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A320 > Pneumatics: Air Cond/Pressurisation/Ventilation > Flashcards

Pneumatics: Air Cond/Pressurisation/Ventilation Flashcards

1
Q

How are Pack Flow Control Valve operated, controlled and what keeps it closed in the absence of air pressure?

(Same for Hot-Air Pressure-Regulating Valve)

A

Pneumatically operated.
Electrically controlled.
A spring.

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2
Q

With RAM AIR push button ON, what condition must be met to open outflow valve to 50%?

A

Under automatic control and ^P less the 1 PSI.

*if >1 PSI ^P, a check valve downstream of ram air inlet will not open

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3
Q

What causes Hot-Air Pressure-Regulating Valve to automatically close? (3 items)

A

If:
‐ Both lanes of ACSC 1 or ACSC 2 fail, or
‐ The duct overheats, or
‐ At least two trim air valves fail.

The valve remains operative, even if either the forward or aft cabin trim air valve fails.

DSC-21-10-20 P 7/8

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4
Q

Which ACSC control which trim air valves?

A

ACSC 1 controls cockpit trim air valve and hot air valve.
*because hot air valve closes, all trim valves are lost.

ACSC 2 controls cabin trim air valves.

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5
Q

Where are cabin temperatures measured?

A

In the lavatory extraction circuit and galley ventilation system.

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6
Q

What is the temperature selection range?

A

18 to 30 deg C

12 o’clock position is 24 deg C

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7
Q

When and why does ram air inlet flap close during takeoff and landing?

A

-CLOSES-Takeoff power set, main gear struts compressed.
-during landing, when main gear struts compressed and airspeed above 70kt. Opens 20 sec after below 70kt.

To avoid ingestion.

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8
Q

What happens if LO PACK FLOW selected and temperature demand cannot be satisfied?

A

System delivers normal flow.

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9
Q

What happens when cooling demand cannot be satisfied in a zone, if bleed pressure is too low?

A

Signal sent to EIU to increase minimum idle.

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10
Q

What happens in case of Air Cycle Machine (ACM) failure (eg. turbine seizure)?

A

Affected pack may be operated in heat exchanger cooling mode.

Main part of cooled air goes directly downstream of ACM turbine through bypass valve, and rest goes through failed ACM.

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11
Q

What temperature triggers a HOT AIR fault?

A

88deg C

Fault light goes out when below 70 deg C and pb selected OFF.

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12
Q

Pack flow control valve is automatically controlled. When is it closed?

A

-upstream pressure below minimum
-compressor outlet overheat
-engine start sequence
-FIRE pb on related engine side is pressed
-ditching is selected

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13
Q

Where is outflow valve located?

A

Right side of fuselage, behind aft Cargo compartment and below the flotation line.

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14
Q

Where are safety valves located, and at what pressure do they operate?

A

Rear pressure bulkhead, above the flotation line.
High 8.6 PSI
Low -1PSI

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15
Q

When does automatic transfer of pressure controller systems occur?

A

-70sec after each landing
-if the operating system fails

*can manually switch by switching MODE SEL to MAN for at least 10 sec then back to AUTO.

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16
Q

What maximum is the cabin altitude target limited to?

A

Approx 8000ft

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17
Q

What does the outflow valve do after landing?

A

At touchdown, any residual pressure is released at a cabin v/s 500 ft/min. 55s after landing, it fully opens.

*manual mode it will not open.

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18
Q

What is the maximum cabin descent rate?

A

750ft/min

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19
Q

What temperatures trigger high and low speeds through Fan Speed Controller (FSC)?

A

High- ventilation temperature above 40deg C

Low- ventilation temperature below 35 deg C

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20
Q

Ventilation close-circuit configuration operates in flight at what conditions?

A

Beneath:
+35 deg C, temperature increasing, or
+32 deg C, temperature decreasing

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21
Q

Ventilation close-circuit configuration operates on ground at what conditions?

A

Beneath:
+12 deg C, temperature increasing, or
+9 deg C, temperature decreasing.

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22
Q

Ventilation intermediate configuration operates in flight at what conditions?

A

Above:
+35 deg C, temperature increasing, or
+32 deg C, temperature decreasing

*Note- also operates outside of measuring range of skin temp (-50 to 80 deg C).

23
Q

BLOWER pb at OVRD, what happens to fans?

A

Blower fan stops, extract fan runs.

24
Q

EXTRACT pb at OVRD, what happens to fans?

A

Both run, extract is controlled directly from push button.

25
Q

Smoke configuration- causes BLOWER and EXTRACT FAULT lights. Pushing OVRD on both does what?

A

A/C supplies cooling air, which is then exhausted overboard. Blower fan stops.

*Same configuration applies to controller failure, except that skin exchange isolation valve stays open.

26
Q

How are batteries ventilated?

A

A venturi in skin of aircraft draws air from space around batteries and vents in overboard.

27
Q

How is pressure surge avoided at rotation?

A

The controller pre-pressurises the aircraft at a rate of 400ft/min, until ^P reaches 0.1PSI.

28
Q

How are lavatories and galleys ventilated?

