Left tank plumbing

Came home today to a nice little gift from Van’s: the prefab fuel pickup I ordered! Time to get some more work done. My goal for the night was to temporarily assemble the left tank with all the bits and pieces in place so I could verify that everything was in place for eventual assembly.

The main thing that needed addressing was the fuel vent line. First up, I needed to drill the inboard rib for the vent line bulkhead fitting. The plans aren’t picky about the location of this, so I located it as best I could off the plans and first drilled a small pilot hole. Then I clamped both inboard tank ribs together and drilled a larger pilot hole through both; this will give me consistent location of the fitting between wings. Not super important, but it assists with my neurosis of symmetry. Finally, I opened the holes to full size with a Unibit.

Here’s the left inboard rib with the vent fitting hole (top center) and the new fuel pickup in place as well:

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Next up was the vent line itself. One issue here was that I’d be needing to flare the inboard end of the tubing…did I mention I’ve never flare a line like this before? Fortunately there’s lots of extra tubing, especially since I’m going to use soft lines for the pitot tube instead of the aluminum stuff, so I cut myself a test length, did some reading up on technique, and went to town. It took a few tries before I got the hang of the tool and started making good in-spec flares.

Time for the real fun. I rolled out a length of tubing slightly longer than the width of the tank itself, giving myself some extra length in case I messed up the flare and had to do it over again. This turned out to be unnecessary, as I got the flare right on the first try (it’s a little more tense when you’re flaring a 4.5’ long piece instead of some random scrap). Next I clecoed the interior ribs to the top tank skin, inserted the snap bushings, and routed the vent line through the bushings. Then the inboard rib was clecoed in place, with the vent line bulkhead fitting preinstalled. From there, it was a simple matter to make the two gentle bends needed to get the vent line to mate with the fitting.

I was feeling quite proud of myself until I realized that I’d forgotten one thing: the BNC connector for the capacitive fuel sender. That required me to remove the inboard rib again so I could drill the required 3/8” hole with the Unibit. With the rib back in, I’m confident that this tank has all the little parts in place. All that’s left to do is final drill the screw holes in the trailing edges of the skin and get the skin and ribs deburred and dimpled, and this thing will be about ready to seal.

Here’s the inboard rib with all the fittings in place:

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Inside that same rib, showing the fuel pickup as well as the vent line routing to the bulkhead fitting:

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And the outboard end of the tank:

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Observant readers will note that the little clip I made last time is actually in the wrong place. Well…that’s what temporary assemblies are for, to figure out stuff like this. Imagine if I’d riveted that cap on before discovering this… Also, there’s obviously lots of extra material on the vent line. I thought about cutting it to length, but I want to put a little upward bend in the outboard end of the tube here to place it as high as possible. Doing so would make it difficult to get the line out, so for now I’m just leaving the extra material there. I’ll mark the cut point so I can trim it the next time this tank comes apart, and then I’ll do the final bend once everything is together for good.

On another note, I got in my replacement rib this earlier this week. I suppose I’ll get that prepped and primed this weekend, and maybe we can get the rest of the right wing skeleton riveted together in the near future. It’ll be nice to have that out of the way and more-or-less permanently affixed to the stands.

These wings are coming together fast enough now that I’ve found myself starting to consider when I should order the fuselage kit. Lead times are sitting at eight weeks, but the concern I have is storage space here. I’ll need to have the wings off the assembly stands before I have the floor space necessary to get the crate for the fuse kit in the garage. So it’ll be an interesting balancing act of ordering late enough to have somewhere to put the stuff, but early enough that I don’t end up with a bunch of downtime. Decisions, decisions…

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