What happened
Following the first landing of a flight, the co-pilot notified the captain that the left brake did not feel normal while taxiing. The captain concurred, and the crew taxied the aircraft to a maintenance facility for an inspection.
A mechanic performed a visual inspection of the brake system but found no defects. Because the brake lines had been recently replaced, the mechanic instructed the flight crew to pump the brakes to clear any potential air from the lines. The crew reported that after pumping the brakes prior to takeoff, the pressure felt adequate.
During the ground roll of the second landing, the left braking action failed. To prevent the aircraft from running off the end of the runway and into a river, the captain executed a deliberate maneuver involving hard right rudder and right brake to ground loop the aircraft.
The investigation
Investigators inspected the brake system and removed the left side brake master cylinder for testing. A functional test revealed that the master cylinder assembly met all engineering requirements. The presence of spot putty locking the cover to the body was consistent with original Cessna production assembly practices, indicating the cylinder had not been overhauled. Upon disassembly, no evidence of wear, scratches, or pitting was found within the unit.