Originally Posted by
tdracer
Yes, any information that comes from LRUs that are not on the battery buss would be lost when main bus power is lost.
I'm not familiar with the specifics of the 787 avionics, but the following are required for continued safe flight and landing, and are on the battery:
Left EICAS
Left PFD
One ADIRU (likely the left).
At least one level of the FBW system
I
assume the EECs were also sending data to the front recorder, as N1/N2 speeds and EGT were mentioned in the report.