Pneumatics Flashcards
Where is pneumatic pressure derived?
Bleed air system.
Where does engine bleed air come from normally?
Low pressure bleed port. Automatically supplemented by the High pressure port as required.
When does the BLEED HOT caution light illuminate?
Temp over 290 degrees in the associated duct (#1 or #2)
If the nacelle shut off valve closes, is the de-ice system affected?
No, there is a supply upstream of the nacelle shut off valve.
What is the purpose of the HBOV?
To prevent compressor surge, stall and reduce noise levels. Automatically controlled by ECU.
Does the nacelle shut off valve fail to open or closed?
Open, allows for pressurisation to be maintained in an electrical failure.
In the event of a BLEED HOT caution light, why is the HP shutoff valve closed?
To prevent the thermal hazard posed by hot HP bleed air.
Why can the BLEED HOT caution cycle on/off?
The nacelle shut off valve is closed and then cools down so is reopened.
If a BLEED HOT caution light illuminates, does this affect the opposite side bleed air?
No, they are totally independent.
Can all bleed requirements be met with one engine shut down?
Yes
What happens to the bleed system in the event of an electrical failure?
The HP bleed valve closes to prevent a thermal hazard.
