Mounted leading edge assembly on right spar and clecoed in position. Mounted tank on right spar and clecoed in position. Match-drilled leading edge skins to ribs and spar and rib aft flanges to spar. Match drilled tank attach brackets to spar. Removed tank and fitted platenuts to tank attach ("Z") brackets
I decided not to disassemble the right skeleton, as I had done with the left, and instead I carried on to fit and match-drill all the wing skins to the skeleton. In that way, the ribs will be fully prepared before I go on to prime and assemble them. If I followed the Vans instructions exactly, I would be match-drilling, deburring and dimpling the top and bottom flanges of the ribs after final assembly of the skeleton and (presumably) after they were primed. I don't think that is a great idea. Probably, the priming would survive the deburring and dimpling but my way seems better. I am only sorry that I did not think of this before disassembling the left wing skeleton as that was a waste of time -
I needed to take the sag, which was considerable, out of the wings by stretching a fishing line between clecos inserted in the two end-most skin attach holes on the top flange of the spar. Once that was done, the join between tank and leading edge was perfect. With such a good fit, I was confident enough to go ahead and match-drill the leading edge skins to the spar and match drill up through the spar into the aft flanges of the leading edge ribs. Changing to a #12 bit for the AN3 bolts, I also match-drilled through the spar into the tank attach brackets. I didn't have a drill stop big enough for the #12 bit so I took it extra-easy to avoid punching through the back of the tank just over an inch behind.Next step was to fit the tank attach platenuts to the tank attach brackets (three on each except the inboard one, where the platenuts go on the aft side of the spar). The manual advises that these platenuts should be fitted before the brackets are riveted to the back of the tanks as it is difficult to do afterwards. The manual is right on this point; it is difficult. However my pre-built tanks did not allow me this luxury as the brackets are already attached. The problem is that there is not enough room behind the bracket to allow the squeezer yoke to be positioned straight on to the rivet and there is certainly not enough room to hold the moving set against the outer machine head of the rivet to hold it in place before the squeeze begins. A hand squeezer would be better here, but with an air squeezer you have to start with the squeezer at a slight angle and neither set actually touching the rivet. Then, once the squeeze is completed and the yoke is firmly clamped on the bracket and squeezed rivet, everything wants to become square and parallel and in that position, the thicker end of the yoke near the U bend doesn't have enough space any more and pushes against the back of the tank, putting leverage on the bracket and twisting it out of position. Fortunately the extent of this twist is not enough to permanently move the bracket and it springs back into position (I hope).
With care and good trigger control (on the air squeezer) it is possible to get the rivets properly set. However, I was not able to get the factory head as fully flush with the surface of the bracket as I would like (nowhere near bad enough to get a finger nail under them, so not in the 'reject' class, but just not good enough). Not wanting any disturbance to the fit of the tank brackets against the spar (which would have thrown the screw - platenut alignment out and messed up the seam with the adjoining skins), I decided to shave off the tops of these rivets with a file and polish them afterwards with a small scotchbrite wheel on a die-grinder. In any case, rivets in a platenut are not actually structural. Their purpose is only to hold the platenut in position and withstand the torsional forces while the screw is being inserted. It is the screw itself that carries the structural load.
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