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Airbus A320 > Ventilation > Flashcards

Ventilation Flashcards

1
Q

What is the purpose of the ventilation system ?

A

It is designed to cool down the main avionic rack, LCD screens, CBs, TRs, radar and batteries, all of which generates a lot of heat.

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2
Q

What does control the avionic system ?

A

The AEVC - Avionics Equipment Ventilation Controller

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3
Q

How is the avionics cooled down ?

A

By ambient air, on a schedule based on the aircraft skin temperature, position of the aircraft (inflight or on the ground), and engine power settings.

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4
Q

What are the main components of the avionics system ?

A
  • Fans
  • Skin air inlet/outlet valves
  • Skin exchange inlet/outlet bypass valves
  • Air conditioning inlet valve
  • Skin exchange isolation valve
  • Avionics equipment ventilation controller - AEVC
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5
Q

What FANS are used for ?

A

Two electric fans continuously circulate air around the avionics compartment, when the aircraft is supplied with electricity.

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6
Q

What is the Fan Speed Controller (FSC) ?

A

The Fan Speed Controller (FSC) controls the fan speed as a function of temperature.
- High speed when ventilation air temp is above +40°C
- Low speed when ventilation air temp is below +35°C

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7
Q

What are the SKIN AIR INLET/OUTLET VALVES used for ?

A

These valves admit air from outside the aircraft and evacuate hot air from the avionics compartment

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8
Q

What are the SKIN EXCHANGE INLET/OUTLET BYPASS VALVES used for ?

A

These valves enable air to circulate between the avionics bay and the space under the cargo compartment floor.

The skin exchange inlet valve is installed downstream of the extraction fan and discharges any excess ventilated air to the cargo underfloor.

The skin exchange outlet valve just does the opposite. It allows additional air to enter the skin heat exchange if there is a lack of ventilated air.

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9
Q

What is the AIR CONDITIONING INLET VALVE used for ?

A

This valve opens to enable the air conditioning circuit to supply fresh air to the avionics compartment.

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10
Q

What is the SKIN EXCHANGE ISOLATION VALVE used for ?

A

This valve connects or isolates the skin heat exchanger.

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11
Q

What is the Avionics Equipment Ventilation Controller (AEVC) ?

A

It controls the operation of all the fans and valves of the avionics equipment system.

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12
Q

How many configurations are there ? And what are they ?

A

There are 5 possible configurations, all of which provide cool air in different ways.

Normal operation :
- Open Circuit
- Close Circuit
- Intermediate

Abnormal operation :
- Blower Fault or Extract fault
- Smoke Configuration

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13
Q

How does the Open Circuit configuration work ?

A

In the Open Circuit configuration, ambient air is drawn by a blower fan through a skin air inlet valve.
As the ambient air makes it way inside, it goes past a check valve and a filter into the avionics compartment for cooling.
After cooling the avionics compartment, air is drawn overboard by an extract fan through the skin air outlet valve.

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14
Q

How does the blower/extract fan work ?

A

The blower/extract fan is powered by a motor driving high efficiency fan blades. The extract fan is identical to the blower fan.

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15
Q

Why is there a two-staged filter after the skin air inlet valve ?

A

To remove any dust or water particules.

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16
Q

What are the triggering conditions for the Open Circuit configuration ?

A

According MSN :

  • Avionic Duct temp > 40°C
  • A/C on the ground
  • T/O CONFIG pb not activated
  • Avionic Duct temp > 40°C
  • A/C on the ground
  • T/O POWER not at T/O
  • Skin temperature > Ground threshold :
    +12°C increasing
    +9°C decreasing
  • A/C on the ground
  • T/O POWER not at T/O
17
Q

How does the Close Circuit configuration work ?

A

In the close configuration, the skin air inlet and outlet valves are both closed. Both fans operate and draw air through the avionics compartment. The skin exchange isolation valve opens and air from the avionics compartment is drawn through the skin heat exchanger.

From the skin heat exchanger, air makes it way back to the blower into the avionics compartment.

