On June 12, 2005, about 1900 central daylight time, a Cessna 172N, N6454J, piloted by a private pilot, sustained substantial damage during takeoff at the Dane County Regional Airport, Madison, Wisconsin. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The pilot and passenger were not injured. The local flight was originating at the time of the accident. In a written statement, the pilot stated that he had pre-flighted the rental airplane and was issued a takeoff clearance. He stated that during the takeoff, he applied full power and upon reaching 70 knots he began to pull back on the yoke. He said that the airplane became airborne and then subsequently struck the ground. He stated that the airplane became airborne a second time and again struck the ground. The pilot stated that at this time, he reduced power and held the brakes. The airplane struck the ground again and came to a halt. A Federal Aviation Administration Inspector examined the airplane subsequent to the accident. The Inspector determined that the airplane had received substantial damage due to damage to the engine firewall. The inspector also found that the control gust lock was still installed. He noted that the warning flag for the gust lock was broken off.