06 Air Conditioning & Pressurization
Terms in this set (86)
What is the purpose of the Pack Control Valves?
Control the amount of bleed air supplied to the packs and also act as shutoff valves
How are the pack control valves controlled?
They are controlled by the flight crew via the PACK pbs and they are regulated by the pack regulators.
When will the pack control valves automatically close?
- DITCHING pb is selected ON
- Pack OVERHEAT has been detected
- A FIRE pb is pushed
- Engine START is initiated (for 30 seconds)
After engine start will the pack control valves automatically reopen?
Yes. However, on the ground, reopening of the valves is delayed for 30 seconds after the first engine start.
What does a FAULT light in the PACK pb indicate?
Disagreement between the actual and selected position of the pack flow control valve exists due to an overheat
(FAULT light remains illuminated as long as the overheat conditions exists If the pilot selects the PACK pb to OFF, the FAULT light extinguishes when the pack temperature drops back below a threshold. The pack flow control valve can then be reopened by selecting the PACK pb to on)
Explain the basic operation of an air conditioning pack.
They receive hot bleed air from the pneumatic system and cool it for distribution to the mixing unit. Each pack is controlled by a pack regulator and operates independently of the other.
Where does the air go after it leaves the PACK?
It goes to the mixing unit, mixes with recirculated air from the cabin, and is sent to the cabin and cockpit
What recirculates the cabin air?
Two cabin fans are normally operated at all times and are controlled by the CAB FANS pb
The airflow from the mixing unit is distributed into what three zones?
2. Forward cabin
3. Aft cabin
Other than the packs, from where else can the mixing unit receive conditioned air?
Low pressure ground air conditioning cart. This is does not go through the packs.
What is the purpose of the emergency ram air inlet?
It directs external air into the mixing unit for cabin ventilation in case both packs are inoperative or to clear the cabin of smoke.
What happens when the RAM AIR pb is selected ON?
1. The ram air valve opens
2. Outflow valve will fully open when the cabin differential pressure is less than 1 psi
What is the purpose of the hot air valve?
It controls the supply of hot air to all of the trim air valves.
Can the hot air valve be manually closed by the flight crew?
Yes, by selecting the HOT AIR pb to OFF.
What does a FAULT light in the HOT AIR pb indicate?
Duct overheat. HOT AIR and trim air valves close automatically.
What is the purpose of the trim air valves?
They add hot air to the air flowing from the mixing unit. They are supplied with air from the hot air valve and are controlled by the zone regulator.
If 1 or all of the trim valves fail, what happens?
1 valve - the zone controller will operate normally but that zone will be excessively hot or cold. If this happens, selecting the HOT AIR pb off allow cabin temp to the controlled by regulating pack output.
All valves - the zone regulator will go to its backup mode and temp optimization will be lost
What is the purpose of the zone regulator?
It is a computer that receives inputs from the cockpit controls and temperature and flow sensors. It uses these signals to manage the trim air valves and other components to maintain the selected temperature in each zone.
How does the zone regulator control the temperature of each zone?
The zone regulator determines which zone requires the coldest air and directs the pack to deliver air at that temperature to the mixing unit. It then adds hot trim air to the other zones as necessary to maintain selected temperatures.
What is the full COLD to full HOT range of the zone temperature selectors?
18 C (64° F) to 30 C (86° F).
Approximately what is the 12 o'clock position of the zone temperature selectors?
24 C (75° F)
What can the zone regulator do if the zone temperature requirements are not being meet?
1. It can override the cockpit selected airflow settings.
2. It can also increase APU speed or engine idle
What happens if the primary channel of the zone regulator fails?
1. Secondary channel operates as a backup
2. ATLN MODE appears in green on the ECAM COND page
3. Temperature and PACK flow selectors in the cockpit are inop
4. Temperature regulation fixed at 24C
What happens if only the secondary channel of the zone regulator fails?
No effect on temperature regulation
Amber XX appears on the ECAM COND page where system data is not available.
What happens if both the primary and secondary channels of the zone regulator fails?
Temp regulation is lost
Packs deliver fixed temp (Pack 1 - 20C, Pack 2 - 10C)
What is the purpose of the pack regulator?
1. It provides temperature regulation of its associated pack to meet the outlet temperature demanded by the zone regulator.
