jb747
Enthusiast
- Joined
- Mar 9, 2010
- Posts
- 12,958
It’s not really anything to do with parts per se. The MELs state explicitly that some items must be repaired if they can be, or perhaps that an aircraft can transit but not through a major maintenance base (for that airline). There’s a few permutations. Almost all MELs also include time or sector limits.