Pressurization & Ventilation Flashcards
When does the delta P indication become amber?
It becomes amber when out of normal range delta P 8.5 psi.
What is the function of the DITCHING pushbutton?
The DITCHING pb closes the outflow valve the emergency ram air inlet the avionics ventilation inlet and extract valves and the pack flow control valves.
How many motors are available to operate the outflow valve?
There are two automatic motors and one manual motor.
How does the cabin pressure control work? Where does it receive signals from?
Two identical independent digital controllers automatically control the system by maintaining the proper cabin pressure. They receive signals from the Air Data Inertial Reference System (ADIRS) the Flight Management and Guidance Computer (FMGC) the Engine Interface Unit (EIU) and the Landing Gear Control Unit (LGCIU).
What are the main components of the pressurization system?
Two cabin pressure controllers (CPC) one residual pressure controller (RPCU) one outflow valve one control panel and two safety valves.
How many safety valves are installed? What pressures do they keep the cabin within?
Two independent pneumatic safety valves prevent cabin pressure from going too high (+8.6psi above ambient) or too low (-1psi below ambient).
Can you switch between the two cabin pressure controller (CPC)?
Switching the MODE SEL pb to MAN for at least 10 seconds then returning it to AUTO will select the other system.
Where is the outflow valve?
The outflow valve is on the right hand side of the fuselage behind the aft cargo compartment and below the flowtation line.
When does the cabin vertical speed (V/S) indication of the cabin pressure become amber?
It becomes amber when the V/S is greater than 2000ft/min or less than -2000ft/min
What is the purpose of the Residual Pressure Control Unit (RPCU)?
The RPCU automatically depressurizes the aircraft in case of abnormal residual pressure on the ground.
What is the function of the abort mode in the pressurization system?
If the aircraft does not climb after takeoff the abort mode prevents the cabin altitude from climbing. Cabin pressure is set back to the takeoff altitude + 0.1psi.
When does the color of the cabin altitude indication on the ECAM change to red?
The indication becomes red for excessive cabin altitude >= 9550ft.
When does the safety valve open?
The safety valve opens when the cabin differential pressure is between 8.2 and 8.9 psi. The range is due to the reduced accuracy of delta P measurements (in MAN mode) combined with the decrease in cabin differential pressure that occurs immediately after the safety valves open.
What are the four general functions of the cabin pressurization system?
Ground function Pre-pressurization Pressurization during flight De-pressurization
What is the function of the LDG ELEV selector (CABIN PRESS Panel) when in AUTO? How about when selected to another position?
AUTO: FMGS data used to construct an optimized pressure schedule.
Other position: The pressurization schedule does not use the landing elevation from the FMGS, but instead uses the landing elevation selected with this knob (from – 2,000 to + 14,000 feet) as its reference.
MODE SEL pb (CABIN PRESS Panel) - AUTO - MAN - FAULT Light
AUTO: Automatic mode is operating. One of the two cabin pressure controller moves the outflow valve. Recycling this pb (MAN 10 sec then back to AUTO) switches controllers. MAN: MAN V/S CTL switch to control the outflow valve. FAULT Light: With ECAM caution light comes on only when both automatic systems are faulty.
MAN V/S CTL toggle sw (CABIN PRESS Panel) - UP - DN
Springloaded to neutral. Controls the outflow valve position through operation of the MAN motor, when the MODE SEL pushbutton is in the MAN position. UP: The valve moves towards the open position. DN: The valve moves towards the closed position
DITCHING guarded pb (CABIN PRESS Panel) - ON
ON: sends a “close” signal to: - fwd cargo isolation outlet valve The cargo recirculation fans stop automatically. - avionics ventilation inlet and extract valves - emergency ram air inlet - pack flow control valves - outflow valve
BLOWER and EXTRACT pb (VENTILATION Panel) - AUTO - OVRD - FAULT Light
AUTO (Both pb): Open/closed config depending on temperature until TO power, then closed or intermediate. (Either pb in OVRD): - Closed config. A/C system supplies cooling. - With BLOWER pb in OVRD blower fan stops. (Both pb in OVRD): - Air flows from the a/c sys and then overboard - The extract fan continues to run. FAULT Light (blower pb): - blowing pressure low - duct overheats - computer power supply fails - smoke warning is activated FAULT Light (blower pb): - extract pressure is low - computer power supply fails - smoke warning is activated.
