hangar queen
1. An aircraft that spends more time being serviced or requiring maintenance than it does flying. The new stealth jet was a promising addition to the Air Force's fleet, but due to its frequent breakdowns, it has proved to be more of a hangar queen than a useful plane.
2. An airplane that is permanently grounded so that its parts may be used to repair other aircraft. I loved my first plane, but as I began buying more, it became a mere hangar queen to replace the parts of the newer ones.