What happened
On June 1, 2000, a private Bell 206 helicopter, registration F-BSGB, was performing a navigation flight near Corneville sur Risle, France. After departing from a private helisurface in Boucquelon and refueling at Le Havre, the pilot began returning to the starting point. Before landing, the pilot decided to fly over a friend's house located near the departure site.
While approaching the house, the pilot initiated a left turn and reduced the aircraft's airspeed. During this maneuver, witnesses observed the helicopter, flying at an altitude of approximately 30 meters above a grove of trees, begin to yaw to the left and simultaneously descend. The aircraft struck the treetops and crashed into the grove. The impact resulted in two fatalities (the pilot and one passenger) and two injuries (one serious and one light). The aircraft was destroyed.
The investigation
Investigators examined the wreckage and found the airframe resting on its right side. The tail boom had been severed at the rear bulkhead, and the main rotor blades showed varying degrees of damage, including one blade that had been deformed by ground impact. The engine and its components, including the fuel control and power governor units, were inspected; tests confirmed that the engine and the regulator were functioning correctly at the time of the accident and that the fuel used was standard Jet A1.
Technical analysis focused on the aircraft's performance capabilities. The investigation established that the aircraft was operating near its maximum takeoff weight. The investigators also analyzed the flight dynamics, specifically the relationship between airspeed, altitude, and the power required to maintain lift during a turn.
Findings
- The aircraft was operating at a high mass, near its maximum limit, in high ambient temperatures.
- The pilot attempted a low-speed maneuver outside of ground effect while in a left-hand turn.
- A lack of anticipation regarding the power required for the maneuver led to the loss of control.
- Because the engine/regulator system has an inherent latency, the sudden increase in collective pitch requested by the pilot was not immediately met with the necessary power increase, causing the helicopter to sink.
- The pilot's limited experience and the psychological factors related to flying over a familiar location may have contributed to an inadequate risk assessment and an improvised, difficult maneuver.