Clarify the question...
Are you asking about a physical failure of the bus DC1 or DC2 or just a failure of power to the bus?
There is an automatic change of power source if the normal power source for each DC bus fails.
That is explained clearly in the electrical chapter.
'our company modified manuals include guidance as to which bus powers each system.'
Indeed, over the years, the manuals have been steadily reducing the information given about the 'nuts and bolts' of the systems. Big example being MCAS omission. Truth is without constant review, remembering that kind of information is very difficult and in case something does happen, trying to out think the QRH and going outside the "legal" recommendations contained therein will be frowned upon in this ever increasing regulatory climate.
peppered throughout the manual one will find an occasional clarification of the specific bus source of various items.
at the end of the electrical chapter is a list of operating items with all generators inop. That's best you may get.
try to contact a mx individual at your airline. They can be a good source of extra information.
Sometimes.
Last edited by 70 Mustang; 29th April 2023 at 15:39.