Accident Overview
A non-scheduled air taxi cargo flight, operating under 14 CFR Part 135, experienced a loss of engine power while in cruise flight. The pilot subsequently executed an emergency landing on snow-covered tundra.
Post-Accident Examination
A post-accident examination of the powerplant was conducted by a Federal Aviation Administration Aviation Safety Inspector. The inspection revealed that the number 3 cylinder intake valve stem had failed. This failure caused the valve to pass through the piston, resulting in extensive internal damage to the engine.
Conclusion
The investigation determined that the loss of engine power was due to the mechanical failure of the number 3 cylinder intake valve stem, leading to catastrophic internal engine damage and necessitating the emergency landing.