Z brackets/spar attach for tanks

I can't figure out the way I should read the plans for attaching the Z brackets to the web spar.
Do I need to understand the normal pattern is as per DWG 7 (section G-G) : only 2 bolts ?
If yes, why should it be different at root rib sta on DWG 12 (section C-C) with 2 bolts + 3 rivets ?

If you look closely at dwg 12, section C-C, the three rivets are only in the spar, not the Z brackets. The rivets are necessary to attach the front flange of the main rib.

If they also joined the Z bracket, you wouldn't be able to remove the tank.

Dave

You're right Dave, that makes sense...I was wondering about the fact rivets just making the whole thing un-removable....need to "learn to read the RV-3 plans"

So normal pattern is the one called per DWG 7, except at root, right ?...

The root rib is the only main rib that has Z-bracket bolts through its flange, hence those differences.

Dave