Fuel tank adjustment

In the last episode about the fuel tanks, we attached them in a hurry before moving, and some of the skin edges were still overlapping with the adjacent parts. I finally got around to removing the tanks, filing them down and reattaching. I also took the opportunity to torque their bolts properly.

Torque seal on the fuel tank bolts

This (finally, really) concludes the work on the tanks.

And of course, I couldn't have done it without my wife's help and support:

zzzzZZZZZzzzz

Time lapse:

Total fuel tanks rivets: 30
Total fuel tanks time: 21.9h

Fuel tanks tested and attached

Before moving, we wanted to put the wing parts together, such as attaching the tanks back in place - for that, we had to leak-test them.

We used a product called Snoop (thanks once again VAF!).

Applying snoop to the rivet lines

Applying Snoop to the sealed baffle

We weren't finding any leaks and I kept wondering if we were doing it right, but then Snoop proved that it really works - there was a tiny bit of air leaking from the return line cap (which was temporary and thus not sealed), and it produced a lot of bubbles:

Bubbles from the fuel return cap (underneath it)

We're looking forward to those camping trips, sleeping under the airplane :)

We then attached the tanks and moved both wings onto the same wing stand:

Attaching the left fuel tank

Attaching the right fuel tank

Tanks attached

We then realized that there was some skin overlap between the tank and the other skins which was making them buckle:

Buckled skin which needs to be trimmed down to match the inboard skin

Buckled skin which needs to be trimmed down to match the leading edge skin

This was just a couple of days before moving, though, and we didn't have the time to fix it then. The only remaining step is to fix that, but it involves removing the tanks, filing down the skin edges, and then attaching them again.

Time lapse:

Total fuel tank time: 14.2h
Total fuel tank rivets: 30 

Fuel tank assembly complete

The tank comes mostly assembled, with a few finishing items not yet done.

The first task was to remove the tanks, which was easy but time-consuming (lots of screws and bolts):

Tank removed from the right wing

riveting the bearing:

Bearing riveted to right tank

I installed the skin nutplates, including those that are only called for much later in section 44 (didn't find a reason not to):

Nutplates riveted to right tank

I bent and cut the fuel sender arms, only to find that I, like others, had screwed up and cut it too short without realizing the arm is supposed to go through the sender. Ordered new arms, re-did it - correctly this time:

Fuel sender arms after bending

Fuel senders, VA-261 pickups, drain and other hardware for the tank

I read up a little more on the fuel system and realized that, if I decide to use a FADEC, I may need a fuel return line. Much easier to do it before installing the tank, so I did some careful planning - some people from VAF pointed out that it can't be too far aft or it'll get in the way of the wing attachment. I got two more VA-141 brackets for this, and used a 3/8" NPT tap to make sure I could screw VA-261s in from the other side. I then used those to drill the holes on the side of the tank, next to the vent line:

Holes drilled for fuel return line bracket on left tank

We did the drilling with a vacuum cleaner extension (piece of conduit taped to the tip of the vacuum) strategically placed to catch aluminum bits, which greatly minimized the mess inside the tank, but we still had to later move that extension around to clean up all the bits that flew around the tank.

When I drilled the left one, I realized I, too, had made a small mistake - notice the J-channel from the tank's structure shows through the hole - the hole was too close to it, so I had to shave off the corner of the J-channel to ensure the VA-261 would still fit.

On the second tank, I drilled the hole a bit further to the side, and instead trimmed the bracket itself to fit, this time hitting no obstacles inside:

Holes for fuel return line bracket

Trimmed VA-141 bracket for fuel return line

Finally, I installed the senders, return bracket, pickup, and drain, using tank sealant and thread-locking sealant. For the fuel return brackets, I used CR3212-4-2 rivets:

Fuel return bracket, fuel level sender and fuel pickup installed on left tank

Fuel return bracket, fuel level sender, fuel pickup and drain installed on left tank

Right fuel tank with all plugs and brackets installed

We then installed the Newton fuel caps - even in the garage, the Van's caps were annoying enough to open and close to make me want to replace them:

Cleaning the excess sealant from the fuel cap bracket the best we could

Newton fuel cap installed (needs some cleanup afterwards)

Last but not least, someone at VAF called my attention to the fact that I hadn't left a ring terminal around one of the fuel sender screws, so after the sealant cured I checked the ground continuity between the fuel sender plate and the skin, and it seems to be conducting just fine.

Among the next steps are leak-checking the tanks and reattaching them to the wing spars.

Time lapse:

Total fuel tank time: 12.1h
Total fuel tank rivets: 30