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Desert Rat 08-29-2021 03:11 PM

Hardware stackup for fuel line vent?
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Hey all-

Looking at build logs, I see that most people put a big spacer/washer on each side of the skin where the 90* elbow goes through to connect to the -4 vent line in the fuselage.

That would seem to make sense, but looking at section D-D on print 36, standard blueprint naming conventions implies that they should both go on the inside, which would have the effect of making that first bend not as sharp, but also not providing quite as much support for the skin in that area.

Of course, the print isn't clear enough to make out which way is correct, and I don't really want to wait until tomorrow to ask Vans.

I suspect it will work either way, but has anybody asked vans what the "correct" stack up was intended to be?

Here's a pic of what I'm talking about.

gasman 08-29-2021 11:54 PM

Place a washer on each side of the skin.

Desert Rat 08-30-2021 06:01 AM

Is that the word from the mother ship or your opinion?

I agree that makes sense, and I'll likely go that way, but the naming convention on the print implies they both go on the inside and I see several pictures in build logs where people have done it that way.

People complain about how hard it is to correctly bend the vent tube in that area and it would definitely be easier if both those washers were on the inside, which would stand off the fitting another 1/8"

I guess I'm more curious than anything.

gasman 08-30-2021 12:33 PM

Actually, it was my opinion.... I would ask Van's. There is no value to having both on one side, EXCEPT for making the stand off like you say.

543TB 08-31-2021 07:56 AM

I had to go back and look through all my build photos to see what we did. Ended up with washers only on the inside. As I recall, I tried doing it both ways, and did not get a satisfactory fit with one on each side of the skin. It was just too difficult to bend the vent line around without both washers on the inside acting as spacers.

Running the vent lines was one of those "deceptively simple" LOOKING tasks that ended up almost ruining my day... the first one went so easy and perfect, and then replicating the mirror image, well... yeah. I highly recommend starting at that fitting, so you can get the bend connection correct first, there's much more flexibility with what happens at the firewall end.

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