Pneumatics Flashcards
What Systems do the Pneumatics power?
Air Conditioning,
Pressurization,
Wing and Engine Anti-ice,
Potable Water Pressure,
Engine Starters,
Pressurization of the Hydraulic System Reservoirs.
Aft Cargo Heat,
Leading Edge Flaps,
Hydraulic System Demand Pumps.
How many pneumatic systems are there?
3
How are the three pneumatic systems powered?
Left - Engine 1/2
Center - APU/ HP ground
Right- Engine 3/4
All systems are interconnected
Where is the pneumatic synoptic located?
EICAS ECS page
T/F: High Pressure Air can be provided by engine bleed air, APU bleed air, or a ground source.
True
The APU can provide high pressure air to the system in flight up to what altitude?
15,000’
What do the Left and Right Sections provide power to?
Air Conditioning Pack
LE Flaps
Wing Anti-ice
Associated Air Driven Hydraulic Demand Pump
Associated Hydraulic System reservoirs for the respective side (reservoir 1 and 2 on the left side; reservoir 3 and 4 on the right side).
What are the components of the Engine Bleed air system?
Intermediate Pressure (IP) stage
High Pressure (HP) stage
Pressure Regulating Valve (PRV)
Fan Precooler
Engine Bleed Valve.
What occurs when an Engine Bleed Air Switch is OFF?
Switch Shows amber OFF
HP valve Closed
PRV Closed
Engine Bleed valve Closed
amber OFF is displayed anytime the Engine bleed valve is closed
When would the IP stage provide bleed air?
At high thrust settings
When does the HP stage provide bleed air?
At idle or reduced thrust settings
What the purpose of the PRV?
Limit bleed air pressure to prevent damage.
What is the purpose of the ENGINE BLEED VALVE? and how does it operate?
Control bleed air delivery, they are Electronically controlled and pneumatically operated.
If an ENGINE BLEED VALVE is ON, when will the valve open?
When the engine provides forward air pressure.
What happens to the ENGINE BLEED VALVE when another source of bleed air is higher?
It closes to prevent reverse airflow from the duct to the airflow.
What are the pneumatic valve positions during engine start?
ENGINE BLEED VALVE is Open
PRV is closed (to prevent reverse airflow into the compressor)
During normal start what happens to the valves as N2 reaches 50%?
Start Valve closes
PRV opens to allow forward airflow
What happens if the start valve does not close after start?
PRV and bleed valve will remain positively closed, and engine nacelle anti-ice is not available.
How does the fan precooler function?
By using ducted airflow from the engine fan.
What will a bleed air Amber SYS FAULT illuminate for?
- bleed air overheat
- bleed air overpressure
- HP bleed valve open when it is commanded closed
- PRV open when it is commanded closed.
What message would accompany a bleed air overheat?
Amber BLD 1,2,3,4, OVHT/PRV EICAS message
With engine running and the BLEED Air switch ON, when would Nacelle anti-ice not be available?
- PRV has failed closed
- PRV is closed as a result of a detected bleed air overheat
- Engine start valve has not closed.
With engine running and the BLEED Air switch OFF, when would Nacelle anti-ice not be available?
- PRV has failed closed
- PRV is closed as a result of a detected bleed air overheat
- the engine start valve has not closed
- the HP bleed valve has failed open.
How does the APU bleed valve work?
It is a one way check valve to allow, to prevent reverse flow into the APU.
What does the Amber valve like on the APU bleed valve indicate?
A switch position disagreement with the valve.
How is an APU duct leak is detected? What happens?
Overheat detectors
The APU will shut down automatically and cannot be restarted.
What duct pressure information do we have? Where is it located?
Only the Left and Right systems
ECS page of the EICAS
What happens in the event of the Left or Right section isolation?
- Affected LE Flaps will not be pneumatically operated
- Max of 1 pack should be on
What happens when Trim Air is OFF.
The temperature control of the cabin zones operates in a backup temperature control mode.
What should the crew do in the event Center section isolation?
AFT cargo heat to OFF
Should not operate the APU bleed or HP bleed
What does the air flow display on the ECS page represent?
Valve and switch position, not an actual display of airflow.
Caution BLD DUCT LEAK L, C, or R EICAS message
Bleed air leak or overheat detected in associated sections.
Advisory BLD 1,2,3, 4 OVHT/PRV EICAS message
An associated engine bleed air overheat is detected or if t
he associated PRV has failed closed.
Advisory BLEED 1,2,3, 4 EICAS message
Engine bleed air overpressure, or if the associated HP bleed valve or PRV has failed to close when commanded.
Advisory HP ENG 1,2,3, 4 EICAS message
The associated HP bleed valve has failed closed.
Advisory BLEED ISLN L,R EICAS message
The position of the associated Isolation Valve switch disagrees with the position of the isolation valve
Advisory APU BLEED ISLN EICAS message
The APU bleed isolation valve position disagrees with the commanded position.
Advisory BLEED 1,2,3,4 OFF EICAS message
The Engine BLEED Air switch is OFF and the associated engine bleed air valve is closed when the engine is operating.
How many Sections does the pneumatic system have?
3
