Pressurization

Question 1

Pressurization

How is cabin pressurization controlled ?

Answer 1

By regulating the discharge of conditioned cabin air through the 2 outflow valves: FWD and AFT.
The outflow is normally split between the two.
Note: 1 valve is sufficient for full cabin altitude and ventilation rate control.

Question 2

Pressurization

How many Positive Relief Valves are there ?

Answer 2

2

Left side of the fuselage.

Question 3

Pressurization

How many Negative Relief Valves are there ?

Answer 3

4

Two on each side of the fuselage.

Question 4

Pressurization

How many operating modes does the CPCS (Cabin Pressure Control System) have ?

Answer 4

3
• Climb
• Cruise
• Descent

Question 5

Pressurization

If CRZ altitude is not available from the FMC in AUTO, which altitude will be used by the CPCS (Cabin Pressure Control System) ?

Answer 5

43 000 ft

Question 6

Pressurization

In MANUAL mode, how long will the outflow valves take to go from FULL OPEN to FULL CLOSED and vice-versa ?

Answer 6

30 seconds.

Question 7

Pressurization

Which color is the outflow valve indication on the EICAS in MAN ?

Answer 7

AMBER

M also appears on the outflow valve indication.

Question 8

Pressurization

When the LDG ALT button is pulled ON, in which color is the landing altitude displayed on the EICAS ?

Answer 8

AMBER

Question 9

Pressurization

What does an Amber LANDING ALTITUDE message displayed on EICAS mean ?

Answer 9

• Landing altitude is unavailable from the FMC and,
• Landing altitude is not set in MAN.

When this occurs, the cabin altitude controller assumes a landing altitude of 2000 feet.

Question 10

Pressurization

After a depressurization, at which altitude do the outflow valves fully open for the remainder of the flight ?

Answer 10

• When the airplane reaches 15 000 feet or,

* When the airplane descends below the cabin altitude.

Question 11

Pressurization

What will happen to the cabin altitude during a planned level segment in the FMC ?

Answer 11

The cabin altitude will continue to climb as scheduled.

Question 12

Pressurization

What altitude does the cabin descend to during the descent mode ?

Answer 12

Slightly below the destination airport elevation.

Question 13

Pressurization

What system automatically provides the landing altitude to the CPCS (Cabin Pressure Control System) ?

Answer 13

the FMC.