FWD ISOL VALVE pb (CARGO HEAT Panel) - Auto - OFF - FAULT Light
Auto: - The inlet and outlet isolation valves open. - The extraction fan runs when the aircraft is on ground, or if diff P 1 psi, the fan stops. - If smoke is detected in the forward cargo bay, the valves close and the fan stops. OFF : The inlet and outlet isolation valves and the trim air valve close; the extraction fan stops. FAULT lt: With the ECAM caution when either inlet or outlet valve is not in the selected position.
Temperature selector (CARGO HEAT Panel) - COLD - Middle position - HOT
- COLD: Approximately 5° C (41° F) - Middle position: Approximately 15° C (59° F) - HOT: Approximately 26° C (79° F)
Zone temperature selector sw: (AIR COND Panel) - COLD - Middle - HOT
- COLD position: 18°C (64°F) - Middle position: 24°C (76°F) - HOT position: 30°C (86°F)
HOT AIR pb (AIR COND Panel) - ON - OFF - FAULT light
ON: Hot Air Pressure Regulator Valve regulates hot air pressure. OFF: Valve closes, and the trim air valves close. The FAULT circuit is reset. FAULT light on: duct overheat temp = 88°C (190°F). Triggers ECAM msg. The valve and the trim air valves close automatically. The FAULT light goes off when temp < 70°C (158°F), and the flight crew selects OFF.
PACK pb (AIR COND Panel) - ON - OFF - FAULT Light
ON: Pack flow control valve is automatically controlled. It opens, except: - Upstream pressure below minimum; - Compressor outlet overheat; - Engine start sequence; - Fire pb on same side is pressed; - Ditching pb ON; OFF: The pack flow control valve closes. FAULT LT: Comes with ECAM - valve position disagree with selected position - compressor outlet overheat - pack outlet overheat
ECON FLOW pb (321) (AIR COND Panel) - ON - OFF
ON: ECON flow is selected. OFF: Normal flow is selected. Normal flow provides 20 % more than ECON flow.
PACK FLOW sel (319) (AIR COND Panel) - LO - NORM - HI
LO (80 %) NORM (100 %) HI (120 %) Goes into high when automatically when: - single pack operation - with APU bleed supply If LO is selected, the pack flow can be automatically selected up to 100 % when the cooling demand cannot be satisfied.
RAM AIR pb (guarded) (AIR COND Panel) - ON - OFF
ON: - The RAM air inlet opens if the DITCHING pb is not selected ON. - If differential press => 1 psi: The outflow valve control remains normal. No emergency RAM air flows in. - If diff press < 1 psi: The outflow valve opens to about 50 % when under automatic control. It does not automatically open when it is under manual control. Emergency RAM airflow is directly supplied to the mixer unit. OFF: The RAM air inlet closes.
CAB FAN pb (VENTILATION Panel) - ON - OFF
ON: The two cabin fans are on. OFF: The two cabin fans are off.
CREW SUPPLY pb (OXYGEN Panel) - On - OFF
On: The valve is open, and supplies low pressure oxygen to the masks (normal position in flight). OFF: The valve is closed, and the white light comes on.
PASSENGER SYS ON Iight (OXYGEN Panel)
This light comes on white, when the control for the oxygen mask doors is activated, and it remains on until the TMR RESET pb is pressed.
MASK MAN ON pb (OXYGEN Panel) - AUTO - Pressed
AUTO: The mask doors open automatically when the cabin altitude exceeds 14,000 feet. Pressed: The mask doors open.
From what source does the pressurization system obtain landing elevation?
FMGC database
How many controllers are in the pressurization system?
2, only one is used at a time and they swap roles after each landing
When out of the AUTO position, what is different?
The pressurization system uses the manually selected landing elevation
When out of the AUTO position, what is different?
The pressurization system uses the manually selected landing elevation
When out of the AUTO position, what is different?
The pressurization system uses the manually selected landing elevation
What is the maximum cabin rate of descent with the pressurization in AUTO?
