Pressurization Flashcards
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
What is the negative differential pressure limited to?
-0.5 PSID
What is the ground valve and how does it work?
Valve that limits differential pressure drop by discharging air from the avionics compartment air.
Normally opens when: PAX or SERVICE DOORS OPEN.
Closes when: doors are closed and locked OR the pre-pressurization sequence is initiated
OVBD COOL means what?
Exhaust valve is not closed and PAX SERV doors are closed and locked.
OVBD COOL FAIL status means?
Ground valve didn’t open on the ground.
What is the “EMER DEPRESS” Switchlight used for?
Depressurization in an emergency. It causes outflow valve to open
What cabin altitude do the altitude limiting devices prevent the aircraft from exceeding if the EMER DEPRESS is pushed?
14,500 +/- 500’ when above 15,000’
ALT LIMITER caution means?
The altitude limiter function is INOP
CABIN ALT caution means?
Cabin altitude is 8,500-10,000 feet.
CABIN ALT warning is displayed when?
Cabin altitude exceeds 10,000’
If cabin altitudes reaches _______, a ________ in the control panel sends a signal to deploy the PAX o2 masks
14,000’, microprocessor
When will the C ALT on the ECS synoptic page display amber? Red?
AMBER: above 8,500
RED: above 10,000’
What does “LDG ELEV” show on ECS synoptic page?
The LDG ELEV set by the LDG ELEV selector
In manual mode, where is the pressurization information displayed? Automatic?
Manual: ECS synoptic and primary page
Automatic: ECS synoptic and status page
What are the 8 modes of the pressurization system?
- GROUND
- PRE-PRESSURIZATION
- TAKEOFF ABORT
- CLIMB
- FLIGHT ABORT
- DESCENT
- LANDING
- TOUCH AND GOq
Describe GROUND MODE of the pressurization system
Aircraft is on the ground,
outflow valve and ground valve fully open
Describe PRESSURIZATION MODE of the pressurization system
Thrust levers moved to take-off postion
Outflow valve begins to close
Aircraft pre-pressurized
Cabin pressure moves towards scheduled cabin pressure at 300 FPM
PACKS OFF: outflow and ground valve fully closed
Describe TAKEOFF ABORT mode of the pressurization system
Thrust levers restarted after aborted take-off
Cabin climbs at 500FPM for 20 seconds
Outflow valves driven fully open
Describe CLIMB MODE of the pressurization system
Cabin climb rate 300-500 FPM
Controller compares selected landing alt to climb schedule and selects the highest pressure schedule
Describe FLIGHT ABORT of the pressurization system
Activated when:
- Aircraft maintained 6,000’ or less
- 10 min
- Descent of 1,000’ per minute
System will assume elevation of departing airport regardless of selected landing elevation
Describe DESCENT MODE of the pressurization system
Rate of descent 300-750 FPM
Maintains descent rate to landing field pressure altitude or maximum differential, whichever is highest.
Describe LANDING MODE of the pressurization system
On touchdown
Cabin altitude driven below field elevation or airplane is unpressurized
If CA below FE, CA is pressurized at 600fpm for 30 seconds
Outflow valve and ground valve commanded fully open
Describe TOUCH and GO MODE of the pressurization system
Activated if thrust levers advanced after touchdown
Schedules pre-pressurization mode
Maximum positive differential pressure is limited to:
8.6 +/-1 PSID
Negative differential pressure is limited to:
-0.5 PSID