Fuel Line Fabrication Pattern

[Bcone1381]

I am having success making fuel lines, and thought I would pass along how I am fabricate a pattern. I first fabricate the tubing bends in soft aluminum tubing, then attach wood dowels to connect all of my bends. I pay close attention to getting the approach of the flare exactly in line with the targeted AN hardware fitting.

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[Chris In Milwaukee]

Then after this you'll bend the real thing? Or are you planning to run fittings and build the line in segments?

[Bcone1381]

Edit, While I was writing this, Chris wrote post #2

I first place a long blue reference line lengthwise along the tube, and a second short black line across the tube where the tube bender will be placed onto the tube. The lengthwise line can also be called a "Bend Away" line....as the bend will alway go away from the line.
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The reference lines position the tube in the bender in the correct rotational axis and the proper place along the tube. The cross reference line is abundantly handy when its time to duplicate the pattern. The exact location of the black and blue reference lines for each bend on the pattern is duplicated on to the real fuel line. Its exact, no guesswork.
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After the angle is bent, I write the angle of the bend onto the tube, and put Scotch tape over it to protect my index marks.
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[spinningwrench]

That looks like a nice bender what did you buy?

[Bcone1381]

Answer to Chris' Post #2...

After the pattern was completed, I made the actual fuel line at the kitchen table using the pattern. I used 5052-0 rigid fuel line for the real thing. Soft 3003 aluminum tubing was used for the patterns, because it's less than 1/2 the cost, I had it on hand, and my supply of 5052-0 was limited.

So far, I have completed two fuel lines. The first one I fabricated is long a single segment line that goes from the right rear tank area down the back of the door post, and forward, underneath the door to the Tee just ahead of the entry door. After the winds are installed, the fuselage fuel lines will tie in with the right tank thru a short rubber hose that Bob calls for in The Patrol Book.

The second line I made went from the TEE to the fuel selector.



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[whee]

Nice work Brooks! Looks great.

[interstate al]

Good idea Brooks, I like it!
In the LSA booklet Bob calls out for 3003. Any reason not to use it vs the 5051-O temper? Just curious?

[Mark Goldberg]

I imagine that would be OK Al. Usually in aviation you use 3003 or 5052.

[Bcone1381]

Al,

Before I started bending fuel lines, I vacillated between 3003 and 5052. I found that 5052-0 tubing is used in the marine environment because of its corrosion resistant, fatigue strength. My impression is that its bit tougher but lacks the workability of 3003. 3003 is no slouch either regarding corrosion resistance. But I doubted 5052 was the right choice for me.....because

1) 3003 is a suitable material for fuel lines called out in AC43-13.
2) I had never made fuel lines before.
2) I believed I would make several errors and have lots of waste. (BTW, Errors are part of the educational process, but too much education for me creates frustration and anxiety.)
3) Using the softer 3003 could provide ability to fine tune my fuel lines in place and hit the targeted AN fitting with a higher accuracy and success rate.
4) 3003 is shipped in a coil, and less than 1/2 the price of the rigid 5052 tubing.
5) I had it on hand from a hardware order I made back in March.
5).....so my impression was that 3003 aluminum tubing was suitable, easier to form, cheaper, comes in a coil so it easier and less expensive to ship.

But my mind debated about the 3003 because
1) Bob calls out 5052 aluminum tubing for the Patrol! (Imaging that!!!)
2) Tony Bengellis called for it in a 1993 article he wrote on fuel systems, but he was silent on 3003.
3) I think the straight rigid 5052-0 lines will be more visually appealing to my nervous passengers if I leave the fuel lines exposed.
5) I believe Cessna used it.
4) But, the one thing that finally swayed me towards 5052......In the midst of my doubt of which to use, I found a nearby supplier and could get it with no shipping cost at the same price as Aircraft Spruce was selling it.

I have time on the road to research, and when I found the idea of making patterns for each fuel line with wood dowels, I think my motivation and confidence of success went up. It turns out making those patterns and using the index marks to duplicate a line works great! Plus, small adjustments with the 5052 are very doable. Rotational adjustments are pretty easy as are smallish angular adjustments.

I am truly a rookie and need tricks to have success. I approach fuel lines as a series of single elementary bends. Every turn in a fuel line has a measurable distance, angle and rotational variable that needs to be accommodated. My most complex line is 5 feet long, has 9 bends, was fabricated once, its fit required two slight hand adjustments that took a minute to do for bullseye fit. I am finding that securing the fuel lines with the MS21919 WDG Adle clamps every 16 inches (IAW AC43.13) is resulting in a very solid installation.

[interstate al]

I stand corrected, Bob's LSA manual does specify 5052 and nor 3003. I think I picked that up in another builders manual? Either way, like Mark mentions, both materials are acceptable. As I have both I'll be using 5052.

[James]

Lots of guys talking about making the aft fuel lines in a single piece so they don't have to worry about removing trim to inspect fittings.
Well, are there any bearhawks out there flying without any interior trim?

I'm not planning on having any lining, because I like being able to see everything that's gone in to my aircraft.
Plus it makes all the annual inspections much easier :-)

Any thoughts?

[kestrel]

Lots of guys talking about making the aft fuel lines in a single piece so they don't have to worry about removing trim to inspect fittings.
Well, are there any bearhawks out there flying without any interior trim?

The Five prototype is little to no interior.

Any thoughts?

I think it is a fantastic way to reduce complexity and weight. Just take care for safety. Things can get caught or lost where they shouldn't.

[whee]

My BH has no interior trim. The passenger side rear fuel line has some exposure but it hasn’t been an issue.

Depending on what level of fit and finish your looking for should determine if you use trim or not. Even if you use one piece lines those trim prices should come off during inspections.