What happened
On March 31, 2017, a Robin DR400-180, registration F-GAHR, was performing a local flight for instructional purposes departing from Aix-les-Milles aerodrome. The aircraft was carrying the pilot and three passengers. During the initial climb, at an altitude of approximately 300 feet, the engine stopped.
The pilot maintained the best glide speed and attempted to restart the engine by switching to the right wing tank. When the engine failed to restart, the pilot performed a forced landing in a field to the left of the runway axis. During the landing roll, which lasted about 250 meters, the aircraft veered left toward the edge of the field, causing the right wing to strike the ground. The impact resulted in heavy damage to the aircraft structure.
The investigation
The investigation focused on the fuel system and the pilot's pre-flight preparations. The aircraft is equipped with a 110-liter central tank and two 40-liter wing tanks. The central tank's location prevents visual or manual fuel level verification.
Investigators found that while fuel was present in the carburetor, the central tank was empty. Although the aircraft was equipped with low-level and low-pressure fuel warning lights, these lights did not illuminate during the flight. The reason for this failure was not determined.
Evidence showed that during a flight the previous day, the crew had refueled with 90 liters at Mende Brenoux aerodrome. Because fuel had overflowed from the central tank, the crew recorded a "full tank" in the logbook. However, this amount was insufficient to fully replenish the central tank, leaving a deficit of approximately 30 liters. On the day of the accident, the pilot had performed two 30-minute flights and, relying on the logbook entry and the fact that the wing tanks were full, estimated that 40 liters remained in the central tank. The pilot chose to take off using the central tank.
Findings
- The engine failure was caused by fuel exhaustion in the central tank.
- The pilot's estimation of the remaining fuel was incorrect due to a misleading logbook entry from the previous day.
- The pilot did not verify the central tank gauge during the pre-flight inspection because of a lack of confidence in its accuracy.
- The failure of the low-level and low-pressure fuel warning lights prevented the pilot from receiving an early warning of the fuel depletion.