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Fuel lines

PeteP

Well Known Member
Well after a long weekend of try to make the tank to fuel selector lines all I have amassed is an extensive collection of junk 5052 tubing to add to my wall of shame! Is there a good / simple way to do this if so I am suffering from a bad case of can not figure this $@&% out. Any recommendations or even emotional support will be appreciated.
Pete
 
Hang in there

Pete, I may be guilty of flinging several sections of tubing across the shop out of frustration myself. It's amazing how few mistakes it can take to burn through 8' of tubing. Usually this is due to finally getting it perfect only to realize I left the B-Nut off when I flared the end. After two failed attempts, I go to something else for the rest of the day. You'll think more clearly when you get back to it, and I've actually found ways to improve my original plan and sometimes make some of those pieces serviceable after all.

Make the shorter runs first so you don't waste more tubing than necessary, and make them one bend at a time. Sometimes I even make partial bends, and then test fit. Use a sharpie to mark the tubing where the bend needs to be, and the direction. And take your time with the flares. Treat that part as art. A bad flare can ruin a fairly short run if there's no length to adjust.

Bart
 
And on your next VANS order, get more tubing. It's cheap and it feels really good to take a ruined piece and twist it up like a pretzel. :D
 
Get more tubing!

And on your next VANS order, get more tubing. It's cheap and it feels really good to take a ruined piece and twist it up like a pretzel. :D


What Greg said. You will get it sooner or later :D. It's educational part of recreation.
 
I had similar troubles installing the same line in my -9A...the landing gear weldment made it difficult and Vans plans and instructions were no help.

Are you using Vans supplied tubing? That is 3003 and is the easiest to work with. I used 5052 elsewhere.

There seem to be two most commonly used methods to deal with the fuel selector-to-wings lines:

  • With the gear weldment in place, start pushing the line from the fuel selector to the wing, bending and unbending as you go. Use bending springs or just carefully bend with your hands.
  • Use Bonaco or other flexible fuel lines. These have a large outside diameter and won't fit through the existing holes in the two cover support ribs. You have to enlarge them or simply cut out the section.

I did the first method, a friend used the latter. Either seems acceptable.

Edit: BTW, for other bends, use a good bender, not the cheapo Harbor Freight thing I used :(
 
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I bought a lot more tubing from AS than I thought I'd need. Most of it is in the scrap bin. The gentle radius bends were pretty easy but those connecting to the AFP fuel pump required some tighter bends. I found the bending springs only got me so far. I tried a tubing bender from Home Depot and ruined more tubing. Finally, a friend showed me how to use the tubing bender. It's a slow iterative process. You bend just a few degrees, move the tubing, bend a little more, then back and forth and 'sneak up' on the bend.

Without question it is a skill. My buddy can do bends I still can't and he's using my tubing and my tools. It doesn't seem fair but he's bent copper tubing since he was a teenager. The transition to aluminum even took him some time to get but without a question, it's a skill that can be learned. Go slow and sneak up on the bend.
 
I Feel Your Pain...

...Keep on going, I have a pile of shame too. I ended up putting an additional connector in the line just aft of the fuel selector so I didn't have to do so many bends. Showed it to Van's, they liked the idea and published it in the RVaitor a few years back. Glenn
 
Making these fuel lines was the most painful part of the build. My hands were sore for weeks after bending these lines. I used the Van's supplied 3003 material, which is softer than 5052. Doing these lines was tough. The first one took me several hours, the second one about 30 minutes.

I used the tubing bender to get the tight bends done under the fuel valve. I have the Andair valve so these bends are pretty straightforward. Straight down, then 90 degrees to horizontal, and then a bend to the rear to align with the spar carrythrough.
1155055784_YBpfF-M.jpg

Once that end is fairly close, make a long section with the remaining length that has a long gentle curve to it. This will make it possible to thread the tubing through the support brackets. Straighten as you go to get it to go through the support bracket holes and grommets.

