On December 28, 2007, about 1130 Pacific standard time, an amateur built Hein Sonex experimental airplane, N365SX, made a forced landing following a loss of engine power while maneuvering near Murrieta, California. The airplane was registered to, and operated by, the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot, the sole occupant of the aircraft, was seriously injured. The airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The personal flight originated from the Flabob Airport (RIR), Riverside, California, at 0930. In a written statement, the pilot reported that after a non eventful flight, he descended from 6,500 feet mean sea level (msl) to 3,500 feet msl. A few minutes later, the engine lost power. The pilot stated he was able to restart the engine momentarily but it lost power a second time. He initiated a forced landing to a nearby open field. During the landing roll, the right main landing gear struck a hole and the airplane nosed over. The pilot added that prior to departure, he refueled the airplane with 100 low lead fuel until he could "touch the gas with his finger." Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the airplane came to rest inverted within an open field. The horizontal stabilizer and rudder were structurally damaged. The inspector stated that there was no evidence of fuel on the ground at the accident site or leaking from the airplane. No fuel was observed in the airframe fuel sump. According to a Murrieta Police Department deputy, shortly after the accident, the pilot stated that he "believes he possibly ran out of fuel."