6400 Rpm
The DAC told us in '78, near the end of instrument training..."Beep it down to 6400, then pull 32 lbs of torque...that'll get you about 30 miles farther down the road on a tank of gas." He was right (thanks Mr. Whitehead). Army doctrine was to set cruise power to hover power (usually around 28 ft.-lbs. torques) and fly at 90 KIAS. But in the field we'd usually always do the 6400/32 thing & fly about 110 KIAS. It did get you more range. The before landing checklist had you check the N2 & beep it back up to 6600.