On August 19, 1995, at 0902 central daylight time, a Taylorcraft DCO-65, N57527, was substantially damaged following a loss of control while maneuvering near the Elmdale Airpark, in Abilene, Texas. The private pilot and his passenger were seriously injured. The airplane was being operated as a personal flight under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local flight for which no flight plan was filed. According to the operator, the pilot lost control of the airplane while circling the airport in a "loose" formation with two other aircraft. The flight of three had completed a low pass over runway 17 as part of the annual fly-in and open house at the airport. On the enclosed Pilot/Operator report, the pilot states that the engine failed to respond when he added power to initiate a climb following the low pass. He further stated that during his last pass, "while operating at 2/3 power, he heard 5 popping sounds coming from the area of the engine." The pilot added that he had intended to land in an open grass field to the west of the airpark. Witnesses observed the nose of the airplane pitch up to clear wires across its flight path. The airplane was observed descending in a nose down attitude into an unoccupied metal office building. The airplane came to rest on the roof. Post accident examination of the powerplants and related systems by a Federal Aviation Administration (FAA) inspector did not reveal any anomalies that would have prevented normal engine operation. A report of his examination is enclosed.