On September 19, 1998, approximately 1430 mountain daylight time, a Bell UH-1L helicopter, N5107J, was substantially damaged following impact with terrain near Price, Utah. The commercial pilot, the sole occupant of the helicopter, received minor injuries. The helicopter was owned/operated by Precision Air LLC of Provo, Utah, under Title 14 CFR Part 133. Visual meteorological conditions prevailed for the external load flight which had been moving logs in the local area for the previous 60 minutes. No flight plan had been filed. According to the pilot, he was moving logs off the hillside (elevation 7,860 feet, density altitude 10,775 feet), up a narrow canyon (Cow Canyon, 38 miles northeast of Price) that ran approximately north and south. He was using a 180 foot long-line and the wind was out of the south at 10 to 12 knots. He stated that "I set down the logs and was hovering with a left quartering crosswind to pick up chokers when the aircraft suddenly started to turn to the right." The pilot reported that he applied full left pedal, but the right turn continued. He stated that prior to the turn, "there were no unusual noises and I did not feel any control feedback." He further stated that "I realized that I had lost tail rotor directional control." After several attempts to move away from co-workers on the ground, he entered an autorotation to a landing spot. He reported that his skids contacted a beaver dam and the aircraft bounced into the air nosing over allowing the main rotor blades to hit the ground. The helicopter came to rest on its left side and an engine fire ignited which was immediately extinguished by co-workers. Postaccident examination of tail rotor by the pilot revealed that "one of the tail rotor blades was broken almost in half." He said that he did not "see mud or impact damage on the leading edge of either [tail rotor] blade." The pilot's written statement did not indicate any abnormal aircraft vibrations prior to the accident. The FAA inspector that visited the accident site stated that the tail rotor blade was bent, and that he identified "several tail rotor blade and main rotor blade ground strike scars." He further stated that the ground scars were located in damp, soft, humus, grass covered soil. Additionally the main blade had struck vegetation and the beaver dam. He reported that postaccident examination of the aircraft's drive train confirmed continuity throughout, and that no operational abnormalities were identified with the anti torque pitch change mechanism.