11.16 Pneumatic and Vacuum

Question 1

What does the pneumatic system do?

Answer 1

Transfers energy through manipulation of air pressure.

Question 2

What are the power sources for pneumatic systems?

Answer 2

Engines
APU
GPU

Question 3

What four basic category systems are there?

Answer 3

Vacuum
Low pressure
Medium Pressure
High pressure

Question 4

What is the main purpose of the vacuum system?

Answer 4

Gyros

Question 5

How is the vacuum reduced for the turn and bank indicators?

Answer 5

Needle valves.

Question 6

What is the low pressure system used for?

Answer 6

Anti-icing

Question 7

What pressure does the medium system run at?

Answer 7

50-150 psi

Question 8

When is engine LP or IP air used?

Answer 8

During take off, climb and cruise.

Question 9

When is APU bleed air available?

Answer 9

When it is running above 95%

Question 10

What three types of compressor are there?

Answer 10

Positive displacement
Multi stage
Centrifugal

Question 11

What do stack pipes do?

Answer 11

prevent contamination from passing to the system or pressure gauge.

Question 12

What does a rotary compressor look like?

Answer 12

Two screwjacks

Question 13

What two types of vacuum pump are there?

Answer 13

Wet
Dry

Question 14

How is the wet pump design been improved?

Answer 14

Incorporating carbon into the vanes and rotor.

Question 15

How are venturi tubes rated?

Answer 15

When they produce 120mph

Question 16

What are the two inch venturis used for?

Answer 16

Two inches of Mercury suction to drive one turn and bank indicators

Question 17

What are 4 inch venturis used for?

Answer 17

Directional and attitude gyros

Question 18

What is the purpose of a check valve?

Answer 18

One way

Question 19

Where is the moisture separator located?

Answer 19

Downstream of the compressor

Question 20

What system automatically controls the pneumatics?

Answer 20

Air supply control and test unit (ASCTU)

Question 21

What is the duct pressure?

Answer 21

20 psi

Question 22

What is the flow of air in a duct approx?

Answer 22

10 lbs/sec

Question 23

With the fan air valve, the higher the temp rises what happens?

Answer 23

The wider the valve opens

Question 24

When does the engine bleed valve automatically close?

Answer 24

When the temp exceeds 254 degrees c

Question 25

What does white circle with flow bar in-line with the duct mean?

Answer 25

Open

Question 26

What does white circle with flow bar perpendicular to the duct mean?

Answer 26

Closed

Question 27

What does amber valve open symbol with amber ‘X’ mean?

Answer 27

Failed open

Question 28

The APU starter disengages at what RPM?

Answer 28

55%