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Brakes sticking

Started by paullapoint, May 23, 2023, 06:36:29 AM

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paullapoint

I'm having trouble with my brakes not releasing after applying them. I've had the right one stay on 3 different times always after using the parking brake. I would get out and release it by opening the bleeder valve. I stopped using my parking brake and haven't had any issues until last week when I did my first ground loop without damaging anything but my pride. It was the left one that stuck this time (I believe). After coming to a stop, all I could do was taxi in circles. I kept tapping the pedal and was finally able to taxi straight. It was very windy and we were in a hurry to get our dog to the vet because it couldn't breath so I wasn't trying to figure out what was going on with the airplane. When I took off, I made a sweeping turn because of the wind and probably didn't have the tailwheel locked after takeoff. Would that have caused a problem ? My tires were a bit soft and I made a bit of a hard landing but I wasn't drifting sideways and had the wings level and almost straight into the wind.(The ground loop was to the left and on a big concrete runway. The trip home was uneventful and made a nice smooth landing even though it was in heavy wind. Thank You in advance for any suggestions.   Paul

Jason Stephens

Hi Paul.  The only experience I have with brakes getting stuck on is when the parking brake was set when the brakes were hot from use or it was a hot day in AZ.  I've had it happen with both Pawnees and a Porter.  The Porter was frustrating as it was my day to get checked out in it and I left that job before that ever happened.  Sounds like your issue is different though.

Kevin Dunn

Paul,

Remind me if those are Goodyear or Cleveland?

Kevin

paullapoint

Being hot seems to have an effect after using the parking brake and having to make a long taxi using brakes to keep slow and steer to see, heating them up. They have been changed to Clevelands. I flew again yesterday and found another problem that I think contributed to the ground loop. I had mechanics pump my struts up. They said that the struts didn't move with the multiplier maxed out so I asked if they moved the aircraft back and forth on the floor as they did it. They didn't, so they went back and moved it and the struts pushed all the way out. They let some nitrogen out, said it was within spec, and I didn't double check it as I usually do. When I landed yesterday, the right strut wouldn't collapse at all and wanted to ground loop again but was easier to control on the grass. I taxied back with the left wing drooped because the right strut was all the way out. I will be letting more nitrogen out.

Kevin Dunn

Paul,

If they were Goodyears I would go a different direction, but since they are Clevelands I think you are on the right track. Parking brake and heat seem to be the factors.

Getting the struts serviced is always special. I have found giving the tire a way to move in as you service the strut is a big help. Either grease plates or someway to allow the tire to slide towards the fuselage. A nitrogen bottle with a good regulator so you can know exactly how much pressure you are putting in is a big help. And then....roll it back and forth!

Kevin

paullapoint

Thank You Kevin and Jason. The manual says you can land with the brakes locked for a shorter roll out. I don't think it's a good idea with the Clevelands because they do stop well.

Kevin Dunn

It works on grass with the Clevelands. Three point only! Never tried it on pavement.

Heliopilot

I have landed, brakes locked in both wheel and 3-pt landings. Yes, there was a reason.

Heliopilot

Rrv brakes sticking. I had the right brake engage on takeoff long ago, in a land far away. One of the lower tabs holding the right master cylinder had broken allowing the mate cylinder to "drop" and the parking brake cable pull up on the parking brake valve, locking that brake. Goodyear wheels. Also, an improperly rigged parking brake cable may cause locked brakes.

paullapoint

Thank You Heliopilot.
  We just finished the annual so pulled the whole brake system apart and washed out all the parts and pulled rags through the lines like cleaning a gun barrel. Got quite a bit of jelly stuff out. New pads and o rings on the cylinders. Only flown once since but all went well.
  Installed rebuilt gear shock struts. Huge difference in the way the gear system works with the proper amount fluid and nitrogen in them. Takes a lot of work out of landing having everything set up properly.   Paul

yukonranger

Interesting, do you have any pictures of the jelly stuff?

I recently had a locked brake on my MU2 while taxiing after landing.  Actually the brake was dragging but the wheel was not locked up.  The Maitenance center immediately suggested moisture in the hydraulic fluid (5606). I bled some fluid and it was a milky color and water did eventually settle out.  This was after a 4hr flight at -42C

Kevin Dunn

I have seen 5606 turn to jelly like consistency a few times. Mostly in older airplanes. Especially if they are a hangar find and haven't flown for 15-20 years. Also, the fluid near the brakes really never gets changed, we just add more fresh fluid at the top. If the system doesn't leak, that fluid can be in there for years. Thus the reason to drain the system and put fresh fluid in at some regular interval.

Just my thoughts.

Kevin