Pressurization ***

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.

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.

Question 3

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

Answer 3

• Climb, cruise, and descent

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

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.

Question 6

What is maximum cabin altitude in cruise mode?

Answer 6

• 8,000 feet

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.

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.

Question 9

When does the cabin rate limiter close both outflow valves?

Answer 9

• When cabin altitude exceeds 11,000 feet.

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.

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

Question 12

Describe the NORM position of the Cabin Altitude Selector.

Answer 12

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

Question 13

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

Answer 13

• The secondary controller is automatically selected.

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
.

Question 15

Describe pressurization upon touchdown?

Answer 15

Small positive pressure

At touchdown, the outflow valves open to depressurize the cabin

Question 16

What protection is lost when both outflow valves are operated manually?

Answer 16

Cabin Altitude Limiter

Question 17

What happens is excessive cabin pressurization occurs?

Answer 17

Positive pressure relief valves OPEN and PACK 2 shuts down until pressure is relieved.

Question 18

During climb, the cabin altitude gradually increases so that when cruise is reached a target differential pressure of ____ is achieved?

Answer 18

9.4 PSI

Question 19

When does the cabin altitude controller enter cruise mode?

Answer 19

When within 200’ of cruise altitude or when the aircraft vertical climb falls below 100FPM for more than one minute.

Question 20

When does CABIN ALT AUTO message appear on EICAS?

Answer 20

• Both cabin altitude controllers FAILED
• Both manual switches are on

Question 21

When does EICAS Warning CABIN ALTITUDE and aural warning message sound?

Answer 21

10000’ cabin altitude

Question 22

When do O2 masky automatically deploy in flight?

Answer 22

14000’ cabin altitude

Question 23

When can pax oxygen system be reset?

Answer 23

Once cabin altitude has dropped to below 12000’

Question 24

When do cabin warning messages re-arm after being triggered?

Answer 24

Below 9500’ cabin altitude. EICAS message CAB ALT returns to amber

Question 25

If you forget to enter a CRZ altitude into FMC, what will controllers assume cruise altitude to be?

Answer 25

FL390

Question 26

What is the cabin altitude sequence of events?

Answer 26

8500’ - Cabin Altitude Indicator turns amber
10000’ - Warning, Aural
11000’ - Outflow Valves Close
14000’ - Masks Drop
12000’ - Passenger O2 system can be reset
9500’ - Cabin Warning Messages Rearm

Question 27

How many positive pressure relief valves? Location?

Answer 27

• 2 total
• In EE Compartment + FWD Left Fuselage

Max differential pressure 9.4 psi

Question 28

Where are negative pressure relief valves located?

Answer 28

• Side cargo door
• FWD + AFT low Cargo Doors