SNOHOMISH, WA, USA
N65PR
Piper PA-23-250
The pilot reported that the touchdown and rollout were normal for about 300 feet. The pilot stated that as he applied the brakes, the left brake failed and the airplane swerved to the right and off the side of the runway. Due to people and equipment near the runway, and in the aircraft's path, the pilot utilized nose wheel steering and right throttle control to redirect the aircraft. The aircraft continued about 80 feet over freshly graded terrain before entering an open field covered with tall grass. The aircraft collided with a ditch and subsequently an abandoned truck before coming to rest. Shortly after the accident, the brake system was inspected. It was found that the left brake pedal would make full travel with no apparent braking action. After applying pumping action, there was a gradual rise of the pedal and braking action. Further inspection of the system did not reveal any mechanical failures or malfunctions. The brake lines were then bled and a considerable amount of air bubbles were noted.
On July 11, 1999, at 2010 Pacific daylight time, a Piper PA-23-250, N65PR, registered to Skycrab Aircraft Sales, and operated by the pilot as a 14 CFR Part 91 personal flight, experienced a brake malfunction during the landing roll at Harvey Airfield, Snohomish, Washington. The airplane veered off the runway and collided with a ditch and parked vehicle. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged. The private pilot and his five passengers were not injured. The flight departed from Wilbur, Washington, about one hour and 15 minutes prior to the accident. During a telephone interview and subsequent written statement, the pilot reported that touchdown and roll out were normal for about 300 feet. The pilot stated that as he was applying braking action, the left side brake failed and the airplane swerved to the right and off the side of the runway. The pilot reported that there were people and equipment in the aircraft's path so he utilized nose wheel steering and right throttle control to redirect the aircraft. The aircraft continued about 80 feet over freshly graded terrain before entering an open field covered with tall grass. The aircraft collided with a ditch and subsequently an abandoned truck that was parked in the field, before coming to rest. Shortly after the accident, a mechanic inspected the brake system and reported that initial inspection of the left brake showed that the left pedal would make full travel with no apparent braking action. The mechanic reported that with pumping action, there was a gradual rise of the pedal and braking action. The mechanic checked and confirmed that the reservoir was full of fluid. The mechanic also checked and confirmed that no leaks were evident in the fluid-carrying lines, master cylinders, parking brake cylinders and brake assemblies. The mechanic reported that the brake pedals showed no abnormal wear or looseness at the attach points. The mechanic then bled the brake lines and reported that considerable amounts of air bubbles were noted. After the lines were clear of the air bubbles, the pedal would make one-third to one-half travel, with braking, then on the release and reapplication, the pedal was at the top. The left brake and pedal were then disassembled. The mechanic noted minimal wear to the brake pads, and the brake rotor was not excessively grooved or worn.
Brake system failure due to the presence of air bubbles in the hydraulic fluid.
Source: NTSB Aviation Accident Database
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