When you get to the gear weldment, the fun begins. Get out a spring tubing bender and start massaging the line through and around the hole in the weldment. There is a rubber grommet that should go on the tubing to center it in the weldment hole. Once you can get the end out the fuselage, you can tweak the line to make a gentle curve.
1155055704_NyTNG-M.jpg

1206906948_ue96P-M.jpg

The tubing that comes out of the fuselage can get pretty beat up by the time it has been snaked around the weldment, so take it easy and try not to over do it.
 
You can always go with flexible fuel hose if you want to trade aggravation for $. It was worth it for me.

erich
 
I will often mock up the run using welding rod first just so I have a roadmap of sorts to follow. For higher value runs, I will mock up using the 3003 junk tube. Don't worry about flares or anything - just get the bends right. Once you are happy, then move to the 5052 (or stainless) tube and duplicate it. That 3003 trash can be purchased in rolls from the hardware store for next to nothing, so buy plenty and go for it!.
 
Well worth the $ (for me, anyway) to buy nice flexible braided steel, teflon-lined, tygon-coated lines. Being flexible and stainless, there is less chance that they will wear through and cause a leak.

Greg
 
Keep it on point...

Properly installed aluminum hardlines will last as long as the airframe (the same can't be said for flex), so the only practical advantage of flex is "easier". For some, that may be worth the considerable price and weight increase.
 
Agree with Michael. Use 3003 or hdwr tubing for practice, then order twice what you need in 5052. Also ensure bender is very smooth and lightly lubricate any parts of bender that make contact with aluminum tubing.

Recycle that scrap. Miller needs it.
 
Use 3003 or hdwr tubing for practice, then order twice what you need in 5052.

I agree, but the lines from the fuel selector to the wings on the A models are a complete !@&#^%. Perhaps a pro could get them done with 5052, but for us amateurs it's either 3003 or flexible.
 
Flex fuel lines

i have to do my fuel lines shorty. where are you getting the flex fuel lines from.
thanks
russel koch
RV9A Working on wiring and conopy.
 
Here's a Tip

Bruce Swayze did a great job of documenting a relatively easy way to do this on his site here: http://www.europa.com/~swayze/RV-7A/Fuselage/20100528.html for his 7A. I imagine this would also work as well for a 9A. I just completed the lines for my 7A last weekend using the same process and it worked great. One key is to put each tube through the middle hole in the weldment, not the bottom hole as I first assumed. My tanks have flop tubes which make the job even tougher. You can see photos of my installation here.

John Harrell
RV-7A Tip-up
Empennage done, wings done, fuselage 90% done
Finishing kit scheduled to ship Feb 6
http://www.johnsrv7a.wordpress.com
 
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Have you researched Bonaco fuel lines? And they make brake-lines too! :)

GREAT customer care and great product! Saves you ALOT of trouble...
Talk to Brett.

You'll find their add on the front page on this forum.
Here's a link: http://www.bonacoinc.com/
 
I attempted 3 times to make that line on my 9A, each resulting in an addition to my pile of shame, before calling Brett at Bonaco. Now life is good...:cool:
 
Consider using additional fittings to break the line into shorter segments with fewer bends. That's what I do on tailwheelers, should help on a nosedragger.
The fitting for left and one for right is -6 universal bulkhead, straight or 45 as suitable, though the side of the fuel valve pedestal receiving the short kinky lines from valve to fitting, then the long straight section with merely a S-turn from fitting out the fuse.

John Siebold
 
good idea John-

but more connections gives more chances for a leak point. Alot of guys are using flex lines.
Tom
 
I attempted 3 times to make that line on my 9A, each resulting in an addition to my pile of shame, before calling Brett at Bonaco. Now life is good...:cool:

I would recommend calling Tom at TSFlightlines.

Both TsFlightlines and Bonaco make great products. My brake lines are Bonaco and my fuel lines and some brake lines are TSFlightlines.

Brent @ Bonaco was difficult to reach, didn't return email, had to call to get information.

I've sent an email to Tom at 9pm and he responded quickly. Several times he phoned me to get clarification. I also had some issues, which were self induced. Apparently I have problems with reading a ruler. He took care of me beyond what I would have expected any vendor to have done.

