PRESSURIZATION

Question 1

How many outflow valve are there?

Answer 1

2
One FWD and one AFT

Question 2

Through which outflow valves is cabin air normally discharged?

Answer 2

20% via the FWD valve and 80% via the AFT valve

Question 3

How is excessive differential pressure protection achived?

Answer 3

Via 2 positive pressure relief valves and
via 4 negative pressure relief valves

Question 4

For T/O, is the aircraft pressurized or depressurized?

Answer 4

A small pressurization prior to rotation is supplied to achieve a smooth cabin altitude transition to the cabin altitude climb schedule

Question 5

Without accurate FMC Cruise altitude data, what is the assumed cruise altitude?

Answer 5

39’000 ft

Question 6

At 43’100 ft, what would the cabin altitude be?

Answer 6

8’000 ft

Question 7

Does the Aircraft land pressurized or de-pressurized?

Answer 7

Cabin altitude decreases to slightly below the FMC planned landing altitude to ensure a small positive pressurization at touchdown.

Question 8

Where does the landing altitude barometric pressure correction come from?

Answer 8

The captains altimeter setting

Question 9

What two manual actions will provide pressurization data on the EICAS?

Answer 9

Setting either outflow valve switches to manual or pulling the LDG ALT selector

Question 10

After a loss of cabin pressurization, what two events will cause the outflow valves to re-open?

Answer 10

The airplane reaching 15’000 ft or descending below cabin altitude

Question 11

What is the max cabin differential?

Answer 11

9,1 PSI

Question 12

What is the target altitude for the cabin during a descent?

Answer 12

190 ft below field elevation to land slightly pressurized for structural reasons

Question 13

Which airport landing altitude does the ASCPCs use for calculations?

Answer 13

Landing altitude depends on distance from the departure airport.
If the distance is less than 400nm or less than halfway along the route, the ASCPC uses the departure airports landing altitude

Question 14

Does a return to the departure airport require any interaction to set landing altitude for the pressurization?

Answer 14

No, unless you are more than 400nm away or more than halfway away

Question 15

What are the landing airfield elevation limits?

Answer 15

From -1’000 ft below to 14’000 ft above msl

Question 16

At what cabin altitude does the Cabin Altitude Limiter close the outflow valves?

Answer 16

When cabin altitude exceeds 15’000 ft

Question 17

What does the EICAS message “LANDING ALTITUDE” mean?

Answer 17

The FMC does not supply a landing altitude or the landing selector knob is pulled
The cabin altitude controller assumes a landing altitude of 2000 ft

Question 18

For landing, if the airport is not in the FMC data base. What action is required from a pressurization perspective?

Answer 18

To manually set the landing elevation.

Question 19

If an airport is not in the FMC data base, what landing elevation is assumed if you don’t manually set an elevation?

Answer 19

2000 ft

Question 20

What is the max cabin differential for take-off and landing?

Answer 20

0,11 PSI