Accident Summary
A helicopter pilot selected a landing site on a ridge above 8,000 ft mean sea level and initiated an approach. During the approach, the helicopter descended below effective translational lift airspeed, and the pilot turned the nose to the right. The helicopter developed a rapid right yaw, prompting the pilot to apply full left pedal and forward cyclic in an attempt to arrest the yaw and fly out of the condition. However, the main rotor blades struck the ground, and the helicopter came to rest on its left side. The accident resulted in substantial damage to the fuselage, tailboom, and both rotor systems.
Weight and Pilot Observations
The pilot reported that the helicopter's maximum gross weight was 3,000 pounds, and its weight at the time of the accident was 2,700 pounds. According to the Recommendation section of the National Transportation Safety Board Pilot's Aircraft Accident Report, the pilot stated that the accident could have been prevented if the helicopter was not so heavy. He also noted that he should have selected a better landing area with the landing direction into the wind.
Loss of Tail Rotor Effectiveness at Altitude
The Federal Aviation Administration Helicopter Flying Handbook (page 11-20) discusses Loss of Tail Rotor Effectiveness (LTE) at altitude. When operating at high altitudes and high gross weights, especially while hovering, the tail rotor thrust may not be sufficient to maintain directional control, and LTE can occur. In such cases, the hovering ceiling is limited by tail rotor thrust and not necessarily by power available.
Mechanical Condition
The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.