Approach and Air Taxi
The helicopter conducted an approach to a low hover above a hard-surfaced runway. After establishing the hover, the pilot began a slow air taxi.
Loss of Directional Control
During the air taxi, the pilot felt the helicopter become unstable in the directional axis. The pilot considered performing a run-on landing to recover. However, before the landing could be executed, the nose of the helicopter began moving to the right very quickly. The pilot attempted to carefully accelerate forward, but this action did not arrest the rotation.
Ground Strike
The helicopter rapidly turned through approximately 360 degrees of rotation before striking the ground in a level attitude.
Environmental Conditions
The temperature at the time of the incident was 90 degrees Fahrenheit, which resulted in a density altitude of 2,200 feet.