I'm trying to figure this out too.....
edit
For anyone wondering it is possible. I used long inserters and made it work. Set a marker on my map called Heli Restock. I land the helicopter there under autopilot and then positioned chests and inserters around. Its finnicky to get the positioning right but it does work. Only one item type per chest or your inserters will get stuck. So I have it loading Rail, Signals, Fuel and ammo all from separate chests. I also have one inserter pulling out the wood from construction.