About
Build log for an RV-10

By
Jae Chang
web@jline.com

Contents (Index)
These are links to the major kits for the project.

Section 16: Top Wing Skins (60 / 422 wings / 759 total)

The total time spent is now a complete estimate.

The top wing skins posed another major challenge. The left top wing skin went on fine and fit perfectly. However, when I tried to fit the right top wing skin, i discovered that the inboard holes near the wing root on the rear spar were slightly off by 3/32. There is no fudge factor in this area, with the wing walk area, so this was going to be a big challenge. I ultimately worked it as well as I could to bend the rear spar flange any way I could to close the gap. The results are not perfect but workable.

This is an exchange I had in email with Van's.

--> RV10-List message posted by: "Jae Chang"

Has anyone else dealt with this issue? I am on page 16-2 on the Top Wing Skins section. My left wing lined up perfectly. On the right wing, to my surprise, I have an alignment problem between the top wing skin and the rear spar.

Here are some photos to illustrate...

Every other hole lines up between the top wing skin and the wing skeleton, except for the inboard rear spar holes. The holes are out of alignment and gradually come closer into alignment until they are lined up perfectly again between the 4th and 5th rib, counting the root rib as rib #1.

Broader picture of the general area...

The inboard most hole is the furthest out of line by about 1/16". The rear spar hole needs to come further aft by 1/16".

I then did a lot of measuring to compare my left wing (perfect) with right wing (problem). The problem appears to be with the rear spar. The upper flange seems to taper from 22/32" wide down to 20/32" wide at the inboard edge, which would account for the 1/16" alignment error in the top skin.

Photo of rear spar top flange on left (correct side):

Photo of rear spar top flange on right (error side):

I spoke with Van's this morning. They made 2 recommendations:

1. Does the bottom skin line up? Answer: surprisingly enough, YES. It's not perfect, but will be manageable.

2. Drill and rivet the misaligned holes with 1/8" rivets.

The problem with this solution is that the new hole will have an edge-distance problem. I should have 1/4" clearance to the edge, but I will only have 3/16" clearance to the aft edge on the rear spar. As I work outboard, the edge distance issue should get better and better, but still not within spec.

1/16" would not be a problem anywhere else on the wing, as far as I can tell. I could have "massaged" things possibly by that amount. However, this problem is at the wing root and wing walk area, which is heavily reinforced. There is no "massaging" possible here.

Finally, I could get a new rear-spar, however, that means removing all of the doublers and tons of AN470AD4-8 and 4-6 rivets!!!

Thus, the warning to other builders, BEFORE riveting the rear spar, measure the top flange on your rear spar, to make sure it stays even in width. Even better, try fitting the top skin on before riveting the rear spar.

Can anyone provide any other recommendations?

Another thought is, can I somehow put in a shim between the rear spar and the 2 inboard ribs? The shim would have to only be along the top holes, since the bottom holes are lined up.

Thanks,

Jae

Once I got going on riveting the top wing skins, the next challenge was figuring out how to rivet these by myself. I attempted a few rivets solo, but quickly realized that the best thing was to get help.

Thus, I recruited help from Sandy. She took the gun, and I did the bucking. After working out the "kinks" and getting a pattern going between us, things worked out very well at the end. In the beginning, I would say we were drilling out every 10th rivet. However, when we finished, there were very few mistakes. Overall, I am happy with the results.

posted at: 13:29 | path: /aviation/build/airframe/wings | permanent link to this entry | add a comment