Side Doublers (6-ZU-3-2) - Holy Moly!!

I haven't had an issues with the fuselage warping, etc. while the Center Spar has been in and out numerous times. I started installing the Side Doublers yesterday, the right side first and had some minor alignment issues after removing the rivets and bolts. I managed to block up the bottom of the fuselage to get it all lined up and I was able to install the Side Doubler.

The Left side gave me more significant problems. I supported the bottom, but once I removed the rivets and bolts, weird things started happening. Alignment was farther off and the fuselage side skin was more distorted. This was my first Holy Moly! moments.

Never figured out how to properly address the issue. I installed the Center Spar and Uprights and was very well clecoed, but that didn't help. To fit the Side Doubler, the Center Spar needs to be out if you haven't removed the Seat Pans. The Side Doubler needs some minor length trimming and the Rear Upright is the reference.

So, I went for it and managed to get a couple of alignment holes using the A5 rivet hole in the gear support and another in the upright directly above the gear support. Then I put it all back together, lined it up and back drilled through the Side Doubler. I'm going to debur in place, my fuselage skin is painted and that will suffice for corrosion protection.

I will never intentionally remove this Side Doubler again ;-)

Here is the link to Part 23 of the ZAC blog with some pictures.

It might not happen to you, but you have been warned.

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Comment by Jake Reyna on January 18, 2010 at 7:57am
Mark, it's all about templates. I think that ZAC added the Bottom Doubler later in the Upgrade to cover the existing front Center Spar holes. They went down the obvious path, reinstall the Center Spar in the aircraft as you describe. I didn't try it their way and won't because I'm done, and they won't try it my way because they are done. I submitted my procedure so that other builders would have a choice.

I expect to see some variations in the near future. There is no "right" way as long as it is done correctly.
Comment by Mark Ertz on January 17, 2010 at 9:25pm
On your earlier blog you had foto of center section w/ uprights attached (temp w/ holes drilled)outside the a/c on a bench. I was under the impression that one should place the center section in the a/c and then attach the uprights (?). Maybe I miss understand the order of of assembly. Seems to me that we work the center section from the back uprights and back bottom to the front when reassebling.
Comment by Lance Gingell on January 17, 2010 at 4:07pm
I guess I'll have it worse. I have .040 rear uprights in my XL from 2003. According to the photoguide, these need to be replaced with .063 ones. I just ordered them (they are not it the kit ....wish I knew before...more shipping cost, and delay!)

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