02 November 2013

Wings: Bottom skins. Left inboard bottom skin on.

I managed to rivet on the left inboard bottom skin by myself.  Nine hours!  I had a few very minor dents in the skin as it's extremely difficult to manage this task alone.  Also put a bit of a dent around the flap bracket mount and ended up with a Rivet of Shame there.  It's dangerous to use a mushroom set and a back rivet set in this area.  I've since ordered a narrower and longer flush set to work with the remaining flap brackets.

The plans say to cleco the bottom skin from the rear spar to the J-stiffener, then carefully lift the skin to access the underside for bucking.  Well, that's just not possible frankly.  Or at least, I couldn't manage it without kinking the skin.  So I cleco'd each row progressively as I went and ultimately forwent riveting from the center out and forward.  I was fastidious about that approach with the top skins and outboard leading edges but it wasn't an option here.  I noticed no "oil-canning" of the skin.

During this process, I recalled how my friend with an RV-9A had dropped his bucking bar when putting in his bottom skins.  He put a nice dent in the top skins that is quite unsightly.  I desperately wanted to avoid something similar.  However, I indeed dropped my bucking bar once.  Since I riveted with the wings in the position shown in the images, the bar fell (corner down, no less) into the main spar, bounced twice and ended up two ribs outboard from the drop point!  My butterfingers caused two very nice gouges in the spar which took 45 minutes to carefully sand out.  Ugh.  I'll need to clean and spot prime these areas as the alodine is gone now.

Subsequent riveting of the bottom skins will see a nice thick towel adorning the spar to accommodate any falling objects.

Accessing the rivets under (fore) the J-stiffener is a challenge.  I used the left bar on those guys.  Elsewhere I used the right bar and my tungsten friend in the center.  The gun was calibrated so that two short half second blips fully set a rivet.

An MS21053-L08 single leg nutplate is called out on the aft inboard bottom skin.  The plans previously had the skin/rib rivet holes for this part dimpled.  However, this steel nutplate has its rivet holes undimpled.  I tried to dimple them but the part just warped rather than taking on a good dimple.  After several attempts to rectify, I gave up, pressed out the skin/rib dimples and countersunk the skin holes.  All good.  This advice was give to me by Sterling at Van's.  He's always so helpful and thorough.

Left inboard bottom skin locked down for good.

And here is the left bottom skin ready for riveting.  I'll try going at it myself once I get my narrower and longer flush set, but I bet I forgo the attempt in favor or some help.

Now it's time to let my hands and arms heal from all that close-quarters trauma.

No comments:

Post a Comment