What happened
An airline transport pilot arrived at the departure airport in a reciprocating engine-powered airplane to prepare for flight. During the pre-flight process, an airport service technician refueled the aircraft using Jet A fuel. Following the refueling, a witness observed the aircraft flying at a low altitude from north to south. The aircraft then executed a sharp left turn toward the east, during which the left wing dipped significantly. Shortly thereafter, the aircraft was observed on the ground near an intersection.
The aircraft impacted a level, dry, and hard field. The impact resulted in the total destruction of the aircraft. Analysis of the wreckage path and the damage sustained by the airframe were found to be consistent with an accelerated stall during the flight.
Findings
Post-accident investigations of the fuel system confirmed the presence of Jet A fuel. Examination of both engines revealed evidence of detonation, a direct consequence of using Jet A instead of the mandatory 100 low lead fuel. The use of improper fuel in these engines caused cylinder detonation, which led to catastrophic engine failure. The investigation noted that the pilot should have monitored the refueling process to verify that the correct fuel type and quantity were provided and to ensure all cowls and caps were secured.