Originally Posted by
Machinbird
This may be dissembling however. Suppose the FACs remained engaged in Normal Law and failed to detect a failure of that system. Could the FAC system then activate overspeed protection without an actual overspeed?
This need not be a design issue, it could also be a maintenance issue. In any case, if the DFDR data continues to point to the FACs, they should probably salvage the cockpit and recover those boxes for examination.
Apart from the fact that the FACs aren't where you think they are, I think you'll also find that the ELACs and SECs are the flight control computers that apply the control laws, and not the FACs.