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  #1  
Old 07-14-2022, 10:07 AM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
Posts: 350
Default Stuck Parking Brake

I normally set the parking brake prior to engine start. This is a purpose built hydraulic valve that sets a check valve in place on both brake lines, then releases the check valves to release the brakes.

On my last start I noticed the right brake remained locked after I put the valve back in the release position. I wasn't going anywhere but in circles, so I shut down and cycled the valve a few times. I could hear the left side set and release, but the right side remained quietly locked. Then unfortunately the left side also began to remain quiet and then both brakes were locked.

I mounted my valve where I can actuate the valve lever itself, meaning it is not remoted with a cable.

So I was stuck blocking traffic until I could get the wheel pants off and loosen the hyd fittings at the brakes to release the pressure. The good news if any is that this was an engine warm up prior to my annual condition inspection so no disappointed passengers.

Anyone ever encountered this? Seems impossible but it was a very real nuisance.
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LtCol USMC (Ret)
F-18/F-5/F-16, AH-1/UH-1/CH-53/CH-46, C-130/AN-2
RV-7 complete with all the gadgets
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San Jose State University Av Faculty, CFI/GFI S/M (I)

Last edited by wawrzynskivp : 07-14-2022 at 10:10 AM.
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  #2  
Old 07-14-2022, 10:21 AM
TS Flightlines TS Flightlines is offline
 
Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 3,139
Default

Duck, what kind of purpose built valve? Sounds like its a piston valve and one is stuck.

Tom
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  #3  
Old 07-14-2022, 10:25 AM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
Posts: 350
Default

Matco Unit, looked like this guy: https://www.chiefaircraft.com/aircra...xoCPBAQAvD_BwE
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Vincent 'Duck' Wawrzynski
LtCol USMC (Ret)
F-18/F-5/F-16, AH-1/UH-1/CH-53/CH-46, C-130/AN-2
RV-7 complete with all the gadgets
Aviation Safety/Accident Inspector/Investigator
San Jose State University Av Faculty, CFI/GFI S/M (I)
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  #4  
Old 07-14-2022, 10:35 AM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
Posts: 4,111
Default

Quote:
Originally Posted by wawrzynskivp View Post
I normally set the parking brake prior to engine start. This is a purpose built hydraulic valve that sets a check valve in place on both brake lines, then releases the check valves to release the brakes.

On my last start I noticed the right brake remained locked after I put the valve back in the release position. I wasn't going anywhere but in circles, so I shut down and cycled the valve a few times. I could hear the left side set and release, but the right side remained quietly locked. Then unfortunately the left side also began to remain quiet and then both brakes were locked.

I mounted my valve where I can actuate the valve lever itself, meaning it is not remoted with a cable.

So I was stuck blocking traffic until I could get the wheel pants off and loosen the hyd fittings at the brakes to release the pressure. The good news if any is that this was an engine warm up prior to my annual condition inspection so no disappointed passengers.

Anyone ever encountered this? Seems impossible but it was a very real nuisance.
Have you tried pumping the brake after releasing. In most cases, it will release after pumping it once or twice.
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  #5  
Old 07-14-2022, 10:49 AM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
Posts: 350
Default

Quote:
Originally Posted by Bavafa View Post
Have you tried pumping the brake after releasing. In most cases, it will release after pumping it once or twice.
Yes, tried pumping, rocking the airplane back and forth by hand, resetting and releasing, all to no effect other than to get the other brake to also jam.

Just had dialogue with Matco and there is an issue with O-ring distortion. Apparently we are supposed to put pressure back on the brake pedals when we release the valve in order to keep from distorting internal O-rings. But they couldn't offer a failure mode to account for what I saw and asked for the valve to be returned to them.
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LtCol USMC (Ret)
F-18/F-5/F-16, AH-1/UH-1/CH-53/CH-46, C-130/AN-2
RV-7 complete with all the gadgets
Aviation Safety/Accident Inspector/Investigator
San Jose State University Av Faculty, CFI/GFI S/M (I)

Last edited by wawrzynskivp : 07-16-2022 at 08:09 AM.
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  #6  
Old 07-15-2022, 03:45 PM
ian greenland ian greenland is offline
 
Join Date: Jul 2013
Location: goondiwindi qld australia
Posts: 11
Default Duck

I had to put stronger Springs on my pedal release, the pedal on the Matco must be absolutely 100% up to release the brakes. Just one more thing to check?
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  #7  
Old 07-15-2022, 05:41 PM
Stevea Stevea is offline
 
Join Date: Jun 2008
Location: San Jose, CA
Posts: 239
Default parking brake rebuild kits

Quote:
Originally Posted by wawrzynskivp View Post
Anyone ever encountered this? Seems impossible but it was a very real nuisance.
A sticking valve? So, maybe try throwing one of these rebuild kits at it (depending on which Matco parking brake valve you have):

http://www.matcomfg.com/PVRBDPVPV1PV...dv-3745-8.html
http://www.matcomfg.com/PVRWKEPDMPVP...dv-3840-8.html
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  #8  
Old 07-16-2022, 09:24 AM
TCW TCW is offline
 
Join Date: Nov 2010
Location: Fl
Posts: 33
Default Stuck parking brake

I had the same issue on my RV-9a. Finally removed it .
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  #9  
Old 07-16-2022, 10:04 AM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 1,055
Default

I just rebuilt a matco valve that I had bought used a couple of months ago.

The lever on the side rotates a camshaft that pushes the individual valve pistons one way, then when you rotate the lever the other way, The internal springs push the pistons back up to keep them nestled up to the cam lobes.

seems reasonable that a stuck o-ring could bind up the works so that the spring couldn't do it's thing.

If it were me, a $20 rebuild kit would be where I would start.
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  #10  
Old 07-16-2022, 04:15 PM
MGR1977 MGR1977 is offline
 
Join Date: Jul 2020
Location: Seattle
Posts: 109
Default

I don't have the parking brake but have the Matco brakes. Mine doesn't want to release on the right hand side after applying pressure on the pedals. Super annoying and my right hand wheel pants almost caught fire yesterday. So I'm also thinking deformed o-ring. Sounds like the culprit to me.
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