Pneumatics

Question 1

What Systems do the Pneumatics power?

Answer 1

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.

Question 2

How many pneumatic systems are there?

Answer 2

3

Question 3

How are the three pneumatic systems powered?

Answer 3

Left - Engine 1/2
Center - APU/ HP ground
Right- Engine 3/4
All systems are interconnected

Question 4

Where is the pneumatic synoptic located?

Answer 4

EICAS ECS page

Question 5

T/F: High Pressure Air can be provided by engine bleed air, APU bleed air, or a ground source.

Answer 5

True

Question 6

The APU can provide high pressure air to the system in flight up to what altitude?

Answer 6

15,000’

Question 7

What do the Left and Right Sections provide power to?

Answer 7

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).

Question 8

What are the components of the Engine Bleed air system?

Answer 8

Intermediate Pressure (IP) stage
High Pressure (HP) stage
Pressure Regulating Valve (PRV)
Fan Precooler
Engine Bleed Valve.

Question 9

What occurs when an Engine Bleed Air Switch is OFF?

Answer 9

Switch Shows amber OFF
HP valve Closed
PRV Closed
Engine Bleed valve Closed
amber OFF is displayed anytime the Engine bleed valve is closed

Question 10

When would the IP stage provide bleed air?

Answer 10

At high thrust settings

Question 11

When does the HP stage provide bleed air?

Answer 11

At idle or reduced thrust settings

Question 12

What the purpose of the PRV?

Answer 12

Limit bleed air pressure to prevent damage.

Question 13

What is the purpose of the ENGINE BLEED VALVE? and how does it operate?

Answer 13

Control bleed air delivery, they are Electronically controlled and pneumatically operated.

Question 14

If an ENGINE BLEED VALVE is ON, when will the valve open?

Answer 14

When the engine provides forward air pressure.

Question 15

What happens to the ENGINE BLEED VALVE when another source of bleed air is higher?

Answer 15

It closes to prevent reverse airflow from the duct to the airflow.

Question 16

What are the pneumatic valve positions during engine start?

Answer 16

ENGINE BLEED VALVE is Open
PRV is closed (to prevent reverse airflow into the compressor)

Question 17

During normal start what happens to the valves as N2 reaches 50%?

Answer 17

Start Valve closes
PRV opens to allow forward airflow

Question 18

What happens if the start valve does not close after start?

Answer 18

PRV and bleed valve will remain positively closed, and engine nacelle anti-ice is not available.

Question 19

How does the fan precooler function?

Answer 19

By using ducted airflow from the engine fan.

Question 20

What will a bleed air Amber SYS FAULT illuminate for?

Answer 20

• bleed air overheat
• bleed air overpressure
• HP bleed valve open when it is commanded closed
• PRV open when it is commanded closed.

Question 21

What message would accompany a bleed air overheat?

Answer 21

Amber BLD 1,2,3,4, OVHT/PRV EICAS message

Question 22

With engine running and the BLEED Air switch ON, when would Nacelle anti-ice not be available?

Answer 22

• PRV has failed closed
• PRV is closed as a result of a detected bleed air overheat
• Engine start valve has not closed.

Question 23

With engine running and the BLEED Air switch OFF, when would Nacelle anti-ice not be available?

Answer 23

• 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.

Question 24

How does the APU bleed valve work?

Answer 24

It is a one way check valve to allow, to prevent reverse flow into the APU.

Question 25

What does the Amber valve like on the APU bleed valve indicate?

Answer 25

A switch position disagreement with the valve.

Question 26

How is an APU duct leak is detected? What happens?

Answer 26

Overheat detectors The APU will shut down automatically and cannot be restarted.

Question 27

What duct pressure information do we have? Where is it located?

Answer 27

Only the Left and Right systems ECS page of the EICAS

Question 28

What happens in the event of the Left or Right section isolation?

Answer 28

- Affected LE Flaps will not be pneumatically operated - Max of 1 pack should be on

Question 29

What happens when Trim Air is OFF.

Answer 29

The temperature control of the cabin zones operates in a backup temperature control mode.

Question 30

What should the crew do in the event Center section isolation?

Answer 30

AFT cargo heat to OFF Should not operate the APU bleed or HP bleed

Question 31

What does the air flow display on the ECS page represent?

Answer 31

Valve and switch position, not an actual display of airflow.

Question 32

Caution BLD DUCT LEAK L, C, or R EICAS message

Answer 32

Bleed air leak or overheat detected in associated sections.

Question 33

Advisory BLD 1,2,3, 4 OVHT/PRV EICAS message

Answer 33

An associated engine bleed air overheat is detected or if t he associated PRV has failed closed.

Question 34

Advisory BLEED 1,2,3, 4 EICAS message

Answer 34

Engine bleed air overpressure, or if the associated HP bleed valve or PRV has failed to close when commanded.

Question 35

Advisory HP ENG 1,2,3, 4 EICAS message

Answer 35

The associated HP bleed valve has failed closed.

Question 36

Advisory BLEED ISLN L,R EICAS message

Answer 36

The position of the associated Isolation Valve switch disagrees with the position of the isolation valve

Question 37

Advisory APU BLEED ISLN EICAS message

Answer 37

The APU bleed isolation valve position disagrees with the commanded position.

Question 38

Advisory BLEED 1,2,3,4 OFF EICAS message

Answer 38

The Engine BLEED Air switch is OFF and the associated engine bleed air valve is closed when the engine is operating.

Question 39

How many Sections does the pneumatic system have?

Answer 39

3