Accident Overview
The accident occurred during an approach to the airport at low altitude. The aircraft experienced an engine failure and subsequently struck trees while executing a descending turn aimed toward a power company right-of-way.
Investigation Findings
Post-accident investigation revealed that the impulse drive springs on both magnetos had failed due to fatigue. The impulse drive springs are components within the magneto that assist in engine starting and timing. Notably, these springs are not assigned a service life limit by the manufacturer.
During magneto overhaul, rejection criteria for the impulse springs are limited to distortion of coil symmetry and obvious signs of wear. Investigators could find no record of the impulse springs ever being replaced on the aircraft's magnetos. It is possible that the springs were original equipment dating back to 1948, suggesting they had been in service for an extended period without mandated replacement or inspection for fatigue.
The failure of both springs contributed to the magnetos' inability to provide proper spark timing, leading to the engine failure. The aircraft's subsequent collision with trees occurred during the pilot's attempted emergency landing.