Primary finding
Probable cause
A malfunction of the airplane’s right main wheel brake, which resulted in a loss of control and runway excursion during landing.
Investigator assessment
Analysis narrative
During a checkout flight with a flight instructor to meet flying club currency rules, the pilot flew to a nearby airport. Upon arrival at the airport they practiced landings. Immediately after the fifth landing, during the roll out, the airplane turned abruptly to the right, exited the runway onto the grass area between the runway and taxiway, and impacted a drainage ditch. The airplane’s fuselage and right wing were substantially damaged. Postaccident examination of the airplane’s wheels and braking system revealed that the right main wheel would not rotate on its axle. When pressure was applied to the top of the pilot’s side right rudder pedal, the actuator rod for the master cylinder would stick in the retracted position and would not automatically extend when the rudder pedal was released. Additionally, a gurgling sound (which indicated that air was in the system) could be heard during actuation. Further examination of the brake system revealed that the right brake assembly was not functional, displayed evidence of overheating, and was leaking fluid from around the upper piston, which was stuck in the extended position. The lower piston was also partially extended and was covered with brake fluid. The pressure plate would not move, and the anchor bolts that the pressure plate slid on displayed evidence of corrosion. Additionally, both piston O-rings appeared flat and did not stand proud from the sides of the pistons, the brake linings displayed higher than normal wear, and the brake disc displayed grooving. Based on this information, it is likely that the airplane’s right brake malfunctioned during the landing, which resulted in the loss of directional control during landing.