Pnuematics

Question 1

What are the three sources of air on
ground?

Answer 1

External, APU and engine air
Ref: AOM 2A

Question 2

What’s another name for 5th And 8th
stage air?

Answer 2

Mid and high stage
Ref: AOM 2A

Question 3

What’s the purpose of pressure
regulating shutoff valve?

Answer 3

Maintain a maximum bleed manifold pressure of
approximately 40.5 psi
Ref: AOM 2A

Question 4

What’s the preferred source of air
and why?

Answer 4

5th
stage because it has lower pressure and
temperature
Ref: AOM 2A

Question 5

What’s the purpose of 8th

stage bleed valve?

Answer 5

To supply supplemental air to maintain bleed
manifold pressure of 14 to 35 psi depending on
configuration and existing conditions
Ref: AOM 2A

Question 6

What’s the caution associated with
use of external air?

Answer 6

Do not connect air with electrical power off
Ref: QRH NG-16

Question 7

What are the requirements for APU
load control valve to open in-flight?

Answer 7

Both engine bleed air switches, both pack switches,
and both wing anti-ice switches must be in OFF
position
Ref: AOM 2A

Question 8

What’s the purpose of isolation
valve?

Answer 8

In the normally closed position, it isolates left and
right bleed air manifolds
Ref: AOM 2A

Question 9

Other than using ISOLATION valve
switch, how else can isolation valve
be opened?

Answer 9

APU air switch with weight on wheels, or engine
MASTER START or CRANK
Ref: AOM 2A

Question 10

If isolation valve cannot be opened
electrically, how else can it be
opened?

Answer 10

It incorporates a manual wrenching device
Ref: AOM 2A

Question 11

Why does one pack shut down after
selection of MASTER START or
CRANK, and another shut down with
selection of L or R ENG START?

Answer 11

This shutdown is designed to prevent large pressure
bump during start by initiating two smaller ones that
shouldn’t be as noticeable
Ref: AOM 2A

Question 12

What’s the caution associated with
use of engine bleed air and APU air?

Answer 12

They shouldn’t be selected ON at same time
Ref: QRH

Question 13

What are BAC’s responsible for?

Answer 13

Regulation of bleed air manifold temperature and
supply pressure (i.e., responsible for min pressures
and all temperatures)
Ref: AOM 2A

Question 14

What wing temperature is maintained
during wing anti-ice operation?

Answer 14

Approximately 130°F
Ref: AOM 2A

Question 15

What happens to high stage bleed
pressure when a PACK switch is
selected to OFF?

Answer 15

It’s reset to 35 psi
Ref: AOM 2A

Question 16

What temperature would you expect
at precooler inlet during wing anti-ice
operation?

Answer 16

Maximum of 630°F depending on power lever
position

Ref: AOM 2A

Question 17

What precooler outlet temperature
would you expect under normal
operating conditions?

Answer 17

400°F

Ref: AOM 2A

Question 18

What’s the maximum temperature of
bleed air at precooler outlet during
wing anti-ice operation with single
WING ANTI ICE switch or single
ENG BLEED switch selected to ON?

Answer 18

500°F

Ref: AOM 2A