I half remember, sometime in the past, there were different costs in turbine powered aircraft that were allowed to be put into the bucket for cost sharing.
Do I remember correctly or incorrectly?
If this a correct memory, what are the additional shareable costs in a turbine powered aircraft?
addendum: My ancient brain has come up with some vague answers.
IE, the hourly payments for engine and airframe maintenance. This was comparable to rental cost, but because it is a defined amount in a turbine totally owned by the pilot, it was quantifiable.