Pressurization *** Flashcards

1
Q

How many cabin altitude controllers are provided?Each Controller controls both ______?

A

• Two controllers, A and B. Each controller controls both outflow valves.

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2
Q

Can either outflow valve maintain cabin altitude and full ventilation?One pack is selected off to ensure ___-?

A

• 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.

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3
Q

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

A

• Climb, cruise, and descent

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4
Q

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

A
  • They use ambient pressure, and

* Flight plan data from the FMC

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5
Q

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

A

• Continues to increase during the level segment.

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6
Q

What is maximum cabin altitude in cruise mode?

A

• 8,000 feet

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7
Q

When do the cabin altitude controllers enter descent mode?

A
  • T/D, or

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

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8
Q

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

A

• Small positive pressurization at touchdown.

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9
Q

When does the cabin rate limiter close both outflow valves?

A

• When cabin altitude exceeds 11,000 feet.

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10
Q

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

A

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

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11
Q

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

A

• 2,000 feet

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12
Q

Describe the NORM position of the Cabin Altitude Selector.

A

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

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13
Q

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

A

• The secondary controller is automatically selected.

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14
Q

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

A

• Turn both Outflow Manual switches to ON.
• All automatic cabin altitude control functions are bypassed
.

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15
Q

Describe pressurization upon touchdown?

A

Small positive pressure

At touchdown, the outflow valves open to depressurize the cabin

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16
Q

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

A

Cabin Altitude Limiter

17
Q

What happens is excessive cabin pressurization occurs?

A

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

18
Q

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

A

9.4 PSI

19
Q

When does the cabin altitude controller enter cruise mode?

A

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

20
Q

When does CABIN ALT AUTO message appear on EICAS?

A
  • Both cabin altitude controllers FAILED
  • Both manual switches are on
21
Q

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

A

10000’ cabin altitude

22
Q

When do O2 masky automatically deploy in flight?

A

14000’ cabin altitude

23
Q

When can pax oxygen system be reset?

A

Once cabin altitude has dropped to below 12000’

24
Q

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

A

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

25
Q

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

A

FL390

26
Q

What is the cabin altitude sequence of events?

A

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

27
Q

How many positive pressure relief valves? Location?

A
  • 2 total
  • In EE Compartment + FWD Left Fuselage

Max differential pressure 9.4 psi

28
Q

Where are negative pressure relief valves located?

A
  • Side cargo door
  • FWD + AFT low Cargo Doors