Heck, I'm the guy that goes through the trach can at the flying field. I strip anything that is usable off creshed planes. Screws, control horns, tail sections, bolts, nuts, cross braces, fuel line, control rods, etc... there is always that time when you need that tiny control horn screw. As for taking a plane out of flight status, I ground em when I can no longer adjust trim for mid stick hands off level and straight flight (usually a foamie that I've crashed and taped back together to keep it flying).