What happened
On March 8, 2008, a Cessna 152, registration F-GKAX, was conducting a local flight training mission near Limours, France. After approximately thirty minutes of flight, the student pilot contacted Toussus-le-Noble air traffic control to join the airfield circuit. While maintaining an altitude of roughly 800 feet, the engine began to lose power.
The instructor attempted standard troubleshooting by activating the carburetor heat and checking the fuel gauges, which indicated slightly less than one-quarter of fuel remaining in each tank. Despite verifying that the fuel selector was set to 'BOTH' and the mixture was at 'FULL RICH,' the engine continued to lose power. The instructor took control of the aircraft, declared an emergency, and performed an emergency landing in a field. During the landing roll, the aircraft overturned onto its back, resulting in substantial damage to the airframe.
The investigation
The investigation focused on the discrepancy between the estimated fuel remaining and the actual fuel levels found in the tanks. Investigators discovered approximately ten liters of fuel remaining in the tanks at the time of the accident.
It was established that the instructor had calculated the remaining flight endurance based on the aircraft's logbook, which indicated that three hours and thirty minutes of flight time had elapsed since the last refueling. Based on a total endurance of six hours, the instructor believed there was sufficient fuel for the planned one-hour flight. However, the investigation revealed that the previous flight, lasting one hour and forty-two minutes, had not been accounted for in this calculation. Furthermore, the logbook contained an error; the previous pilot had recorded the fuel level as "full" after a visual inspection, but no actual refueling had taken place.
Findings
- The primary cause of the engine failure was fuel exhaustion.
- An incorrect fuel quantity was recorded in the aircraft logbook, leading to a false sense of security regarding remaining endurance.
- The instructor utilized an inadequate procedure for verifying the actual fuel quantity on board, relying on logbook entries rather than physical measurement.
- The instructor failed to account for the duration of the preceding flight when calculating the remaining endurance.