What would lead to the attitude indicators failling, RWA?
It has been explained to me in the various other threads on this topic that the attitude indicators are driven by ring
laser gyros. I had posited that perhaps the pilots were on a "partial panel" sort of scan, and was advised with some vigor that my supposition was groundless.
There don't appear to be ACARS messages indicating Inertial Reference kicking off, so what anomaly do you think would account for both (all three?) of the "gyros" dropping off?
Or, if you think there was a single failure, the pilot flying, how would the BEA know that his failed and left seat pilot's didn't? Unless the BEA is able to find and publish evidence of an attitude indicator failure, it's hard to point to that as a causal factor.
FWIW (From a summary of
how an ADIRU works on wikipedia, consider the source ...) :
An ADIRS consists of up to three
fault tolerant ADIRUs located in the aircraft electronic rack, an associated Control and Display Unit (CDU) in the cockpit and remotely mounted Air Data Modules (ADMs).
The No 3 ADIRU is a
redundant unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU.
There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data.
An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of
attitude and navigation information on their associated
Primary Flight Display (PFD) and Navigation Display (ND) screens.
An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
As I understand how the ACARS messages were deciphered, it was that ADR faults that stood out, not IR faults. I may misunderstand what was reported.