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Thread: Nylo-Seal Tubing & Fittings for Fuel Lines

  1. #1

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    Nylo-Seal Tubing & Fittings for Fuel Lines

    After seeing Cub Crafters' and Legend's aircraft fuel systems I'm thinking about using Nylo-Seal Nylon II 3/8" (Not Nyla-Flow) tubing and fittings for my Javron airplane. I like that it is not rigid and routing would be much simplified. I've not decided yet and I can do an aluminum tube system, but the Nylo-Seal is looking like it would work very well.

    What do y'all think?

  2. #2
    irishfield's Avatar
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    I use it, or Parker Parflex, for hydraulic lines and it stands up for years (decades) with Dextron III or 5606 in it. Not sure how well it does with 100LL and especially would be cautious of car gas. Is that what CC and Legend are using Nylo-Seal??

  3. #3

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    Quote Originally Posted by irishfield View Post
    Is that what CC and Legend are using Nylo-Seal??
    Yes.

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    Probably better in a crash also. I ve taken crashed ultralights apart that used that blue plastic fuel line (urethane?), dirt bikes and snowmobiles use it. It stretched but didn't break or leak. It made a believer out of me. That Nylo stuff will be real light also.

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    Legend uses Nyla-flo for brakes. Alum tubing for fuel

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    The fittings are a bit larger than AN fittings but I don't think it would be a problem. It is my understanding that the connections at the fittings are far less likely to leak than conventional systems.

    I believe it would be particularly good to use from the right-rear tank outlet to the fuel valve. Easy to route and no intermediate connections.

  7. #7

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    I just spoke, by phone, with Seal Pneumatics' owner and discussed the suitability of Nylo-Seal tubing and fittings with respect to aviation fuels and fuel system installations into aircraft. He said the tubing and fittings are well suited to our [experimental] applications. Further, he said that Seal Pneumatics has had no repercussions/problems with people using their product for this application.

    So, I guess that answers my questions.
    Last edited by Jasperfield; 05-27-2015 at 09:53 AM.

  8. #8
    40m's Avatar
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    My Cub Crafters S2 was factory built with this type of tubing. When temps drop to 10F. and below I often think I own an SR-71. Most of the leaks but no all are at the fuel valve connection. I suspect this is due to expansion/contraction rates of dissimilar materials, either way in a cold climate I would go with a proven material. If others have experience this or have a fix I would appreciate reading about it.

    40M

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    Just this evening, I found some comments on other forums where a few people have had problems with tightening the male NPT fittings into fuel valves. It seems as if the plastic fitting may not have enough taper to tighten into the metal female threads.

    Any fixes or thoughts about this?

  10. #10
    spinner2's Avatar
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    No leakage issues with my CC EX. And it has seen flying temperatures from 100 to -15.

    This tubing is very easy to work with and lightweight.
    "Fast is fine, but accuracy is everything." Wyatt Earp

  11. #11

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    Quote Originally Posted by spinner2 View Post
    No leakage issues with my CC EX. And it has seen flying temperatures from 100 to -15.

    This tubing is very easy to work with and lightweight.
    I'm glad to hear that. Did you do anything special to NPS connections or did you just screw them in?

  12. #12
    Lowrider
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    I just started running 3/8" alum fuel line but haven't bought the AN fittings yet...what's the verdict on nylon for fuel? I'm using nylon for brakes and am pretty well sold on it. Does anyone run the right rear line across the cabin and then along with the left rear line? I put sumps in the tanks on the inside rear with drains to collect water before it gets to fuel line.

    How about a non-hardening thread sealer at the tank selection valve?
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

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    skywagon8a's Avatar
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    Like this?

    Click image for larger version. 

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    I'm not sure about mixing nylon fittings with aluminum tubing. That is the question you're asking isn't it?
    N1PA

  14. #14
    nanook's Avatar
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    It doesn't work very well at all. Fittings have to be super-glued after installing! You ever try painting acetone on a hard to get at fitting to dissolve the super-glue? Just went through this on a CC-EX that leaked fuel when cold. Just because CC uses it, doesn't mean it is a good idea.

