Hypo #4

Joe Roy and Kenny Luk buy a Beech Sundowner aircraft as "joint tenants with right of survivorship" while they both live in Illinois

Roy, having graduated from law school, passed the bar, and earned his pilot's license, decides to open up a law practice in Alaska, specializing in springing-executory-interest litigation

He flies the Sundowner to Juneau, contracts with a fixed base operator there for tiedown and maintainance, and uses it to travel to see potential clients

He also makes it available to a local flying school to give flying lessons in it, at $50 per hour

Luk sues him for conversion of the aircraft and the flying-school rental proceeds.