Pneumatics Flashcards
What happens when one BMC fails?
The other BMC controller takes over and it monitors over pressure and wing leak. It does not monitor over temperature, it loses that functionality.
And the associated bleed wall does not close automatically.
APU leak warning is also lost if BMC 1 has failed.
When and how does the bleed valve shut?
It shuts
A.) pneumatically
If upstream pressure is lesser than 15 psi
If there is a return flow
B.)Electrically
i) By pressing the bleed push button on the overhead panel
ii) By pressing the engine fire push button
iii) By the BMC, In case of:-
Overtemperature Overpressure Leak Open starter valve Engine shutdown Apu bleed on No bleed consumers HPV valve failed open Bleed temperature lost Fan duct burst detected by FADEC 
What is the pressure is normally maintained by the bleed valve?
The pressure normally maintained by the bleed valve is 42+ or -3 in dual bleed operations and 50+ or -3 in single bleed operations.
When does the over pressure valve close?
Over pressure valve closes when the pressure coming is above 75 psi
What pressure is maintained by the high pressure valve?
65+ or -15 psi
In case of an APU bleed valve opening, how long does it take for the HP valve to close?
30 seconds after the closure of the bleed valves.
When and how does the HP VALVES close?
The HP valve closes
i)Electrically
When the bleed valve is closed electrically
ii)Pneumatically
If it detects a excessive upstream pressure
If it detects low upstream pressure
How many motors does the cross bleed have?
It has two motors. One for automatic operation and another for manual operation.
When does the Cross Bleed valve open in automatic mode?
It opens when the APU bleed while has been switched on.
When does the cross bleed valve close automatically?
 It shuts automatically when it detects a wing leak except during engine start.
When does the APU bleed valve supply pneumatic power?
It supplies pneumatic power when N is greater than 95%.
When does the APU bleed valve close automatically?
It closes automatically when it detects a left wing leak wing, APU LEAK or pylon 1 leak(except if in case an engine is starting)
