What happened
During a low-altitude flight, the pilot of N3 and 4TM, a single-engine aircraft, reported a loss of power on the right engine, followed by a loss of power on the left engine. At an altitude between 200 and 400 feet, the aircraft experienced wing oscillations before banking approximately 90 degrees to the left. The aircraft then entered a nose-low attitude and struck a flat, hard-packed sod field. Witnesses observed white smoke emitting from the underside of the aircraft roughly 20 seconds before the collision. The impact resulted in zero survivors.
Upon investigation of the wreckage, both propellers were found partially embedded in the soil. Evidence of rotational paint transfer was present on the ground, and the propeller blades showed specific wear patterns, including chordwise scratching and leading edge polishing.
Findings
Technical examination of the engine components revealed significant mechanical failures. The piston in the #2 cylinder was broken, with the piston pin remaining attached to the rod. Laboratory analysis of the #2 exhaust valve stem identified a fracture face consistent with bending fatigue separation. Additionally, the exhaust valve guides for both the #2 and #6 cylinders exhibited heavy wear, which had caused the bores to become ovalized. No specific cause for the initial power loss was explicitly attributed to the recent annual inspection, though the mechanical fatigue in the valve assembly was a primary finding.