Pressurization

Question 1

How many cabin altitude controllers are there?

Answer 1

Two - A and B

Question 2

How many controllers work with each outflow valve.

Answer 2

Each controller can control both outflow valves

Question 3

What are 3 modes controlled by cabin altitude controllers?

Answer 3

Climb, cruise, and descent

Question 4

What do cabin altitude controllers use to calculate schedule?

Answer 4

Ambient pressure and flight plan from FMC

Question 5

What does controller do during an intermediate level off during climb?

Answer 5

Cabin altitude continues to increase during the level segment.

Question 6

Max cabin altitude in cruise mode?

Answer 6

8000’

Question 7

When do cabin altitude controllers enter descent mode?

Answer 7

• TOD

- Initial descent of 1000’

Question 8

Describe pressurization upon touchdown?

Answer 8

Small positive pressure

Question 9

When does cabin rate limiter close both outflow valves?

Answer 9

When cabin altitude exceeds 11,000’

Question 10

What altitude is assumed if no auto or manual landing field elevation is selected/available?

Answer 10

2000’

Question 11

What happens if primary controller fails?

Answer 11

Auto switch to secondary controller

Question 12

What action would allow manual operation of pressurization system?

Answer 12

Turn both Outflow Manual switches to ON

Question 13

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

Answer 13

Cabin Altitude Limiter

Question 14

Which Cabin Altitude Controller is used for a flight segment?

Answer 14

Alternates between controllers for each flight.

Question 15

What happens is excessive cabin pressurization occurs?

Answer 15

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

Question 16

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

Answer 16

8.9 PSI

Question 17

When does the cabin altitude controller enter cruise mode?

Answer 17

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

Question 18

When does CABIN ALT AUTO message appear on EICAS?

Answer 18

• Both cabin altitude controllers FAILED

- Both manual switches are on

Question 19

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

Answer 19

10000’ cabin altitude

Question 20

When do outflow valves close?

Answer 20

11000’ cabin altitude in AUTO mode

Question 21

When do O2 masky automatically deploy in flight?

Answer 21

14000’ cabin altitude

Question 22

When can pax oxygen system be reset?

Answer 22

Once cabin altitude has dropped to below 12000’

Question 23

When do cabin warning messages rearm after being triggered?

Answer 23

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

Question 24

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

Answer 24

FL390

Question 25

What is the cabin altitude sequence of events?

Answer 25

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 26

How many positive pressure relief valves? Location?

Answer 26

• 2 total

- In EE Compartment + FWD Left Fuselage

Question 27

Where are negative pressure relief valves located?

Answer 27

• Side cargo door

- FWD + AFT Cargo Doors