.ipt => .wpn (www.xplane.org)
As a shot in the dark...
Perhaps if you go Inventor => 3DS Max => What ever X-plane file importer.
Years ago, I did some CAD conversion to games, and they all had an importing program that could open 3DS files and convert to the format required by the game. The models could not be too detailed or they would be too slow when used in the game.