2. Provides flow regulation by modulating the associated pack control valve.
3. Monitors for pack malfunctions and shuts them down if necessary
What controls the amount of intake air over the pack heat exchanger?
The pack regulator
When are the heat exchanger intake scoops automatically closed?
Temporarily during takeoff and touchdown to avoid ingestion of foreign matter
What happens if the primary channel of the PACK regulator fails?
Secondary channel operates as backup
Regulation not optimized
PACK flow is fixed at previous setting
What happens if the secondary channel of the PACK regulator fails?
No effect on PACK regulation
Backup mode is lost
ECAM signals related to corresponding PACK are replaced by amber XX
What happens if both the primary and secondary channels of the PACK regulator fail?
1. The pack outlet temperature will be regulated to 15 C
2. ECAM BLEED System page pack indications are replaced with an amber XX
What happens if the hot air valve fails in the open or closed position?
Open - no effect on the system
Closed - individual zone temperature control is lost.
If the HOT AIR pb is selected OFF, can the cockpit and cabin temperatures still be controlled?
Yes. The cockpit knob will control the output of pack 1 and pack 2 output is an average of the FWD and AFT cabin knobs.
What do the PACK FLOW selector positions LO, NORM and HI represent?
Selects the pack flow rate according to the number of passengers and ambient conditions.
LO 80% of norm
HI 120% of norm
When would you select LO on the PACK FLOW selector?
Less than 115 passengers
When would you select HI on the PACK FLOW selector?
abnormally hot and humid conditions
When is the pack flow automatically selected to HI?
APU bleed air is in use or during single pack operations
What four parts of the plane are pressurized?
3. Avionics Bay
4. Cargo compartments
What are the three pressurization modes?
How many pressurization controllers are there?
When does automatic switching from one pressurization controller to the other occur?
Following each landing
Is it possible to manually switch from one pressurization controller to the other?
Yes. Select the MODE SEL pb to MAN for 10 seconds and then return the pb to AUTO (lights out).
How can the flight crew determine the active pressure controller?
The active pressure controller is displayed in green as SYS 1 or SYS 2 on the ECAM CAB PRESS System page.
On the CABIN PRESS panel, what does an amber FAULT light in the MODE SEL pb indicate?
Both automatic pressure controllers have failed
In the automatic mode, when is cabin initially pressurized?
When takeoff power has been selected.
The outflow valve is controlled by how many motors?
Three total. Two automatically controlled motors associated with each of the pressurization controllers. One manually controlled motor.
Where is the outflow valve located?
On the right hand side of the fuselage, behind the aft cargo compartment, below the floatation line.
What is the purpose of the two independent safety valves?
They are pneumatically actuated valves that prevent excessive positive or negative differential pressure.
Where are the two safety valves located?
They are located on the rear pressure bulkhead above the flotation line.
What are the six automatic pressurization modes?
1. Ground - ensures aircraft is depressurized
2. Takeoff - pre-pressurizes the aircraft prior to liftoff
3. Climb - cabin altitude will vary with actual airplane climb rate
4. Cruise - maintains the min cabin altitude compatible with the max pressure differential
5. Descent - optimizes cabin descent to reach an altitude slightly below field elevation just prior to landing.
6. Abort - cabin altitude automatically returns to departure field elevation
The Takeoff mode pre-pressurizes the aircraft when thrust is set for takeoff by descending the cabin at what rate until the differential pressure reaches 1 psi?
What is the maximum positive differential pressure?
What is the maximum negative differential pressure
The pressure controllers optimize the cabin altitude to not exceed a limit of what altitude?
What is the maximum cabin rate of descent with the pressurization system in AUTO?
In automatic mode, at touchdown, any remaining cabin pressure is released at what rate?
When will the Climb pressurization mode switch to the Abort mode?
1. The aircraft is below 8,000 ft MSL
2. The aircraft rate of descent is greater than 200 ft/min for 30 seconds
3. The altitude change since takeoff is less than 5,075 ft
How is manual pressurization mode selected and controlled?
It is selected by selecting MAN on the MODE SEL pb. In manual mode the outflow valve is controlled by the UP or DN positions of the MAN V/S CTL switch.
Approximately what rate of cabin change does one click of the MAN V/S CTL switch produce?
The LDG ELEV selector in the AUTO position does what?