Two additional valves open : the skin exchange inlet bypass valve and the skin exchange outlet bypass valve.

18
Q

What is the SKIN HEAT EXCHANGER ?

A

It is a thermally insulated wall between the pressure hull and the outer skin, which uses the low temperature to assist in cooling.

19
Q

What are the triggering conditions for the Close Circuit configuration ?

A

According MSN :

Inflight :
- Skin temperature < Inflight threshold :
+35°C increasing
+32°C decreasing
- A/C not on the ground
Ground :
- Avionic Duct T° < 40°C

Inflight :
- Skin temperature < Inflight threshold :
+35°C increasing
+32°C decreasing
- A/C not on the ground
Ground :
- Avionic Duct T° < 40°C

Inflight :
- Skin temperature < Inflight threshold :
+35°C increasing
+32°C decreasing
- A/C not on the ground
Ground :
- Skin temperature < Ground threshold :
+12°C increasing
+9°C decreasing

20
Q

How does the Intermediate Circuit configuration work ?

A

The Intermediate Circuit configuration is similar to the Close Circuit configuration,. Air is drawn from the skin exchange outlet bypass valve by the blower to the main avionics compartment.
The skin air inlet and outlet valves are both closed. But on the skin air outlet valve, there is small intermediate flap which opens.
From the main avionic compartment, air is sent back to the skin heat exchanger or is sent overboard by the extract fan through the skin air outlet valve, or beneat the cargo floor through the skin exchange inlet bypass vavle.

21
Q

What is the measuring range for the skin temperature ?

A

From -50°C to +80°C
Outside of this range, it operates as Intermediate Circuit configuration until the temperature is within the range again.

22
Q

What might happen when the skin temperature on the ground is between the minimum threshold of +9°C and +12°C ?

A

The close and open positions indications on the SD page may become amber. This is the result of the AEVC not knowing which configuration should be selected.

23
Q

How do the BLOWER FAULT or EXTRACT FAULT configurations work ?

A

When the BLOWER or EXTRACT pb is set to OVRD, the system is in Close Circuit configuration, and adds air from the air conditioning system to the ventilation air.
This configuration may be used in heavy precipitation to prevent water from entering the ventilation system.

24
Q

What happens when BLOWER is set to OVRD ?

A

The blower fan is stopped and the extract fan continues to run.

25
Q

What happens when EXTRACT is set to OVRD ?

A

The extract fan is controlled via the pb and both fans continue to run.

26
Q

What could trigger a BLOWER FAULT ?

A
  • Low blowing pressure
  • Duct overheat
  • Computer power supply failure
  • Smoke detected
27
Q

What could trigger an EXTRACT FAULT ?

A
  • Low extract pressure
  • Computer power supply failure
  • Smoke detected
28
Q

What is the SDCU ?

A

Smoke Detector Control Unit

29
Q

How does the SMOKE configuration work ?

A

A smoke detector is installed upstream of the extract fan. If smoke is detected, the SDCU triggers an AVIONIC SMOKE ECAM, and BLOWER and EXTRACT pb illuminate, and a SMOKE legend in GEN 1 line.

When BLOWER and EXTRACT pb are set to OVRD, the air conditioning supplies cooling air, which is then set overboard.
The blower fan stops.

All the other valves are commanded to close position : except the small intermediate flap on the extract valve.

30
Q

What happens during a controller failure ?

A

In case of a controller failure, the BLOWER and EXTRACT lights come on and the pb are set to OVRD.

The controller failure configuration is the same as the SMOKE configuration concerning the blower fan (it stops), the skin exchange inlet bypass (closed) and the skin air outlet valve (partially opens)

However, the skin air inlet valve, the skin exchange outlet bypass valve and the skin exchange isolation valve remain in the last position checked before the failure occured.
The extract fan continues to run.

31
Q

How are batteries ventilated ?

A

Each battery is ventilated by two ducts. Cool air from the avionics compartment is drawn through an inlet around the batteries and vented overboard by venturi.
This only takes place inflight with cabin differential pressure.

Airbus A320 (22 decks)

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