[UCANSEE2]

What are the possible (given the scenario) causes for the FBW Flight Controller problem?

[expatpat]

The ADIRU, which prepares the input data for the computers in the FCS, has a known failure history (it has had 2-3 emergency ADs in the last few months). It is surprising to me that the planes are still allowed to fly passengers with such serious ADs on a flight-critical component.

If the ADIRU fails, it feeds garbage to the computer(s) which then output garbage to the flight-surface actuators. There is no back-up to the FBW control system -- if it fails, the A/C is uncontrollable.