Incident Overview
The pilot had just departed from his private airstrip for the fourth flight of the day when witnesses heard the engine cease operation. The aircraft had been flown for 3.4 hours since its most recent refueling. At the time of the incident, the aircraft was being operated on a mixture of aviation gasoline (avgas) and automotive fuel, without a Supplemental Type Certificate (STC) authorizing such a fuel blend.
Sequence of Events
After the engine stopped, the pilot initiated a turn back toward the private strip. During this maneuver, the aircraft entered an aerodynamic stall and subsequently impacted the terrain in a nose-down attitude.
Post-Accident Examination
A post-accident inspection of the aircraft was conducted. The examination failed to reveal any mechanical failure or malfunction that would have resulted in the loss of engine power. The precise reason for the engine quitting was not determined from the available evidence.
Fuel Considerations
The aircraft's fuel system was found to contain a mixture of avgas and automotive fuel, which was not approved for use in that aircraft. No STC had been obtained for such operation. The impact of this fuel mixture on engine performance was not addressed in the inspection report, and no direct causal link was established between the fuel blend and the engine failure.