The flight instructor reported that during a Civil Air Patrol evaluation flight, he decided to demonstrate a power off landing to the pilot being evaluated. The flight instructor further reported that the airplane touched down within the first 400 feet of the 2,160-foot runway and reported that the brakes were ineffective during the landing roll. The pilot witness who observed the landing from the left seat reported that he observed heavy braking, some swerving, a loss of control, and the airplane exited the left side of the runway near the departure end of the runway. During the runway excursion, the airplane nosed over and sustained substantial damage to the fuselage, empennage, and the right wing lift strut. In a Civil Air Patrol online system, the pilot witness reported that over the runway threshold the airspeed was 84 knots, the altitude was 20 feet, and the airplane touchdown zone was 1/2 to 2/3 down the runway, with 1000 feet of runway remaining. The local flight school provided video surveillance of the landing. The video showed the airplane still airborne while in the camera frame, which was about 700 feet past the runway threshold. The airplane subsequently moved out of camera view and was still airborne. The video did not show the airplane touch down on the runway. In a post-accident examination four days after the accident by the Federal Aviation Administration (FAA), both brakes were found to be functional. In a post-accident inspection almost two weeks after the accident by the repair mechanic, it was revealed that the left brake was working, but the right brake was "full of air." The mechanic reported that when the airplane was upside down air can enter into the hydraulic system, so "all bets are off". The mechanic further reported that there were no flat or bald spots on the tires.