The pressurization system uses the FMGS data to construct an optimized pressurization schedule
How is the semi-automatic pressurization mode selected?
With the MODE SEL pb in the AUTO mode and manually selecting a landing elevation on the LDG ELEV switch. The pressurization system uses the manually selected landing elevation to construct the pressurization schedule.
When would the flight crew be required to manually select a landing elevation?
1. Destination not in the FMGC database
2. Dual FMGC failure
What happens when the DITCHING pb is selected ON?
All valves on the exterior of the aircraft below the floatation line are closed - Pack FCV, pack inlet and outlet, emer ram air, and outflow valve.
The outflow valve will not automatically close if it is being controlled manually by the MAN V/ S CTL switch with the MODE SEL pb in MAN
In what situation will the outflow valve not automatically close when the DITCHING pb is selected ON?
When the pressurization system is operating in the manual mode.
When is the Cabin Vertical Speed displayed on the DOOR/OXY page?
Only in flight
How is avionics ventilation provided?
The operation is fully automatic. Air is circulated by a blower and an extract fan which operate continuously as long as electrical power is available.
What are the the three ventilation configurations of the avionics ventilation system?
Each refers to the inlet and extract valve configuration
Where is the avionics ventilation system inlet valve located?
On the left forward fuselage
Where is the avionics ventilation system extract valve located?
On the right forward fuselage
What is the normal configuration of the avionics ventilation system in flight?
If warm ambient conditions exist in flight, the system can be ventilated in the intermediate configuration
What is the normal configuration of the avionics ventilation system on the ground?
If cold ambient conditions exist on the ground, the system will switch to the closed configuration.
In the closed configuration, how is the warm air from the avionics equipment cooled?
Skin heat exchanger. The extract fan draws air from around the avionics equipment. The air then passes through an aircraft skin heat exchanger and a filter before reentering the circuit through the blower fan.
When the OAT is above 120 F, are there any avionics systems limitations?
Do not power the avionics for more than two hours unless the avionics ventilation system is operating normally.
If a blower (inlet) fault is detected, what happens?
The blower fan stops, air conditioned air is added to the system and the ECAM will instruct the pilots how to reconfigure the system.
If an extract (outlet) fault is detected, what happens?
Both fans continue to operate and air conditioned air is added to the recirculated air. The ECAM will instruct the pilots how to reconfigure the system.
What happens when either BLOWER or EXTRACT pbs are placed in OVRD?
The system goes into closed configuration and conditioned air is added to ventilation air (the BLOWER fan stops)
Explain the Smoke Configuration (Blower and Extract fans to OVRD)
The blower fan will stop and inlet valve will close. The extract fan will continue to run. Additional air is provided by the air conditioning system and extracted overboard. The skin heat exchanger is completely bypassed.
What does a FAULT light in the BLOWER pb indicate?
Low blower pressure or ventilation duct overheat (if these occur on the ground with engines off the external horn sounds)
Avionics ventilation computer failure
What does a FAULT light in the EXTRACT pb indicate?
Low blower pressure (if these occur on the ground with engines off the external horn sounds)
Avionics ventilation computer failure
What are the indications of smoke in the avionics ventilation duct?
BLOWER and EXTRACT fans FAULT lights
SMOKE on EMER ELEC panel
Explain the aft cargo ventilation and heating (if installed).
It is fully automatic. An aft cargo extract fan pulls cabin air through the aft cargo compartment and dumps it overboard through the outflow valve. A trim air system similar to the cabin is installed to mix hot air with the cabin air to maintain a selected cargo compartment temperature.
Explain the function of the cargo isolation valves.
Isolation valves are installed before and after the cargo compartment. The valves can be closed from the cockpit but are automatically closed if smoke is detected. If closed, the cargo fan stops.
If in MAN pressurization mode, will the outflow valve close if you select the DITCHING pb ON?
Explain the open configuration of the avionics ventilation.
Outside air is drawn in through the inlet by the blower fan, and after passing around equipment, the air is extracted overboard through the fully open extract valve.
Explain the closed configuration of the avionics ventilation.
The extract fan draws recirculated air through and around the equipment. The air is cooled by a skin heat exchanger before reentering the circuit through the blower fan.
Explain the closed configuration of the avionics ventilation.
Similar to the closed configuration except the a small flap on the extract valve opens to exhaust some of the heated air overboard.
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