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.
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.
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.
The pilot told an NTSB investigator that during the taxi, he applied a little extra power and right brake to maintain a straight taxi. By the time the fire department arrived, the right wing had collapsed.
The pilot reported that two weeks before the accident, he complained about the pulling to the left, and maintenance personnel found that the left-brake cylinder and assembly had been leaking fluid. They repaired the brake assembly, and returned the airplane to service.
A squawk-sheet entry from three days prior to the accident noted that the airplane pulled hard left, and was "not normal."
The Pilot's Operating Handbook advised pilots that excessive braking could result in overheated or damaged brakes, which could result in brake-system malfunction or failure.
The NTSB determined that the probable cause of this accident was the pilot's excessive braking during taxi that resulted in the right brake overheating and a fire. A factor in the accident was the pilot's continued operation with known deficiencies.
A tricycle-gear Piper PA-22-135 overran runway 28 at the Emmett Municipal Airport, Emmett, Idaho. Neither the pilot nor passenger was injured. The flight originated from Emmett approximately 45 minutes earlier. The pilot reported that he conducted the engine run-up while holding the hand brake. He then departed, remained in the pattern and executed two touch-and-goes to runway 28. He didn't use brakes during these landings. The pilot left the pattern and later returned.
The airplane touched down at approximately 50 miles per hour, and as the speed bled off, the pilot applied the hand brake. He stated that, "...I immediately realized there were no brakes. At that point I pumped the hand brake several times in hopes of building up some pressure. This did not work...," and, "...I continued to hold the brake handle all the way back in the stopping position. I did not feel any resistance..." The passenger reported that he "...observed the pilot apply and recycle the brakes at least twice without noticeable braking or effect..."
The pilot maintained the aircraft on the centerline, and rolled out straight ahead, exiting the upwind end of the runway at about 10 miles per hour. The aircraft then rolled down a gravel embankment and into a ditch. Runway 28 was 3,250 feet long by 50 feet wide. "
A local mechanic/pilot who had owned a Piper PA-22 for 40 years at the Emmett Airport was interviewed, and reported that the PA-22's brake system is highly sensitive to temperature changes. He said that when the system is fully serviced under cool conditions, and then allowed to increase in temperature, the system will lock up. A small amount of fluid has to be bled in order to release the brakes. Conversely, when the system is taken from a warm temperature to a cold temperature, the fluid contracts and the brakes become loose requiring the addition of brake fluid. The mechanic/pilot indicated that pilots new to the aircraft often aren't familiar with this behavior. The accident pilot reported a total of 118 hours of flight experience with 15.7 hours in the PA-22.
The NTSB determined that the probable cause of this accident was brake failure as a result of inadequate hydraulic fluid. Contributing factors were the pilot's overall lack of experience in the aircraft make/model, the cold, soaked brake system due to the low temperatures, and the embankment and ditch.
A Cessna 172S overran a taxiway at the Anacortes Airport, Anacortes, Wash., and was substantially damaged. The pilot and passenger were uninjured. The destination had been East Sound, Wash.
The pilot told an NTSB investigator that he experienced complete brake failure while taxiing for takeoff. The pilot said that he applied brakes as the airplane neared the end of the inclined taxiway, but it continued off the end of the taxiway. It eventually came to rest, nose down, in a drainage ditch.
The pilot reported that on the previous landing, the airplane "shuttered violently" when he applied brakes during the landing roll. He stated that after parking the airplane, he noticed brake fluid "dripping" from the area of the wheel brakes. He said he contacted the operator of the airplane who instructed the pilot to "...ferry the aircraft back for maintenance." The operator told the NTSB the pilot advised him that only a small amount of brake fluid had leaked from the system.
Examination of the brake components by an investigator revealed that the pads were worn beyond limits, which allowed the caliper seals (O-ring) to unseat, resulting in a loss of brake fluid.
The NTSB determined that the probable cause of this accident was the pilot attempting to taxi the airplane with a known system deficiency. Factors include worn brakes and a drainage ditch.
A Piper PA-32-300 went off the right side of runway 36, and struck a part of the VASI light system while landing at Canton-Plymouth Airport, Plymouth, Mich. The aircraft was arriving from Sparta, Mich. The pilot and passenger weren't injured.
The pilot reported that he applied braking, but the right brake wasn't working. The pilot attempted to slow the airplane by using left braking and right rudder. The pilot reported that the aircraft then veered to the right and went off the runway. The left wing hit the VASI lights, and the airplane caught fire. The pilot and his passenger got out, and the fire was put out by the pilot and airport staff.
The pilot reported that he had maintenance performed on the brakes twice in the few weeks before the accident flight. The mechanic bled the lines and added fluid. After the accident, a seal in the brake master cylinder was found to be defective, and this allowed the fluid level to be low, and air to enter the brake lines.
The NTSB determined that the probable cause of this accident was the pilot not maintaining directional control during landing, and the inoperative right main landing gear brake. Contributing factors were the failed brake master cylinder seal, resulting in a hydraulic leak, the inadequate preflight by the pilot, the fuel fire, and the pilot intentionally operating the airplane with a known brake-system problem.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.