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Lower firewall brackets

JDA_BTR

Well Known Member
Fitting the two right and left lower firewall brackets. The F801-E side angle does not nest properly in the weldment. I nested it in the right position, but it seems the paint on the weldment along with the amount of angle material on the F801-E keeps the flange from nesting flat in the weldment.

My choices are to strip the paint from the weldment and/or relieve the edge of the F801-E so it doesn't bind in the corner.

I don't know what later step needs hole distance at the bottom of the F801-E side angle if I remove material to make it nest properly.

Any ideas?

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For some context, take a look at DWGs 67 and 74. The F-844 aux longerons will end up being riveted in assembly with the weldment, the firewall angle, and the skin. There will be five 426-4 rivets in this location.

Here's a look at the shop heads of those rivets from my fuselage. There seems to be a pretty healthy edge distance margin here. (pay no attention to the june bug carcass)

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What s the best way to strip or sand this material? Is it powder coat or really thick paint? Acetone and MEK hasn?t done much on it. I only want to clean up the surface that nests the side flange but I can strip the whole thing if I need to.
 
I went back and looked at mine. They didn't sit perfectly flush. I relieved the foward edge of the lower ends (F-801E) just a little. I did not disturb the powder coating on the weldment. Even so, that's a pretty thick stack up of materieal with the F-801 angle, the weldment, the mid-longeron, and then the skin.

When I drilled those first 5 holes, I used 1" X 1/8" hex-nut clecos, starting at the foward most hole, then drilling and clecoing aft. It pulled everything together nice and snug.

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[/url]IMG_0381 by Ken Wilkerson, on Flickr[/IMG]
 
I would have to do something similar to make mine lay correctly. I'm not sure how much the coating affects it but it is on quite thick. I had to ream the #30 holes out just to cleco anything; 50% of each hole had paint.
 
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