What happened
On May 31, 2015, at approximately 12:20 UTC, a Robinson R22 Beta II helicopter was conducting a VFR flight near Mitterfeld, Lower Austria. The flight originated from the Kilb helipad, traveling via Obergrafendorf and Wilhelmsburg, with the pilot intending to visit an acquaintance in Kasten.
While flying at an altitude of approximately 150 to 200 meters above ground level near Kasten, the pilot performed two to three full turns. During these maneuvers, the aircraft entered an uncontrollable rotation. Despite the pilot applying maximum anti-torque pedal input, the rotation could not be arrested. The pilot subsequently attempted an emergency landing. Although the rotation appeared to diminish during the descent, the aircraft began to rotate even more violently as it approached the ground. The helicopter struck the roof of a residential building, hit a porch, and finally impacted a gravel driveway. The impact resulted in two serious injuries (the pilot and one passenger) and the total destruction of the aircraft.
The investigation
The Austrian SUB investigation reconstructed the flight sequence using statements from the crew and witnesses, as well as radar data and police findings. The investigation examined the aircraft's technical condition, weight and balance, and the environmental conditions at the time of the accident. Investigators also analyzed the aerodynamic phenomenon of Loss of Tail Rotor Effectiveness (LTE) in the context of the aircraft's flight path.