For Nick Lappos,
1. Why was the S-70 aft quadrant not used on the S-76. This would of allowed full control with a single tail rotor cable failure?
2. Also how did the test run go for the S-76 landing sequence with a double tail rotor servo actuator pressure failure. Is it similar to the S-70?
I guess I missed this one 3 years ago - here is a somewhat late set of answers!
1) The 76 aft quadrant is actually very similar to the BH, and allows almost the entire envelope to be flown with a single cable failure, because the tensioning device pops out and tightens the remaining cable. A dual cable failure turns the quadrant into a centering spring. It is not as elaborate as the Hawk, but then again, the odds of major control damage (combat damage that would take out a cable) is considerably less.
2) Without any pressure to the TR, some control is possible, as long as the isolation valve to the primaries is actuated, so that #1 mains stay pressurized. Hover is not possible, but quite a bit of range about the neutral TR pitch point is possible. I do not specifically recall the airspeed range (which really depends on weight/power required of course) but I believe it is about 40 Kt to 120 Kt.