The last rib sealing/riveting tasks are installing the end ribs on each tank. Here’s the right tank with the outboard rib riveted; there’s obviously some cleaning-up to do.

The only detail worth mentioning on the outboard ribs is how to fit the T-410 nose reinforcement plate. With the rib clecoed in place, I laid out and drilled pilot holes in the reinforcement plate, then taped it in place against the inside of the rib with two-sided tape. That kept the plate in place while I removed the rib. It was easy, then, to match drill the plate and rib. The plate was sealed and riveted to the rib before the rib itself was riveted to the tank skin. Clear as mud, right?

Not too many more pictures to show; I’ve haven’t accomplished much on the airplane recently and what little I’ve done, I don’t have too many pictures of. But here’s one thing I did – fabricate a fuel pickup for the right tank, connecting to the fixed pickup and anti-rotation bracket I put together on 15 January.

What’s missing here are the slots cut with a saw into the aft end of the pickup tube. I think this is a cheezy approach by Van’s – anything the size of the saw kerf or smaller will go straight to the gascolator or fuel filter. My tech counselor thought the same thing, so he bought some brass screen from McMaster-Carr and fabricated a pickup like those used in production aircraft. I ordered some of the same material – 16×16 brass screen – and I’m going to try my hand at doing the same thing.

I’ve been on the road a lot recently, having started a new job. John and I finished riveting all the ribs in both tanks except for the inboard and outboard end ribs. With the interior ribs in place, I plumbed the vent line into the right tank. Here’s the inboard vent line fitting; the wire coming from the BNC connector attaches to the inboard capacitive sender plate, and it gets routed with and wrapped around the vent line.

And here’s the outboard end affixed to the clip previously riveted to the fuel cap flange.

Unfortunately, I didn’t get any pictures while I wired up the capacitive sender plates. The outboard plate is installed with the vent line, and the connecting wire from it is wrapped around the vent line as heads in toward the inboard sender plate. It connects there with the wire from the BNC connector installed on the inboard rib (see the first picture for this entry).

While waiting for another rib riveting session with John, I worked on fabricating the fuel pickup anti-rotation bracket for the right tank. My airplane will have a flop tube pickup in the left tank for inverted flight, and a standard pickup in the right. The anti-rotation bracket keeps the fixed pickup from rotating around its bulkhead mount, raising the end of the pickup and making more fuel unusable. When I mount the pickup later, the bracket’s function will be clear.

Here’s the inside face of the sender plate with the bulkhead mount and bracket Prosealed and riveted.

Here’s the outside face of the sender plate; this is where the fuel pickup will attach to the rest of the fuel system.

John Sannizzaro came up today and we riveted the first three ribs into the right tank skin. This was mostly a mess, so it was good that John was there to help. As with the stiffeners, it’s somewhat difficult to tell during riveting when the shop heads are correctly formed because they’re covered in Proseal. John looks at the circular “print” of the shop head in the residual Proseal on the bucking bar to make sure the shop head is the correct diameter, and that seems to work.

Another thing I learned is that the $120 tungsten bucking bar I bought from Bucking Bars by Webster was worth what it cost. It’s very easy to maneuver that small 5/8″x1″x4″ bar into the tank leading edge, and it’s a lot easier to keep a grip on it when your hands are covered in Proseal.

The last thing I learned is that an ordinary mushroom set on a 2X rivet gun can do a great job of riveting once you get the hang of placing the set squarely on the rivet. By rocking the gun and set very slightly, you can actually feel the set “center” on the dimple even with a rivet installed. Use one hand to keep the set in place, and the other to hold the gun and squeeze the trigger, and you can get very nice rivets with no ‘smileys’. This also helps avoid the need to press firmly with the rivet gun, which would cause slight ‘dips’ in thinner skin. Of course, this only works when you have a partner who’s bucking the rivet.

Here’s the first couple of ribs we installed…

John had a good time…or maybe it was just the MEK fumes.

I’m just happy that we didn’t ‘smiley’ a tank skin…

After a little success on the stiffeners I sealed and back-riveted the fuel cap flanges, then sealed and riveted drain valve flanges. The only tricky area is making sure the fuel cap flange and skin are pressed down tightly against the back-riveting plate when setting those flage rivets. Here’s the right tank fuel cap flange. No pictures of the left tank cap, but you get the idea.

And here’s one fuel flange sealed and riveted.

And then there was Proseal. Vans’ instructions cover this process pretty well, and I used Dan Checkoway’s narrative as well to help visualize the process.

It’s really helpful to have everything you need in one place before doing any mixing and sealing. I found a relatively cheap digital scale which made it relatively easy to measure out the Proseal. I also spent a fair amount of time cleaning the skin and stiffeners with MEK to get them nice and clean. It’s important to have lots of latex or nitrile gloves – you’ll need ’em. Also have lots of rags and MEK (or naptha) on hand for cleanup. I also put a couple dozen rivets in a glass jar with some MEK to keep them clean.

There’s not much I can add to Dan’s process, so I won’t try – except to emphasize the difficulty in checking shop heads on the back-riveted stiffener rivets. There’s one rivet there I’m not proud of on the right tank skin, but it wasn’t worth the trouble to drill out – and it’s covered with Proseal anyway. Here’s my first attempt at tank sealing…

Nothing much doing over the holiday week but deburring and dimpling tank parts – skins, ribs and baffles. Not too exciting, except for one issue. After reading some VAF posts about cracking dimples, I examined some of the tank skin dimples with a 10x jewelers loop and saw what looked like some tiny cracks on four or five dimples. Somewhat concerned, I emailed Van’s. Their response was that a lot of things on the airplane woudn’t look very pretty when magnified ten times, and that if there were no cracks visibile to the naked eye – which none were – then everything was probably ok. I decided to go with their recommendation.

Any surface that gets Proseal must be scuffed to improve adhesion, so I did just that. Here’s one of the skins scuffed with a maroon scotchbrite pad.

Today’s mission – fabricate the little trapdoor that keeps fuel in the first “bay” formed by the end rib and first interior rib. This is a part of the inverted fuel system – the door opens inward, but obstructs fuel flow outboard when the airplane is in less-than-coordinated flight. In my airplane, only the left tank is so equipped…