The purpose of the flight was to transport ski guides to the top of a 13,000 ft mountain ridge. After climbing in moderate to high winds, the pilot approached the intended landing area from the lee side at an angle of about 45 degrees to the ridgeline. He reported that during a normal approach, a severe downdraft was encountered about 50 ft short of the intended landing spot. The helicopter began a descent which exceeded its capability to stop. The pilot initiated a pedal turn away from the ridgeline. However, the helicopter continued to settle. It contacted the terrain while heading almost directly downhill. The helicopter slid approximately 50 to 75 ft down a 10 to 15 degree slope until the right skid contacted rocks below the snow and slowed the helicopter to a stop. The helicopter was inspected for obvious damage. The passengers were off-loaded and the helicopter was flown back to Marble, CO where maintenance personnel discovered damage to the box beam doubler.