On July 12, 1998, at 1600 central daylight time, a Forney 415-C, N99294, was destroyed on impact with trees and the terrain, and a post accident fire, about 3 miles southwest of Laurie, Missouri. The pilot and one passenger received serious injuries. A witness saw the airplane making a steep turn prior to disappearing below the trees. The personal 14 CFR Part 91 flight was operating in visual meteorological conditions. No flight plan was on file. The flight was originated from a private airstrip near Laurie, Missouri, at the time of the accident. The pilot said in a written statement, "... climbed to approximately 1700' mean sea level, made left turn to crosswind leg. While in left bank tried to level wings and found both aileron and elevator jammed." He further stated that he was unable to regain control of the airplane and it conti8nued in a descending left bank until impact. A post impact fire then ignited. A examination of the wreckage after the accident failed to reveal the nature of the jammed controls. One wing and a portion of the tail were not consumed by fire. An examination of the engine was negative for anomalies and is attached to this report.