View From the Shop
Bill,
Others may be reading, so here's my report after clecoing the ready-to-seal/rivet the tank end ribs, and looking things over before mixing the sealant. I'm real wary of these corners because it's my second -7, and the neighbors are reminding me of the blue language emanating from the shop when I closed the first airplane's tanks.
You can seal and rivet the 405 (and the other reinforced end rib) on the bench, but prep the nose rivet holes for the pops before inserting the rib. Bench riveting the 405 and installing the rib should be accomplished in the same sealing session because there is indeed a very slight change in relationship between the rib flange and the 405/stiffener when on the bench verses matched with the skin. It won't fight you with uncured sealant, but if the sealant cures between 405 attachment and later rib installation, there may be hell to pay aligning the skin holes. The sealant isn't structural, but it's nearly stiff as your tires when cured. One other point. Remember to deepen the rivet clearance notches in the 405 to accommodate unpulled pops; they're a lot longer than bucked solids.
Or, install the rib with solid rivets, followed by the 405, again in the same session. No pops needed, and reaching in with a suitable bucking bar isn't all that tough. Just be ready with the right tools and a lot of toluene (the correct solvent for the sealant, not acetone).
John Siebold