747-400 EIU logic
This question relates to a Sim but ought to be the same as the live aircraft.
Whereabouts is the decision made for an EIU to be selected ? On our Sim it naturally will sit with the centre and left DUs fed from the left EIU until the left fails, when it then passes all of those 4 DUs to the centre EIU. Is this non-standard? I assumed that the centre displays would be powered normally from the centre EIU. We have an odd fault in that the left EIU sometimes trips off during engine starts and can be reset by the breaker. The CMC display test shows which DUs are powered by which system and when the fault occurs it suggests the left EIU issue is not with the box itself, but more likely in whatever system selects it. Changing EIU units over between left and centre racks doesn't move the fault. I hope this makes sense.
It is staring to give me a headache!
Thanks
B