I have 43.13 and CAA 18 and the EAA book on welding. (I'm using
OxyAcy).

They talk about how to do various splices and patches. However, they
seem to be missing some of the practical aspects.

I"m taking apart a tailfeather for a taildragger that has considerable
rust. Some members are so rusted that they are no longer connected. In
some cases, I can see how a finger patch or a gusset might address the
problem, but there are other cases where I"m not sure.

Is there a reference somewhere that shows fixes for common rust
problems (were talking 4130); when to patch, how to patch, when to
replace the member? - Mike