During the 38th load of the day in the afternoon, the pilot performed a left turn into wind while descending into a valley. On completion of the turn, the pilot found that they had insufficient power to arrest the rate of descent and that a hard landing w as imminent. They prepared for the hard landing by attempting to find a flat spot to conduct a running landing but was unsuccessful and the aircraft rolled onto its left side, damaged beyond repair. The pilot was uninjured.
The operator conducted an internal investigation as well as reviewed the activation of their ERP.
A review of the aircraft loading and performance calculations based on a density altitude of 2,446 feet determined that the aircraft was within limits and had IGE hover capability up to 6,100 feet, but an OGE of 2,000 feet (446 feet lower than the operating altitude, requiring close power management while operating at low airspeed).
The valley had increased in temperature throughout the day resulting in an increased operating density altitude with an under appreciation/identification of the degrading aircraft performance associated with the temperature increase.
The operator has elected to replace the helicopter with a model that offers greater performance capability.