Good points, all. The actual cost of running and maintaining any aircraft is largely a mystery to those outside the business, however the breakdown of the costs associated along with running a helicopter is especially opaque. In particular, the cost of maintenance and overhaul are so far outside most peoples experience that they usually can’t fathom it, there’s no parallel along with owning a car and little in common even if they own an airplane. Of note though, while fuel cost is always just a small fraction of the overall operating cost for helicopters it can still be a fairly large expense when you get into larger helicopter types, especially multi-engine turbines.
When I flew Bell 212’s, they burned right around 100 gallons an hour of jet fuel no matter if you were cruising, hovering, or just running on the ramp. The twin-engine tandem-rotor CH-47 Chinook burns between 350-400 gallons an hour in flight. At one Army base I was stationed at (along with mostly Cobras and Hueys) our refueling rig didn’t supply fuel fast enough to hot-refuel (fill the tanks along with the engines running) a CH-47 in a reasonable amount of time, since their idle burn rate was almost as much as the system could put into the tanks. Of course there’s big, and then there’s REALLY big! The gigantic Mi-26 burns between 800 -1100 gallons an hour in flight, however it’s feeding two 11,000 horsepower turbines. As helicopters go it’s actually rather fuel efficient for the job it can do, however it does a LOT of job so it burns a lot of fuel doing it. Just the APU (auxiliary power unit) they use to start their main engines can burn twice as much fuel per hour as your R-44 does at max power.
And surprisingly, when it comes to worst-case scenarios for maintenance expense, helicopter aren’t the top of the list. Check out the stats on how much it takes to maintain the engine on a top-fuel dragster.
And when it comes to fuel burn rates nothing that flies will ever come close to rockets. Especially the huge F-1 engines that powered the Saturn rockets for the Apollo moon missions