Avionics Vent

Question 1

In the “Ground” Mode at High Skin Air temperatures, which Config is in operation?

Answer 1

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

Question 2

In the “Ground” Mode at Low Skin Air Temperatures, how is the Circulatory Air now cooled?

Answer 2

The closed-circuit configuration operates when skin temperature is beneath the on-ground threshold.
Avionic bay – heat exchanger – cargo underfloor

Question 3

In the “Flight” Mode at Low Skin Air Temperatures which Config is in operation?

Answer 3

The closed circuit configuration operates when skin temperature is beneath the in flight threshold of +35 degrees to +32 degrees.
Heat exchanger – cargo

Question 4

In the “Flight” Mode at High Skin Air Temperatures which Config is in operation?

Answer 4

The intermediate configuration operates when skin temperature is above the in-flight threshold of +35 degrees to +32 degrees.
Heat exchanger - cargo – extract

Question 5

What causes the system to transit from the GROUND mode to the FLIGHT mode?

Answer 5

Takeoff power + weight on gear

Question 6

When might you have to put both switches (BLOWER and EXTRACT) to OVERRIDE?

Answer 6

Smoke / fumes / avionics smoke

Question 7

What causes a BLOWER or EXTRACT FAULT light to illuminate?

Answer 7

• Pressure is low (blowing + extract) inhibits for engine shut down.
• Duct overheat (blower)
• Computer power supply falls
• Smoke warning is activated

Question 8

What happens when the BLOWER is selected to OVERRIDE?

Answer 8

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.

Question 9

What happens when the BLOWER and EXTRACT are selected to override? (E.g. during AVIONICS SMOKE)

Answer 9

When both p/b SW are on OVRD:

• Airflows from the air conditioning system and then overboard
• The extract fan continues to run