Pressurisation DSC 21 Flashcards
System consists of….
2 Cabin Pressurisation Controllers (CPC)
1 Residual Pressure Control Unit (RPCU)
1 Outflow valve (with an actuator that incorporates 3 motors)
1 Control Panel
2 Safety Valves
The CPC’s receive info from…?
ADIRS
FMGC
EIU
LGCIU
When the system is in auto or semi-auto, 1 CPC is active and the other is on standby. T/F?
True
Where is the outflow valve situated?
RHS fuselage, behind aft cargo and below flotation line
When the RAM AIR pb is ON and ∆P is <1 psi what position does the system drive the outflow valve to if its under automatic control?
50% OPEN
When the RAM AIR pb is ON and ∆P is <1 psi what position does the system drive the outflow valve to if its under manual control?
The outflow valve does not automatically open,
even if the ∆P is <1 psi
At what pressure do the pneumatic safety valves activate?
> 8.6psi (can be a range of 8.2 - 8.9 due to accuracy of ∆P in MAN mode)
<1psi
Where are the safety valves located?
Rear pressure bulkhead,
above the flotation line
What does the Residual Pressure Control Unit (RPCU) do?
Automatically depressurises the aircraft in case of abnormal residual pressure on the ground.
When does the Residual Pressure Control Unit (RPCU) automatically open the outflow valve?
The aircraft is on the ground, and
The outflow valve is not fully open, and
Both CPC’s are failed, or manual mode is selected, and
All engines shutdown, or ADIRS indicate <100kts
How many CPC’s operate at the same time?
only 1
When does automatic change over of the CPC’s occur?
- 70secs after each landing
- If the operating CPC fails
Where does the CPC get landing elevation, QNH and Pressure altitude info from?
FMGC -landing elevation, QNH
ADIRS -Pressure altitude
If FMGC data is not available to the CPC then where does the CPC get BARO and Landing elevation info from?
ADIRS -BARO
LDG ELEV knob -Landing elevation
When is the outflow valve fully open?
Before take-off and
55 sec after landing
At touchdown, any remaining pressure is released at. ______ft/min
500 ft/min
To avoid pressure surge at rotation the controller pre-pressurises the aircraft at a rate of _____ft/min, until the ∆P reaches _____psi
400 ft/min
0.1 psi
During descent the controller maintains a cabin rate of descent such that the cabin pressure is equal to the landing field pressure +_____psi shortly before landing.
+1 psi
What is the maximum descent rate?/
750 ft/min
If the aircraft does not climb after take-off what does the abort mode do?
Prevents the cabin altitude from climbing.
What is cabin altitude set to after an abort?
take-off altitude +1psi
What happens when the mode selector is selected to MAN?
Power is cut to the automatic motors.
MAN motor can control the outflow valve
What does the MAN V/S CTL switch UP position do?
Opens the outflow valve
Increases the Cabin Altitude
Due to the slow operation of the outflow valve in manual mode and the limited resolution of the position on ECAM, how long can the visual ECAM take to indicate the change in position?
up to 5secs
In MAN operation, does the outflow valve open automatically at touchdown?
NO!
What does the DITCHING pb on the CABIN PRESS control panel do?
Closes all hatches below the flotation line: Outflow valve Emergency RAM AIR inlet Avionics vent inlet Extract valves Pack flow control valves
How can the flight crew select the other CPC?
By switching the MODE SEL to MAN, for at least 10sec, then returning it to AUTO
When will the MODE SEL FAULT light illuminate?
When BOTH automatic systems are faulty
If in MAN mode and the DITCHING pb is switched ON, will the outflow valve close automatically?
NO!
When will VS FT/MIN appear in amber?
VS >= 2000 fpm
When will VS FT/MIN pulse green?
VS > 1800fpm
resets at 1600 fpm
When will ∆P appear in amber?
∆P <= -0.4 psi, or
∆P >= 8.5 psi
When will ∆P appear pulse green?
∆P > 1.5 psi during flight phase 7 (800ft to touchdown)
resets at 1 psi
When will the CAB ALT appear in Red?
> 9550 ft
When will the CAB ALT pulse green?
At or above 8800 ft
resets at 8600 ft
SAFETY in amber on the CAB PRESS SD page means?
either safety valve is not closed
When would the outflow valve position become amber?
Valve opens > 95% during flight
