On August 14, 1995, at 1520 central daylight time, a homebuilt Park Wizard, N5297E, collided with a ground structure during a forced landing near Mineral Wells, Texas. The commercial pilot and pilot rated passenger were not injured and the airplane sustained substantial damage. The airplane, operated by the S-TEC Corporation under Title 14 CFR Part 91, departed the Mineral Wells Airport approximately 1515. The purpose of the flight was to flight check several autopilot components manufactured by S-TEC. Visual meteorological conditions prevailed and a flight plan was not filed. During cruise flight at 2,000 feet MSL, the engine RPM decreased from 7,000 to 5,500 and, subsequently degrading to a complete loss of engine power. A forced landing was made to a playground. During the landing roll, the left wing sustained structural damage when it struck a "baseball backstop." The airplane was examined by the operator and the Federal Aviation Administration (FAA) inspector. The water cooled engine was "stiff and felt notchy when rotated by hand." An engine coolant line was found loose from the cylinder head fitting and no engine coolant (antifreeze) remained in the radiator. Disassembly of the engine by the operator revealed that the "front cylinder had overheated and the piston had bound up in the cylinder, leaving aluminum scuff marks on the cylinder wall." An examination of the engine coolant fitting revealed a smooth mating surface with "no mechanical means to retain the rubber coolant hose." Technicians for the operator reported the "fitting appeared as a standard plumbing fitting." According to the engine manufacturer's representative, "all engine and radiator connections distributed by Rotax contain a mechanical means to retain the connections." The FAA experimental airworthiness certificate issued on March 30, 1994, states the airplane was built by Adrian Bloomfield.