Pressurization Flashcards
(48 cards)
How many pressurization controllers are there?
2
One active,
The other standby
Where do the pressurization controllers receive information from?
- Landing elevation selector
- Weight on wheels
- Thrust lever
- ADCs
- Cabin press panel
What do the pressurization controllers do with the information they receive?
Opens and closes outflow valve to maintain 8.33 PSI differential.
What happens regarding the pressurization controllers after landing?
3 minutes after landing the active and standby controller will swap roles
During flight, what will happen if the active pressurization controller fails?
The standby will take over automatically without any degradation of system operation.
If the active pressurization controller fails in flight and automatic switch over to the standby controller doesn’t occur, what can we do to manually activate the standby controller?
Press the “PRESS CONTROL” Switchlight TWICE
How do we know what the active controller is?
By referencing the ECS synoptic page
If one Pressurization controller fails, what will happen?
“PRESS 1/2 FAIL” status message
If both Pressurization controllers fail, what will happen?
- Outflow valve goes into isobaric hold mode
- “AUTO PRESS” caution appears
- “PRESS CONT FAULT” Switchlight illuminates
What does “AUTO PRESS” caution mean?
Indicates automatic pressurization control is INOP
PRESS CONTROL Switchlight allows for what?
When pressed, it allows for manual control of the pressurization system.
What controls the outflow valve when in manual control mode?
MAN alt switch and MAN RATE knob
When will “AUTO PRS 1/2 FAIL” status message be displayed?
When there is a loss of the respective channel while in manual mode
How do we set the destination airport elevation on the pressurization controller?
Using the LDG ELEV knob?
How do we check the setting of the “LDG ELEV” knob?
In automatic mode it will be displayed on ECS synoptic page
“CABIN ALT WARN HI” status message will display when?
If LNDG ELEV set above 8,000’
The control panel microprocessor is responsible for what?
- Controlling automatic drop-down of passenger oxygen masks at a cabin altitude of 14,000’
- Illuminating the NO PED and SEAT BLTS signs when the cabin altitude reaches 10,000’ (if they’re set to AUTO)
- Providing the instruction to limit cabin altitude to 14,500’
- Opening and closing the ground valve during ground sequences.
CPAM FAIL means what?
The control panel indication system has failed
Where is the OUTFLOW VALVE?
Rear pressure bulkhead
How is the outflow valve actuated?
Normally by active controller’s motor
Has manual motor for non-normal situations.
How do we control the manual mode on the pressurization controller?
- Selecting PRESS CONT Switchlight
- Setting desired rate of change using MAN RATE knob
- Increasing or decreasing cabin alt using UP and DN selections
- Selected altitude maintained by MAL ALT switch to HOLD
How many safety valves and where are they?
2 safety valves on top of the aft pressure bulkhead
What is the purpose of the safety valves?
Prevent excessive +/- differential pressures. They will open and close automatically when diff press reaches preset values.
When will “DIFF PRESS” warning be displayed.
When positive pressure differential reaches 8.6 PSID