@rananim: Interesting point.
AT computer is fed by RA#1 or both RA#1 and RA#2 depending on software update.There are diagrams in the AMM showing this.
Seems Boeing is aware of the potential situation this can cause. Can you elaborate if this was:
1. Mandatory safety update (so, not done (yet) on the Turkish?)
2. Software update fitted by default to later built aircraft (if so, why were older NG not updated?)
3. Optional fit when ordering (if so, why is this not default on all NG?)