Plane & Pilot
Tuesday, August 9, 2011

Broken Brakes

There are times when the risk of not stopping should stop you from going

Not too long ago, I was looking forward to an hour or so of poking holes in the sky in a Piper Cherokee 180. What I didn't know when I arrived quite carefree at the airport was that Mr. Murphy was hard at work applying his law, and it didn't take long for me to discover that neither the parking-brake handle nor the foot brakes would develop any pressure unless pumped numerous times. I didn't feel like taking a chance that the plane wouldn't stop after landing. Air trapped in the system during maintenance or because of a leak seemed the likely culprit. As anyone who's familiar with Cherokee brakes can tell you, when there's a lot of trapped air, simple bleeding isn't enough. You need to use a pressure system to force the air out with a flood of fresh fluid. That's just what it took to get the brakes operating again. The experience prompted me to look at the NTSB's files for accidents involving brakes.

Cessna 172K
The airplane had a new student and instructor on board. They were getting ready for a flight from the Habersham County Airport in Cornelia, Ga. The instructor told investigators that the only problem noted during preflight was a low nosewheel tire. Air was added, they started up, taxied out and took off. They flew north of the airport for some air work, then went back for landing. The student pilot made a normal landing to runway 24. The student taxied to the end of the runway, and turned left onto the taxiway. The CFI told the student to stop after clearing the runway. The airplane went further than the instructor wanted, and he told the student to apply brakes. When the airplane kept moving, the CFI also applied brakes. The CFI applied the hand brake, and the airplane still wouldn't stop. The CFI pulled the mixture to idle cutoff. The airplane went down an embankment and hit some trees. The occupants escaped injury.

The registered owner of the airplane reported that the brake system had been serviced a week before the accident by adding brake fluid. FAA inspectors were able to push the airplane with the parking brake engaged. In addition, one FAA inspector got in the left-front seat and applied brakes, and then in the right-front seat and applied brakes, as the other inspector pushed the airplane. The airplane moved each time. Examination revealed that brake fluid was leaking onto the exterior of the master cylinder components. The carpet near the left rudder pedals was saturated with brake fluid.

The NTSB determined that the probable cause of this accident was the failure of the owner/operator to repair or replace a known leaking brake-system component, resulting in a total loss of brakes while taxiing and an on-ground collision with trees.

Cirrus SR22
A Cirrus SR22 was getting ready to begin its takeoff roll on runway 12 at Half Moon Bay Airport, Half Moon Bay, Calif., when it caught fire. Although the airplane was substantially damaged, the pilot and passenger got out safely. They were going to Palo Alto, Calif., on an IFR flight plan in VFR conditions.

The pilot told investigators they flew from Palo Alto to Half Moon Bay for dinner, and this was to be the return leg. He had taxied the airplane from the parking area to the end of the runway for takeoff, which was a distance of about about 11⁄2 miles. As he turned the airplane onto the runway and began to align it with the centerline, the right brake failed. He couldn't control the direction of taxi, so he cut the engine. He then noticed smoke and flames coming from under the right wing. He reported that the airplane had been pulling to the left for several months, and he had to "drag" the right brake in order to taxi straight.


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