On July 28, 2004, about 0730 eastern daylight time, a Robinson R44 II, N442RD, registered to Carolina Kidney, Inc., and operated by the private pilot, collided with the ground during landing at a private residential helipad in Goldsboro, North Carolina. The personal flight was operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed. The private pilot reported no injuries, and the helicopter sustained substantial damage. The flight departed Emerald Isle, North Carolina, about 0700 on July 28, 2004. According to the pilot, he executed a landing on a concrete helipad that was elevated approximately six inches above the ground. He stated the helicopter touched down slightly off center, and he attempted to reposition the helicopter on the pad. The pilot stated that, during repositioning, the rear of the skids went off the rear of the pad, the helicopter tilted backward, and the tail rotor struck the ground. Examination of the accident site revealed the concrete helipad was approximately 13 feet long and 13 feet wide, and the width between the helicopter's skids was seven feet. Examination of the helicopter revealed the ninety-degree gearbox was separated, the tail rotor was separated and fragmented, and the lower portion of the vertical fin was crushed. The pilot reported no mechanical malfunction with the helicopter.