Tip: Installing fuselage fuel lines

Having struggled with installing the fuel lines in the fuselage, and researching various methods on different websites, below is documentation of how I ended up installing the lines. After learning the technique on the first line, the second one took about 30 minutes to complete. This might be old news for all those that have a ready done this, bu I could not find any reference on other sites.

One advantage of this method was the ability to install the lines without removing landing gear weldement.

The first step is to bend the inboard end with a tubing bender to match the fuel selector valve being used, install the fittings, flair the end, then cut it to length and coil in into a half circle.





Slide the outboard end of the tube into the first bulkhead fitting and then thread on the second bulkhead fitting.



Continue feeding the fuel line through and straighten by hand as it feeds through the bulkhead. When the end is near the landing gear weldement, thread a coiled spring tubing bender through the weldement holes and onto the tubing.



Continue pushing, and straightening the tubing until the end of the tube is near the fuselage side skin, passing through the gear weldement. Using the coiled spring tubing bender to protect the fuel line, leverage tube/bender against the weldement and make the bend to the hole in the side sking. Continue feeding line and straighten and bend as it is fed. Alternate between pushing a little more tube through, bend it a little, then feed more.



When the end is at the hole in the fuselage side skin, bend the end and slip it through the hole in the side skin. Continue feeding increments of the tube, and un-bending the tube using the holes in the weldement and the side skin for leverage. Make sure the coiled spring tubing bender protects the fuel line at the two holes that are being leveraged against to form the bending.





Continue little by little, pushing, bending, un-bending, straightening, and then pushing again. Eventually the tubing will be in the right place.





Straighten out the tubing that is outside the fuselage. Adjust the shape of the line to provide good clearance. Once you are satisfied with the fit of the tubing, remove the coiled spring tubing bender. The rubber grommets can then be installed in both the weldement and the side skin.





The whole affair is a bit of a wrestling match, pushing, bending, and unbending, snaking the tubing through the holes, but overall it was pretty straight forward and now that task is done. I'll try the same thing on the brake lines.

Hope this is of some use for others. What other methods are being used out there?

Don't forget the grommet

I was working on the vent lines yesterday and forgot to put the grommet on before I put the fittings on and the flare. Had to split one side to put it on couldn't get it over the nut. The next one wasn't forgotten.

Brice

That has to be one of the all time best "helpful" posts I've seen.

Makes me want to start another project just to try out your method.

One little tip you can use here.

Do not install the snap bushings before putting the tube in. Just slide a snap bushing on the tube at the correct location, but let it float on the tube.

When done getting the tube in place, come back and put the snap bushings in place.

This will give you more "wiggle room" as you install the tube, and you wont need to do quite as much bending.

Did not work for me

Mike S said:

...Do not install the snap bushings before putting the tube in. Just slide a snap bushing on the tube at the correct location, but let it float on the tube. ...

Click to expand...

That makes so much sense I tried it on my first attempt. I found that the snap bushing would NOT go in the hole with the tubing inside the bushing. The snap bushing has the flexible plastic things that need to be pushed inward as the go through the hole - with the tubing inside, they can't move inward and the bushing would be in the hole (hope that made sense.)

snap bushings

A local parts house (The Flight Shop) sell what I call "oops" snap bushings. They come premolded with a split on one side if you forget to first install the bushing in the bulkhead (hasn't happened yet, right?). Perhaps these are the ones to which Mike S refers. As noted above, Van's snap bushings will not slip into a hole after the tube is inside. Wires - yes. Tubing - no.
PS - The Flight Shop is the dealer for those Clik Bond wire stand-off/fastener thingys.

Steve

I was dreading bending the fuel line tubing because of all that I had read on the VAF. I also used the spring bender and also had the gear leg mounts bolted in. I had no problems at all. When I was finished I thought maybe I had done something wrong since it went so quickly and easily!

Another little tip: I got some tygon tubing at Lowes and slid about a 10-inch length of that onto the fuel line instead of the tubing bender. A bit more work (tygon can grab that aluminum pretty well - one needs to push rather than pull the tygon), but when you are done, there is a built-in guard against rubbing on the holes in the gear weldment.

greg

VERY helpful ...

This is a great idea ...s-u-r-e do wish I had this info 10 months ago. The fuel line wrestling match was my most unfavorite part of the whole build so far.

There is a easier way but could take a bit longer. Modify the brackets on the spar that hold the lines with slots instead of holes. The fuel line and grommets easily slide in. No bending etc. When lines are in, fabricate a plate which attaches to the brackets which will in close off the slots to round holes again. If that makes sense. All easily removable if ever needed.
Sorry dont have pics.

Make split bushings

You don't have to spend extra for "split" bushings. One of the Vans tech rep guys (maybe Bruce?, sorry I forget) said to use a sharp utility knife (heavy weight X-acto should work, too) and split the bushing yourself between the "keepers" by setting it on a flat piece of wood. There are a couple of cables that go through the firewall that call out for a pair of concentric bushings, (one inside of the other) and the smaller one will not go over the fitting on the end of the cable sheath. The split will allow you to do this. I've found other places where this works great; i.e. ELT antenna cable, etc.

