In this session, I installed the last two ribs on the left fuel tank. Same process as before... Mix tank sealant and spread on the rib flange, insert the rib into the tank skin, cleco, buck rivets with pneumatic rivet gun and bucking bar, encapsulate all rivets' shop heads with more tank sealant, apply and fillet tank sealant along the seams.
I also noticed that I never installed the nutplates on the Z-brackets after I had finished their alodine treatment, so I used the hand squeezer to install all of those rivets. Each of the 12 Z-brackets had 3 nutplates, and each nutplate had 2 rivets, so this was a nice task to get out of the way.
What's next? Probably install the J-channel stiffener, and then maybe the attach bracket and other half of the inboard rib.