What happened
On April 1, 2014, a Gardan GY 80, registration F-BPAJ, was performing a single-engine piston (SEP) class rating extension flight at the Biscarrosse-Parentis aerodrome. The flight was being conducted by an instructor and a student pilot, with one passenger on board.
Following a touch-and-go maneuver on runway 09, the aircraft was in its initial climb at approximately 150 feet when the engine suffered a sudden loss of power. At the same time, the student pilot was in the process of manually retracting the landing gear. The instructor took control of the aircraft and initiated an emergency landing in a grassy area beyond the threshold of runway 27. The aircraft touched down with the landing gear partially retracted and came to a stop after traveling 150 meters. The aircraft sustained heavy damage.
The investigation
The investigation focused on the engine's performance and the condition of the fuel system. Initial examinations of the fuel, oil, and ignition circuits did not immediately reveal the cause of the partial power loss. However, subsequent inspections of the engine following the accident identified a significant fuel leak on one of the lines between the engine and the fuel tank, as well as advanced porosity on two other lines.
While the aircraft had recently undergone a 100-hour maintenance inspection, the fuel lines had not been noted as problematic during that service. Although these lines had a ten-year calendar life limit, there was no documentation indicating when they were last replaced. The student pilot, who was also responsible for the aircraft's maintenance, noted that he had planned to replace all fuel lines the following month, as he had not previously noticed the level of porosity.