JD-EE wrote:
And where in the BEA reports does it declare the IRUs themselves all went unreliable at the same time. This exhausts my imagination trying to figure out how thus could happen short of a total power cut.
It doesn't. I had the same misconception which Takata helpfully corrected just recently.
In the second report, BEA said "No message present in the CFR indicates the loss of displays or of inertial information (attitudes)."
As I understand them (and again, I stand to be corrected by an expert here!), the BEA discussions of the messages (eg especially sec 1.16.2.4.1, the MAINTENANCE STATUS ADR2 explanation and the ADIRU2 (1FP2) explanation) indicate that only the air data was corrupted/divergent -- the underlying IR data was valid.