On January 8, 2003, approximately 0920 central standard time, a Carlisle Comp Air 6 single engine experimental airplane, N628, sustained substantial damage during a forced landing to a field following a loss of engine power during cruise flight near Groesbeck, Texas. The private pilot, sole occupant of the airplane, was not injured. The airplane was registered and operated by the pilot, who was also the builder of the airplane. Visual meteorological conditions prevailed, and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The flight departed the Easterwood Field Airport (CLL), College Station, Texas, at 0840, and was destined for the Denton Municipal Airport (DTO), Denton, Texas. The pilot reported to an FAA inspector that prior to the airplane's departure from CLL, the airplane's fuel tanks were filled with 53 gallons of 100LL aviation fuel. In cruise flight at 3,000 feet mean sea level (msl), the engine lost power. At the time the engine lost power, the pilot stated that the right main fuel tank selector switch was ON. The pilot then switched the fuel selector to the left main tank, turned ON the fuel boost pump, and attempted to restart the engine; however, the restart was unsuccessful. The pilot then executed a forced landing to a field. During the forced landing, the engine momentarily regained power, and the pilot overshot his intended touchdown zone in the field. Subsequently, the airplane contacted soft terrain, nosed over, and came to rest inverted. The Carlisle Comp Air 6 fuel system was comprised of left and right main fuel tank and a header tank. The left and right main fuel tanks drained into the header tank, and the header tank was connected to the engine. The pilot had the option to open and/or close the fuel valves for the left main, right main, and header fuel tanks. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) Recommendation (How Could This Accident Have Been Prevented) section, the pilot reported the following: "Addition of a header tank low level alarm". A representative from airplane kit manufacturer reported that an optional header tank low level annuciator light and aural alarm system was available. According to the FAA inspector, who responded to the accident site, both wing spars were bent. The inspector also noted that fuel was leaking from the fuel vents.