Skin Crack Found on Rudder

My RV10 has about 60 hours on it and as we were reassembling the plane after paint, I noticed there was a hairline crack on the rudder skin. It is at the lower edge where the rudder joins with the bottom fairing. I chose to make my fairing removable with nut plates and screws rather than pop riveting it in place. The crack appears to be following the perimeter of the spar itself.

I post so that others are aware of the possibility of cracking in this location. It was quite difficult to notice it was even there. I resolved the issue by stop drilling it with a very small bit.

Good eye and thanks for the heads up.

Was that area ever damaged, maybe bent and straightened back out???

The way the crack is following the curve of the edge of the spar like it was sheared against the spar.

Is there a burr on the flange of that piece under the skin? If so, hours of vibrating against that burr looks like it fatigued that metal and cracked it.

aarvig said:

Is there a burr on the flange of that piece under the skin? If so, hours of vibrating against that burr looks like it fatigued that metal and cracked it.

Click to expand...

Or the dimple in the glass part was not deep enough and the portion that cracked was a little higher after assembly, stressing the skin...

The piece was never bent and straightened so that's not an issue.

No burr on the spar either.

The skin is pushed out a small amount by the fairing. However the dimple is fully set in the fiberglass countersink.

Lost like it's just the geometry of the fairing that is put some stress on the area. I might see if I can sand down the fairing flange to eliminate some of the thickness.