Keep in mind that helo engines are designed to maintain 100% RPM at all times. In a helo the pilot does not change thrust by changing RPM. He changes thrust by changing collective on the rotor system
That is so right.
However
So the pilot NEVER controls throttle/fuel flow to the engine.
I cannot agree with that. With all for helicopters I flew in the 60s I had to control the RPM at around max by using a twist grip throttle in the end of the collective. As the years have gone by pilots have been assisted in this difficult task (initially) by suitable mechanical links that adjusted the throttle (roughly) as the collective was moved and latterly by FBW systems which of course free the pilot of the task. How many of the older types are still in operation I do not know, but I am sure there are some.
I mention this just so that tryos do not get confused into thinking the helo world has always been like it is today.