Today, while I was drilling the fuel tanks, Sabine deburred the external part of both upper wing skins. Work is 90% done.

First all the nutplates get riveted to the Z brackets, then all the brackets are bolted to the main spar (I had some difficulties due to some no so optimally placed nutplates).



Then the fuel tanks get clecoed to the spar and the alignment verified.



In the picture is the join between the right fuel tank and the leading edge. On this tank I have a small gap (less than 1/64 in) on the underside. The left tank fits perfectly on both sides.



Then all the drilling gets done, first drill the inboard Z bracket, then drill the junction plate between fuel tank and leading edge, then take the leading edge off, then drill the outboard Z bracket, then get the fuel tank skin off and drill the remaining Z brackets.
To finish the day I bolted the tie-down assembly to the main spar.

Deburred the lower left wing skins.

Primed the Z-beackets and assembled nutplates on one just to see.







It pretty normal that some part of the bracket is not primed. This part will be in contact with the fuel tank and will receive the sealer which does not like to be mixed with paint.

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.