On September 13, 2002, about 1130 Pacific daylight time, a McDonnell Douglas 369E helicopter, N16005, sustained substantial damage subsequent to an in-flight collision with terrain while hovering near Index, Washington. The commercial pilot sustained serious injuries, and the one passenger aboard the helicopter was not injured. The helicopter is owned by the pilot, and was being operated as a visual flight rules (VFR) personal flight under the provisions of Title 14, CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed, and no flight plan was filed for the flight. The flight originated from Sunset Lake, Washington, shortly before the accident. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 16, the pilot reported that he was hover taxiing approximately six to twelve inches above ground level (AGL) when the helicopter's right skid contacted a large rock. The pilot stated that after contacting the rock, the helicopter pitched forward and began to rotate. Shortly thereafter the helicopter rolled onto its left side resulting in substantial damage.