Fixed wing costs:
C172, replace engine every 2000 hrs, known cost
C172, replace prop every x hours, known cost
50/100hrly, known cost
Unscheduled maintenance, cost can be calculated
Helicopter (any type)
50/100hrly, known cost
x hours, replace main rotor blades
x hours, replace tail rotor blades
x hours, replace engine
x hours, overhaul main rotor head
x hours, replace main rotorhead components
x hours, etc, etc
Basically, helicopters have heaps more lifed items than a fixed wing, the cost of which has to be amortised back into an hourly rate. Plus, those lifed items tend to be more expensive, because the lower numbers of helicopters built mean that development costs have to be amortised into a smaller number of items.
Clear as mud
