Pressurization Flashcards
How many modes exist for controlling the outflow of cabin air through the outflow valve?
Two automatic modes available from two digital controllers and one manual mode.
How many safety valves exist?
Two. They operate independent of the automatic and manual modes of pressurization.
Normal operation of the pressurization system is automatic when … ?
The destination airport is programmed into the FMS and the FMS sends the correct landing altitude to the controller.
What is the IASC?
Integrated Air System Controller
What does the IASC control? (4)
All automatic phases of pressurization
pneumatic
air conditioning
ice and rain protection
How many IASC are there.
Two
In the auto mode, each can drive the outflow valve through the auto drive mechanism of its actuator.
In the manual mode, IASC 1 drives the outflow valve through the manual drive mechanism of its actuator.
Are both IASC active at the same time?
No. One is active and the other is in standby. If one fails, the other takes over. IASC 1 typically is the active controller on power-up.
Where are the safety valves located?
Aft pressure bulkhead
Describe the Manual Rate knobs positions and rates of change …
12 o’clock corresponds to 0
@ 2/3 angle range left or right equates to -1000 to +1000 fpm
Full left or right obtains 2500 fpm
EMER DEPRESS in the auto mode depressurizes …
2500 fpm up to 14,000’ + - 100’ or aircraft altitude, whichever is lower
EMER DEPRESS in the manual mode depressurizes …
3000 fpm up to 14,500’ + - 500’ or aircraft altitude, whichever is lower
What does the DITCHING switch do …
Depressurizes the cabin
Shuts off the A/C
Closes the Outflow Valve
What altitude is the DITCHING switch inhibited?
Above 15,000’ and only in the Auto mode
What other means is there to close the Outflow Valve?
Turn the Manual Rate knob fully down
Cabin Altitude Amber is set at what altitude?
8500’
Cabin Altitude Warning is set at what altitude?
9400’
The Pressurization Mode is activated when …
Thrust levers advanced for takeoff. Cabin initially pressurized to 300’ below field.
On takeoff, the aircraft will maintain 300’ below field elevation until when …
6000’ AGL or
10 minutes elapses
Takeoff and Return to Base Sequence
A typical climb rate for the cabin is …
300-500 fpm. For light aircraft climbs, the maximum cabin climb is 635 fpm
Cruise Mode is activated when … (2)
Aircraft rate of climb is less than 500 fpm for more than 10 seconds
Aircraft is climbing at any rate with aircraft altitude greater than 25,000’
Descent Mode is calculated …
Remaining flight time. Time is calculated from aircraft speed received from the ADC
Describe the Depressurization Sequence …
On landing or an aborted takeoff, the cabin depressurizes at 500 fpm and then the outflow valve goes to full open
The Maximum Cabin Altitude is …
7850’
When taking off or landing at a field above 7850’, the Cabin Altitude caution is set …
To field altitude +650’ with a maximum limit of 14,300’
When taking off or landing at a field above 7850’, the Cabin Altitude warning is set …
To field altitude +1550 with a maximum limit of 14,300’
Cabin Delta P warning
Greater than 9.2 or less that -0.5 psid
