This April 2007 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 170A
Location: Watkins, Colo.
Aircraft damage: Substantial.
What reportedly happened: The pilot had been practicing touch-and-go landings. On his final landing, the plane swerved to the right. He was not able to regain control. The right wing struck the ground, bending the spar. The airplane veered off the runway.
According to the FAA airworthiness inspector who examined the airplane, the right brake caliper assembly showed severely worn shoes with uneven wear. The inspector surmised that when the pilot applied the brakes, the uneven brake shoe wear caused the caliper pins to engage misaligned, contacting the rotor, locking and shearing the caliper assembly.
Probable cause: A total failure during landing roll of the right brake caused by severely worn shoes.
For more information: NTSB.gov/ntsb/brief.asp?ev_id=20070514X00554&key=1