Incident Overview
An airline transport certificated pilot was maneuvering a helicopter over snow-covered terrain along a mountain ridge while conducting a photo flight. The end of the ridge line was in a shadow, and as the pilot flew through the shadowed area, he began to lose depth perception. In an effort to move away from the ridge, he added engine power.
Contact with Terrain
During the maneuver, the left landing gear skid tube made contact with snow on the ridge, and the pilot felt a vibration. He subsequently landed the helicopter on lower terrain and shut down the engine.
Inspection Findings
A post-incident inspection of the helicopter revealed internal damage to the tail rotor spars and a torsional twist in the tail rotor drive shaft. No other damage or injuries were reported.