Blackhawk9 Comment
Is it possible that your notes were in reference to the amount of tail rotor control available to the pilot after losing hydraulics to both stages of the tail rotor servos? In that instance a loss of both the No.1 Primary and the No. 3 stage ( powered by the 3rd stage electrically driven backup pump) is assumed , so only the No.2 Primary pump is running. That pressurizes the boost servos however, and so, since you still have a yaw boost servo working for you, between it and your strong legs pushing on the pedals, you can force a limited range of tail rotor control. That control range is under most circumstances good enough to fly level from about 40 kts to 120 kts, ( with the aid of some very small aerodynamic assistance from the remaining very small cambered section of vertical fin that exists ). And it is quite enough range to allow a run-on type landing.
This discussion assumes that tail rotor drive is intact.
Thanks,
John Dixson