With the tank-mount Z-brackets drilled to match the wing spars, it’s time to prepare them to be attached to the wing spars. The Z-brackets are attached to the wing spars using bolts so that the tanks can be removed later for service if necessary.
There are seven brackets per tank. Bracket #1, the inboard-most bracket, is different from the other six. Bracket #1 is attached by placing the bolts on the fore side and brackets 2 through 7 are bolted from the aft side. This arrangement is chosen for bolt accessibility.
Brackets 2 through 7 are fitted with plate-nuts. They need to be drilled for the plate-nut rivets. In this picture, the countersink cage is attached to the drill for countersinking the rivet holes.
For bracket #1, the plate-nuts are attached to the spar. I used small headed “oops” rivets to fasten the plate-nuts to the spars:
After priming the Z-brackets, I riveted the plate-nuts onto the six brackets:
The brackets can now be bolted to the spar in preparation for drilling the tank-side flanges to match the rear baffle of the fuel tank. Here’s bracket #1 with the bolts going rearward:
And here are the remaining brackets with the bolts coming forward through the spar:
With the brackets fastened into their final locations, the next step will be to match drill the forward flanges to the tank baffle.