Air Conditioning & Pressurization

Question 0

What does the RECIRC fan switch do?

Answer 0

It turns on the recirculation fan, located in the ACM Service Bay. It draws air from the aft cargo compartment. It will operate at slow speed, but the ECU will automatically select high speed, when required. It will always operate at slow speed for engine start and single pack ops.

Question 1

What components make up the air conditioning system?

Answer 1

• Dual engine BASs
• One integrated air conditioning pack
• One APU
• Ducts
• ECS ECU

Question 2

What does the Pack Control Switch do in AUTO Mode?

Answer 2

The ECU Digital Channels will control pack, FCSOV, and Pack Bypass Valve operation to regulate cabin and flight deck temperature in response to manual inputs.

Question 3

What do the Pack Control Switches do in MAN Mode?

Answer 3

The Analog Channels modulate only the Pack Bypass Valve to regulate temps and the FCSOV remains fully open.

Question 4

What do the Pack Control Switches do when selected OFF?

Answer 4

The ECU will close the FCSOV and the Turbine SOV.

Question 5

How is pressure maintained and controlled?

Answer 5

• Pressure is maintained and controlled with engine bleed air, the ECS, and a Cabin Pressure Control System that regulates different outflow valves in response to pilot inputs on the Pressurization Control Panel.
• The Aft Outflow Valve is the primary control valve, the AFT Safety Valve assists onb the ground, and the Forward Safety Outflow Valve is for emergency use.

Question 6

Describe the Aft Outflow Valve.

Answer 6

It is an electrically controlled valve on the aft pressure dome, regulated by the CPC computers in response to Pressurization Control Panel inputs. It is the primary valve used for automatic and manual pressurization, and is also used to dump cabin pressure.

Question 7

Describe the Aft Safety Outflow Valve.

Answer 7

It is an electro-pneumatic valve on the aft pressure dome. It provides additional venting on the ground (with at least one bleed source running). It incorporates positive and negative press release functions.

Question 8

Describe the Forward Safety Outflow Valve.

Answer 8

It is a pneumatic valve, located on the forward pressure dome, used for emergency purposes. It can be modulated with the FWD Safety Outflow Valve Manual Control Knob on the PCP or selected fully OPEN or closed with the FWD Safety Outflow Valve Selector, on the copilot side consul. Incorporates positive and negative press release functions.

Question 9

What are the for modes of pressurization operation?

Answer 9

• Automatic
• Manual
• Emergency / Smoke Removal
• Pressure Dump

Question 10

When does the PCP Fault Warning Advisory Light illuminate?

Answer 10

• When the CPC detects a fault.

* Momentarily during the initial start-up self-test.

Question 11

Describe Automatic Pressurization Mode.

Answer 11

• The CPC automatically schedules pressurization in relation to altitude with minimal crew input.
• Begins Pressurization when power levers are advanced past 60° on takeoff.
• The “Takeoff Abort” feature keeps the CPC in takeoff mode for at least 10 minutes, so that for an emergency return, the crew will not have to select a new landing altitude.

Question 12

Describe the Manual Pressurization Mode.

Answer 12

When the mode select switch is selected to MAN, the crew can regulate the Aft Outflow Valve by increasing and decreasing cabin pressure differential.

Question 13

Describe the Pressurization Dump Mode.

Answer 13

Selecting DUMP fully opens the Aft Outflow Valve. Can also be used to vent air / smoke aft.