On July 14, 2004, about 1100 Alaska daylight time, a Canadian registered Hughes 500D helicopter, C-GVHG, sustained substantial damage when a ground crew member inadvertently threw a rope into the idling main rotor system at a remote mine site, about 20 miles west of Iliamna, Alaska. The helicopter was being operated by Prism Helicopter LTD, of Wasilla, Alaska, as a visual flight rules (VFR) external load flight under Title 14, CFR Part 133, when the accident occurred. The solo commercial pilot was not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 15, the pilot said the helicopter was sitting and running at flight-idle while he and two helpers prepared a sling load. He said he was climbing into the helicopter, and did not see the activity, but one of the helpers standing near the cargo door threw a rope to the other helper. He said the rope was inadvertently tossed into the main rotor system, and wrapped around the rotor head. The pilot said that the main rotor blades and rotor head received structural damage during the encounter with the rope. He noted that there were no known mechanical anomalies with the helicopter prior to the accident. During a telephone conversation with the IIC on July 15, the director of operations for the operator said ground crew members receive specific training for handling ropes and equipment around operating helicopters.