in every checklist for the 744 I am never told to de-select apu bleed from the overhead panel once the apu is off. Shouldn't I do this? Or is it not necessary?ThanksAlex

Turning the selector to OFF automatically closes the bleed valve in preparation for shutdown.Paul

Looking through the pmdg documentation it isn't necessary to turn it off as a valve is in place to prevent reverse airflow in the apu duct.Also valves in the engine ducts to prevent it except when starting.John Ellison