My plane is basically bolted together with AN nuts and bolts. Specifically MS21042-3 nut... 1200 of them. They mostly appear to be covered in oxidization (aka rust) and no longer seem to have any cad-plating. At $0.22 its $250 to replace them. Other options are treat them with a chemical solution (phosphoric acid) or sand blast (both are within my abilities) and re-install. The AC43.13 would classify the formation of visible rust as 'light' and both mechanical and chemical removal processes are approved. What is the general consensus?