What happened
On 17 August 2021, a Robinson R22 helicopter, registered F-GFHA, was conducting a local flight near the Roche d’Anse spur in Côte-d’Or, France. The pilot and a passenger had departed from Dijon-Darois aerodrome for a sightseeing flight. While maneuvering at a low altitude near a rocky outcrop, the helicopter experienced a sudden loss of yaw control.
Witnesses observed the aircraft spinning several times before descending into a wooded area. The helicopter struck the tree canopy and fell nearly vertically, coming to rest on its skids. The impact resulted in two severe injuries for the occupants, while the aircraft was destroyed. The pilot and passenger were able to exit the wreckage and alert emergency services.
The investigation
The BEA examined the wreckage, radar data, and meteorological conditions. Investigators found that the tail rotor blades had failed near their attachment points and the tailplane was ruptured; however, these damages were determined to be the result of the collision with trees and the ground rather than a mechanical failure. The engine and flight controls were found to be operating normally prior to the impact.
Radar analysis indicated a change in the flight path, though vertical profile data was unavailable due to invalid altitude information. Meteorological data showed relatively stable winds from the west-northwest at 10 to 15 knots, with no significant turbulence reported other than minor convective activity from distant clouds.
Findings
The investigation concluded that the accident was caused by the pilot encountering unanticipated yaw, a phenomenon where aerodynamic changes—such as a tailwind or wind from the left—cause the aircraft to rotate unexpectedly.
Several contributing factors were identified:
- The aircraft was flying at a low forward speed during a turn, creating conditions highly susceptible to a right-hand yaw movement.
- The pilot, perceiving the rotation as a loss of tail rotor effectiveness, applied incorrect rudder pedal inputs that were insufficient in both amplitude and duration to stabilize the aircraft.
- A lack of specific knowledge regarding the unanticipated yaw phenomenon led to ineffective recovery attempts.