The difficulty is proving that it’s not present. As with all certification activities, the paperwork required is enormous. Additionally, the kit required is going to make production line start-up costs eye-wateringly expensive. Magneto-sensitised gravitonic induction - required in all Unobtainium investigation, is in and of itself an expensive process, but combined with the auto-excited eddy echo technology necessary for production work, it’ll be a killer. Initial and recurrent training for the line workers, plus the health and safety aspects of removing it, if it is in fact found, well…
They don’t want Unobtainium in the aircraft because of the structural and physiological effects it has. Recent research has shown that these effects can be countered using depleted uranium. So, rather than trying to prove that there is no Unobtanium in the aircraft, it’d be far better to make the cabin floor out of depleted uranium. If anybody asks, tell them that I said it was alright. That should do the trick.
More pills please nurse, the aliens are back.