Airconditioning, Pressurization, & Pneumatics

Question 1

Pack control switch AUTO

Answer 1

ECU’s digital channels control the operation of the Pack Flow Control & Shut off Valve (FCSOV) and the respective Pack Bypass Valve (in response to manual inputs) to automatically regulate cabin or flight compartment temperatures

Question 2

Pack control switch MAN

Answer 2

ECU’s analog channels control on the Pack Bypass Valves (in response to manual inputs) to regulate cabin or flight compartment temperatures, FCSOV remains full open

Question 3

Pack control switch OFF

Answer 3

ECU closes the FCSOV and the Turbine SOVs resulting in a shut down of both ACMs

Question 4

Air distribution for dual ACM operation

Answer 4

Half of left ACM for flight compartment, half of left ACM and all of right ACM for cabin compartment

Question 5

Air distribution for single ACM operation

Answer 5

approximately 70% air flow

Question 6

Describe the aft outflow valve

Answer 6

Electrically controlled, located on aft pressure dome, primary valve regulated by Cabin Pressure Controller

Question 7

Describe the aft safety outflow valve

Answer 7

electro-pneumatic valve, located on aft pressure dome, incorporates positive and negative pressure relief valve

Question 8

Describe the forward safety outflow valve

Answer 8

pneumatic valve, located on forward pressure bulkhead, used for emergency operations, incorporates positive and negative pressure relief valve

Question 9

Four modes of operation for pressurization system

Answer 9

Automatic,
Manual,
Emergency/Smoke Removal,
Pressure Dump

Question 10

Pressurization mode select switch AUTO

Answer 10

Cabin altitude is automatically controlled by Cabin Pressure Controller by modulating the aft outflow valve

Question 11

Pressurization mode select switch MAN

Answer 11

Turns off Cabin Pressure Controller and enables manual control via aft outflow valve

Question 12

Pressurization mode select switch DUMP

Answer 12

Fully opens aft outflow valve to dump cabin pressure

Question 13

Manual differential control switch INCR

Answer 13

Increases cabin pressure differential by closing aft outflow valve

Question 14

Manual differential control switch DECR

Answer 14

Decreases cabin pressure differential by opening aft outflow valve

Question 15

Pressurization Fault Warning Advisory Light (amber)

Answer 15

Illuminates when the cabin pressure controller system detects a fault, also momentarily during initial power up self-test mode

Question 16

Describe the “takeoff abort” feature.

Answer 16

CPC remains in takeoff mode for at most 10 minutes after lift off, avoids the requirement to reselect the landing altitude

Question 17

Describe emergency ram-air ventilation.

Answer 17

during unpressurized fight aircraft can be ventilated with outside ram air via dorsal fin NACA vents exhausting through forward safety outflow valve, directed by abnormal checklist

Question 18

Bleed Air System (BAS) air sources

Answer 18

APU

Engine - low-pressure compressor port, high-pressure compressor port (depending on power setting)

Question 19

Describe the Environmental Control Unit (ECU).

Answer 19

serves as the interface for control panel inputs and the mechanical and electrical components of the BAS, has redundant (left and right) digital and analog channels

Question 20

Describe the ECU digital channels.

Answer 20

Control the LP and HP bleed ports of their respective engines, monitor bleed protective sensors to maintain correct temperatures, pressures, flow rates, and positioning of various BAS valves

Question 21

Describe the ECU analog channels.

Answer 21

They serve as a backup and only control LP engine bleed air (HPSOV remains closed)

Question 22

Bleed 1 & 2 ON/OFF switches

Answer 22

Energize respective Nacelle Shutoff Valves (NSOV)

Question 23

Bleed Air Selector (rotary action)

Answer 23

Modulates NSOVs to control volume of bleed air

Question 24

Describe a bleed over-pressure.

Answer 24

switch installed in bleed supply duct downstream of NSOV, signals ECU to close NSOV