Originally Posted by
FCeng84
Some on this thread have suggested that MCAS May have been added to compensate for an elevator authority shortfall. That is not the case. This function was added to address a pitching moment vs AOA issue. With autopilot control of stabilizer to address a speed stability issue (aka STS) already in place on earlier 737 models, adding MCAS was relatively simple. Adding a stick pusher would have been a lot more complicated and would have involved new hardware.
Thats is my understanding, but I am not sure why the increasing aircraft nose down bias applied by the elevator feel system at low speed is insufficient too maintain a stable stick force curve as the stall is approached.
My guess is that the slope of the curve is already very low, so a four times control force increase may be very low compared with that required to overcome the instability (that force could also be fairly low).
Makes me think that this increase in force applied by the EFS is actually just another stability augmentation system which has reach the limit of authority in at least one area with the 737 MAX hence the MCAS. Funny if this capability of the EFS was just a stick nudger in disguise.
Perhaps you or Seattle contacts could make an authoritative comment! Thanks.