Accident Overview
About 20 minutes after takeoff, the pilot of an airplane repositioning after revenue flights switched the left and right engines to their respective auxiliary fuel tanks, then returned to the main tanks 30 minutes later. Shortly after, the right engine began to surge and subsequently stopped running. Turning on the fuel boost pump restarted the engine, but it quit again five minutes later, and the pilot secured it after unsuccessful restart attempts. The left engine then began to surge and was developing only partial power.
Diversion and Forced Landing
The pilot diverted to an alternate airport while the airplane was losing altitude and power in the remaining engine. Upon crossing the airport, he determined he was too high to land with a tailwind, so he circled to land into the wind. On the base leg, he made the decision to land straight ahead in a field due to power lines in his path, rapidly decaying altitude, and power. During the landing roll, the airplane collided with a ditch.
Investigation Findings
Examination revealed that the left and right main fuel filters contained a foreign substance, identified through laboratory analysis as polyacrylamide, a synthetic polymer used as an agricultural soil amendment to reduce erosion. This substance is not typically distributed by aircraft. Inspection of the fueling facility indicated that employees performing refueling had no formal or on-the-job training, and there was no record that the delivery system filters had been inspected or changed. Maintenance of the truck, delivery system, and storage facility was performed by employees on an as-needed basis subject to time availability. The fuel truck was improperly labeled, and the fuel nozzle was lying in a compartment amid dirt, gravel, and other contaminants with no caps or covers for protection.
Probable Cause
The official probable cause is a loss of engine power in both engines due to fuel contamination, which resulted from the fueling facility's improper quality control procedures.
Preceding Events
The pilot had refueled the auxiliary tanks of the airplane at a different airport one month prior to the accident and had not flown on the auxiliary tanks since that time. The accident occurred during repositioning after a series of revenue flights.