Depreciating aircraft parts, dealing with taxes, etc.

Most owners, I assume, have corporations which do the actual owning and
which provide a liability firewall. But how are taxes managed?

The issue I think I'm facing is we pay money into the corporation against
future events like overhaul, repainting, etc. These monies add up. But
since this is really just a reserve that's going to be spent in a few
years, I'm loath to have this considered "profit" and thereby become
taxable.

The answer, I'd imagine, is to depreciate those things against which the
reserves are accumulating. For example, if I pay $25/hour into the bucket
for engine reserve, I want to depreciate the engine by $25/hour.

Can one do that? What [very!] little I know about taxes has
calender-based depreciation schedules. Can one have a use-based schedule?

Thanks, and any suggestions, corrections, pointers, or ideas would be
welcome.

- Andrew