What happened
On 28 August 2017, a Robinson R44 Raven II helicopter, registered F-GPGV, was performing a local flight from Rouen Vallée de Seine airport. The pilot and one passenger were returning to the airport's parking area at approximately 15:39 local time. While flying on a heading of 060° in low-speed forward flight, the aircraft began to yaw sharply to the right. The helicopter completed more than two full turns before colliding with the ground near the airport control tower, subsequently rolling onto its right side. The impact destroyed the helicopter, though the passenger was able to shut down the engine following the crash.
The investigation
Investigators analyzed surveillance footage from a hangar roof, which captured the sequence of the flight towards the parking area, the sudden yawing movement, and the subsequent impact. The video indicated that the engine continued to produce power and the main rotor controls remained effective until the moment of collision.
An examination of the wreckage revealed that while the main rotor controls were intact, the tail rotor controls had ruptured suddenly. One of the two tail rotor blades had also suffered a rupture, with visible impact marks on its leading edge. Using UV light and spectrometric analysis, investigators identified organic material on the broken blade. The presence of these organic deposits, which were oriented from the leading edge toward the blade tips, indicated that the material was deposited while the blades were in motion.
Findings
- The investigation established that the accident was caused by a birdstrike to the tail rotor.
- The impact of a bird on one of the tail rotor blades caused structural deformation and a loss of aerodynamic efficiency.
- This damage resulted in a sudden loss of yaw control, making it impossible for the pilot to maintain the aircraft's heading.
- The low altitude and low airspeed of the helicopter at the time of the event, combined with the sudden nature of the failure, left the pilot with insufficient time or altitude to execute an emergency landing.