On September 24, 1985, a Beech P60 (registration N973T) was involved in an aviation accident near San Jose, CA. Investigators recorded the probable cause as: The pilot's failure to maintain directional control during the landing roll, which was caused by a loss of left brake pressure due to leaking hydraulic fluid and flattened O-rings in the left brake middle piston. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During the landing roll, an aircraft veered right off the runway and struck a taxiway marker. Investigation revealed leaking hydraulic fluid and flattened O-rings in the left brake assembly.
What happened
During the landing roll, the aircraft veered off the right side of the runway. It made contact with a taxiway marker, which was then thrown against the aircraft, puncturing the pressure bulkhead compartment.
The investigation
Examination of the left brake assembly revealed evidence of leaking hydraulic fluid and an empty fluid reservoir. The 'O' rings in the left brake middle piston were found to be 'flattened'.
Findings
The primary contributing factor was fuel exhaustion leading to loss of braking capability on the left side, resulting in the runway excursion.
Safety message
Regular inspection of hydraulic systems and brake components is critical to prevent fluid leaks and ensure proper braking function during landing rolls.
Probable cause
The pilot's failure to maintain directional control during the landing roll, which was caused by a loss of left brake pressure due to leaking hydraulic fluid and flattened O-rings in the left brake middle piston.