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F-7108A fuselage rib Q on Slider

flydjd

Well Known Member
Hi again all,

With ref to the F-7108A fuselage rib on a slider - why doesn't it have pre-punched holes on the fwd flange like the L & R ribs and same Q for why aren't there pre-punched holes in the firewall ? Is it something to do with differences between the slider and tip up ?

Also when is the best time to drill these holes ?
I am working out of order at the moment so all upper deck pieces will come off again for lots more fwd cabin work
 
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I have everything fit in the forward fuselage area except riviting the F-7108A center rib to the firewall. I have the forward top skin cleco'ed in place to locate the center rib. I will have to crawl up inside and drill through the F-7108 and the firewall to make sure I get the proper location on the flange of the F7108-a rib. I can't see why Van's didn't put the holes in the firewall so you could match drill through the Rib using a sharpy center line to locate the rib. Anyone have any advice or thoughts on why this is this way and have I overlooked something. I can't find anything in the drawings or instructions. :confused:
 
I have everything fit in the forward fuselage area except riviting the F-7108A center rib to the firewall. I have the forward top skin cleco'ed in place to locate the center rib. I will have to crawl up inside and drill through the F-7108 and the firewall to make sure I get the proper location on the flange of the F7108-a rib. I can't see why Van's didn't put the holes in the firewall so you could match drill through the Rib using a sharpy center line to locate the rib. Anyone have any advice or thoughts on why this is this way and have I overlooked something. I can't find anything in the drawings or instructions. :confused:

Hey Jim, Here is how I handled that center rib on my 9A fuse; there are a couple of photos with the journal entry as well. Not certain that the 7 fuse is exactly the same as my 9 fuse with regards to this, but if so, did you happen to notice that there are six rivets called for in the center rib forward flange to firewall, versus only five for the left and right rib?

http://www.aclog.com/rv-9a/index.php?c=3#887

Mike
 
Thanks Mike, Mine does show 6 rivets in the center flange. The pictures are a big help too. I figured I was going to have to do something like you did, I just couldn't figure out the reasoning for not having the prepunched holes in the firewall.
 
A little late to the party, but I drilled my firewall yesterday after a little head-scratching. I figured out the distance from left/right rivet hole lines (F-7105 left & right) by measuring the distance between rivet hole lines in the top forward skin. Turns out those holes are in line with the holes in the firewall. I located & drilled six ea. #40 holes in the front flange of F-7108 at 5/16" from the edge, then measured over 8-15/16" from the passenger side (F-7105R) holes and drew a vertical line on the aft side of the firewall. I clecoed the ribs and subpanel in place to hold everything, including the upper firewall, in alignment. Lined my drilled holes in the F-7108 flange over the line I drew, then clamped the rib with a C-clamp. Matched drilled from the backside #40 with an angle drill, then final-drilled #30 from the front side, with clecoes going into holes as I drilled them to keep everything lined up. After that, the forward skin laid perfectly over all three ribs.

That may sound complicated, but, having already had the ribs and subpanel clecoed in place, the entire operation took less than 30 minutes, and I never had to install the skin/crawl underneath to drill. With my not-so-fine back, I'll do anything I can to avoid that activity.
 
While this is old, I thought I'd explain how I did it for future readers.

After clecoing everything in place other than the center rib that still needed drilling, I verified all fit correctly. I then used the top skin as a drill template and created a smaller piece of aluminum that was short of the firewall at the center rib so I could get my hands down there and see what I was doing. With all that in place, it locked the center rib into proper position so I could use it as the drill guide to drill the firewall. This smaller piece needs to cover all 3 ribs so that it locks the center rib to the left and right, while those are all locked to the sub panel and the firewall. It was essentially like creating an access panel to get to that rib flange without actually creating an access panel in my real skin.

After drilling and clecoing that rib in place, I returned the actual top skin to verify everything still lined up perfectly, which it did.
 
I’ve been thinking about doing something like this. There are several small tabs that have to be attached but without the top skin being on there is no way to know where exactly to drill them. I almost thought about ordering a new top skin just so I can cut big access holes in it so I can reach into the sub panel.
 
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