Pneumatics Flashcards
Where does engine bleed air come from?
The 9th and 14th stages of the compressor. Coordination
Reference: OM Vol.2, Section 2-14, Pneumatic System
How would the bleeds and packs be configured for a summer takeoff in IAH with an APU deferred by MEL?
Engine bleeds open, APU bleed closed, PACKS off.
Reference: OM Vol.3, Section 3, Before Takeoff Checklist
When does the aircraft use 14th stage bleed air?
Low thrust settings, cross-bleed engine starts, icing operations
Reference: OM Vol.2, Section 2-14, Pneumatic System
What is the normal, in-flight position of the crossbleed knob and the crossbleed valve?
The cross-bleed valve is in the AUTO position, and the cross-bleed valve is closed.
When will the cross-bleed valve open automatically when the cross-bleed knob is in the AUTO position?
During a cross-bleed start or anytime that there is demand for bleed air from the other side of the system. Other examples include: engine 1 start from an external air source and an engine 2 start with the APU.
Regarding the priority logic of the available bleed sources, if the APU bleed was selected open, what would occur after opening the engine 1 bleed valve?
The APU bleed valve would close.
Reference: OM Vol.2, Section 2-14, Pneumatic System
What are the indications of a bleed leak?
A red ‘LEAK’ inscription appears over the button of the affected bleed. Additionally, the EICAS BLD 1(2) LEAK master warning will be presented.
Reference: OM Vol.2, Section 2-14, Pneumatic System
What automatically happens after a bleed leak has been detected?
The affected bleed valve should automatically close.
Reference: OM Vol.2, Section 2-14, Pneumatic System
What indications would be visible on the APU bleed valve button if the APU is OFF and the APU bleed valve is selected open?
A white line only. The ‘OPEN’ inscription would not be visible.
Reference: OM Vol.2, Section 2-14, Pneumatic System
What does the message ‘BLD 1(2) OVTEMP’ mean?
A bleed over-temp message indicates that the air downstream of the pre- cooler is too hot. The bleed valve, however, will not automatically close.
Reference: OM Vol.2, Section 2-14, Pneumatic System
While taxiing in icing conditions, is it possible for the APU bleed to be used on the ground for the PACKS while simultaneously using engine lip anti-ice protection?
Yes, the bleed air used for engine lip anti-ice protection does not require the engine bleed valve to be open.
Reference: OM Vol.2, Section 2-14, Pneumatic System
When would the crossbleed valve open when in the auto position?
During a crossbleed engine start Reference: OM Vol.2, Section 2-14, Pneumatic System
