[specialist]

Very interesting thread.

Noob me would have guessed the "source of truth" would be whatever identifier(s) is recorded by the insurance company. Or maybe the service and maintenance agreements.

Failing that, I would have guessed some kind of (natural) compound key derived from the transfer(s) of ownership (Airplane Purchase Agreement? Bill of Sale?) noting the unique major components like airframe, interior, and engines? And maybe wings?

Sounds like a fun problem. Thanks for sharing.