By T.S.
Are the following statements true on the B777 if it were an AF447?
1) Turning off the ADRs so as to force it in Secondary Mode à la A330 Alternate 1?
No. You can't turn the ADRs off in flight on a 777. The only way I know to force Secondary Mode is to open the pitot probe heat circuit breakers (which a normal flight crew should NEVER do).
2) B777 is w/o aural SW only yokeshakers so it is not subject to the 60KNS / 30 KNS cut-out set-up?
I *think* (but am not positive) that the shaker would cutout when the airspeed when too low, for the same reasons that the Airbus aural cuts out.
3) B777's equivalent of THS AutoTrim is that trims for speed only not pitch.
Not exactly. The 777 uses elevator for fast commands then trims the stabilizer to offload the elevator. 'Trim" on a 777 is really an aerodynamic state that's a combination of current elevator and stab positions, not an explicit state of either one individually.
4) Pitch authority is always driven via the elevators that command the stabs as opposed to the A330's separate - "divorced" - authority i.e. THS AutoTrim is separate entity that does not rely on elevator authority at all?
Both systems rely on both. AutoTrim and 777 stab trim are both composite systems that work together with the elevators to give the pilots what they ask for with minimum drag. The 777 has speed stability as part of the control law but, depending on the flight regime, the actual pitch command trying to return the airplane to trim speed might be elevator, stab, or both.