The pilot was mustering a herd of cattle across a tree lined dry creek bed, when the mob scattered. He positioned the helicopter at tree top height to block the escape of the cattle from the creek. The rotor RPM rapidly decayed and the pilot was unable to prevent the aircraft sinking and landing heavily on the bank of the creek. The pilot attempted to bring the helicopter to a hover in a 15 knot downwind. At the time the helicopter was being operated near to the maximum all up weight in ambient temperatures of about 45 degrees celcius. Insufficient power was available to maintain flight in these conditions.
