Background
A helicopter pilot attempted to land at an intended landing zone during a flight. The pilot made three landing attempts; the first attempt was abandoned due to excessive slope on the terrain, and the second attempt was closer but the terrain was unstable.
Sequence of Events
On the third attempt, while just slightly above effective translation lift (ETL) at an altitude of 11,900 feet above mean sea level, the pilot executed a left orbit and located a level landing site. As the pilot approached the site, he observed that some trees were laying over, indicating a very strong gust of wind. Subsequently, ETL was lost.
The pilot attempted a pedal turn into the wind. The helicopter resisted an immediate turn, then it took off to the left. The pilot applied right pedal to arrest the turn, reduced power, neutralized the pedals, and applied forward cyclic. The rate of turn accelerated and pinned the pilot back into the seat. Subsequently, the right skid and tail boom struck the terrain, and the helicopter rolled over.
Examination
Examination of the helicopter revealed no anomalies.