Accident Overview
A flight instructor and a pilot receiving instruction were conducting high altitude pinnacle landings. The approach was made to a landing site with an elevation of roughly 8,000 feet mean sea level. The instructor reported that as the helicopter approached the ground, approximately 5 to 6 feet above the terrain with a descent rate of around 100 feet per minute, the rotor rpm began to droop and the helicopter started to descend.
Sequence of Events
The instructor attempted to increase airspeed and execute a go-around, but this action caused further descent. The gradient of the down sloping terrain was insufficient to prevent ground contact. The helicopter skidded forward on the ground, and the right skid caught on terrain, causing the helicopter to roll over onto its left side.
Damage and Findings
The helicopter sustained substantial damage to the fuselage and tail boom. The density altitude for the accident area was calculated to exceed both the in ground effect (IGE) and out of ground effect (OGE) ceiling values provided by the flight instructor for that area. The instructor verified that there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.
Additional information indicated that the latitude and longitude coordinates provided for the pinnacle landing site placed it at 8,269 feet MSL, on the top of a volcano.