Pressurization

Question 1

Pressurization and ventilation are primarily controlled by which two valves?

Answer 1

Outflow valve and the Overboard Exhaust Valve.

Question 2

Where is the outflow valve?

Answer 2

Rear of the aircraft

Question 3

Where is the overboard exhaust valve?

Answer 3

underneath the aircraft kind of aligned with forward doors.

Question 4

How many automatic pressurization controllers are there?

Answer 4

2 installed.

Question 5

The outflow valve is controlled automatically when in either ____ or _____ pressurization modes.

Answer 5

AUTO or ALTN.

Question 6

When does the CLOSE/OPEN switch for pressurization?

Answer 6

Only when the selector switch is in MAN.

Question 7

T/F: The outflow valve indicator always shows the position of the outflow valve

Answer 7

true

Question 8

T/F: The initial planned cruising altitude should be set in the Flight Altitude indicator prior to takeoff.

Answer 8

true

Question 9

Every click of the Flight Altitude selector knob adjusts indication by _____feet over a range of _____ to ______feet.

Answer 9

500, -1000 feet, 42,000 feet.

Question 10

T/F: The intended landing airport altitude should be set before takeoff.

Answer 10

true

Question 11

What lights come on for a single failure of a pressurization controller?

Answer 11

AUTO FAIL AND ALTN (green light) lights come on.

Question 12

What lights come on for a dual failure of pressurization controllers?

Answer 12

Just the amber AUTO FAIL light comes on.

Question 13

What pilot action causes the green ALTN light to come on?

Answer 13

moving the pressurization selector switch to ALTN

Question 14

What causes the amber OFF SCHED DESCENT light to come on?

Answer 14

the aircraft descends prior to reaching the preset cruise altitude.

Question 15

What causes the green MANUAL light to come on?

Answer 15

moving the pressurization selector switch to MAN.

Question 16

What causes the intermittent cabin altitude warning horn to come on.

Answer 16

Cabin altitude exceeds 10,000 feet. The horn can be silenced by pressing the ALT HORN CUTOFF button.

Question 17

How many positive pressure relief valves are there and what do they do?

Answer 17

2 valves in the right rear of aircraft. They limit the max pressure differential to 9.1 PSI.

Question 18

How many negative pressure relief valves are there and what do they do?

Answer 18

1 valve in right rear of aircraft. Prevent atmospheric pressure exceeding internal cabin pressure which can sometimes occur with a very rapid descent from altitude.

Question 19

What types of motors are used to control the outflow valve in all cabin pressure controller modes?

Answer 19

DC motors. Ensure operation in event of AC failure.

Question 20

Where do the Cabin Pressure Controllers get their info from? What info do they use?

Answer 20

Air Data Inertial Reference Units (ADIRUs).

Ambient static pressure,
barometric corrected altitude
non-corrected altitude
calibrated airspeed.

Other inputs:
Throttle position via both stall management computers
Signals from the Air ground sensing system.

Question 21

How does cabin air normally leave the aircraft in flight?

Answer 21

conditioned cabin air exits through foot grills and is then routed to provide heating for aft cargo compartment and then to the outflow valve.

Question 22

What two things cause the overboard exhaust valve to open or close

Answer 22

differential pressure and air/ground status.

Question 23

If there is low differential pressure in air or ground, how is the Overboard Exhaust valve positioned?

Answer 23

open and warm air exits from the E&E bay overboard.

Question 24

If there is high differential pressure in air, how is the Overboard Exhaust valve positioned?

Answer 24

valve is closed and air is diffused to the lining of the forward cargo compartment.

Question 25

If either pack is in ____ and the ___ RECIRC FAN is OFF, the overboard exhaust valve is driven ____ to provide increased ventilation in the smoke removal configuration.

Answer 25

HIGH, R, open.

Question 26

What modes on pressurization do the FLT ALT and LAND ALT need to be set before flight?

Answer 26

AUTO and ALTN.

Question 27

The outflow valve is fully open to depressurize the aircraft on the ground during ________________.

Answer 27

lower power settings.

Question 28

When does cabin pressurization begin?

Answer 28

on the ground with higher power settings.

Question 29

If you make a return to your takeoff airport before reaching planned cruise altitude, do you need to set the landing altitude?

Answer 29

No, the altitude is retained in memory.

Question 30

When does the pressurization controller transition to the cruise phase of flight?

Answer 30

When the a/c reaches an altitude within 0.25 PSI of the selected flight altitude.

Question 31

The pressurization controller always strives to maintain the cabin altitude slightly below the selected____________.

Answer 31

landing altitude. IF not possible, a target differential pressure and cabin altitude based on selected flight altitude.

Question 32

When does the pressurization controller switch to the descent phase?

Answer 32

when the plane descends 0.25 PSI below the selected flight altitude.

Question 33

T/F: you land slightly pressurized?

Answer 33

true

Question 34

What causes the AUTO FAIL light to come on?

Answer 34

Loss of DC Power
Controller Fault
Outflow valve control fault
Excessive diff pressure (>8.75 PSI)
Excessive rate of cabin pressure change (+/-2000 sea level feet/min)
High cabin altitude (above 15,800 feet)* if controller not responding properly.

Question 35

What is the difference in MAN mode vs AUTO or ALTN for pressurization?

Answer 35

Full control. MAN has a separate DC motor powered by the DC standby system. The rate of change of the valve is slower in MAN mode. Full travel range time is 20 seconds.

Question 36

T/F: Control of cabin altitude may be regained by increasing thrust on ensure a sufficient supply of air.

Answer 36

true

Question 37

If cabin altitude is not controllable:

Answer 37

Don mask and set regulators to 100%
Establish crew communication

If cabin altitude might or has exceeded 14,000 ft:
PASS OXYGEN switch ON
Passenger signs ON
Do Emergency Descent Checklist.