"Fuselage to tank" fuel line lengths? - Page 2

apkp777 · #11 01-20-2010, 07:38 AM

Ask yourself, would I want to take off with my loved one over a highly populated area with a know defect in my fuel line?

That being said, if you use a magnifying glass on anything you probably will lose sleep. The tubing is soft aluminum and does get lots of knicks and dings and hold up just fine. Yours seem just a little deep and near the bend which makes it more critical. Plus at this stage of the game, it's just easy to replace it for the sake of piece of mind. You have a nice template to use to bend a new piece. It'll only take 5 minutes to fab a new one (then another 5 when you realize you forgot to put the B nut on, (if you are me). Then 3 hours trying to get the nuts started.

Bob Axsom · #12 01-20-2010, 09:31 AM

If compliance with the drawings are causing you to incorporate defects into your airplane, think about a different way of installing the fuel lines. The installation in my RV-6A is totally different than the "suggested" installation by Van's and there are no kinks or system function or performance problems in nearly 6 years of cruise and racing flight operations. A very significant part of building these airplanes is thinking through the problems of manufacturing and future operations. Obviously you are aware that the condition of your fuel lines is not right or you wouldn't make the post. You are listening to what your mind is telling you - solve the problem before pressing on.

Added note: Sometimes the problem is the design, sometimes it is the tools and sometimes it is the process. You need a good tube bender to get nice precise termination alignment and smooth bends between. As far as the process is concerned, you need to know how the bends need to be made before picking up your flight hardware and starting to bend it. I used coat hanger wire to mock up the tubing runs then used the model to determine the bends necessary on the tubing. Just like wiring, the product is very pleasing to the eye if done correctly.

Bob Axsom

Bob Ellis · #13 01-22-2010, 06:39 AM

I have worked in aviation with the addage "where there is doubt, there is no doubt". Clearly you have doubts as you have posted here. Take the advice posted here, remove the doubt and then build on with peace of mind.

Regards Bob
www.rv-8.co.uk

Bob_pipedream · #14 02-24-2010, 06:17 AM

Hi all,

I have thought about using the elbow bulkhead fitting for the vent outlets instead of the modified straight bulkhead fitting supplied. Should look a bit tidier and be a bit less unaerodynamic.

129TG · #15 02-24-2010, 07:02 AM

I gave Brett from Bonaco (909) 985-3429, a call and had my lines built from braided SS hose. No muss and no fuss; they made the gear leg transition with no problems. He had the lengths already for my 7A. I did the same thing with the brake lines.

sglynn · #16 04-19-2010, 10:31 PM

Please, Do you have a photo of the braided fuel lines installation? thanks

bruceh · #17 01-07-2011, 08:23 PM

So no one has answered the original question. How long does the tubing need to be hanging out of the side of the fuselage to meet the tank?

I took some measurements on my 9A and it looks like 2.5" for the fuel line and a bit longer than that for the vent lines (1/4" line fittings are not as long as the 3/8" fittings).

I'd like to cut these to the proper length in order to be able to fit the wings.

Vlad · #18 01-07-2011, 09:28 PM

Bruce,
Will this thread help?

BSwayze · #19 01-08-2011, 06:53 AM

Quote:

Originally Posted by bruceh

So no one has answered the original question. How long does the tubing need to be hanging out of the side of the fuselage to meet the tank?

I'd like to cut these to the proper length in order to be able to fit the wings.

Bruce, I know it's probably different for a 9A, but here are the measurements for a 7A. Mine are exactly 3-5/8" long. Perhaps this will help someone.

You can always do it the way I did mine if you don't get an answer. Just leave them plenty long and curve them gently downward before you mate the wings, so they're out of the way. Then you can measure and cut to length after the wings are pulled off.

bruceh · #20 01-08-2011, 10:55 AM

I did find several threads with the measurements all indicating about 2.5" for the fuel line and around 2.625" inches for the vent line on the RV-9A. Nothing definitive (a picture with a ruler would be nice). Van's doesn't seem to call out the length either. Looks like there is sufficient wiggle room for the lines to be moved around as needed to mate up with the fitting on the tanks. The vent line has a lot more give on the length.

Getting the fuel lines through the landing gear weldments takes some major persuasion. My fingers and arms are still sore! I don't want to cut them off too short and have to suffer through that again.