500N, in a Huey at least, range and endurance were always critical, and I'd be guessing that that remains a problem with most of the more modern helicopters today.
Particularly if having to do a series of hovers/winches, fuel consumption can be high, so the closer you can have your fuel stocks to where you're working, and preferably in multiple locations, the better.
"The nearest dry location" to leave your fuel stocks can be a problem in flood relief. When we worked out of Wee Wah in the early 70s, the township and airport were considerably below flood level, but dry thanks to the levee bank, which the locals had to constantly patrol and shore up. (Or the pink-skinned locals at least - but let's not go there, for that would be wandering into politically incorrect territory.) However, every day, there was the real possibility of the levee bank breaching, which would have resulted in a situation as catastrophic for Wee Wah as we're currently seeing in Bundaberg.
The surrounding countryside was simply one huge inland sea. You had to see it to believe how big it was, (someone told me at the time that an area the size of Western Europe was under water, perhaps an exaggeration, but it will give you some idea of the scale of the floods), and in those days before GPS, navigation was a matter of heading and airspeed, for 90% of land features were under water. One of the few reliable pinpoints available was (were?) the very few wheat silos. If in doubt of our position, we'd go down to near water level and look to the horizon for the silo before pressing on.
Far from having Ordinance and Supply Units tasked with refuelling the Hueys, the system was very simple. A Caribou would drop off 'n' number of drums at locations 'x', 'y' and 'z', (which were sometimes a farmer's private airstrip), hopefully stand them on their ends (ideally, we weren't supposed to use a drum before it had stood undisturbed for I forget how many hours to allow the water and contaminants to settle), and we'd drop by to that and any other fuel site when and as required, keeping each other and the SES co-ordinators updated as to how many drums were left at each site.
No one stayed with the fuel. Sometimes we'd leave a hand pump or motorised rig at the site, but often as not, we'd carry a pump on the aircraft. Almost without exception, the chopper crews would do the refuelling themselves.
Rather than have supply units manning such sites, the poor bloody grunts, if they were involved, would be hard at work helping the locals with more pressing matters - and what thankless work that often was for the poor buggers.
By the comments made by some here, you'd be surprised to learn that the RAAF guys in their Caribous and Hueys got on very well with the AAVN blokes in their Kiowas. The smaller Kiowas had a slightly different job to do than the larger Hueys, but they complemented each others' operation when as as required. I saw very little rancour between the blokes of the two forces myself. There was always banter, but (as I saw it, at least), it was always in good spirit. The one incident where high emotions were involved and things almost came to blows that I do recall was in PNG, and I've since learned that one of the main players there was a bloke who had some serious issues and was just basically a pain in the arse - and that came from someone who was wearing the same uniform as he was - so I can't put that down totally to Army versus RAAF.
The C-27 should address some of the problems the Blackhawk crews are apparently encountering at the moment, but, as it's been said before here and elsewhere, as welcome as it will be, it won't provide anywhere near the operational flexibility of the Caribou, for it's just too big and too heavy to operate into many of the places a Caribou could go.