Accident Sequence
The pilot reported that the accident landing was to be his last of the day after practicing landings. The first three landings were completed without discrepancies. On the fourth landing, the airplane touched down on the main landing gear in a tail-low attitude. The tail began to rise, and the pilot perceived a slight bounce from the main landing gear. He performed a go-around and returned for the final landing.
On the accident landing, the pilot executed a three-point landing. The landing appeared normal, with power at idle and airspeed at 65 miles per hour. However, the pilot felt as if the brakes were being strongly applied. The tail started to rise, and he immediately pulled the stick fully aft. He checked his foot position on the rudder pedals and temporarily removed them to see if the braking would stop. The braking action continued with no response to full aft stick. The airplane rotated forward and nosed over.
Post-Accident Examination
After the accident, the pilot walked the runway and observed straight skid marks from the main landing gear, extending approximately 150 feet from the touchdown point to where the airplane nosed over. A witness saw black smoke coming from the wheels just after the airplane came to rest inverted. Another witness, who reached the airplane about 25 minutes after the accident, attempted to rotate the main wheels and reported they would rotate but with considerable drag.
Two airframe and power plant mechanics examined the airplane the day after the accident. They found no identifiable brake system anomalies. The parking brake was in the OFF position. The mechanics indicated that the skid marks on the runway were consistent with the brakes being either partially or fully activated from touchdown until the airplane turned over. They theorized that the brake anomaly might have been due to a stuck brake piston, foreign debris in the brake lines or brakes, or high ambient temperature causing internal hydraulic pressure buildup in the cylinder and lines, thereby activating the brakes.