Marked right wing main ribs for position. Installed W-919 joint strip and W908R leading edge rib, match-drilled to leading edge and removed for deburring and edge preparation. Fitted W-902/903 top skins and match-drilled.
With the tank still off the spar, I began the fitting of the W-908R leading edge rib and the W-919 joint strip that joins the leading edge and tank skins. This strip is sandwiched between the inside of the skin and the W-908 rib underneath. I had been dreading this job, knowing how tight the other ribs had been in the skin. However, it went quite easily. With the rib clecoed to the spar through its aft flange, I pulled the tip end well out of position, leaving about a 2" gap between it and the leading edge. Then I put the join strip in place under the skin. Because the joint strip was still not fixed in position, it was quiet easy to angle it's edge slightly upwards to allow the tip of the rib to pass underneath. As it passed under the edge of the joint strip, I paused to fix the strip in positon on the spar with edge-clamp clecoes over the flanges - the strip had not been trimmed for length and was overhanging. Thumb pressure was all that was required to move the rib towards its proper position but the join strip wanted to move as well. Initially, I used a pliers to hold on to it while I pushed the rib but this was awkward and the pliers was marking the aluminium. Instead, I drilled through one of the forward-most pre-punched holes and the join strip. This held the strip in positon until close to the end. Eventually the rib flange hit that cleco and it had to come out to allow the rib to be moved into its final position. By this stage the surfaces are all more or less parallel so the forces involved were smaller and the strip did not move out of position.
After a bit more pushing and pulling to get everyting exactly right, I was satisfied enough to put the tank back in place and then match drill the join strip to the leading edge skin and end rib, clecoing every hole as I went. I didn't match-drill the holes for the tank attach screws just yet as I would prefer to see a perfect join with the top skins fitted before I do that.I marked the ends of the join strip to be cut off flush with the aft edge of the tank and leading edge skins but I am not sure about this. I can't make out from the plans or the manual where the strip should be cut off. It seems to me that they should not be allowed to run aft between the tank and leading edge skins and the spar flange as that would raise these skins above the top of the upper wing skins immediately behind. However on the basis that you can always cut more but you can never put material back, I decided to cut them off flush with the aft ends of the skin for now. The strip and end rib had to come out to allow this to happen but putting them back after the cuts was easy once I knew how.
I got both sets of W-902 inboard top skins out and prepared both wing-walk doublers while I was at it. To save the worktable surface, I did this on my sacrificial sheet of chipboard, setting the forward edge of the wing-walk doublers back by the required amount from the forward edge of the W-902. Fitting the skins was a non-event as they overlap each other and simply but up against the tank and leading edge skins. Again, the join was spot on.
Though I started the match-drilling, I didn't finish out. That's a whole lot of holes! I better get Dorothy mentally prepared before we start to rivet them
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