Are airplane engines like car engines where, if you don’t use ‘em. the seals dry up and the engines are at risk of self-destruction?
I used to loath manning up the first go in my Tomcat squadron if the jets had been sitting around a while. If we could, we would turn up all the systems every couple days even if we were going flying.
Yes. They probably canibalized three for every one they got flying. All machinery is like that--use it or lose it. Seal rot, rust developes, oxidation begins, etc.
Certainly there are parts in any turbine engine (the ones used for these planes are turboprops) that have a shelf life. One overhaul cycle, and assuming there are no corrosion issues, and good to go. Worst case, replace the engines with newer whiz bang versions, made with newer materials and having higher reliability.