On 6 November 2013, the pilot of a Robinson R44 helicopter, registered VH‑UGC, was conducting a private flight from Latrobe Valley to Mount Buller, Victoria, with three passengers onboard.
At about 1425 Eastern Daylight-savings Time, the helicopter arrived overhead the Mount Buller Township. Two orbits at about 500 ft above ground level (AGL) were conducted to assess the landing area (helipad), the wind conditions and confirm the outside air temperature.
The pilot then commenced an approach to the helipad. When in an out-of-ground-effect hover, he conducted a power check at 21 inches hg manifold pressure. He then reduced the engine power to 18 inches hg and reported that, when about 30 m from the helipad, the helicopter became a bit unstable. He then raised the collective, but the engine appeared to lose power. He attempted to increase the power, but the engine appeared not to respond.
As the front of the helicopter’s skids were about to touch down, the pilot applied full forward cyclic, and reported experiencing mast bump. In response, he raised the collective lever. The low rotor revolutions per minute (RRPM) horn then sounded and the pilot reported the helicopter felt as if it was going to fall backwards. The helicopter rolled onto its side and came to rest about 9 m down an embankment. The helicopter was substantially damaged and the passengers were uninjured.
To maintain a steady hover, an increase in the weight of the helicopter requires more engine power. Increases in altitude and temperature reduce air density, and consequently the engine’s ability to produce power. Mount Buller helipad was at an elevation of 5,400 ft above mean sea level. The pilot reported that the helicopter was at a gross weight of about 1,048 kg when it landed.