I was reading through the "Mag Failure" thread and these two posts started me thinking about Mike Busch's books, especially Manifesto. If you haven't read it, he advocates GA going towards a more Reliability Centered Maintenance (RCM) approach to maintaining aircraft much like what goes on at the airlines and military. Basically, RCM says that preventative maintenance has a tendency to do more harm than good and that "Maintenance Induced Failures" are a real thing and is much more of a risk than flying a part until it's obvious that it needs replacement. If I understand Busch's theory, I think he would ask "why would you pull both mags and send them for overhaul just because they were over 500 hours?" Were they giving you a problem? Were they failing a mag check? If they weren't, why mess with them? Look at @Stingray Don's post. I mean, sure he got screwed because the previous owner didn't replace the mags like they promised they would, but apparently the mags lasted at least 15 years and over 1,200 hours (plus what ever he put on it in the last 6 years) without causing any problems. What say you here about the RCM theory and doing unnecessary maintenance just based on time versus waiting until the part in question "tells you" it's time to be replaced?