Accident Overview
An air ambulance flight ended in a crash shortly after takeoff when the airplane’s engines lost power due to detonation caused by misfueling. The airplane, equipped with two reciprocating engines, had been serviced with Jet A fuel instead of the required 100LL aviation gasoline. The pilot had verbally requested 40 gallons of fuel from a line service technician but did not specify the type. The technician added 20 gallons to each wing tank from a fuel truck. The pilot was present during refueling and helped replace the fuel caps.
Events Leading to the Crash
After takeoff, a medical crewmember reported to the company dispatcher that smoke was coming from the right engine. Multiple witnesses observed smoke trailing from the airplane before it impacted terrain in an eastbound, upright attitude. A postimpact fire ensued, consuming most of the wreckage. Investigators arriving the next day detected a strong odor of jet fuel at the scene.
Investigation Findings
The airplane’s fuel filler ports were labeled “AVGAS ONLY,” but the fuel truck nozzle used was small enough to fit into those ports. According to voluntary industry standards, jet fuel trucks should have an oversized nozzle to prevent such misfueling. However, the fixed-base operator (FBO) was using a smaller diameter nozzle. Postaccident review of refueling records, technician statements, and the on-scene smell of jet fuel indicated that the airplane had been misfueled with Jet A. Examination of the engines revealed internal damage consistent with detonation.
Contributing Factors
The line service technician inadvertent misfueling and the pilot’s inadequate supervision of the fuel servicing were identified as contributing factors. The FBO’s use of a small fuel nozzle on its jet fuel truck allowed the nozzle to be inserted into the airplane’s filler port, enabling the addition of jet fuel.