Chapter 36 Pneumatics Flashcards
What is it necessary to do before connecting the ground air conditioning cart?
To have the battery on and packs off.
What happens, pneumatics wise, when the fire handle is pulled?
A close signal is sent directly to the BAR solenoid valve, causing the PRSOV to close and shutting off engine bleed.
This happens regardless of the bleed switch position.
What is the purpose of the AUTO selection of the isolation valve?
If any bleed switch is in the off position, the isolation valve will open.
If all the bleed switches are on, the isolation valve will close.
If you are only running engine two, how would get trigger the blue DUAL BLEED light to illuminate?
APU bleed would have to be on, and the isolation valve in the open position.
What is the maximum altitude an APU can provide pneumatics?
17000ft.
How do you manually control the position of the PRSOV?
If you turn the ENG bleed switch to off, or by pulling the fire handle.
Where is the BAR?
(Bleed air regulator)
Above the PRSOV
How do you lock out the high stage valve and the PRSOV if the MEL requires it?
Manually by loosening the nut, turning the valve and re-tightening.
How does the high stage valve operate?
The operation of the high stage valve is automatic.
It takes bleed air from the 9th stage compressor and attempts to keep a constant pressure of around 34psig
What is the position of the Pre-cooler control valve when the engine is shut down?
It defaults to the open position.
In what position is the PCCV in when we supply bleed pressure to start the engine?
It is in the closed position.
What is the purpose of the 390f temperature sensor in the PCCV?
The 390f temp sensor controls the position of the PCCV allowing it to bleed out pressure and send more or less air through the Pre-Cooler.
In what conditions will the WTAI valve operate?
Only when the aircraft is on the ground.
