My DOC's arouns 26mil...and I mostly use Caravelles (Super10Bs and -12s) and 707/747s/ plus a bunch of newer L1011s. And yes, maintenance is roughly 3/4 of my entire revenue...I'll explore a bit and seeing that it seems older a/c=higher fees, I guess I'll have to bring in newer a/c.
I decided to go after 'market share' and brought in a ton of A300s for a certain hub-with poor results. I think I'll go for DC-9s or 737s and replace my entire shorthaul fleet, followed by my older 707s, bringing in new L1011s.