Left Wing - Top Skins

I didn't intend to do much work tonight, but before you know it, 10 minutes of "just leveling the spar" turned into 3 hours.  Funny how that happens.  Once I get going, it's just tough to stop.

I decided to go with an extremely basic solution of taking the sag out of the spar.  The reality is that the pre-punched holes do 99% of the work of keeping the wings from having any twist, so the support in the middle of the rear spar is simply there to help in getting the holes to line up.

The first step in working on the skins was to create the wing walk doubler.  That just comes as a plain sheet, not drilled, so I laid it out as described and clamped it to the pre-punched skin, flipped it over and match drilled 3 holes in each rib location.  I'm not sure why they don't just have you drill all of the holes at once, but they specifically say to only do 3 per rib for some reason.  Maybe I'll realize why that is the case at some point, but so far it doesn't really make much sense to me.  Leaving all of the other holes undrilled means it'll have to be done in assembly with the ribs. That's going to make it awfully easy to miss the existing rib holes and potentially enlarge them (the wing walk skin is sandwiched between the pre-drilled skin and the pre-drilled ribs, so it's going to be an interesting exercise to get the rib and skin holes to line up).

I clecoed the inboard top skin and wing walk doubler to the main spar and started clecoing the ribs and rear spar to the skin.  That's when I had my nightly "well that was stupid" moment.  It happens about once a night.  I couldn't get one of the ribs to line up with the skin.  After looking at it and the plans for a minute, I realized that I had riveted the rib to the rear spar in the wrong location.  There are two identical sets of 3 holes next to each other in the rear spar.  I thought I had it correct, but didn't see on another drawing that the rib goes in the outboard 3 holes because there is a hinge bracket that goes in the inboard 3 holes.  Oops.  Normally drilling out rivets is pretty easy, but the rib is a pretty tight spot, plus it was already assembled.  I tried drilling them out how you typically would, but there just wasn't enough room.  I tried a 12" bit to give the drill a little more room to get perpendicular to the rivet head, but it was too difficult to center such a long bit. I finally pulled out my die grinder with a small 1" Scotch Brite wheel on it, protected the rib and spar with cardboard, and ground down the rivet head a bit until it was flat and thin.  Usually you drill through the manufactured head to pop out a rivet, but since I couldn't center a bit very well, I decided to go from underneath on the shop head.  I took a #30 bit and drilled through the rivets until I popped them all out.  I did enlarge the holes in the spar a little bit, but not enough to matter.  With that done, I riveted the rib back into the correct location and continued clecoing the skins on.  This photo is before I moved the rib.  You can see how far off it is from the skin holes.  In the picture it looks like there are only two holes to the right of where the rib is, but there are 3.

Having sorted out my rib problem, I finished clecoing the inboard skin.  I started to put things away to call it a night, but one more cleco turned into another one, and another one, until I had the inboard and outboard top skins all done.  I had a slight problem with getting the overlap of the two skins to line up perfectly, but just sliding the rear spar vertical support over a few inches moved things just enough to allow the holes to line up.