Svarin;
Originally Posted by #3383
This means both left and right pilots clicked their FPVs ON and found them failed.
To be precise, there is only one "FPV" pb on the FCU, in the center of the panel. This HDG-V/S:TRK/FPA pb toggles the FD presentation on the PFDs, and FCU mode selections, between "Heading, Vertical Speed", and "Track, Flight Path Angle".
Each pilot has an FD pushbutton which turns the respective FD on or off. FD1 and FD2 are driven by FMGEC1 and 2, respectively and the correct FMA annunciation when both FDs are on and driven by their onside FMGEC is "1FD2". If one FMGEC is offside (fault), say FMGEC2, the annunciation would be 1FD1 on both PFDs, meaning FMGEC1 is driving both FDs, etc.
For the FPV fault to occur, the Hdg-VS/Trk-FPA pb would have to be selected to FPV and one or both FDs selected ON. It would be at the point of selecting an FD ON that the message would be generated, (as it was requesting data that was unavailable).
We cannot know why, or if, the crew intentionally selected the FPV mode for guidance - you're right - it would not be useful guidance (unless one was very good at quickly interpreting and practised at using FPV information). One can toggle very quickly between the two as the button doesn't have much resistance. The selection could be by accident as one's hand was reaching for another control on the FCU or it could be intentional.
02:11:55 WRG:ADIRU1 BUS ADR1-2 TO FCPC2, HARD
(FCPC2 is PRIM2)
What the heck does this message mean?
Good catch on "WRG", Svarin.
I apologize in advance for what follows. I'm trying to convey the meaning of "WRG". From what I'm able to read and understand, this has to do with the verification of faults by the FWC [Flight Warning Computer].
As soon as an internal or external fault is isolated, it is considered as being at DETECTED status. The FWS computer which detected the fault has to confirm it. When confirmed, the fault is "declared". A declared fault is sent to the CMC, [Central Maintenance Computer].
Such a fault is then "consolidated". A consolidation is performed by the computer which declared the fault, which consists in checking the duration of the fault or its recurrence. As we know from past info, if the fault is still present after 10 seconds or if it occurs 3 or more times during the flight, it is "consolidated".
A fault which is declared
not consolidated is transmitted to the CMC as being an "intermittent" fault. A fault which is declared
consolidated is transmitted to the CMC as being a "hard" fault.
A declared fault, whether it is consolidated or not needs to be "correlated" to see more precisely where the fault is. Each FWC starts a correlation process. This correlation is performed on the ARINC buses and on the analog data.
So, here's an example of a message
not correlated:
If a fault is detected only by one FWS computer, the associated message will be:
FWCi(1WWi)/WRG:FMGECn BUS E GEN TO FWCi
- Example of a correlated message:
If the same fault is detected by two computers of the FWS, the associated message will be:
FMGECn(1CAn) BUS E GEN
Consolidation must be done before correlation can be done by the FWCs and the correlation process is contingent on the type of architecture of the connections between the LRU [Line Removable Unit - the PFM boxes] checked, and the computers of the FWS.
I believe this means that the fault indicated cannot be pin-pointed with as much accuracy.