Wish the industry developed the simple gouge we had for the Huey for their aircraft, simple in the extreme. In the Hueys case it was fly at 60 knots at the height you wish to land (or low altitude above the pad), note torque, pull power until rotor bleed, note torque, calculate difference between two torque figures. The gouge then gave figures (forget now but just to make up some) difference of 11 pounds or more OGE hover possible, between 10 and 7 IGE hover possible, between 6 and 4 a zero/zero possible, less than 4 means running landing required.