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  #11  
Old 12-03-2019, 08:15 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 777
Default Ferrule position

I think it is important that the brass ferrule is not too far onto the plastic tube. Both sides of the ferrule must contact the fitting. If the brass ferrule is too far on the plastic tube, then only one side seals against the fitting. So I would make sure the ferrules are sealing on both sides.
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  #12  
Old 12-04-2019, 05:47 AM
fixnflyguy fixnflyguy is offline
 
Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 1,047
Default I made the Braided SS switch..

I was a huge fan of the plastic lines when I built my -4 because they were simple, light and easy to DIY the length and routing. However, after 10 years of service, I found myself continually tightening, snipping and re-furreling the ends to keep from having leaks ,mostly at the high pressure caliper end. The final straw to the demise of my plastic lines was loosing my left brake on the departure taxi from OSH this year (made it back to NC with just the right brake). I have switched over to all SS braided AN fitting lines, and hope to never have any more issues. I never did have any leaking of the low pressure side, but mine were all plastic fittings as well as lines (no brass other than the ferrule. I believe time, temperature and other environmental subjection take a toll on plastic system and eventually they become BER.
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  #13  
Old 12-04-2019, 08:35 AM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,768
Default

After 2 years of futzing around with the plastic lines in my 9A trying to resolve the same persistent leak, I gave up and had Tom make me a set of real hoses for replacement. No problems since. The plastic line and ferrule setup is not a good material choice for that application, IMHO.
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  #14  
Old 12-04-2019, 10:28 AM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
Posts: 723
Default Plastic Lines

I am one that has had leak-free plastic tubes in 860 hours of airframe time.

I think much of the success of getting these to be leak free depends on ensuring that the ends of the tubes are cut very straight and also ensuring that the tubing, ferrule, and fittings are clean and scratch/nick free prior to assembly. In my opinion, throwing braided noses I place of the small diameter very low pressure side of the system just adds unnecessary weight and cost to our aircraft.

Skylor
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  #15  
Old 12-04-2019, 10:52 AM
Warden Warden is offline
 
Join Date: Nov 2013
Location: Mid Michigan
Posts: 17
Default Tubing Size

Make sure the tubing is 1/4" O.D. and not 6mm. Sometime a supplier will substitute 6mm (.236") for 1/4"! I've had this happen to me with industrial equipment. Just a thought.
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  #16  
Old Today, 11:48 AM
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rv8ch rv8ch is online now
 
Join Date: Feb 2005
Location: LSGG
Posts: 2,610
Default Fixed

Thanks for all the hints about how to solve this - really good info in this thread.

The way I solved it was to use the Steinair plastic tubing cutting tool to make a perfectly straight and perpendicular cut on the tubing, clean everything very well, and put it back together carefully. Seems to be holding now, I'll of course keep an eye on it over the coming days to make sure it's holding.

https://www.steinair.com/product/pla...-cutting-tool/

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