What happened
On October 28, 2000, a Cessna 206 (registration F-BUTG) was conducting parachute jump operations near Château-Arnoux Saint-Auban. After completing five jumps at 10,500 feet, the pilot began a descent at 120 knots. During the final approach, while attempting to increase power, the engine failed to deliver thrust.
The pilot attempted to activate the fuel pump, but the engine did not restart. Realizing the aircraft could not reach the runway, the pilot prepared for an off-field landing. While attempting to clear a line of trees approximately 100 meters before the runway threshold, the aircraft's tail struck the treetops. The aircraft pitched forward and struck the ground, resulting in heavy damage to the airframe.
The investigation
The investigation focused on the fuel system and the engine's failure during the descent. Investigators found that the fuel selector was set to the left tank, which contained only 10 liters of usable fuel, while the right tank held 50 liters. The engine was found to be cold upon inspection.
Analysis of the flight logs and fuel levels revealed that the pilot had been flying with the left tank selected. For this specific mission, the club's standard procedure of using the right tank as the primary source had been temporarily altered so the pilot could monitor the left tank's level manually. Furthermore, the investigation noted that the aircraft was flying in an uncoordinated manner due to rudder and trim settings consistent with a climbing flight, despite being in a descent.
Findings
- The primary cause of the engine failure was inadequate fuel management.
- The engine stopped because the fuel pump lost prime, a phenomenon caused by the low fuel level in the left tank combined with uncoordinated flight maneuvers.
- The pilot likely did not realize the engine had failed immediately because the propeller was still rotating at high speed during the descent and the high ambient wind noise—caused by the removal of the door for parachute operations—masked the change in engine sound.
- Because the failure went undetected, the pilot was unable to implement the emergency restart procedure, which requires switching tanks and activating the auxiliary pump at the first sign of power loss.