On June 2, 1994, about 1300 Pacific daylight time, a homebuilt experimental Sharp Scorpion Too helicopter, N288JS, sustained an in-flight separation of the tail rotor system and crashed about 1 mile west of Beckwourth, California. The helicopter was built, owned, and operated by the pilot. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The helicopter was destroyed in the accident sequence. The private pilot, the sole occupant, sustained fatal injuries. The flight originated from the Beckwourth airport on the day of the accident about 1230 as a presumed local area personal flight. Ground witnesses reported that the helicopter departed from the Beckwourth airport and was cruising about 200 feet agl when popping sounds were heard. The witnesses observed parts come off the helicopter, then it descended rapidly to ground impact. Information from individuals on the airport indicated this was the third flight of the day and that the builder/pilot may have been performing test flights. A Federal Aviation Administration (FAA) inspector from the Reno, Nevada, Flight Standards District Office responded to the accident site and examined the wreckage. He reported that the tail rotor assembly was found about 90 yards from the main wreckage along with portions of a 'V' drive belt, apparently used to power the tail rotor. Color transfers similar to the drive belt material were found on the blades. The inspector was unable to determine the mode of failure of the drive belt. According to FAA records, the pilot held a private pilot certificate with an airplane single-engine land rating. The pilot did not hold a rotorcraft category rating and no evidence was found of a solo endorsement for helicopters. The last medical certificate issued to the pilot was dated March 8, 1988. No information was available concerning the last periodic inspection performed on the helicopter. FAA records disclosed that the helicopter was first issued an experimental airworthiness certificate in the amateur built category on December 27, 1987. The helicopter reportedly had accrued a total time of 66 hours.