On June 12, 1994, at 1620 eastern daylight time, N727TB, a Bellah Rotorway Executive home built helicopter, operated by the owner/pilot, impacted terrain in Johnson City, New York, and was substantially damaged during an uncontrolled descent. The descent was precipitated by a loss of control during cruise flight. The commercial pilot, the sole occupant, received minor injuries. Visual meteorological conditions prevailed and a flight plan was not filed. The personal flight was conducted under 14 CFR 91, and departed from Norwich, New York. According to the pilot, the helicopter was in cruise flight at an altitude of 2,300 feet when a sudden loss of tail rotor effectiveness occurred. The pilot stated that he applied anti-torque pedal with no effect. The pilot entered an autorotation and advised air traffic control of his situation. The helicopter continued in a "...slow spin or spiral to the left." The pilot stated that he utilized full up collective which provided "good cushioning action," but the helicopter rolled onto its left side after ground contact. The main rotor blades, tail boom, landing skids, and fuselage frame were damaged. According to an FAA Aviation Safety Inspector from Rochester, New York, an examination of the wreckage revealed that the forward tail rotor drive belt had failed. The belt was examined and its plies were separated and "shredded." The pilot reported that the belt had been replaced during the last annual inspection, and had accumulated 57.9 hours since new. The recommended change out time by the Rotorway International company for the belt was 250 hours. The pilot reported that the company subsequently recommended a new Kevlar-impregnated drive belt. No discrepancies or unresolved open items were found in the maintenance log books.