The International Cessna^® 170 Association

I am trying to educate myself regarding Cessna170 B brake system

Had brake failure Right Master cyl A/C S.N. 26433 July 1954 mfg.. R Brake lost all pressure.

IPC fig 60 page 101 list several P.N. for master Brake cylinder - My is 0541138-6 See Fig 59 for Break Down

My first question is may I simply order a factory brand new assembly? Not a rebuilt but a NEW part.


On line I read that in 1979 Cessna changd the design of the brake master cylinders. Commentater stated " earlier style depended on a poorly understood part called a "Lock-O-Seal" for successful operation"

I found that part 59-16. I think the word "Lock" is a clue. I do not understand function. Is this the culprit?

Brand new Cleveland cylinders are available, but after you check the price you'll decide to rebuild yours.

might just bleed it first.........................................................................

The Lock-O-Seal is a spring washer and O-ring that act as a one way valve between the oil reservoir and the master cylinder piston.
It's sprung open normally and closes when you apply pressure.
If it's worn or torn, you get symptoms from mushy brakes to flat nothing. And the next time you step on the pedal, the o-ring may seat properly and your brakes are fine.

Rebuilding a master cylinder is a very simple process as it's mostly just O-rings. The hardest part is getting them in and out of the airplane.