no evidence of scoring on the cylinder wall. The right magneto operation was intermittent, especially at higher rpm settings. The engine total time was 3,169.9 hours, and time since major overhaul was 2,064.5 hours. The airplane had operated 2.4 hours since the most recent annual inspection.
Source record
Factual narrative
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