Brakes chattering

[B737jenkins]

Another question for the masses. Our 7ECA has had an intermittent “chattering“ of the right brake. At taxi speeds, it chatters. As soon as you apply brake, it stops. We’ve checked the obvious (at least to me) stuff. Nothing is loose, the pads look to be in good shape. Nothing appears to be binding. Our primary Mx guy Is out of town, so we’re just spitballing until the pro gets back.

Any thoughts on things to look at?

 

[Bartman]

define "chattering"....is it binding at all on the disc or affecting how the airplane taxis?

braking problems can sometimes be traced to o-rings in the master cylinders that are swollen from being exposed to incorrect brake fluid since cars use DOT 3 or 4 and planes use hydraulic fluid. it's a common mistake and the brakes get screwy, the master cylinders don't re-extend when you take your foot off the pedal. I'm also wondering if you have mounting holes in the brake assembly (maybe the part that the brake lining is riveted to) that are out-of-round enough to allow movement and the chattering you're hearing?
I don't know, wild ass guess, i think it's going to be that kind of day here!

but what exactly is "chattering"?

 

[B737jenkins]

Chattering is clearly a technical term.

I don’t know how else to put it. When taxiing you hear a loud rattling. The pads are solidly attached to the pressure plates. The brake assembly (calipers) float freely on the pins, without binding. The brakes function normally, and the noise does not affect function. Application of the brake stops the noise immediately. The rotors and wheel appear to track in a straight line, without wobble, while taxiing. The pressure plates don’t appear to be worn at the pin holes. Next up is to verify the pins aren’t worn, causing the pressure plate to rattle. Then it’s to the cylinder and O rings.

 

[Bob Turner]

Yes. Did somebody lubricate the pins? Use only dry graphite.
I had a chatter a couple years ago - cleaned the pins, tried grease the viscosity of candle wax, everything. Cure was a different torque plate and caliper.
My expert is Robbie Grove. His brakes are pretty much identical to the Cleveland’s on Citabrias and Decathlons.