Originally Posted by
BuzzBox
Rubbish. If the crew had lost the left and centre DUs, they would have needed the FO's inboard display selected to EICAS to assess the situation and to provide engine indications. Furthermore, in your scenario it would make sense for the FO in the right seat to fly the aircraft, because he has the only available PFD. That would leave the Capt to run the checklists from the left seat, using the QRH.
If the left and centre DUs are inoperative, only the 2 right DUs are available. The right outboard would be used for the PFD. So if the Captain wants to look at the Electrical Synoptic Display, he/she has to change the right inboard to MFD and select the electrical display, thus at that moment there ISN’T an EICAS display visible.