On July 4, 1996, at 1215 central daylight time, a Cessna 172P, N62511, registered to and operated by a private owner under Title 14 CFR Part 91, overran the runway during an aborted takeoff at Gundys Airport, Owasso, Oklahoma. The private pilot was not injured and the airplane sustained substantial damage. Visual meteorological conditions prevailed for the personal flight and a flight plan was not filed. Local authorities reported to the FAA inspector that during the takeoff the pilot attempted an abort due to low engine RPM; however, the brakes failed and the airplane continued to roll. Subsequently, the airplane crossed a ditch and came to rest on a paved street. During interviews, conducted by the investigator-in-charge, and on the Pilot/Operator Report, the pilot reported the following information. On June 10, 1996, during a static engine runup, 2,000 RPM was indicated; however, after changing the air filter the static RPM was 2,300. The pilot flew the airplane from Bartlesville, Oklahoma, to Gundys Airport on June 23, 1996, for a new interior. On July 4, 1996, the pilot returned to Gundys to get the airplane, completed the preflight and conducted a static runup indicating 2,300 RPM. In order to check the aircraft performance, the pilot decided not to fly the airplane until after conducting a "highspeed taxi test." During the test, the speed reached 40 knots and the pilot pulled the power to idle and applied the brakes. The brakes failed with 1,600 feet (the final 700 feet downgrade) of runway remaining and the airplane rolled beyond the departure end of the runway, crossed a ditch and a road before coming to rest. The FAA inspector and the owner examined the airplane and reported damage to the nose gear, lower engine mounts and the engine firewall. Upon testing the brakes, the FAA inspector did not find any discrepancies that would have prevented stopping the airplane. The owner secured the airplane for examination by a mechanic. On July 22, 1996, a mechanic examined the airplane and reported the following brake system discrepancies. The brake discs were worn beyond approved limits and areas of the brake pads were worn down to the rivet heads. The wheel bearing grease was hard and all the bearings were dry and pitted. The right side brake cylinder was pitted and leaking. Dirt filled the brake master cylinders. A review of the maintenance records by the NTSB investigator-in-charge revealed that the last annual inspection was completed on June 10, 1996, and the airplane was returned to service by a maintenance mechanic with a FAA Inspection Authorization.