On February 15, 2003, about 1610 eastern standard time, a homebuilt Rotorway Exec 162F helicopter, N241WC, was substantially damaged when it collided with trees, then terrain while executing a steep approach to a confined area in Westford, Massachusetts. The certificated commercial pilot sustained serious injuries. Visual meteorological conditions prevailed for the flight that departed Hanscom Field (BED), Bedford, Massachusetts, about 1550. No flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated that he had made a steep approach, and planned to land in his friend's driveway, a confined area. The pilot also noted that he had previously made the same approach and landing on several other occasions. According to the pilot, when the helicopter was just about in a full hover (about 8 feet above the ground), it began a rapid rotation to the left. The pilot applied full right pedal, but could not stop the rotation. He elected not to perform an autorotation from a hover because he was concerned of landing hard, rolling over, and shedding parts that could have possibly hurt his friend, who was standing in the driveway about 50 feet away. Instead, he lifted the helicopter back up and tried to fly to a vacant area. During the ascent, the pilot was able to slow the rotation by reducing power, but was never able to completely stop the rotation. He was not able to perform an autorotation because he had no forward airspeed, so he elected to put the helicopter down into trees. The pilot also stated that just before, and during the rotation to the left, he never heard any unusual noises or felt anything unusual in the anti-torque pedals. There was no warning whatsoever. The pilot's friend stated that he observed the helicopter when it was rotating, and the tail rotor appeared to be working normally. The pilot reported that he had a total of 265 hours in helicopters, of which, 172 hours were in make and model. In the past, he had experienced the onset of Loss of Tail Rotor Effectiveness (LTE), but due to the strong head wind, and the sudden rapidness of the rotation, he did not feel that this was an LTE situation. An FAA inspector performed an examination of the helicopter. According to the inspector, one of the tail rotor pitch change links was fractured, but he could not determine how it failed. The inspector did not take possession of the link at that time. The pilot/owner initially agreed to send the pitch change link to the Safety Board for further examination. However, upon further examination of the link, and without contacting the Safety Board, he determined that the part had failed during impact. The pilot/owner said that the helicopter wreckage had been discarded. Weather reported at Hanscom Field, 10 miles southwest of the accident location, at 1556, included winds from 350 degrees at 11 knots, temperature 12 degrees F, dewpoint -14 degrees F, and barometric pressure of 30.35 inches Hg. The visibility was 10 statute miles, and the sky was clear.