On November 11, 2000, about 1300 Alaska standard time, a high skid equipped Eurocopter AS-350-B2 helicopter, N216EH, sustained substantial damage while maneuvering over snow-covered terrain, about four miles east of Girdwood, Alaska. The helicopter was being operated as a visual flight rules (VFR) on-demand passenger flight under Title 14, CFR Part 135 when the accident occurred. The helicopter was operated by ERA Aviation Inc., Anchorage, Alaska. The airline transport certificated pilot, and the sole passenger, were not injured. Visual meteorological conditions prevailed. VFR company flight following procedures were in effect. The flight originated at the Girdwood airport, about 1115. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on November 21, 2000, the vice president of safety for the operator reported that the pilot was conducting a photo flight in the area of Mount Alyeska. According to the vice president, the pilot related that he was maneuvering along a mountain ridge. The end of the ridge line was in a shadow. While flying in the area of shadow, the pilot began to lose depth perception, and he added engine power to move away from the ridge. The left landing gear skid tube made contact with snow on the ridge, and the pilot felt a vibration. He landed on lower terrain and shut down the helicopter. A subsequent inspection of the helicopter disclosed internal damage to the tail rotor spars, and a torsional twist in the tail rotor drive shaft.