  15. #15
    Lowrider
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    Nanook,

    Understand your point. I just went thru this same thing while researching the use of nylon for brake lines. It seem most of the issues with nylon is due to over tightening fittings and at least where that use is concerned, there are no problems with leaks when properly installed. Apparently, Bendix has used nylon for many years without an issue on brakes and that would involve a lot more pressure than fuel lines...but then I'm no expert.

    Sky,

    I was thinking of running the rear right fuel line across the ceiling straight out of the tank to the left side and down along with the left tank rear line. Since my door opening is almost to the floor, running it down the back of the door frame and across under that frame places the line below the fuel valve and an up hill to get there. To over come that issue I put sumps in the tanks to catch water BEFORE it gets to the rear line. Running it across the ceiling will do away with the "too low" problem by still giving it a little down pitch as it goes across the fuselage. Of course, that only helps if the plane is sitting level.
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  16. #16
    nanook's Avatar
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    Well the issue also appears to be that nylon fittings are too slippery to hold a torque! Why else would CC insist on using superglue after torquing...Their (CC) new fittings were beefier than the old ones that I had to replace.

  17. #17
    skywagon8a's Avatar
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    Low,
    Lots of high wing airplanes have the fuel lines running down under the floor and up to the engine. Just be sure that your low point has a place to drain contaminates.

    I had a T-craft which had an aux wing tank. The valve was at the tank in the wing root. The line ran slightly up hill before going down to the main tank. Every time the tank was used and refilled, the small up hill section would trap an air bubble. This bubble would prevent the fuel from flowing. It was necessary to raise the wing and slip the plane to get enough head pressure to start the fuel flowing.
    N1PA

  18. #18
    Lowrider
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    Wish an expert on nylon lines would chime in! Maybe the heavier fittings will solve the problem. As much as I like super glue...it shouldn't be the answer for poor design.

    Sky,

    I was thinking water trapped in the line that would freeze and break the line. I like slips...any excuse will do!
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  19. #19
    irishfield's Avatar
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    CC is crazy gluing fuel lines that have almost zero pressure in them? That's nuts...

    20 years on 1/4" parker parflex brake lines in my personal ride (still same tubing!), numerous customers with same and I have never had one blow a line. 3/8" on hydraulic lines a few have let go using the plastic Nyflo fittings, but from all I've found that did so they weren't installed and tightened correctly to start with or they took the system way beyond the PSI it was designed for. I'm talking over 400 psi. Can't see why 3/8" at the most 5psi if running a fuel pump would need to be glued.

  20. #20
    Lowrider
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    Agree Irish!

    Looking at the nylon line sizes, the 3/8" is the OD which makes me thing it would take 1/2" nylon to flow enough fuel for an 0-320 or bigger. True?
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  21. #21

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    Anyone one have recent experience and information with Cub Crafters fuel lines? The FX3 build video below shows a pretty good view of the system at 1:30.

    https://youtu.be/eOFuy-0uxFY

  22. #22

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    Does anyone have part numbers for fittings to build a nylo-seal fuel system? Maybe from the CC kit? Has anyone confirmed the nylon fuel system is lighter than the aluminum?

  23. #23

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    I have found Leak loc for threaded connections - best there is and greatly improved thread lock characteristics.

    Be sure to verify that the two threaded components are in fact NPT, I'm starting to see British pipe thread BPT which is slightly different and it can cause problems when assembling fittings, some smaller some larger

    Highside Chemicals · Leak Lock
    leak lock from www.highsidechem.com
    Leak Lock is a state-of-the-art high-strength pipe joint sealant consisting of chemically resistant film formers, plasticers, reinforcing fillers and solvents. A resin based brushable paste which remains permanently flexible, adheres to internal surfaces and fills voids

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