750 FPM
At what cabin differential pressure does the RAM AIR valve open?
1 psi differential or less
Which valves will receive a close command when the DITCHING pushbutton is depressed? (ARPO)
- Avionics Inlet and Extract valves - Ram air Inlet - Pack Flow Control valves - Outflow valve (only if in Auto mode)
Will the DITCHING pushbutton always close the outflow valve?
Not if the outflow valve is under manual control
Can the pilot control the outflow valve
Yes, select MAN on the MODE SEL and use the MAN V/S CTL switch
Will the DITCHING pushbutton always close the outflow valve?
Not if the outflow valve is under manual control
What protects the air frame from excessive cabin differential pressure?
2 pressure relief valves
How many outflow valve motors are installed?
3 - One for each automatic controller and one for manual control
If PACK FLOW is selected to HI, will it automatically shift lower?
No
How do you manually switch controllers?
Switch MODE SEL to MAN for 10 seconds, then back to AUTO
What does an amber “FAULT” light in the MODE SEL pushbutton indicate?
Both automatic pressure controllers are faulty
Describe what occurs when cabin pressure altitude exceeds: - 8,800’ - 9,550’ - 11,300’ - 14,000’
- 8,800’: CAB ALT flashes - 9,550’: EXCESS CABIN ALT warning - 11,300’: All cabin signs illuminate - 14,000’: All passenger masks deploy
If the Lav/Galley Extract Fan fails, what occurs?
Cabin temperature defaults to a set value
Approximately what rate of cabin change does 1 click of the MAN V/S CTL switch produce?
50 FPM
The ventilation system includes ventilation for…
The avionics (controlled be the avionics equipment ventilation controller), the battery, the lavatories and galleys.
How does the smoke configuration work?
When the smoke detector detects smoke in the avionics ventilation air the BLOWER and EXTRACT FAULT lights come on. When both the BLOWER and the EXTRACT pushbuttons are set to OVRD position the ai conditioning system supplies cooling air which is then exhausted overboard. The blower fan stops.
What are the main components of the avionic ground cooling?
1 inlet valve, 1 ground cool fan, 1 cooling unit, 1 outlet valve and one controller.
With the BLOWER and EXTRACT pb switches in AUTO what ventilation configuration do you normally expect to see?
Open configuration on the ground before applying T/O power and closed configuration after applying T/O power in the air.
How does the battery ventilation work?
A venturi in the skin of the aircraft draws air from the space around the batteries and vents it overboard. The resulting airflow ventilates the batteries.
On which ECAM page you will get information about the ventilation system?
PRESS page.
With the BLOWER and EXTRACT pb switches in OVRD what happens to the ventilation system?
The system goes into the smoke configuration and the blower fan stops.
When does the avionic ventilation in the open-circuit configuration operate on the ground?
The open-circuit configuration operates when the skin temperature is above the on-ground threshold: +12°C (53°F) temperature increasing or +9°C (48°F) temperature decreasing.
What is the purpose of the avionic ventilation?
The avionic ventilation system is fully automatic. It cools the electrical and electronic components in the avionic compartment and on the flight deck including the instrument and circuit breaker panels.
During ground function operation the outflow valve is…
Fully open.
What are the main components of the avionic ventilation?
Fans skin air inlet and extract valves skin exchange inlet and outlet bypass valves airconditioning inlet valve skin exchange isolation valve and Avionics Equipment Ventilation Computer (AEVC).
When does the Lav/Galley extract fan operate?
Continuously when electrical power is available
What does an amber “FAULT” light on the BLOWER pushbutton indicate?
- SMOKE warning is activated - Computer power supply failure - Low Blower pressure - Duct Overheat
What does an amber “FAULT” light on the EXTRACT pushbutton indicate?
- SMOKE Warning is activated - Computer power supply failure - Low Extract Pressure
With 2 FAULT lights on the VENTILATION panel, are there any other indications?
Yes, the SMOKE light in the GEN 1 LINE pushbutton
What is the RAM AIR pushbutton used for?
- Smoke removal in cabin - Ventilation of cabin with a dual pack failure
Will there be any other indications?
ECAM warning and amber “FAULT” lights in the EXTRACT and BLOWER pushbuttons on the VENTILATION panel
With BLOWER and EXTRACT pushbuttons in AUTO how does the system operate?
