Brake Failure on Gear Retraction

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3 days 22 hours ago #2332 by Keith Obermeyer
Turns out that when the gear retracted, there was a clearance issue in the wheel well that interfered with the brake assembly. There had been a repair on the lining of the wheel wells Just prior to the problem showing up. The repair was to grind out an area in the wheel well and reseal it to provide the clearance for the brake assembly. Been good ever since. That fix was on the house of course.

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3 days 23 hours ago #2331 by erik carlson
I would love to hear what the fix to the brake issue was . Thanks Erik

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1 year 3 months ago #1362 by STEVE ELLS
Hi, I suggest that your mechanic check closely to determine is the seals in the left master cylinder are in good shape. Two types of master cylinders were used on Cessna singles. The first type, which seems to be standard equipment up until 1979 had a floating piston. This type used a special part called a lock-o-seal on the lower end of the piston in the master cylinder. The floating piston is held away from the lock-o-seal when there's no pressure on the brake pedal to allow fluid to flow from the reservoir to the area below the piston. This allows the fluid below the piston to be automatically replenished. This compensates for brake pad wear which causes the piston(s) in the wheel brake cylinders to move out to compensate for the wear. A pretty elegant system and it works well if the o-rings on the piston and the special washer (which is the lock-o-seal) is in good enough shape to seal when the brake pedal is pushed down. Here's how it works. Relaxed pressure or no pressure on the brake pedal- a small spring pushes the floating piston away from the lock-o-seal. The lock-o-seal is a washer with an o-ring type seal molded into the washer. When the brake is applied, the floating piston move upward on the center shaft and bares against the o-ring part of the lock-o-seal which closes the opening between the reservoir and the piston. Pressure is then applied to the fluid and braking occurs. The critical part of this type of master cylinder that a 0.040 inch gap between the top of the floating piston and the lower edge of the o-ring seal on the lock-o-seal be maintained.
The newer type of master cylinder was much simpler. Change the o-ring and the back up ring is all the maintenance it needs.
The other brake master cylinder headache that's common on Cessna singles is bent brackets at the bottom end of the left master cylinder. The brackets are part number 0411549 and 0411550 (parts manual figure 92, item 18 and 19). The early brackets often bent. Replacement brackets (same part number) are steel and not prone to bending.

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1 year 3 months ago #1359 by Keith Obermeyer
I have a P210 N that I have owned for about a year and am working thru some of the accumulated maintenance needs on this aircraft. The plane just came out of annual and on the first flight I had a complete brake failure(no braking action) on the left side as I landed. After pumping the left brake pedal a few times I was able to get full brake action back in play. I flew another lap and after retracting the gear, lost brake pressure again on the left side. After landing was able to reacquire braking action by pumping the brake pedal. I was able to get the plane in to the shop where the guys found a bent piston in the left master cylinder. It was replaced and back to flying. Same thing happened on the next landing. No left braking action. I flew another lap around the field without retracting the gear and maintained full brake action the entire time. Clearly, retracting the gear is causing the brake failure.

Any thoughts from some of the veteran 210 folks out there on where to go with this? My mechanics are digging into the 210 manual as I send this. Thanks for any input. T

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