bleeding brake help

In article ,
brian whatcott wrote:

Orval Fairbairn wrote:

I was taught ALWAYS to bleed aircraft brakes from the wheel UP.

A simple pump-type oil can with a length of plastic tubing can serve
well as a bleed tool. Just make sure that it has a big enough reservoir
and that there is no air in the line.

Brake bleeding can be pretty messy and a two-man operation.

1. Pump the fluid into the tubing, leaving no air bubbles.
2. Attach the tubing to the bleed valve on the wheel cylinder.
3. Have assistant at the appropriate rudder pedal ready, with a drip
container, to open the master cylinder.
4. After assistant has opened the master cylinder, open the wheel
cylinder and pump until assistant sees only fluid and no air.
5. Close wheel valve; have assistant close the master cylinder valve.

6. Repeat #3-#5 for any other rudder pedal cylinders on that wheel.

7. Repeat #1-#6 for the opposite gear.


As it happens, I had the day off, so today I headed over to an A&P not
far away with a main tire for fitting. They packed the bearing, replaced
the brake pads, and retracted the slave cylinder.
When it came time to go, I pumped the pedal, but the brake action did
not go hard.
So I taxied back, and they added brake fluid using Orval's recipe.
THEN the pedals came up firm....

Brian W

You should not have needed additional fluid. When you remove a main
wheel, part of the process is to expand the calipers physically. When
everything is done, all you should have to do is press the brakes a
couple of times to get a firm pedal, since, theoretically, no fluid has
left the system, unless somebody disconnected a brake line during the
process.

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