Originally Posted by
NSEU
I assume the EECs were also sending data to the front recorder, as N1/N2 speeds and EGT were mentioned in the report.
The EEC/FADECs will stay powered down to about 8% N2(N3) using the dedicated PMA. So yes, they will keep transmitting data so long as they are powered even if aircraft power is lost.
Naturally, the interfacing electronics between the EECs and the FDR need to stay powered for that data to do any good, but it appears that on the 787 they keep enough stuff on the battery that the EEC provided engine parameters still made it to the battery powered FDR (that's not the case on many aircraft).