Rather than post a new topic, thought I would jump in on this one.
Notice on leases they have silly things like 999 months. Is their a penalty for returning early, i.e. like a %age of the remaining lease. Can't seem to work it out for myself from the manual 
No there is no penalty for early returns.
You put 999 months in to represent an open-ended lease, where the lessee can keep the plane as long as they want to, without having a set contract period. The programmers made a lease change in the last round, so as a lessor you now have to enter an amount of months, where you didn't need to before. Look at my leases, they all have 120 months. Which would be the entire round.
