11.16 Pneumatic Systems

Question 1

What are the 3 sources a pneumatic system gets its power from?

Answer 1

engines, APU & GPU

Question 2

What are the 3 main parts of a pneumatic duct system?

Answer 2

left wing ducts, right wing ducts & crossover ducts

Question 3

What psi does a low pressure system produce, where does it get it from & what is it used for?

Answer 3

1-10psi, from engine or APU, used for anti-icing

Question 4

What psi does a medium pressure system produce, where does it get it from & what is it used for?

Answer 4

50-150psi, from compressor section of turbine engine & used to pressurize reservoirs in a hydraulic system

Question 5

What psi does a high pressure system produce, where does it get it from & what is it used for?

Answer 5

1000-3000psi, from metal bottles, used in pneumatic braking system

Question 6

When is LP & IP bleed air used?

Answer 6

during take-off, climb & cruise

Question 6

What 3 places is air bled of an engine compressor from & what type?

Answer 6

LP bleed port (twin shaft), IP bleed port (triple shaft) & HP bleed port

Question 7

When is HP bleed air used?

Answer 7

when LP & IP bleed air is inadequate

Question 8

When is APU bleed air available?

Answer 8

APU running above 95%

Question 9

What are the 2 types of positive displacement, vane type vacuum pumps?

Answer 9

wet pumps & dry pumps

Question 10

What are positive displacement, vane type vacuum pumps driven by?

Answer 10

engine accessory drive

Question 11

How are wet pumps lubricated?

Answer 11

from engines LP oil system

Question 12

What is the function of a separator in a wet pump?

Answer 12

Captures oil to prevent oil streaks across the fuselage

Question 13

How are dry pumps lubricated?

Answer 13

self-lubricated

Question 14

What are the vanes & rotor made of in a dry pump design?

Answer 14

carbon

Question 15

What are the vanes made of in a wet pump design?

Answer 15

steel

Question 16

What do Pressure Relief Valves (PRV) function as in a pneumatic system?

Answer 16

pressure limiting units

Question 17

What keeps a PRV in the closed position?

Answer 17

spring

Question 18

What is the duct pressure controlled to?

Answer 18

20psi

Question 19

How is the Fan Air Valve (FAV) operated and what type of valve is it?

Answer 19

pneumatically operated - butterfly valve

Question 20

What is the purpose of flow sensors?

Answer 20

monitor air supply in the distribution system

Question 21

What is used to control the pneumatic system manually & then automatically

Answer 21

Pneumatic control panel - pneumatic controller

Question 22

What is the main parameter controlled in the flight deck?

Answer 22

pneumatic manifold pressure

Question 23

Where is the isolation valve control switch located?

Answer 23

overhead panel in the flight deck

Question 24

Where are the overtemperature & duct sensors located, what are they controlled by?

Answer 24

ducting system - pneumatic controller

Question 25

What is used to turn the core engine spool during engine starting?

Answer 25

pneumatic power

Question 26

What is the function of the overpressure valve & when does it open?

Answer 26

protects users against overpressure - opens in case of PRV malfunction