The last plug for Tom, since he's active on VAF (Brent doesn't appear to be), is we have to get him to change his signature:

Tom Swearengen, TS Flightlines
Newbee--no RV --YET
Helping others build their dreams
Debating a RV7/7A-Looks like a 7A!!

to

Tom Swearengen, TS Flightlines
RV7A Tail Kit Ordered
Helping others build their dreams

The best way is to buy a few more lines from. BTW, if you are like me and dorked up your flares, he makes perfect hard lines too.

bob
 
Go around it!

I have return lines to the tanks so that is 4 tubes instead of 2!

I did not go through the holes in the weldments but went around the weldments, that certainly made life easier. With the CAD-weldment covers installed, nobody notices that anyway!

Regards, Tonny.
 
Make the first set out of a coat hangar. Then remove and copy with the benders. You'll have to tweak it once in place but it'll be close enough. Probably more difficult on the nosedragger with all that clap trap in the way, but it worked great for me. :)
 
Tubes

Took me a while to figure out. Easy once I did.
Cut a length long enough to extend from the fuel selector
And extend outside 8" or so. Measure, bend 90 deg. and install
The fitting that will later be installled at the selector before you install the line.
Put a slight curve in the entire line and start to feed the line
From mid ship outboard. Work it through the gear weldment.
Bending to then fit through the large hole in the side skin. I just used my
Fingers to make the slight bends. The lines end up as a straighter
Run between the gear w. and the side skin than what is shown on the drawing
But was 100% easier to deal with. And yes I messed up a few lines before this process.
Take your time.
 
rigid tubing--

Guys seem to have some issues bending their rigid lines. There have been alot of posts in the past on this, so I wont bore everyone. I guess because I do this all the time, that is easy. Heck---I had a hard time riviting--so you get my point.
Bending tubing does take practice with the bender or benders you are going to use. I have some thoughts that might help some of you.
1st- get a good bender, and not a $14.95 special at brand X autoparts. The Imperial 370 and 470 benders will do anything that we need to do. 180* bends, with nice concentric radii. Unless you have a hydraulic powered mandrel bender at your disposal (if you do, let me know!), then these bender will serve you well. Avery, GAHCO, Spruce, and others have them. By some extra tubing in the sizes you will be using; for most of us thats 1/4 & 3/8.
2nd)- PRACTICE the type of bends you will be doing. I take a blue Sharpie, and make a line where I want the bend centerline to be, and then practice hitting that line. Once you do it several times, you will see where the scale on the handle lines up with your index mark. Repeat this until you can do it over and over. Then draw another line further down the tube, and make a different angle bend, oriented in a different plane. Do that until you are comfortable doing multiple angle assemblies.
3rd)- can you make a multi-angled tube that has to go over, under, around, or through something? Gee, I dont know. Try this. I use a piece of either 3/16 or 1/4 bundyflex brake tubing (the straight lengths you can get at X autoparts). You can use cooper tubing, but its getting expensive. The object is to make a pattern of the assembly you want before you ever pick up the bender. Take the tubing and make some rough bends by hand to approximate the bends and angles. ALOT easier to do this than to scap a bunch of tubing, because the angles were off. Once this pattern is done, remove it, and see if there are any limitations as to why you cant bend a real tube with your bender. (Let me say here, that I am NOT a muscle guy with hands the size of baseball gloves. So I made a bracket to put my benders in my vise, so I can use both hands to do my bending).
4th)- I may be necessary to flare your tubing before bending. If so, ok. Take your new tubing and using your pattern, make your first centerline. Bend it, using your pattern as a guide. Then, just continue to the next bend and repeat. You can even measure the centerline distances between bends if you wish, and make those bends. Having your pattern will certainly help.

This seems VERY long a drawn out, but in fact its pretty straight forward. Has worked for me for many years. And unless you have a CNC mandrel bender, with laser coordinate capabilty in your shop, it can work for you to.

I hope this helps--
Tom
 
Managed to do my fuel lines last weekend

Andair valve

Cut 36 inches length of tubing.

