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  #1  
Old 07-01-2022, 09:08 AM
WingnutWick's Avatar
WingnutWick WingnutWick is offline
 
Join Date: Jun 2013
Location: Fresno, CA (KFCH)
Posts: 326
Default Leaking brake fitting

All, have a brake fitting that is leaking slowly but enough to put drips down overnight. I've tightened this as much as I dare, the only other option is to cut off the tip and re-do the flare (provided there is no other obvious cause causing a bad seal - like a piece of dirt etc). Is this correct thinking or should I try something else prior?

Thanks
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  #2  
Old 07-01-2022, 09:45 AM
Stevea Stevea is offline
 
Join Date: Jun 2008
Location: San Jose, CA
Posts: 221
Default brake line fitting leak

Looks like leakage from the flared tubing to steel fitting interface.

You might already have a cracked flare or other damage to the aluminum tubing at this point. The "B" nuts on a 1/4" aluminum flared fitting like this one have a required torque range of 50-65 in-lbs (table 9-2 from AC43.13-1B). Higher torque is not better, it runs the risk of causing flare damage.

Open it up and check the flare to steel fitting interface for debris or damage. If nothing obvious is found (sometimes cracks are hard to find) you might just have to cut off the flare and re-do it.

Second thought: you can also try one of these - https://www.aircraftspruce.com/catal...ickkey=2719162
I have no personal experience on how well they work....but might be worth a try. Although, even one of these might not seal a crack in the flare.
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Last edited by Stevea : 07-01-2022 at 09:49 AM. Reason: added "second thought"
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  #3  
Old 07-01-2022, 09:55 AM
abwaldal@gmail.com abwaldal@gmail.com is offline
 
Join Date: Jan 2017
Location: Battle Ground WA
Posts: 529
Default leaking fittings

Look on ACS and look up Del-seals. Expensive fix, But, really cheap in the long run. They are an soft aluminum gasket sort of affair for flared connections. Some people use them on every fitting , Because they work so well.
They come in all the sizes you will need. Shipping is going to kill you, But that's life.
I've had leaks, used them and leak no more.
But if the line flare is cracked ain't nothing short of re-flare gonna fix it.
my three cents worth Art
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  #4  
Old 07-01-2022, 10:06 AM
deek deek is offline
 
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Default

Del seals are also made in copper, and seem to work better on steel AN fittings than the aluminum version.
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  #5  
Old 07-01-2022, 10:57 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Default

Quote:
Originally Posted by abwaldal@gmail.com View Post
Look on ACS and look up Del-seals. Expensive fix, But, really cheap in the long run. They are an soft aluminum gasket sort of affair for flared connections. Some people use them on every fitting , Because they work so well.
They come in all the sizes you will need. Shipping is going to kill you, But that's life.
I've had leaks, used them and leak no more.
But if the line flare is cracked ain't nothing short of re-flare gonna fix it.
my three cents worth Art
Unless you can confirm where it is leaking from, you could have a crack somewhere creating a compromised tube/flare. If that is the case, masking with a sealing device potentially sets you up for a more pronounced and unpleasant failure of the interface down the road. losing one brake on a strong X wind day is no fun with a castering nose wheel and down right scarry with a TD. A well formed flare should not leak and should not require any sealing devices or chemicals. Take the leak as a warning that something is not right and address it correctly.

I would cut the end off and re-flare it. I had one fail 5 hours into phase I. Just luck it was a calm day. Clearly something was compromised in the flare, but had no visual cues that it was bad prior to the failure.

Larry
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Last edited by lr172 : 07-01-2022 at 11:04 AM.
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  #6  
Old 07-01-2022, 02:24 PM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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Default

If you have fluid coming from the aft end of the nut, the sealing surface is compromised. Either a bad flare, cracked flare, or like the pic, a really damaged steel adapter fitting. YES, believe it or not, client called and said our hose was leaking. Naaa---take it apart and take a pic of the adapter==OOPS----. This was installed by an A&P.

So take things apart, and INSPECT them. Dont guess.

Tom
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  #7  
Old 07-01-2022, 03:36 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default Hose

Tom's hoses work so much better in that location.
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  #8  
Old 07-01-2022, 03:57 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,322
Default

This is a long shot, but check the flare angle is correct. Aviation and automotive use different angles. As others have said, ovrr-tightening is not the solution. Open it up and look. Yes, you’ll need to catch the fluid as it comes off or have a big mess.
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  #9  
Old 07-01-2022, 08:57 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 2,328
Default Check B nut and sleeve

I would also check the B nut and sleeve, the gap between the B nut and sleeve looks too big for an aircraft standard part
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  #10  
Old 07-05-2022, 09:18 AM
BruceW BruceW is offline
 
Join Date: Aug 2005
Location: Elk Grove, CA
Posts: 260
Default

The Del-seal thingys.
Used a couple as needed during the phase 1.
No problems after 500+ hours.
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