Ascend Charlie
On the 205A-1, the civil Huey with a T53-13B Lycoming, 6600 N2 gives 100% Nr. Reducing N2 by beeping to say 98% Nr puts the a/c into a "higher gear" thus producing more fuel economy in the cruise. Bell probably chose 6600 N2 as a convenient setting for 100% to cover all the types of missions that could be expected, and could probably give more lift, though I Could Be Wrong (added to protect my six o'clock).