Rivethead,

The Andair fuel selector valve did make things easier without the crossing fuel lines. I read your method and liked that there is less extra bending of the tubing to complete the installation. I ended up bending the outboard sections 90 degrees three times to snake it out the fuselage hole. This work hardens the tubing an unknown amount.

Hawkeye7A said:

You don't have to spend extra for "split" bushings. One of the Vans tech rep guys (maybe Bruce?, sorry I forget) said to use a sharp utility knife (heavy weight X-acto should work, too) and split the bushing yourself between the "keepers" by setting it on a flat piece of wood. There are a couple of cables that go through the firewall that call out for a pair of concentric bushings, (one inside of the other) and the smaller one will not go over the fitting on the end of the cable sheath. The split will allow you to do this. I've found other places where this works great; i.e. ELT antenna cable, etc.

Click to expand...

I use a single edged razor blade, works real nice.

Another method to run the tubing

What worked for me was to use a piece of clear nylon hose (the kind with reinforcing threads in it) with an inside diameter slightly larger than the outside diameter of the aluminum tubing. I put a few drops of tool oil in the nylon tubing and ran it from the hole in the brace next to the fuel selector, through the weldment and out the hole in the fuselage. I then put a slight curve in the aluminum tubing, burnished the end to remove any burrs, and pushed it through the hose from the selector side until it exited out the fuselage. The hose did a nice job of bending the tubing through the weldment. I then slide the hose off the tubing from outside the fuselage.

Super Post

Brice this is a super post. I struggled all afternoon bending 3/8 tubing and attempting to put in this fuel line in my 7A. I finally decided to check the forum and other construction sites. This post is exactly what is needed and I found it. Super.

I'll go try it tomorrow.

I sure didn't want to remove my main gear weldmounts. They are torqued. And I didn't want to slot the brackets on the wing spar.

I've got my wings on temporarily so it looks like I'll have to take them off, but I'm ready to do that anyway. I'm following the sequence in Van's plan and your process looks like it fits right in. I'll reference you on my site after I get it done. www.mykitlog.com/sglynn

thanks

Aeroquip 601/AE701 Hose

BJohnson said:

Having struggled with installing the fuel lines in the fuselage, and researching various methods on different websites, below is documentation of how I ended up installing the lines. After learning the technique on the first line, the second one took about 30 minutes to complete. This might be old news for all those that have a ready done this, bu I could not find any reference on other sites.

One advantage of this method was the ability to install the lines without removing landing gear weldement.

The first step is to bend the inboard end with a tubing bender to match the fuel selector valve being used, install the fittings, flair the end, then cut it to length and coil in into a half circle.

Slide the outboard end of the tube into the first bulkhead fitting and then thread on the second bulkhead fitting.

Continue feeding the fuel line through and straighten by hand as it feeds through the bulkhead. When the end is near the landing gear weldement, thread a coiled spring tubing bender through the weldement holes and onto the tubing.

Continue pushing, and straightening the tubing until the end of the tube is near the fuselage side skin, passing through the gear weldement. Using the coiled spring tubing bender to protect the fuel line, leverage tube/bender against the weldement and make the bend to the hole in the side sking. Continue feeding line and straighten and bend as it is fed. Alternate between pushing a little more tube through, bend it a little, then feed more.

When the end is at the hole in the fuselage side skin, bend the end and slip it through the hole in the side skin. Continue feeding increments of the tube, and un-bending the tube using the holes in the weldement and the side skin for leverage. Make sure the coiled spring tubing bender protects the fuel line at the two holes that are being leveraged against to form the bending.

Continue little by little, pushing, bending, un-bending, straightening, and then pushing again. Eventually the tubing will be in the right place.

Straighten out the tubing that is outside the fuselage. Adjust the shape of the line to provide good clearance. Once you are satisfied with the fit of the tubing, remove the coiled spring tubing bender. The rubber grommets can then be installed in both the weldement and the side skin.

The whole affair is a bit of a wrestling match, pushing, bending, and unbending, snaking the tubing through the holes, but overall it was pretty straight forward and now that task is done. I'll try the same thing on the brake lines.

Hope this is of some use for others. What other methods are being used out there?

Click to expand...

I think for my sense of order that I would rather stub off the soft tubing behind the landing gear weldment with an AN815 male fitting and then run the stainless braid 3/8 aeroquip hose the remainder of the distance. This hose can be all made up and connected to the tank outlet and ready for wing attachment. Of course you would want to safety wire the B-Nuts on both ends. This leaves nothing stubed out at the side of the fuselage to get dammaged during asembly. Hope this gives a new perspective to the problem.
Chuck Garland
EAA T/C 5289

I'm already past this point and ended up doing the bending in an almost identical fashion. Thought I'd bring this thread back to life to help others.

I didn't try removing the grommets first, but that wasn't really a factor.

Great advice, thanks.