Pressurization and Air Conditioning

Question 1

Describe the flow of air through the PACKs.

Answer 1

Preheater.
Heat exchanger.
Compressor.
Heat exchanger.
Re-Heater
Condenser.
Water separator.
Turbine.

Question 2

What are the components of the pressurisation system?

Answer 2

Outflow valve, two safety valves and a ground valve.

Cabin pressure controllers (auto and manual).

Question 3

When is the ground valve open?

Answer 3

When the aircraft is on the ground and the passenger or service doors are open.

Question 4

How does the system operate in ground mode?

Answer 4

Outlfow and ground valves are driven fully open to depressurise the airplane. Active on the ground, weight on wheels plus 60 seconds.

Question 5

How does the system operate in pre-pressurisation mode?

Answer 5

When the thrust levers are advanced for take-off, the outflow and ground valves close and the system pressurises the airplane to 150 ft below the field elevation.

Question 6

How does the system operate in take-off abort mode?

Answer 6

When an aborted take-off occurs, the outflow valave opens to bring the cabin pressure to field elevation, then reverts to ground mode.

Question 7

How does the system operate in flight abort mode?

Answer 7

For the first 10 minutes after take-off, provided the aircraft does not exceed 6000 ft, the system will ignore the destinatio field elevation and reset to the departure elevation.

Question 8

What does depressing the EMER DEPRESS switchlight do?

Answer 8

Overides the auto man manual modes, drives the outflow valve to the fully open position and rapidly depressurises the cabin to a limit of 14500 ft -/+ 500 ft.

Question 9

When will the no smoking and fasten seatbelt signs come on in the auto mode?

Answer 9

When the aircraft cabin altitude greater than 10000 ft.

Question 10

When do the passenger masks deploy?

Answer 10

At cabin altitude above 14000 ft or PASS OXY switch is depressed.