Equipment and Configuration
The helicopter involved in the incident was outfitted with "bear paws," devices resembling snowshoes that attach to the skids to distribute the aircraft's weight over soft surfaces. Investigation revealed that these bear paws were not secured according to design specifications; instead, they were able to rotate freely around the skids. Furthermore, the Federal Aviation Administration (FAA) does not approve the use of bear paws on American aircraft.
Sequence of Events
The pilot executed a landing on a surface that was perceived to be firm. However, the actual conditions consisted of approximately five feet of snow topped by a thin crust of ice. Prior to the accident, the pilot had deboarded a passenger approximately 900 feet down the mountainside. That passenger later stated that he observed the helicopter roll onto its right side about five minutes after he had disembarked. He also noted that the pilot did not shut down the helicopter's engine after his departure.
Post-Event Observations
During the rollover event, one of the main rotor blades cut through the cockpit structure and separated from the helicopter.