Empennage

[Pounder]

I suppose this info is already out there, but who is aware of a product (adhesive?) and application technique internal to rudder (and other empennage surfaces) to prevent oil canning or otherwise cracking?

[Michael Henning]

RTV silicone between the skin stiffeners by the trailing edge.

[smokyray]

Originally Posted by Pounder

I suppose this info is already out there, but who is aware of a product (adhesive?) and application technique internal to rudder (and other empennage surfaces) to prevent oil canning or otherwise cracking?

Michael's technique works well.
Additionally:
Since I had .016 skins, I used Hy-Sol, a structural epoxy (used by Lancair and other composite/wood/metal builders to glue skins together) for additional strength and to fight cracking between rivets.
https://www.rshughes.com/p/Loctite-E...180516224238:s

I spread it thin between the stiffeners and skin prior to riveting. Working time is 40 min, cure 24hrs.
Excellent product, Grumman aircraft were assembled with a similar epoxy.
V/R
Smokey

PS:Side benefit is it holds everything in place and augments the rivets with impressive shear strength.