Hello,
I've noticed several times that when flying at high altitude (11–12000 ft), the Apache doesn't respond as I expect it to ...
Basically, I receive warnings about rotor RPM being low while at 80 / 85 % torque
It would seem that the low rpm alert is tied to the amount of collective I pull and not the amount of torque being used. To me, it looks like an error, but since I'm not an expert about helicopter physics, I might be wrong.