Marcus - In a GIV, ten mil note, 500 hours, two pilots, 3k direct op cost..that's about 2.5 mil a year. The assumption being your actually putting money away for engines, not paying $6/gal for fuel, that you didn't buy a dog that's in the shop every ten minutes, etc etc...
2.5 mil write off against a 40% tax rate = 1 mil tax savings.
You should be out roughly 1.5 a year and we haven't even gotten creative yet.