Wing Bottom Skins

Time: 24.0 hrs

Over the past few weeks I did quite a bit of work on the wings. I haven’t posted much because the bulk of the work is prepping and priming parts… not too exciting The wings have been going along fairly well, no big issues or problems. The only problem so far was with the fitment of the bottom skins. One particular area is the row of rivets that attach the fuel tanks to the main spar. The main bottom skin also uses those holes and if you line up the bottom skin so that most of the other holes align then this row is fairly far off. I had been waiting for the factory to let me know what to do about the alignment issue. The final fit come was that this is an issue on the Sling 4’s and to just widen up the hole in the skin (not the spar). So with that answered I could finally move onto riveting the bottom skins.

It’s a bit hard to see in the photo, but the row of hole in the primed area are a bit off. TAF said just to open them up a bit. I checked the fuel tank skin and the holes seem to line up OK so these holes will just be sandwiched in between the spar and the fuel tank skin so I guess it’s OK if the rivets don’t fit tight.

Prior to riveting the skins I installed the REV1 of the rear spar lower join angle (WG-ANG-005). When doing inventory I notice that I had a REV0 of the right one and a REV1of the left one so I had TAF send me REV1 for the right. The difference is the notches in the ends of the bends to help prevent cracking. The upper left one in the photo is REV1 and the lower right is REV0. I suppose I could have just made the REV0 a REV1 by notching it… Oh well.

Right wing bottom skins are done. It actually went pretty quick. I think only about 1.5-2 hrs. Now they need to be filled 😦

I have a stray hole in the skin. I will need to drill it out from the other side (to make a hole in the correct location) and then fill this one. I don’t want to drill out this hole because it seems like it will hit the actual rib and not the flange on the rib.

That rivet there will need to be cut. It hits one of the parts that make up the bracket that holds the bell crank for the ailerons.

Left wing ready to rivet.

And it’s finished. Only took about 2 hours. I hand riveted the rivets around the aileron and flap hinges since the pneumatic riveter didn’t fit well.

So next I’ll rivet on the leading edge skin I have (for the right wing I think). Still waiting on the other from TAF. I’ll also rivet the bottom part of the top inner skins, the wing walk area so that I have those bottom rivets done. After that I can fill and sand the rivets.. oh and install the rivets for the inspection plates.

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