Forward top skin problems

TCONROY · #1 03-07-2011, 07:21 AM

Am I the only one that is having trouble getting the forward top skin (between firewall and sub-panel) to fit right? I started clecoing it to the sub-panel so I cold mark the hole locations on the firewall. I'm finding the bottom rows of holes (which go through the fuselage side-skins and upper longerons) are at least 1/4" off. I rolled the skin a bit to help it take the contour of the forward fuselage but that didn't seem to help a lot.
Any one else have this problem? I couldn't find much with the Forum Search option.

rcarson · #2 03-07-2011, 08:53 AM

I had the same problem but not quite so dramatic maybe 1/8" or a little more. I final drilled all of the holes to 40 and it gave me enough to draw the skin down without much trouble. Give it a try it worked for me.

Noah · #3 03-07-2011, 10:20 AM

Hi Trevor-

My front top skin did not match the tip up canopy skin very well, so I had to shim the subpanel on the sides at the "air scoops" by as much as a quarter inch or so. Because this increased the radius of the front skin at the subpanel, the hole spacing no longer matched - either on that radius or at the sides/longerons. As a result, I bought a blank sheet of .032, and match drilled all of the holes from the original skin into it with the exception of the holes along the sides of the subpanel, and the holes you're having trouble with on the sides/longerons. I clecoed the new skin into position and then match drilled the new skin from below so all the holes lined up. A bit of a PITA, but the end result fits nicely. I suspect you might need to do the same?

rv9av8tr · #4 03-07-2011, 11:19 AM

Yes, the top skin is an extremely tight fit as it rolls over to the fuse side holes. The forward most 4 or 5 holes are 3/16 so those larger clecos help to hold it in place.

I rolled the skin to take some of the bending force off and used the clecos to pull and guide the holes together. Once you start driving those rivets it sucks up well.

Caveman · #5 03-07-2011, 06:33 PM

Trevor,

That skin is one of only a handful of parts that I messed up and I ordered a new replacement. I ended up using ratchet straps to pull it down very tight and finally was able to get all the cleco's in the second time around.

Joe

eatenbyagrue · #6 03-07-2011, 06:41 PM

I just did this skin last weekend, and ran into the same problem. I unclecoed and reclecoed the skin a few times different ways to try and get it into a better position, and slightly bent the edges over, in place, with a rubber mallet. Finally was able to baaarely get the last few clecos in.

Hoping it all works out when I put it back on after deburring and dimpling

Jekyll · #7 03-07-2011, 09:26 PM

They are tight. that's for sure.

Don Jones · #8 03-07-2011, 10:30 PM

.....take off the stinking blue plastic film. You will be amazed how much better it fits without it!!

Scott_F · #9 03-08-2011, 06:23 AM

Trevor - I had the same problem that you and others mentioned. Like Caveman, I used ratcheting straps to help pull it down, but even without the blue plastic it was still hard. Make sure your center rib is not standing a little high (mine was originally because I had the reinforcing angle slightly misplaced) and start clecoing from the center down BOTH sides alternately. I was finally able to get the aft portion pulled down on each side, then worked my way forward along the longerons. It took lots of grunting and airplane building language, but I finally got it pinned down.

Good luck!

TCONROY · #10 03-10-2011, 10:40 AM

Last night I worked with the top skin for a few hours. I took Don's suggestion and first removed the blue film in hopes it would allow the skin to bend more. I started from the center and worked my way down each side along the sub-panel. I used 2 ratcheting straps to help pull the skin down but that didn't seem to help enough. The rear #40 clecos go in and I can get them to set with a little rubber mallet action, but the front where the #30 clecos are doesn't seem to want to go down enough.

See pictures here