N944URobinson Helicopter R44 II · 2005

While en route to her destination, the pilot elected to fly the helicopter up a canyon toward rising terrain. Soon after making a "low pass" over a ridge above 8,000 feet mean sea level (MSL), the pilot increased collective in order to climb over upcoming terrain. As the collective was increased, the rotor RPM started to drop. The pilot immediately increased throttle, reversed course to fly downhill, and lowered the collective. During the turn, the helicopter encountered a quartering tailwind and began to settle toward the snow-covered terrain. Soon thereafter the helicopter contacted the terrain, but bounced back into the air. Immediately thereafter a main rotor blade severed the tail boom, and the helicopter impacted the terrain. According to the pilot, there was no evidence of an engine power loss or any anomaly with the flight control system.