As I understand things, Lycomings have a TBO associated with each engine model. That number is usually something like 2000, OR some duration of time like 12 years, whichever comes first. My question is... When does the clock start, after purchase, or after initial certification? I mean, if you buy a new engine 10 years ago and it is in storage waiting to be installed, do you only have two years left before you have to overhaul it, even tho the engine only has 100 hours on it?