Engine overhaul. An overhauled O-360 will cost close to $20k
installed, with a TBO of 2000 hrs, so this is $10/hr. Even if you do
not save an overhaul resever, your plane will depreciate at roughly
half this value ($5/hr) because of the increased engine time.


Although the rest looked good, I gotta disagree here.

it will depreciate for about 8 or 9 per hour over all due to engine time.
Near the beginning and near the end it can get more complicated, but in the
middle its at least 8 per hour.