Quote:
Originally Posted by OK465
In the incident under discussion, the 'plumbing' caused temporary problems with all 3 ADR's, which 'latched' ALT 2...
When an ADR is recovered, is high speed stability regained?
If 2 ADR's are recovered, is low speed stability regained?
Is VLS redisplayed?
There are all valid questions.
We have been told ALT2 was latched, but still the FD bars reappeared so 2 ADRs ceased their disagreement.
Agreed! ALT2 as function of FCPCs and FD Bars as function of FMGEC.
FWIW, FD Bars can be displayed on ground (no fwd speed) by selecting a V/S.
Pitch bar is limited to a value ~ +1000 ft/s even when selected V/S is at max. +6000ft/s.
If I remember it well the Pitch bar was just above the 2.5° mark (1.5° ND on ground makes ~ 4°).
It is said that high speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?
It is said that low speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?
BEA IR#3:
1.16.4.2 Analysis of the flight control law
The flight control law switched from normal to alternate at about 2 h 10 min 05.
The alternate law adopted was alternate 2B and it did not change again subsequently.
In ALT2B no Hi and Lo speed stabilty (= VMO2/ Vc prot).
This was not due to ADR DISAGREE but due ADR2 being the voted (median) value and not returning within Δ50kts of initial airspeed at -10s.
(ADR DISAGREE was set on 02:12:xx not before, at 02:10:08 there was a disagreement between ADRs but the duration was less then 10s.
Just before the 10th second ADR1 & ADR3 became consistent, but wrong)
AP is also lost if ADR DISAGREE, could it have been reengaged to also follow the reappearing FD bars ?
NO, all ADR speeds were below VLS after 02:10:08.
If 2 speeds would have been above VLS then
YES,... See
VH-EBA