Accident Sequence
The airline transport pilot arrived at the departure airport in a reciprocating engine-powered airplane. An airport employee/line service technician fueled the airplane with Jet A jet fuel. A witness reported observing a "low flying" airplane traveling from north to south. The airplane executed a "sharp left turn" to the east, during which the left wing "dipped low." The witness lost sight of the airplane and later, upon approaching an intersection near the accident site, saw the airplane on the ground. The airplane came to rest in a field characterized by dry, level, and hard terrain, conditions that were conducive to an off-airport landing. The airplane was destroyed in the accident.
Examination Findings
The wreckage path length and the impact damage were consistent with an accelerated stall. A postaccident examination of the airplane revealed the presence of Jet A jet fuel in the fuel system. Evidence of detonation was found in both engines, attributed to the use of Jet A fuel instead of the required 100 low lead fuel. The use of Jet A in an engine designed for 100 low lead fuel would result in detonation in the cylinders, leading to damage and a catastrophic engine failure. According to the Airplane Flying Handbook, the pilot should witness refueling to ensure that the correct fuel and quantity are dispensed and that any caps and cowls are properly secured after refueling.
Probable Cause
The official probable cause was determined to be the pilot's exceedance of the airplane’s critical angle of attack following a dual engine power loss caused by the line service technician fueling the airplane with the wrong fuel, which resulted in an aerodynamic stall and subsequent loss of control. Contributing to the accident was the pilot's inadequate supervision of the fuel servicing.