What happened
On July 4, 2004, at approximately 18:55 local time, a Piper PA-31P Navajo pressurized, registration EC-CTG, performed an emergency landing in Chinchilla, Albacelle, Spain. The aircraft, operated privately, was conducting a non-commercial pleasure flight from Biscarrosse, France, to Alicante, Spain, carrying a pilot and five passengers.
During the flight, which had transitioned from VFR to IFR rules, the pilot reported a sudden drop in fuel indicators at approximately 18:40. Shortly after, the pilot requested a direct route to Alicante due to low fuel levels. By 18:41, the pilot reported that the zero-fuel indicator had activated and requested vectors to Albacete Airport. Following a period of maneuvering, the pilot reported engine failure at 18:50. Realizing the aircraft could not reach the airport, the pilot declared an emergency and executed a forced landing in a military maneuver field. The aircraft sustained significant structural damage to the wings and fuselage, but all six occupants survived without injury.
The investigation
The investigation focused on the fuel consumption and the operational status of the aircraft's fuel system. The aircraft's six-tank system was designed to provide a total usable capacity of 236 gallons. Investigators analyzed radar data, which showed a descent and a subsequent increase in speed, suggesting the pilot utilized the remaining engine power to extend the glide distance before the second engine failed.
Investigators examined the fuel logs, noting that the aircraft had been refueled in Pamplona and subsequently in Biscarrosse. While the pilot had noted a higher-than-normal fuel consumption earlier in the flight, the investigation scrutinized whether a leak or a calculation error was responsible for the sudden depletion of fuel.
Findings
- The aircraft experienced the successive failure of both engines due to fuel exhaustion.
- The primary cause was an incorrect estimation of the total fuel on board at the start of the flight.
- This error may have been exacerbated by an unidentified cause that led to a fuel consumption rate significantly higher than the manufacturer's specifications; while the manual suggested a consumption of approximately 34 gallons per hour, the actual consumption during the flight was estimated at roughly 78 gallons per hour.
- Investigators ruled out simultaneous fuel leaks in both wings, as the fuel systems are independent and such a simultaneous event is highly improbable.
- The pilot attempted to mitigate the impact by lowering the landing gear and feathering the propellers to maximize the glide ratio.