Quote Originally Posted by Tom Downey View Post
I'd like to mention a point that you may have missed. many old structures have linseed oil in the tubes, what happens to it when you heat the structure to 400 degrees?
That is a very good point. Boiling off the protective oil, doesn't sound like a good thing. Someone with old tube experience please speak up. Vegetable oils degrade over time, free fatty acids form, especially with oxygen and heat. Maybe old vented tubes would have fatty residues (grunge) and unvented tubes that were opened up might have surprisingly fresh oil.

Cessna flat spring gear is not hollow, so no factor there.