On 14 July 2015, the pilot of a Robinson R44 helicopter, registered VH-VOH, was conducting aerial mustering operations on a property, about 70 NM east of Alice Springs.

At about 1300 Central Standard Time, the pilot was mustering cattle along a creek system. The helicopter was at about 50 ft above ground level, when the pilot slowed the helicopter to an airspeed of about 40 kt. The pilot felt a small vibration, and initially thought it was due to loose tape on the main rotor blade. The pilot looked for a suitable landing site, but the vibration increased significantly.

As the helicopter descended, the pilot manoeuvred the helicopter through a gap between trees, and pushed the cyclic forward to maintain airspeed. The pilot lowered the collective and noticed the engine seemed to go very quiet. The low rotor revolutions per minute warning horn sounded. The pilot made a radio call to advise another pilot operating nearby that the helicopter was going down. The pilot then flared the helicopter to try to cushion the landing impact. The right skid touched down first, and the helicopter rolled onto its right side.

The pilot sustained minor injuries and the helicopter was substantially damaged.

According to the Carburettor Icing Probability chart, the conditions indicated a high probability of serious carburettor icing at descent power. The ATSB advises all pilots of aircraft fitted with a carburettor to check the forecast conditions and know the risk of carburettor icing prior to each flight.


Aviation Short Investigations Bulletin - Issue 43

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