On September 5, 2000, approximately 1130 central daylight time, an Abernathy Streaker aerobatic experimental biplane, N1LM, was substantially damaged while maneuvering near Sherman, Texas. The commercial pilot, sole occupant of the airplane, was not injured. The airplane was registered to a private individual and operated by the pilot. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulation Part 91 personal flight. The local flight originated from the Grayson County Airport, Sherman, Texas, at 1123. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), and a telephone interview conducted by the NTSB investigator-in-charge, the pilot departed Grayson County Airport for the first of three aerobatic contest flights. At 4,300 feet agl, the pilot began a 45 degree nose down dive into the "aerobatic box". After the "second wing wag (used to signify the start of aerobatic performance)," the airplane experience a "high rate" roll to the right. The pilot reported that the right aileron "jammed," however, he eventually regained control of the airplane, and landed it on runway 17L without further incident. Examination of the airplane by the pilot revealed that the skin on the top of the right wing failed and separated from the rear spar. The rear spar was buckled and the aileron's leading edge was "jammed," in the full up position, under the wing's trailing edge. The airplane had accumulated 1,123 hours of total flight time at the time of the accident.