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Bob Hoffman

Well Known Member
Hi evewryone,
Ok here goes,I'm rebuilding an RV6A -- have it pretty much appart when I notice the fuel selector (Vans standard type) is leaking and loose -- no problem, I order the Andair knowing that the fuel lines will need to be redone.
Well as I start pulling the old lines out I see many kinks and cracks in the MANY bends .NOW I have to remake all the lines and even though the interior and floors are out there is still a lot of things in the way.
So my question -- do the fuel lines need to be alum tubing or can braided flex hose be used instead ?? Has any one done this before ? If so any suggestions on type / size and source ??
 
I used 3/8" aluminum tube and the braided hose

I think whether building new or replacing you have the same problem. I used coat hanger wire to model the needed tube shapes, then drew the required dimensional drawings for the fuel lines, bent the tubing to conform using a nice constant radius bending tool and every one of them looks very good and fit properly. It is worth the effort. I have a VERY densely packed console in my RV-6A that is designed to come apart for maintenance and the fuel lines in there have to be movable for access - they are the braided hoses. There are no reliability issues.

Bob Axsom
 
You can but

Tubing is much smaller in outside diameter and it has structural properties that make it hold its shape and stay out of the way with minimal clamping. I found this great for routing around the cockpit where you want to hide the plumbing as much as possible. I have right angle "AN" fittings in the side of the fuselage and in the confined area of the space brtween the fuselage and the wing root I use a "U" shaped routing involving right angle connectors and braided hose to facilitate service and any relative motion. I also use the hoses in the console as I said before and in the interface between the fixed fuselage and the dynamic engine position. As far as getting the gas from the tanks to the engine, hoses will do the job but I think there are places in the routing where each is better for the job and that makes using both a better fuel supply system. For good tubing installations you must have a good precision bending tool and a good flare tool.

Bob Axsom
 
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Less joints is good...

gp456 said:
Why not use braided lines the entire length, from selector to tank?
Click to expand...

And the less joints and/or unions in the path the better.... each switch from tube to flex is another potential leaking spot.
You don't even need a union at the fuselage side with a flex hose, just go through with a grommet....

gil in Tucson
 
What type of aluminum for fuel lines

While we're on the subject, what's the best grade of aluminum to use for fuel lines?
 
Thank you everyone for your responses,sure is some good "food for thought".One bit of info I just found out - I was told that hoses (any type) have a 10 year life,beyond that they should be replaced,alum tub has no limit.Something to take into account.

Bob Axsom - good points - I especially like the coat hanger trick,I'm going to try that. Another question -- You state that you have a right angle fittings in the side of the fuselage , do you have tube from the outside of the fuse to the fuel tank ? If you are using tube are you concerned about wing flexing and what that flexing might do to that short tube ?? The guy who built my plane drilled a "big"hole in the fuselage and has the tube going through to the tank -- this is one of the areas that I found chafing . No matter which way I go I like your idea of using a fitting.

Az Gila -- Also a very good point

RV10Pilot - Thank's for the info. BTW Where did you buy the BASF RM UNO-HD paint?
Thank's All
 
I have a mix

I am concerned about the flexing but really it is fairly small movement. For the main tank I have braided hose but for the tip tank and the main tank vent lines I am using aluminum tubing with an good strain relief loop so any flexing is distributed over this large area. In the engine area I have complete loops in the 1/8" primer lines to minimise stress and I use a hose between the firewall bulkhead fitting and the mechanical fuel pump (no gascolator in my plane - a filter for each tank).

Bob Axsom
 
Bob Hoffman said:
RV10Pilot - Thank's for the info. BTW Where did you buy the BASF RM UNO-HD paint?
Click to expand...

I got the BASF RM paint at a local auto paint supply house here in southern New Jersey.

Larry
 
Update

Got home last night and my GOOD neighbor Norm called.Norm is a neighbor who lives here in the Airpark and has built a beautiful RV-6A that anyone would be proud to have.
Norm: Hey Bob what is this thread going on Doug,s web site about you not wanting to do the interior fuel lines in alum. tubing??

Me: yeah Norm,when I pulled out the old lines it was a mess,and trying to get them through the hole in the landing gear all buy destroyed the lines. -- I was just lookingfor a better way.

Norm: Well I already see your problem.
First -- You didn't call me (sorry Norm)
Second -- You DON'T want to route your fuel lines through the landing gear mount -Think for a minute and think the worst -- Crash landing pulls out the landing gear , what happens to the fuel lines??they get cut by the mount. NOPE - you need to route the lines around the LG mount NOT through. It's easy, when you'r ready give me a call and I'll come over and help you.

Thank's Norn
Thank's Vans Airforce
Life is GOOD
 
Fuel Line Around Gear Leg

I'd like to see a pic of the setup when you get it done.

Thanks,
Sam
 
Weight Difference?

What is the weight difference per linear foot between alum and braided line? Just curious. Every ounce counts!
Marty
 
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