Do the bends closest to the valve first. For Andair valve and RV-9A, dimension for bends closest to the valve are 3 inch down, 2.45 inch left or right (depending on side being worked), install nut then ferrule and make the flare. Making the tube ends square and polishing made nice flares.

Install the snap bushings in the tube support brackets. Let the small support bracket be free at this time.

Bend the long portion of the tubing into a big arc so you can begin to feed the tube thru the support closest to the valve. After the tubing is started in the first bracket, add the small bracket to the tube and let it hang free. Add any additional grommets to be used at the weldment to the tube at this time.

Now the hard part, slide on a tube spring bender to the tube for support and begin to bend the tubing by hand a little at a time to work the tube thru the holes. The most difficult part is where the tubing exits the fuselage. Keep working it. To get the proper fit at the fuselage, pull the tube thru the fuselage a little more than the final fit and then push it back in. Then straighten the remaining tubing outside the fuselage. Secure the grommets.

Note: the best bend points for the tube by hand I found were: 1) just outside of the larger support bracket (closest to the valve), pull forwards, 2) straight down between the weldment and fuselage, pull forwards, 3) straight down outside the fuselage, push backwards.

Note: the short bends (near the valve) are easier on the left hand side (pilot’s side) than the right hand side because of the cheap (black color) tubing bender I was using. For the right hand side tube, it required that I bend the short 2.45 inch bend first then the 3 inch bend. Expect a slight mark on your tube when you do the right hand side but can that be buffed out nicely with scotchbrite. I minimized the mark by bending the final portion of that bend with palm force. Add some Boelube or other to the sliding side of the tube bender to smooth the bend process.

Do a mockup with 1/4 inch 3003 first to get the sizing of the tight bends. I did my final with 5052 and noted the 5052 made better looking bends than equivalent sized 3003. Also, keep wire handy when you are making bends to be able to bend the wire to mockup the direction you are bending to help visualize. In trying to make the right hand side I made 2 left hand side tubes before I used the wire for a mockup at the tube bender.

Put the tube bender in a vise. Use a digital level indicator to align the tube bender to vertical and then horizontal on the tube to get a true 90 degree bend.

Left hand side was 30 minutes. Right hand side was 2 hours. On one of these I made the flare without putting a ferrule and nut on, that's makes it Doo-Doo, don't do that. I had never used a tubing bender before and when I was finished I felt the accomplishment of learning something. I am glad that job is done.

BTW I plan on installing a Flow Ezy Series 3000 74 micron fuel strainer between the valve and the pump just after the valve and resting on the floor on some insulation.
 
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Guys seem to have some issues bending their rigid lines. There have been alot of posts in the past on this, so I wont bore everyone. I guess because I do this all the time, that is easy.

You know, even though I am a long time away from needing my fuel and brake lines, I'm kind of wanting to order them from Tom now just to reward him for his excellent service and regular postings on this site. Here he is giving a long list of helpful suggestions, all of which are only useful to builders not paying for his hoses. It's a little like he's in competition with himself! That's classy, and I hope he's getting enough business to start his own RV really soon. He deserves it!

--
Stephen
 
Gee Steve-

Thanks, but that wasnt what I had in mind! Alot of you have helped me get things rolling, and If I can make life easy for someone, then its worth it to me. Just like SEVERAL people on this forum, that have allowed me to go to their hangars, or see their RV's, and visualize what some of you guys are talking about.
Just returning the favor. One day--soon--I'll be the one asking questions on how to build an RV!!
Tom
 
Modern Art

Perhaps recycling all of those bent and destroyed pieces of aluminum tubing into some really nice glass covered frames for wall hangings would be appropriate. What a conversation piece. "Tubes under Glass". Something to remind you of all the fun in building an RV. :D
 
The major disadvantage of flexible line is weight. They are actually quite heavy, and although it may only be a pound or two....

PS- my lines are flex. I will be changing them out when they are due for replacement to hard lines. I am much better at bending tubing now than I was then.
 
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