What happened
On May 27, 2023, a Robin DR400/180, registration F-BUSU, was performing a local flight at Tarbes-Laloubère aerodrome when the engine lost power during the approach phase. The pilot, while flying the downwind leg, had reduced engine power to idle. As the aircraft reached the glide slope, the pilot attempted to readjust the power, but the engine failed to respond.
Facing a forced landing amidst a grove of trees on a nearby golf course, the pilot managed to maintain sufficient airspeed to navigate the aircraft between two trees. However, during the landing sequence, the rear section of the fuselage struck one of the trees, causing the airframe to rupture and the aircraft to spin before coming to a stop. The accident resulted in two injuries (the pilot and one passenger) and the destruction of the aircraft.
The investigation
The investigation focused on the cause of the engine power loss and the state of the fuel system. Investigators found that while the propeller continued to rotate during the descent, it was not transmitting torque, as evidenced by the propeller deformation.
Examination of the fuel tanks revealed that the left tank was empty, while the right and main tanks still contained significant amounts of fuel. The investigation established that the pilot had been using the left tank for the duration of the flight. Upon inspecting the wreckage, the fuel selector was found in the "CLOSED" position, and the electric pump switch was in the "OFF" position. The investigation also noted that the pilot's recent experience was primarily on DR400/120 models, which utilize a single-tank system, unlike the multi-tank configuration of F-BUSU.
Findings
- The engine power loss was caused by fuel starvation because the left tank had been depleted.
- The pilot's flight preparation was incomplete, leading to an inaccurate understanding of the fuel distribution across the various tanks.
- A lack of specific training in fuel management for aircraft equipped with multiple tanks contributed to the event.
- The pilot likely inadvertently switched the electric pump off and the fuel selector to a closed position while attempting to implement emergency procedures during the high-stress approach.