A

An extraction fan draws ambient cabin air through them and exhausts it near the outflow valve.

29
Q

Where are the 2 packs located?

A

In wing root area.

30
Q

What is the function of the BYPASS VALVE?

A

Allows warm air to bypass the second heat exchanger and mix.

31
Q

What feeds the MIXING UNIT?

A

Both packs and emergency RAM AIR.

32
Q

How many lanes per ACS Controller?

A

2

33
Q

When engine mode selector set to ENG START, PACK FLOW VALVEs close (so all air can be used for start). What happens next?

A

If >30 seconds to set ENG MASTER on, valves reopen until ENG MASTER on.

PACK VALVEs reopen 30 sec after start sequence complete, or engine mode selector set back to NORM.

34
Q

How does external condition unit work?

A

Can be connected to low pressure connection point. Fed to mixing unit.

No indications in cockpit.

35
Q

FWD CARGO is ventilated with cabin ambient air via INLET ISOLATION VALVE, then removed by extraction fan or differential pressure via OUTLET ISOLATION VALVE.
When does extract fan run and can temperature be controlled?

A

Fan runs on ground or differential pressure <1PSI.

If installed, TRIM AIR VALVE controls hot air.

No heating if FWD CARGO door open or HOT AIR VALVE closed.

36
Q

When does AFT CARGO extract fan run, and how is it heated (if installed)?

A

Runs continuously as long as isolation valves are open.

With hot air supplied via CARGO PRESSURE REGULATING VALVE and then the TRIM VALVE.

37
Q

What is the 12 o’clock position on CARGO temp selector?

A

Approx 15deg C. (5-26 deg range).

38
Q

What do PACK FLOW selector positions correspond to?

A

LO- 80% normal flow rate
NORMAL- 100%
HIGH- 120%

39
Q

When is pack HI flow rate automatically commanded?

A

-operating on a single pack.
-APU is providing bleed air.

40
Q

What does ALTN MODE label on COND page indicate?

A

Zone regulator primary channel failure.

41
Q

What happens to pressurisation mode as Thrust levers are placed in FLEX or TOGA for takeoff?

A

Pressurisation enters takeoff mode- outflow valve begins to close and aircraft pre-pressurises to avoid a pressure surge at rotation.

42
Q

Where do APU bleed air or an external air cart connect to the system?

A

At the cross bleed duct to the left of the cross bleed valve.

43
Q

When is HP stage air used?

A

When there is insufficient pressure from IP stage.
Normally the case when engines are at idle during ground ops or long idle thrust descents.

44
Q

Engines bleed valves are spring loaded to closed position in the absence of airflow. When will BMCs command valves to close? (6 items)

A

-bleed leak detected.
-overpressure/temperature is sensed.
-reverse airflow is sensed.
-APU BLEED is selected ON.
-onside ENG BLEED selected OFF.
-onside ENGINE FIRE pb pressed.

45
Q

What has priority out of APU and engine bleed air?

A

APU Bleed has priority.

46
Q

What 2 reasons cause the crossbleed valve to be closed?

A

-X BLEED knob is in the SHUT position.
-X BLEED knob is in the AUTO position and the APU bleed valve is not open.

It will normally open when the APU bleed is selected ON, allowing APU to provide bleed air to both sides of the pneumatic system.

47
Q

Where is external high pressure air connected to the system?
How must the crossbleed valve be used?

A

Connection point adjacent to the low pressure connection point used for supplemental air conditioning.

The crossbleed valve must be manually opened to supply both sides of the crossbleed duct.

48
Q

Which BMC controls and monitors the APU bleed system for operation of the cross bleed valve in normal operations?
And what happen if one BMC fails in normal ops?

A

BMC1

The BMCs are interconnected, and if one fails, the other acts as a backup and performs many of its functions.

49
Q

How are bleed air leaks detected and managed?

A

There are leak detection loops installed in the vicinity of hot air ducts which detect high temps from bleed leaks.
If sensed, BMCs isolate the leak by closing the associated bleed valve or crossbleed valve as needed.

*will not close the crossbleed valve if X BLEED selected to OPEN.

50
Q

What does the RACK POWER pb do when selected OFF?

A

Removes power from aft avionics rack.

This depowers entertainment services such as Wireless aircraft data link, customers sales/service, live tv and satellite radio.

51
Q

How does the aircraft skin heat exchanger cool avionics ventilation system air?

A

Air is cooled by the cold temperature of aircraft’s skin. It uses the space between two ribs in the fuselage through which air is circulated.

52
Q

What is the difference between avionics ventilation intermediate and closed configuration?

A

Intermediate is the same as closed except a small internal flap on extract valve opens to exhaust some air overboard. As skin temp drops the flap will close for remainder of a normal flight.

53
Q

What happens if HOT AIR PRESSURE REGULATING VALVE FAILS?

A

Failed open: No effect.

Failed closed: Optimized regulation is lost. Trim air valves are driven to the fully closed position.
Pack 1 controls the cockpit temperature to the selected value and pack 2
controls the cabin temperature (FWD and AFT) to the mean value of the selected
temperatures.

DSC-21-10-40

A320 (29 decks)

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