HISTORY OF FLIGHT On March 18, 2007 about 1100 Atlantic standard time, an experimental Challenger II Special, N7023D, registered to and operated by a private individual, experienced a loss of control during takeoff and crashed on the runway at Antonio (Nery) Juarbe Pol Airport (TJAB), Arecibo, Puerto Rico. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal, local flight. The airplane was substantially damaged and the non-certificated pilot, the sole occupant, sustained serious injuries. The flight was originating at the time of the accident. Witnesses state the pilot departed on runway 8 at TJAB and lost control shortly after the aircraft became airborne. Another pilot who was on final approach to runway 8 stated the aircraft took off, and crashed on the runway and rolled about the length of two and a half runway centerline dashes. The pilot immediately stated after the accident to law enforcement personnel that the rear seat lapbelt was engaged on the rear seat control stick of the two place experimental aircraft acting as a control lock. A formal statement and accident report from the pilot has been precluded due to the injuries sustained by the pilot in the accident. PERSONNEL INFORMATION According to FAA personnel, the pilot was not issued any FAA pilot certificate, but he was issued a ultralight pilot certificate by the U.S. Ultralight Association (USUA). The accident aircraft is a two seat registered aircraft; therefore, a FAA issued pilot certificate with appropriate category and class rating is required. The pilot was not issued a FAA issued medical certificate. AIRCRAFT INFORMATION The airplane was manufactured in August 1992, by Jimenez Reymundo, as model Challenger II Special, and was designated serial number CH20892CW0805. It was certificated in the experimental category and was equipped with a Rotax 503 engine. METEOROLOGICAL INFORMATION A surface observation weather report taken at the Eugenio Maria de Hostos Airport (TJMZ), Mayaguez, Puerto Rico, on the day of the accident, at 1050, or approximately 10 minutes before the accident, indicates the wind was from 290 degrees at 7 knots, the visibility was 10 statute miles, scattered clouds existed at 3,500 feet, the temperature and dew point were 30 and 20 degrees Celsius respectively, and the altimeter setting was 29.99 inHg. WRECKAGE AND IMPACT INFORMATION The accident aircraft was moved from the runway and placed in a secure area on the airport before FAA arrival. Examination of the wreckage by an FAA airworthiness inspector revealed flight control continuity for roll, pitch, and yaw; however, the rear restraint was latched and was found wrapped around the rear control stick. Examination of the engine by the FAA inspector revealed no evidence of preimpact failure or malfunction. MEDICAL AND PATHOLOGICAL INFORMATION The pilot was immediately hospitalized for treatment of his injuries, but died while hospitalized on May 7, 2007.