Question for RB211 757 drivers

[kmox29]

When you complete a crossbleed start, say from right to left, will the left engine bleed air valve open automatically (switch is ON) if the isolation valve is still open?

 

[Big Beer Belly]

When you complete a crossbleed start, say from right to left, will the left engine bleed air valve open automatically (switch is ON) if the isolation valve is still open?

Yes. The valve is electrically controlled, pressure actuated. Once air pressure is sensed (with the switch ON) the bleed valve will open. (Selecting GND on the engine start selector signals the engine bleed valve to close during the start sequence as a protection against back pressure to the APU even though a check valve in the line should prevent this ... a redundant protection.)

BBB

 

[kmox29]

Thank you...