What happened
On 30 September 2021, a Tecnam P92 S Echo (identified 01VA) departed from Saint-Rambert-d’Albon aerodrome for a local flight. The aircraft was operated by a private pilot accompanied by one passenger. After a flight duration of approximately 46 minutes, the aircraft returned toward the departure aerodrome. During the initial climb, a witness observed a significant decrease in engine speed. The microlight subsequently entered a right-hand turn, during which it stalled and collided with the ground approximately 300 meters northeast of the runway's northern end. The impact occurred in a quarry basin, and the two fatalities were confirmed at the scene.
The investigation
The BEA examined the wreckage and the engine's fuel system to determine the cause of the power loss. Investigators found that the fuel system had been modified with an electronic injection kit. While the fuel valves were in the open position and no fuel contamination was found, the investigation identified a critical issue with the fuel filter. The seal between the filter top and the strainer had been pinched and protruded outward. This defect caused a substantial fuel leak of approximately 1.4 to 1.5 liters per minute when the fuel pumps were not active.
Testing confirmed that such an air leak in the system between the filter and the surge tank can cause major engine malfunctions, including significant power loss and heavy vibrations. The investigation also noted that the pilot was using an active noise reduction (ANR) headset, which may have masked the auditory cues of the engine's deteriorating performance.