On September 23, 1993, about 1510 hours Pacific daylight time, a Robinson R22-Beta, N2407X, crashed during landing at Livermore Municipal Airport, Livermore, California. The helicopter was being operated as a visual flight rules (VFR) local area photo flight when the accident occurred. The helicopter, operated by Tri Valley Helicopters, sustained substantial damage. The certificated pilot and a passenger received minor injuries. Visual meteorological conditions prevailed. The flight originated at the Livermore Airport at 1445 hours. The pilot reported that he was preparing to land and began a steep approach to a landing pad from about a 45-foot above ground level (AGL) hover. About 25 feet AGL, the helicopter's engine began losing power. The pilot ensured that the throttle was full open and reduced collective pitch and applied forward cyclic to attempt a running landing. The pilot reported that his rate of descent was about 300 feet per minute. The helicopter contacted an asphalt airport ramp in a level attitude with about 20 knots of airspeed. The helicopter received damage to the landing gear skids, tail boom, rotor blades, and fuselage. The pilot reported that during his preflight inspection of the helicopter, he observed the engine primer "IN" and "LOCKED". After the accident, the pilot reported that the primer was found unlocked and an inspection of the lower spark plugs revealed that they were fouled. In addition, the pilot said that the accident helicopter had two previous cases of the primer becoming unlocked. The first occured during an engine run up, and a second occurred during a flight in which the pilot made a precautionary landing. An operations inspector, Federal Aviation Administration, Oakland Flight Standards District Office, inspected the helicopter. He reported that the primer is an optional engine item and is installed under and forward of the right seat cushion. His inspection of the primer also revealed that it was unlocked. The helicopter and engine had accumulated a total time in service of 1,631.6 flight hours. Examination of the maintenance records revealed that the most recent annual inspection was accomplished on June 2, 1993, 239.6 flight hours before the accident. In addition, a 100-hour inspection was completed on September 6, 1993, 33.6 hours before the accident.