PRESSURIZATION SYSTEM

Question 1

How many cabin altitude controllers are provided?

Each Controller controls both ______?

Answer 1

• Two controllers, A and B. Each controller controls both outflow valves.
• FCOM, VOL 2; 2.30.1

Question 2

Can either outflow valve maintain cabin altitude and full ventilation?

One pack is selected off to ensure ___-?

Answer 2

• Yes
• One pack is selected off to ensure cabin doors may be opened
regardless of the position of the outflow valves if an emergency
evacuation is required immediately after landing.

Note:FCOM, VOL 2; 2.30.2

Question 3

What are the three modes controlled by the cabin altitude controllers?

Answer 3

• Climb, cruise, and descent

Note:FCOM, VOL 2; 2.30.1

Question 4

How do the cabin altitude controllers calculate a cabin pressurization schedule?

Answer 4

• They use ambient pressure, and
• Flight plan data from the FMC

Note:FCOM, VOL 2; 2.30.1

Question 5

Does cabin altitude continue to increase, or level-off, if there is a planned level segment during the climb phase?

Answer 5

• Continues to increase during the level segment.

Note:FCOM, VOL 2; 2.30.1

Question 6

What is maximum cabin altitude in cruise mode?

Answer 6

• 8,000 feet

Note:FCOM, VOL 2; 2.30.2

Question 7

When do the cabin altitude controllers enter descent mode?

Answer 7

• T/D, or
• An initial descent of approx. 1,000 feet from cruise altitude, regardless of T/D.

Note:FCOM, VOL 2; 2.30.2

Question 8

When in descent mode, do the cabin altitude controllers program a positive or a negative pressurization at touchdown?

Answer 8

• Small positive pressurization at touchdown.

Note:FCOM, VOL 2; 2.30.2

Question 9

When does the cabin rate limiter close both outflow valves?

Answer 9

• When cabin altitude exceeds 11,000 feet.

Note:FCOM, VOL 2; 2.30.2

Question 10

How can you gain manual control of the landing altitude, if the airport for takeoff or landing is not in the data base?

Answer 10

• By pushing the Landing Altitude (LDG ALT) Switch on the overhead
panel.
• MAN (amber) displays on primary EICAS.

Note:FCOM, VOL 2; 2.10.23

Question 11

What altitude is assumed by the cabin altitude controllers if landing altitude is not available from the FMC, and MAN is not selected?

Answer 11

• 2,000 feet

Note:FMC, VOL 2; 2.30.2

Question 12

Describe the NORM position of the Cabin Altitude Selector.

Answer 12

• Cabin altitude controller A or B selected automatically on alternate flights.

Note:FCOM, VOL 2; 2.10.24

Question 13

What happens if the primary controller selected by the cabin altitude selector switch fails?

Answer 13

• The secondary controller is automatically selected.

Note:FCOM, VOL 2; 2.10.24

Question 14

What action would allow you to gain manual operation of the pressurization system?

Answer 14

• Turn both Outflow Manual switches to ON.
• All automatic cabin altitude control functions are bypassed
.
Note:FCOM, VOL 2; 2.30.3