What happened
The aircraft experienced a complete loss of engine power while established on the final approach segment at an altitude of approximately 350 feet above ground level. In response to the emergency, the pilot executed a 90-degree course change to avoid obstacles and attempted a forced landing. The aircraft impacted the ground in a churchyard adjacent to the airport environment.
The investigation
Post-acc examination of the aircraft revealed that the fuel tanks contained a mixture of 80-87 octane aviation gasoline and unleaded automotive gasoline. This combination is not approved for standard operation without specific authorization. Investigators noted that while an STC existed addressing the use of automotive gasoline in this type of engine, the operational requirements outlined in that STC were not complied with at the time of the incident.
Findings
The primary factor contributing to the accident was fuel contamination due to the use of unauthorized fuel types. The presence of automotive gasoline in the system led to engine power loss. The failure to adhere to the specific conditions of the STC for using automotive fuel resulted in the unsafe operating condition that caused the crash.
Safety message
Pilots must ensure that only approved fuels are used in their aircraft. If an STC permits the use of automotive gasoline, all operational limitations and procedures specified in that STC must be strictly followed to maintain engine reliability and safety.