Rather than worry about Nr at FLY, why not ask "why does the pilot have to manipulate the throtles to set Nr outside the avoid range, at IDLE, in a FADEC equiped aircraft" ? Seems very 1980's S-76A to me
Really strange to touch the throtles at all, do you have the off,start,idle,fly typical switch, in the 92?
In that case, don't you need to put the FADEC in manual mode to have any effect the change in throtles position?
Regards.
Aser