Cat. 2 investigation report: simplified-format report, adapted to the circumstances of the occurrence and the investigation stakes.
The pilot, accompanied by five passengers, took off from Aix-Les-Milles aerodrome (Bouches-du-Rhône) bound for Toussus-le-Noble aerodrome (Yvelines) making a stop at Clermont-Ferrand airport (Puy-de-Dôme). Having refuelled at Clermont-Ferrand, and re-embarked his passengers, the pilot started the engine. On entering hover, the helicopter turned rapidly around its yaw axis several metres from the ground. After approximately two turns, the pilot, who was unable to stop the rotation, lowered the collective pitch control to bring the helicopter to the ground. The helicopter landed hard and bounced before coming to a stop. After the pilot shut down the engine, all of the occupants evacuated the helicopter.
On entering hover, it is likely that the pilot’s insufficient action on the right pedal caused the helicopter to rotate left around the yaw axis. Taking into account the proximity to the ground and the rapid rotation, the pilot wanted to gain height by increasing the power required for the main rotor to ensure climb. This action increased the torque to be countered by the tail rotor whilst reducing its available power and therefore its effectiveness. The yawing movement to the left of the helicopter increased. Unable to regain yaw control of the helicopter, the pilot changed his mind and decided to bring the helicopter to the ground by lowering the collective pitch control.