Forward Bottom Skins

Time : 4 Hours

Today I start work on the forward bottom skins. I had several tasks at hand, besides finishing the edges of the three skins.
The first task was to trim the edge of where the key or access panel will be to make sure it cleared for the newly installed gear brackets and bolts. This Took some time putting the skin on, marking it, removing the skin, removing the material and return in the skin to the fuselage. The plans have you do the step earlier on however since my gear alignment moved aft I needed to readjust this trim.

(null)The next task was to enlarge the 4 holes in the skins that will allow a socket to gain access to the AN4 bolts on the outboard wear plates.

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(null)I then deburred all the holes, enlarged the screw holes to a #19 drill bit and rolled the aft edge of the aft skin. I then grabbed my DRDT dimpling machine and dimpled all the required holes. The inside of the skins got scuffed, cleaned and primed as well.

(null)I ran some errands and let the primer dry for an hour or so. When I returned I started the riveting process. Van’s has you put 2 blobs of blue RTV sealant in the space that is too narrow for a bucking bar to give some skin support on the aft end of the aft bottom skin.

(null)The plans have you rivet the aft ribs first by lifting the outboard edge of the skin while the rib/skin joint is clecko’d. It’s a tight fit but you can do it with a very thin bucking bar. Next you are supposed to remove the forward crossmember as this will give you access to rivet the aft crossmember. Well since I created my battery box on the angled support I had riveted the two nut plates to it, oops. So I could either drill all those out or I could use blind rivets on the 9 holes that I could not access on the forward crossmember. I chose the later! So that meant that I had very limited access to rivet the aft crossmember by lifting a small flap of the skin. That was tough but I was able to get all the rivets done. I then drilled the rivets that would get the blind rivets to a #34. I calculated the thickness and it was at the top range of my MK-319-BS flush rivets so that worked well.

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(null)Thats where I stopped for today as I need a bucking partner to get the aft edge of the skin rivets as well as the forward edge of the forward cross member. The outboard edges of that cross member get covered by the two forward skins and you would have no bucking bar access if you went ahead of this step. After I get help I will be able to rivet the two forward skins and the cooling ramp. Another good day in the Hangar oh and today marks the crossing of the 1000 hour mark!

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