Incident Overview
A pilot was operating a helicopter on a local sight-seeing flight with a passenger. The flight involved navigating up a mountain canyon. As the pilot began ascending the canyon, a slight wind gust was encountered, but the decision was made to continue. Eventually, the aircraft encountered gusting variable wind conditions and significant downdrafts.
Maneuvering and Downdraft Encounters
The pilot decided to turn around and exit the canyon. During the turn, the helicopter encountered a strong downdraft, causing a rapid descent. The main rotor rpm began to decrease. The pilot responded by increasing power and lowering the collective control. Although the helicopter managed to fly out of that downdraft, it immediately entered another strong downdraft, sinking toward terrain while main rotor rpm continued to decrease.
Descent and Landing Attempt
To arrest the descent, the pilot raised the collective, but the helicopter continued to sink, and main rotor rpm decayed further. With terrain close, the pilot chose to land rather than attempt to continue flying in the downdrafts. A successful touchdown was made in an open area, but soon after the skids contacted the rough, steeply-sloped terrain, the helicopter rolled onto its side.
Damage and Outcome
The helicopter sustained damage as a result of the rollover. The pilot's decision to land likely prevented further descent into terrain, but the uneven ground contributed to the final rollover event.