Airconditioning, Pressurization, & Pneumatics

Question 1

Location of RECIRC fan

Answer 1

Behind AFT pressure bulkhead

Question 2

When does the RECIRC fan operate at slow speed?

Answer 2

Initially selected on, during engine start, and during single ACM operations

Question 3

Pack control switch AUTO

Answer 3

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 4

Pack control switch MAN

Answer 4

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 5

Pack control switch OFF

Answer 5

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

Question 6

Air distribution for dual ACM operation

Answer 6

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

Question 7

Air distribution for single ACM operation

Answer 7

approximately 70% air flow

Question 8

Describe the aft outflow valve

Answer 8

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

Question 9

Describe the aft safety outflow valve

Answer 9

electro-pneumatic valve, located on aft pressure dome, supplies additional vent on ground with at least one engine running at idle or APU is operating, incorporates positive and negative pressure relief valve

Question 10

Describe the forward safety outflow valve

Answer 10

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

Question 11

Four modes of operation for pressurization system

Answer 11

Automatic,
Manual,
Emergency/Smoke Removal,
Pressure Dump

Question 12

Pressurization mode select switch AUTO

Answer 12

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

Question 13

Pressurization mode select switch MAN

Answer 13

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

Question 14

Pressurization mode select switch DUMP

Answer 14

Fully opens aft outflow valve to dump cabin pressure

Question 15

Manual differential control switch INCR

Answer 15

Increases cabin pressure differential by closing aft outflow valve

Question 16

Manual differential control switch DECR

Answer 16

Decreases cabin pressure differential by opening aft outflow valve

Question 17

Pressurization Fault Warning Advisory Light (amber)

Answer 17

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

Question 18

When does the aircraft being to pressurize?

Answer 18

PLA greater than 60 degrees

Question 19

Describe the “takeoff abort” feature.

Answer 19

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

Question 20

Describe emergency ram-air ventilation.

Answer 20

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 21

Environmental Control Unit (ECU) location

Answer 21

Avionics equipment bay

Question 22

Bleed Air System (BAS) air sources

Answer 22

APU

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

Question 23

Describe the Environmental Control Unit (ECU).

Answer 23

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 24

Describe the ECU digital channels.

Answer 24

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 25

Describe the ECU analog channels.

Answer 25

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

Question 26

Bleed 1 & 2 ON/OFF switches

Answer 26

Energize respective Nacelle Shutoff Valves (NSOV)

Question 27

Bleed Air Selector (rotary action)

Answer 27

Modulates NSOVs to control volume of bleed air

Question 28

Describe the BAS high stage pre-cooler.

Answer 28

Cooling air from P2.2 engine bleed port is routed through a high stage pre-cooler to reduce temperature of HP bleed air when necessary as decided by ECU

Question 29

Describe the BAS deice pre-cooler.

Answer 29

Continuous flow of P2.2 bleed air is routed through deice pre-coolers to reduce temperature of both LP (P2.7) and HP (P3.0) bleed air before it goes into the deice system

Question 30

Describe a bleed air over-temperature.

Answer 30

An over-temperature switch is installed in the bleed supply duct downstream of the high stage pre-cooler to monitor temp just prior to NSOV, signals ECU to close NSOV

Question 31

Describe a nacelle duct leak over-temperature.

Answer 31

switches are installed in the outer jacket of the bleed air supply duct downstream of NSOV, signals ECU to close NSOV

Question 32

Describe a bleed over-pressure.

Answer 32

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

Question 33

1 or #2 BLEED HOT caution light

Answer 33

bleed air supply duct temperature is more than 354C

Question 34

FLT COMPT DUCT HOT caution light

Answer 34

flight compartment supply duct temperature is more than 213C

Question 35

CABIN DUCT HOT caution light

Answer 35

cabin supply duct temperature is more than 213C

Question 36

CABIN PACK HOT caution light

Answer 36

cabin pack temperature is more than 88C

Question 37

FLT COMPT PACK HOT caution light

Answer 37

cabin air cycle machine compressor discharge temperature is more than 88C