Control - Other involving a Robinson R22 Beta, VH-JNT, Gogo Station, 9 km south of Fitzroy Crossing, Western Australia, on 6 May 1996

The pilot was flying the helicopter sideways,15 ft above the ground, as he attempted to herd a bull into a paddock. He felt a shudder through the tail rotor pedals and the helicopter immediately began to rotate to the right. Full left pedal did not stop the rotation. After two and a half turns the pilot was able to land the helicopter, cushioning the touchdown with the collective control.

During the landing the tail rotor struck a fence. A ground witness reported that the tail rotor system appeared intact until the collision. The engine was already stopped when the pilot attempted to shut it down after landing. The fuel tank contained 60 L of fuel, and no water was evident. Wind strength at the time of the accident was reported to be 5 kt.

Sideways movement, shuddering in the tail rotor pedals and loss of directional control to the right are all precursors or symptoms of a condition, in helicopters, commonly known as loss of tail rotor effectiveness. In this state the airflow through the tail rotor is reduced by the sideways movement and the relative wind (the combined effect of the actual wind and the direction of movement of the helicopter). As a result, the tail rotor can no longer supply sufficient thrust to counter the turning effect caused by the rotation of the main rotor system and the helicopter will yaw to the right. If the effect is severe enough, application of left pedal may aggravate the situation.

The evidence indicates that loss of tail rotor effectiveness is the most likely factor in this accident.