Cunning,
These days fuel costs more than the airframe costs by about 3 to 1
Bear in mind I am referring only to the maintenance costs of the airframe NOT crewing etc.
This assumes a fuel cost of 75c AUD for fuel and about .7 as the USD-AUD exchange rate.
The addition of costs such as crewing, headoffice etc adds a fair bit to the cost of operating the aeroplane, but they are mostly fixed regardless of the amount of time the aeroplane spends in the air (overtime etc excepted)
It is often much "cheaper" to sit at 41 than down at 27, the cross over point varies for each company.