Yesterday I hit the Z brackets with some rattle can primer so that I'd be ready to do some more work today. Thankfully that primer is just about gone so I can try something else. It just lays down really strange on corners, as opposed to the Stewart primer that sticks great. Once the tank is fully built, I'll hit the back baffle with primer anyway, so these brackets will get another dose. Because of their shape though, it would be really hard to prime up underneath the overhand once assembled on the tank, which is why I did some preemptive priming. I didn't prime the bottom surface that will butt up against the tank baffle, because that will have a layer of proseal on it.
Today I started with the Z brackets and countersunk the holes for the platenuts and riveted the platenuts on.
I tried to remember a few of the lessons I learned on the last tank and fabricated the inboard attach angle. I got this one positioned appropriately this time, so it didn't shift while I drilled the holes, like the last one did. The actual fit is still TBD. These attach angles fit inside the rib flanges at the nose of the rib, meaning that there will be rivets from the rib/skin protruding through the rib flange around the perimeter of the angle that could interfere with how the angle sits. I think I've got just enough room around the perimeter of the angle to allow for the rivets, but it's hard to know until it all goes together. I can always shave a little off if need be.
I fabricated the inboard and outboard rib doublers. These aren't really doublers in the sense of being in place to just stiffen up an area. From what I gather, they're really mostly inserted at the nose of the rib to help block all the notches at the rib flanges from fuel leakage - these pressed up against the rib and skin, along with proseal, will keep those big flange notches from leaking. Just using proseal on its own would be iffy, because the spaces from the notches are pretty significant.
As I was getting my pneumatic squeezer ready for the next task, I noticed that the yoke was wiggling a bit, even though the pins were in place. It turns out, one of the pins had snapped in half. I'm not sure how that would have happened, outside of a manufacturing defect. I'll email Cleaveland Tools about it. I'm sure they'll probably just replace the pin for me.
I match drilled the holes from the attach angle through the inboard rib (and drilled the doublers shown above). Then I got out the spinning wheel of death - fly cutter - and cut the access hole in the inboard rib.
It didn't seem all that cold today, but by this point my fingers were ice cold, so I finished up by deburring the access plate doubler ring, match drilling the screw holes to the rib, then match drilling the smaller nuplate rivet holes to the rib. The rib gets dimpled to accept the rivets for the nutplates, and the doubler ring gets countersunk to go over the dimple. I limped along with my broken squeezer and got the ring and nutplates riveted to the rib. With that, I'm done with most of the initial assembly of the tank, outside of match drilling the fuel filler flange and fuel drain to the skin. Then I will start prepping the parts of this tank (deburr and dimple skins and ribs mostly) and move back to finishing up the right wing prep (deburr and dimple skins and ribs and countersink a billion holes in the spar).
