Each fuel tank is screwed to the main spar by means of the nutplates installed during spar preparation, but each tank is also bolted to the spar web via Z-brakets that are also riveted to aft flange of the tank.
Today I decided to prepare the Z-brakets using Dan Checkoway'smethod.

In fact you make an initial hole in the bracket, then the other holes get backdrilled and then you just have to make all the nutplates installation holes and countersinks.
It was quite some work, I finished by reassembling the right tank. Tomorrow I'll prime the Z brackets before installing the nutplates and the tank.



Here are all the parts, it's normal that the two brackets on the right have a different drill pattern, the nutplates for these are installed on the spar.