On May 26, 2002, at 1300 central daylight time, an Ercoupe (Eng & Research Corp.) 415-C single-engine airplane, N99044, was substantially damaged when it impacted a ditch during a forced landing following a loss of engine power near Hinton, Oklahoma. The airplane was registered to and operated by the pilot. The private pilot sustained a serious injury and the passenger sustained minor injuries. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The local flight originated from Anadarko, Oklahoma, at 1200. The 170-hour pilot reported to an FAA inspector that while in cruise flight, he noted that the center fuel tank quantity gauge indicated "zero." He then looked at the left wing fuel filler cap and observed fuel siphoning out of the tank. Subsequently, the engine lost power, and he executed a forced landing to a pasture. During the landing roll, the airplane impacted a ditch, two-foot deep and four-foot wide. An examination of the airplane by an FAA inspector revealed that the nose landing gear was separated from the aircraft, the left wing partially separated, and the right wing was bent. Visible evidence of fuel siphoning from the fuel filler cap to the wing trailing edge was found. The fuel cap was found secured and no anomalies were noted.