Originally Posted by
megan
A good reason for not doing ground runs to find where the problem is when the trend check has taken a massive nose dive.
Sir Korsky, most of the schematics I've seen would have you interpret that as being the case, because the orientation of the graphic is so poor. See below for a clearer view. You can see the tail rotor is only driven from the #1 engine side. As Sikorsky saysSo its theoretically possible for a #1 engine drive failure into the MGB where #2 is what supplies main rotor power and you you have to keep #1 running to drive the tail rotor ie shutting down #1 will deprive you of tail rotor drive. A fact I've never seen pointed out in training or simulator.
Sikorsky Archives | S-76
I suspect that it hasn’t been pointed out to you because your interpretation is incorrect. The tail rotor drive will continue regardless of the engine giving power, via the MGB bull gear as described in the previous quote. Should the No 1 fail then the freewheel disconnects it from a drive input.
Have you not started No 2 first and seen the main and tail rotors spin up together?