JanetFlight Lease contracts are typically 600+ page documents (I know, I once had to sign off on a batch of six on every page...) with provisions for a near infinite number of scenarios, many of which have yet to occur on planet Earth. One set of provisions declare what the lessee may and may not do with the aircraft, and also contain some pretty hefty penalty clauses should the lessee fail to comply. I'm sure in what was a field day for lawyers, the lessor decided that there was a need to protect their asset to the full extent permitted by the contract, and the lessee, after reading the fine print, agreed that this was indeed a great idea. The UR- registration has no bearing, this is entirely a game between the lessor and the lessee.