Robinson R44 F-GVSB Accident at Villefranche Tarare

Incident Overview and Flight Details On April 10, 2016, at 11:15 local time, a Robinson R44 helicopter, registration F-GVSB, operated by a club for general aviation, experienced a loss of control in yaw during a local flight at the Villefranche Tarare aerodrome (69). The aircraft was carrying a pilot and three passengers. The pilot and all passengers sustained minor injuries, while the helicopter was destroyed. ## Sequence of Events The pilot departed the aerodrome at 10:45 for a local flight. After approximately 20 minutes, the helicopter entered a final approach facing south, positioned to the right of the paved runway 18. At a low altitude of about ten meters and low speed, the pilot turned right to clear the runway and headed toward the parking area along the taxiway, following a heading of approximately 250°. During this translation, the helicopter began to yaw to the right. The pilot applied left rudder and pulled the collective pitch control. The helicopter gained altitude and continued to rotate. After a second turn with a high pitch-up attitude, the yaw rotation stopped. The helicopter then moved backward, struck the ground violently, tipped onto its right side, and came to a stop. ## Pilot Experience and Meteorological Conditions The pilot held a private pilot license for helicopters (PPL(H)) obtained in December 2013, with type ratings for the R22 and R44. He had a total of 106 flight hours, including 28 hours as pilot-in-command and 1 hour 40 minutes in the preceding three months. At the time of departure, the pilot estimated the weather conditions as calm wind and CAVOK (Ceiling And Visibility OK). However, video recordings from the aerodrome's surveillance cameras indicated a turbulent wind of 10 to 15 knots, with a variable direction between 150° and 180°, during the final approach and the loss of control. ## Technical Examination and Analysis The examination of the wreckage, particularly the anti-torque rotor, did not reveal any mechanical failure that could explain the loss of control in yaw. The weight and balance calculation showed that the helicopter was within the authorized flight envelope at the time of the accident, with a total mass of approximately 1,000 kg against a maximum of 1,087 kg. Video analysis confirmed that the rotor disk was about ten meters from the ground during the translation, suggesting the helicopter was at the limit of ground effect. A passenger video's audio analysis confirmed the nominal operation of the engine, main transmission, rear transmission, and anti-torque rotor. During the event, the rotor speed varied between 101.5% and 91.9%, with a brief 'LOW NR' alarm triggered for one second, followed by a continuous alarm until the ground collision. ## Probable Cause and Contributing Factors The accident likely resulted from the pilot's insufficient consideration of the wind during the translation and a delayed reaction to counter the initial yaw. The helicopter's position at the limit of ground effect and the action on the collective pitch control contributed to placing the aircraft in a difficult-to-recover position. The pilot's right rudder input during the turn likely initiated the right yaw, which was exacerbated by the lateral wind and the loss of tail rotor effectiveness (LTE) phenomenon. The subsequent left rudder action stopped the yaw after the second turn, but the simultaneous collective pitch action reduced the main rotor speed, preventing the pilot from regaining control of the trajectory.