Originally posted by JB73 
the 109 for example could have a new engine dropped in in 15 min. thats how they designed the mount. 
 wow, thats fast, but still would take a while to get new engine mounted, rigged and run-out.   probably a 2 hour job on that 109.....8 or so for some planes.   even so, we fly 5 minutes to get to the fight, when in R/L they flew for an hour or two.  so, why not speed up the repair process too.