What happened
On February 11, 2006, a pilot conducted a local test flight in an Aviakit Hermès ultralender, registration 59-CGM, following recent technical maintenance. The flight departed from Saint-Omer aerodrome on runway 27. Witnesses observed the aircraft experiencing several pitch variations during the initial climb.
While performing a left-hand circuit at approximately 1,000 feet, the pilot transitioned to the final approach and deployed the flaps. After crossing the runway threshold at a height of roughly 20 meters, the pilot executed a go-around. During the subsequent second circuit, the aircraft maintained a low altitude and a high pitch attitude while on the downwind leg. As the pilot entered the base leg, the aircraft remained below the glide path with a significant nose-up attitude. During the final turn, the aircraft banked sharply to the left and struck trees.
The investigation
The investigation focused on the aircraft's flight dynamics and mechanical condition. Examination of the wreckage confirmed the Aviakit Hermès was in a left-hand turn at the moment of impact. The vertical and horizontal velocities were low at the time of the collision. No anomalies were found in the control linkages, and the engine and propeller were functioning normally at impact, with fuel present in the tanks. The electric flap actuator was found at a position of 2 to 3 degrees.
Prior to the flight, the pilot, who was a mechanic, had performed a complete overhaul of the engine to address previous overheating and seizing issues. Ground tests, including one on the morning of the accident, had been conducted successfully.
Findings
- The aircraft experienced an asymmetric stall during the turn.
- The pilot's decision to perform the first flight of control on an aircraft without prior knowledge of its specific handling characteristics was the primary cause.
- The pilot had very limited experience as a commander, with only 2 hours and 40 minutes of command time in the preceding three months.