On June 11, 1999, about 0015 Eastern Daylight Time, a Cessna 172, N62953, was substantially damaged during an aborted landing at Portage County Airport (29G), Ravenna, Ohio. The certified flight instructor (CFI) and student pilot were not injured. Visual meteorological conditions prevailed for the flight that originated from Kent State University Airport, Kent, Ohio. No flight plan was filed for the instructional flight conducted under 14 CFR Part 91. The student pilot stated that he and the CFI completed three full stop landings before the accident, and experienced no problems with the brakes. The airplane landed on Runway 27, a 3,500 foot long, 75 foot wide runway. According to the student pilot, during this approach, he landed "about half way down the runway." He did not feel the brakes working properly, and proceeded to abort the landing. The airplane became airborne at the end of the runway, but settled toward the ground. The flight instructor took control of the airplane, and performed a forced landing to a field. The student pilot further stated that he later went back to the airport and observed approximately 800 to 1,000 feet of skid marks on the runway, beginning beyond the touchdown point, extending to where the airplane became airborne again. The CFI stated that the airplane touched down at about 55 knots, with approximately 2,000 feet of runway remaining. He did not feel the airplane slowing, and depressed the brakes. He noticed that the airplane was not braking effectively, and instructed the student pilot to abort the landing. As the airplane passed over the departure end of the runway, it began to lose lift. At this point, the CFI took control of the airplane and performed a forced landing to a field. When asked about the skid marks, he stated that although the brakes did not seem to be working during rollout, they must have worked during the aborted landing. He believes the student pilot may have "dragged the brakes" during the aborted landing. According to the owner of the flight school, he inspected the brakes after the accident and found no mechanical malfunctions. He also sent the airplane to an independent maintenance facility. The facility did not find any discrepancies with the braking system. The owner further stated that the airplane had undergone an annual inspection the day before the accident, and the flight was the first after the inspection. New tires were mounted on the airplane during the annual inspection. While inspecting the wreckage, he noticed significant wear on both tires. Examination of the wreckage by a Federal Aviation Administration Inspector revealed no mechanical malfunctions. The Inspector observed skid marks beginning approximately 300 feet from the departure end of the runway, and ending approximately 2 feet before the end of the runway. The skid marks were in line with marks on the grass where the airplane had traveled off the end runway.