What happened
On 26 May 2000, a modified PA31, registration HB-LTC, was involved in a fatal accident during the departure phase from Zurich Airport. The aircraft had recently completed a flight from Béziers, France, and was preparing for a subsequent flight to Geneva. During the refueling process at the General Aviation Centre, the aircraft's fuel tanks were contaminated with the incorrect fuel type.
While the aircraft had been correctly refueled with AVGAS for its earlier flight, the return leg involved a refueling error. An attendant, acting on an instruction that specified JET A-1, pumped 50 liters of the kerosene-based fuel into each of the two inboard main cells. The pilot, who was occupied with a telephone call and preparing for departure, did not prevent the addition of the incorrect fuel.
After receiving takeoff clearance at 20:20:58 hrs, the aircraft climbed normally. However, at an altitude of approximately 50 meters, the aircraft ceased its climb and began a descent. The pilot initially performed a right turn before entering a steep left turn with a high bank angle. During this maneuver, the landing gear was observed to be extended. The pilot declared a Mayday emergency at 20:22:21 hrs as the aircraft lost altitude rapidly. The PA31 eventually struck a group of trees at roughly 10 meters altitude, flipped, and came to rest upside down in the Glatt river. The pilot was 1 fatality.
Findings
- The primary cause of the accident was the introduction of JET A-1 fuel into an aircraft designed for AVGAS.
- The refueling attendant did not identify the specific fuel requirements for the modified airframe.
- The pilot was distracted by a mobile phone call during the period when the incorrect fuel was being loaded.
- There was a lack of clear communication regarding the specific fuel type required during the refueling transaction.