from post #392,
clandestino, (a few days ago)
Seems that FCS gives up restoring itself back to normal law after it detects long lasting ADR disagreement, however AFCS keeps checking indefinitely and will restore itself as soon as two ADCs agree, not necessarily at correct value. Page 86 of the report refers.
(my bold)
It appears the 'magic'
agree number is
ANY two ADR's
<20 knots difference, no matter how 'off the wall' the actual values are as long as they meet other engagement criteria. [Of interest, this can be the two PFD displayed values
OR one of the displayed and the other not selected ADR value (i.e. the other displayed PFD
>20 knots difference with both 'agreeable' ones).]
This appears to also be the point at which the FD's return.
Pardon if this figure has been provided before in other threads, I may be late for dinner here, but does anyone have a reference for confirmation of this value, if in fact it is correct?
A33Zab?
@A33Zab: With ALT2(B?) 'latched', the SPD LIM flags displayed and no characteristic speeds displayed (including no VLS), and no FMGEC VLS (dashes), the A/P pb latching appears to depend only on 2 ADR's within 20 knots, not FMGEC VLS. The A/P pb apparently latches with the 2 values in 'agreement' below actual VLS. Is there a reference somewhere? Once again, apologies if it has already been provided previously.
It would be interesing to know, if the law Alt2b changed intermittently when the speeds came back on line or the above limited protections reactivated itermittently.
@RF4: The report states that ALT2B was 'latched' so I would assume there were never any intermittently available speed stability functions, but I erroneously thought the same of the A/P pushbutton.