- Ground: system is normally in the OPEN configuration - Flight: system is normally in the CLOSED configuration - Intermediate: Closed configuration except small internal flap in Extract Valve is open.
With both BLOWER and EXTRACT pushbuttons in OVRD (smoke configuration) what are teh positions fo the INLET and EXTRACT valves?
- INLET valve closed - EXTRACT valve OPEN
With a CARGO SMOKE warning what happens to the Isolation Valve and Extract Fans?
- Isolation Valve closes - Extract Fans stop
What does the CARGO HEAT AFT ISOL VALVE amber “FAULT” light indicate?
Valve disagreement of inlet or outlet valve
What is the purpose of the CABIN FANS?
To re-circulate cabin air to the mixing chamber and then back to the cabin
What does the CARGO HEAT HOT AIR amber “FAULT” light indicate?
Duct Overheat
How many Automatic Cabin Pressure Controllers are there?
2
How many motors can drive the Outflow Valve?
- 3 (2 auto AC, a manual DC) - Slow on DC for manual to slow OFV.
What causes a safety valve to operate?
> 8.6 PSI or < 1 PSI
What is the OFV position with the AC on the ground?
Before takeoff and 55secs after landing, the outflow valve fully opens to ensure that there is no residual cabin pressure. At touch down, any remaining cabin pressure is released at a cabin v/s of 500’/min.
During climb, cabin ROC is a function of what?
The cabin attitude varies according to a fixed pre-programmed law that takes into account the aircraft’s actual ROC.
What is the (approx.) Max ROD of the cabin in AUTO?
750’/min
What happens to the OFV after touchdown?
- At touch down, any remaining cabin pressure is released at a cabin v/s of 500’/min. - 55sec after landing, valve fully opens.
If the MAN V/S CTL is moved UP, what happens to the Press Diff, Cabin V/S, Cabin Alt, and OFV?
- Pressure Difference: decreases - Cabin Vertical Speed: increases - Cabin Altitude: increases - OFV: selecting UP moves the valve towards the open position.
What does the Ditching switch do?
Close the OFV (only if its in auto position, not in manual position), emergency ram air valve. Inlet, avionics ventilation inlet and extract valves, pack flow control valves.
When is cabin v/s displayed on the doors SD?
Phase 5-7 (lift off til touchdown)
In the “Ground” Mode at High Skin Air temperatures, which Config is in operation?
The open-circuit configuration operates when skin temperature is above the on-ground-threshold from +12 degrees to +9 degrees. Inlet valve – blower – avionics – extract – extract
In the “Ground” Mode at Low Skin Air Temperatures, how is the Circulatory Air now cooled?
The closed-circuit configuration operates when skin temperature is beneath the on-ground threshold. Avionic bay – heat exchanger – cargo underfloor
In the “Flight” Mode at Low Skin Air Temperatures which Config is in operation?
The closed circuit configuration operates when skin temperature is beneath the in flight threshold of +35 degrees to +32 degrees. Heat exchanger – cargo
In the “Flight” Mode at High Skin Air Temperatures which Config is in operation?
The intermediate configuration operates when skin temperature is above the in-flight threshold of +35 degrees to +32 degrees. Heat exchanger - cargo – extract
What causes the system to transit from the GROUND mode to the FLIGHT mode?
Takeoff power + weight on gear
When might you have to put both switches (BLOWER and EXTRACT) to OVERRIDE?
Smoke / fumes / avionics smoke
What causes a BLOWER or EXTRACT FAULT light to illuminate?
- Pressure is low (blowing + extract) inhibits for engine shut down. - Duct overheat (blower) - Computer power supply falls - Smoke warning is activated
What happens when the BLOWER is selected to OVERRIDE?
When either p/b switch is on OVRD: - The system goes to closed circuit configuration. - Air from the air conditioning system is added to ventilation air. - The blower fan stops if BLOWER p/b is on OVRD.
What happens when the BLOWER and EXTRACT are selected to override? (E.g. during AVIONICS SMOKE)
When both p/b SW are on OVRD: - Airflows from the air conditioning system and then overboard - The extract fan continues to run
