What happened
On July 1, 2016, an Airbus Helicopters EC1ered B, registration F-GVTA, departed Avignon Caumont for the Courchevel helipad with a pilot and three passengers. During the final approach from the south, the pilot executed a wide left turn toward a westerly heading to align with the landing area.
As the aircraft descended to an altitude of approximately ten meters, the pilot noticed a left yaw. In an attempt to correct this movement, the pilot applied full right pedal and increased the collective pitch. During this maneuver, the "Over Limit" alarm sounded, and the helicopter began to sink rapidly before striking the ground hard and tilting onto its right side. The impact resulted in the destruction of the helicopter.
The investigation
The investigation examined the wreckage, the aircraft's engine monitoring systems, and local surveillance footage. Analysis of the wreckage confirmed that the damage was solely due to the ground impact and subsequent rollover, with no mechanical failures identified. The Fuel Control Unit showed normal fuel flow, and the VEMD (Vehicle and Engine Multifunction Display) recorded a significant drop in main rotor speed to 348 rpm, compared to the normal 412 rpm, along with a torque of 120%.
Surveillance footage established that the loss of control occurred while the helicopter was flying outside of the ground effect (IGE). Post-accident calculations, considering the aircraft's mass of 1,600 kg, the altitude, and the ambient temperature, revealed that the helicopter was operating at its maximum power limit for IGE conditions. This specific performance calculation had not been performed prior to departure.
Findings
- The pilot did not perform the necessary performance limit calculations for the day's specific temperature and altitude during flight preparation.
- The chosen approach trajectory forced the helicopter to operate outside of the ground effect at a low speed with a tailwind component.
- The pilot's attempt to correct a left yaw by applying full right pedal and increasing collective pitch pushed the aircraft beyond its available power limits, leading to the sudden loss of altitude and subsequent crash.