On July 21, 2012, about 1120 central daylight time, a Piper PA-22-150, N4749A, was substantially damaged during a runway excursion while landing on runway 18 (4,201 feet by 60 feet, asphalt) at the Augusta Municipal Airport (3AU), Augusta, Kansas. The pilot and sole passenger sustained minor injuries. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from 3AU about 1115. The pilot reported that the preflight run-up was uneventful and the brakes worked normally at that time. After takeoff, she remained in the airport traffic pattern and returned for a full stop landing. The pilot stated that the approach and landing were normal; however, on rollout the brakes were completely ineffective. Upon reaching the end of the runway, she thought that the airplane was still traveling too fast to safely turn onto the taxiway. She elected to overrun the end of the runway and encountered a concrete culvert. A postaccident examination conducted by Federal Aviation Administration inspectors was inconclusive with respect to the brake system. The examination did not reveal any anomalies consistent with a brake system failure. However, the main landing gear tires did not exhibit any flat areas indicative of a skidding tire, nor were any skid marks corresponding to the accident airplane observed on the runway pavement. According to the pilot, the airplane was equipped with the original handbrake. There were no toe brakes installed. The pilot reported a total flight time of 136 hours, with 96 hours in Piper PA-22-150 airplanes.