augustusjeremy:
I know you didn't post it... but what do you think is a guess and what is indeed documented ?
How can you get a fault of a inertial reference unit out of conflicting raw air data ? Isn't inertial reference data independent from air data ?
And isn't this fault detected by simple comparison involving INERTIAL DATA only ?
This is a mess...
Well, indeed, I didn't posted it but I'm sure it is mostly documented and very difficult to decode without the full data stream and maintenance experience... I think that Mandala 499 (the original poster on Airliners.net) is quoted out of context and this list posted like that without the discussion concerning its meaning isn't complete. The first post concerning the decoding was from Pihero:
Pihero:
After a lot of research through dozens - if not hundreds of pages - from the A330 manuals, coming from different sources, Mandala 499 and I have managed to identify the meaning of the ACARS messages.
To explain it simply is not easy. Let's just say that the messages represent two of the functions of the CMC - Central Maintenance Computer - of the airplane :
1/- A report from the flight warning computer on what is showing on the instrument panels : PFDs, ECAM...etc...
2/- A report from the different BITEs that are present in each system, comparators...etc... They are , I repeat once again, totally transparent to the flight crew, but for us they could give a better picture of what is happening.
I confess I had a terrible problem sorting things out as I started with the assumption that the messages came out on the ground telex machine in their order of detection...It is not so, and thanks to Mandala's good work, we've arrived at a logical linkage of all the messages.
I also had to very carefully take Zeke's caution as to wheter these messages are genuine failures or just transients. I now believe that these faults / failures are for real and there was no indication - or logical explanation - of a return to normal functions.
So I propose that first we'd introduce you to the messages as they appeared on the initial summary document, then Mandala would walk you through what we think was the actual chain of events.
Bear with us, it's quite interesting.
So here is the decode of all the messages in the order of the first summary :
0210Z
A/P OFF : The AFS monitors the air data from the ADRs. Any brutal variation of CAS, ALT, Mach causes the A/P to disengage : here, as the pitot system is suspect, a variation of 20kt or Mach.04 for .45 second is enough to disconnect both FDs and the A/P.
Reactive windshear detection: with the ADRs been rejected by the AFS,, AoA is not accessible any more.
F/CTL Alternate Law : is normally a result of the "ADR DISAGREE" condition. The flight Control Laws revert , from "Normal Law" to "Alternate Law 2". The Prims are in charge of the voting and elimination of a duff ADR, but it takes them 10 seconds to do so (threshold is 16 kt / 10 sec.
Flight Director Flag on captain's PFD
Flight Director Flag on F/O's PFD
Auto Throttle OFF (These last three should have appeared at the same time as the A/P OFF warning.)
TCAS Fault : Result of the loss of the associated ADR (for altitude data)
Speed Limit Flag on Captain's PFD
Speed Limit Flag on F/O's PFD ( these two result of rejected Airspeed information by the EFCS, might be a sign of the PROT LOST, which hasn't been indicated)
Rudder Travel Limiter Fault is normally a result of the "ADR DISAGREE" condition.
EFCS 1 Fault on Maintenance Status
EFCS 2 Fault on Maintenance Status
Probe-Pitot 1+2 / 2+3 / 1+3 / (9DA. Relates to Heating element PITOT 1
Primary Flight Computer #2 (ADIRU1 signal to Prim 2)
0211Z
FPV Flag on Captain's PFD
FPV Flag on F/O's PFD
Speed or Mach function on ISIS (Suspect loss of ADIRU 3 for ISIS MACH )
IR2 Fault (Discrete data streams = Pitot, Static , TAT, OAT to ADIRU 2)
0212Z
ADR DISAGREE : TOOK IT A LONG TIME TO APPEAR NOW !
0213Z
Primary Flight Computer #1 Fault (Crew manipulation suspected, on ADR DISAGREE C/L )
Secondary Flight Computer #1 Fault ------Idem----------------------
ADR2 Fault on Maintenance Status Another very late message
Intermittent Fault on FMGEC #1
0214Z
Cabin Vertical speed Advisory. We now believe that this advisory message is just a result of ADR data
There is a glaring conclusion : there is no way that the ACARS have been transmitted in the order of the summary.
Firstly because we find a 0212z event in the middle of the 0211 ones, and the same for two 0213Z's between 0214z messages...
Secondly, it is also obvious that the ADR DISAGREE message/warning is too late in view of all the happenings that should have been its consequences .
But looking at the system, we can see in fact the trouble-shooting "reasoning" of the system facing multiple incoherent data at the same time.
The explanation will come in the second part, in which we deal with the time tags and propose one - for us the most logical - chain of events.
See this post and below:
AF A332 Crash (F-GZCP) - Part 19 — Civil Aviation Forum | Airliners.net