Final Report

Summary

On 17 May 2017, the pilot of a Robinson Helicopter R44 II, registered VH-MNU, was conducting aerial work at Moreton Island, Queensland with one passenger on board. The pilot departed for a local flight at about 1005 Eastern Standard Time.

At about 1130, the helicopter was approximately 50 ft above ground level and tracking in a south-westerly direction, at an airspeed of about 10 kt (and groundspeed of about 20 kt), when the pilot commenced a right turn.

The pilot felt a loss of tail rotor effectiveness (LTE) as the helicopter continued to yaw to the right and reported that they were unable to arrest the yaw with left pedal input. The pilot applied forward cyclic to try to increase the helicopter’s forward speed and some right cyclic to try to follow the turn. As the helicopter turned back into wind and rotated through about 110 degrees, the rate of yaw started to increase. The pilot then raised the collective in an attempt to increase the helicopter’s height above trees, which further increased the yaw rate due to the increase in torque.

The helicopter completed about two full rotations and reached about 80 ft above the ground, when the low rotor RPM warning horn sounded. The pilot immediately lowered the collective and the helicopter descended.

As the helicopter neared treetop height, the pilot deployed the emergency floats and the pilot raised the collective to cushion the impact. The pilot and passenger sustained minor injuries and the helicopter was substantially damaged.

In order to avoid the onset of LTE in this downwind condition, it is imperative to maintain positive control of the yaw rate and devote full attention to flying the helicopter.

This accident also highlights the effectiveness of wearing a helmet to prevent a more serious injury.

 

Aviation Short Investigations Bulletin - Issue 62

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