What happened
On March 16, 2019, a Cessna 150, registration F-BXQZ, was conducting a dual instruction flight for PPL training near Millas, France. During the flight, the instructor was demonstrating landing configurations to the student pilot. While descending through 1,000 feet, the instructor instructed the student to apply full power and maintain a climbing attitude. At that moment, the engine began to sputter and subsequently lost all power.
The instructor performed an emergency landing in a nearby clearing. During the maneuver, the right wing of the aircraft struck a tree, resulting in heavy damage to the aircraft. No injuries were reported.
The investigation
The BEA investigation focused on the fuel levels and the sequence of events leading to the engine failure. The investigation established that the aircraft's total fuel capacity was 98 liters, but 13 liters were unusable, leaving only 85 liters of usable fuel. Based on previous flight logs, the aircraft's consumption was approximately 19 liters per hour at 68% power, but could increase to 26 liters per hour at higher power settings.
The instructor reported that he had previously refueled with 81 liters and estimated the aircraft departed with approximately 23 liters. Before the final flight of the day, the instructor had measured 3.5 US gallons in the right tank using a graduated dipstick. The instructor also noted that he did not account for the unusable fuel volume during his pre-flight calculations. The student pilot testified that the instructor had suggested a manual fuel gauge check was unnecessary due to the recent refueling.
Findings
- The aircraft departed with a fuel quantity sufficient for only approximately one hour of flight.
- The engine failure was caused by fuel exhaustion resulting from the fuel supply reaching the unusable limit.
- The instructor failed to account for the 13 liters of unusable fuel when calculating the remaining flight endurance.
- The training area selected for the flight did not provide sufficient space for a safe forced landing without encountering obstacles like trees.
- Previous refueling records indicated that several flights had been completed with low fuel reserves.