Air Conditioning and Pressurization

Question 1

What sources of bleed air do we have have on the CRJ-200

Answer 1

• 7th Stage- Used for pressurizing some seals and gaskets.
• 10th Stage- Used for engine starts, air conditioning, equipment cooling, and pressurization.
• 14th Stage- Thrust reversers, wing and cowl anti-icing

Question 2

What sources do we have for 10th stage bleed air?

Answer 2

Normal is the 10 stage of the engine compressors but can also be supplied by the APU or a ground power cart.

Question 3

What purpose does the ISOL valve serve?

Answer 3

• Isolated the left from the right side of the 10th stage bleed manifold.
• Allows for crossover engine starts (known as Cross Bleed engine starts)
• APU Engine starts
• Ground air supply engine starts
• Crossover air conditioning

Question 4

Why are the 10th Stsge bleed air valves interconnected?

Answer 4

• This prevents the airflow from the engines back flowing THROUGH the APU LCV into the APU causing damage to the APU compressor
• With Engines and APU running if the L/R 10th stage bleed is opened the APU LCV will close

Question 5

What kind of leak detection do we have for 10/14th stage bleed air?

Answer 5

• Dual Loop for 10th Stage ( more than one source of bleed air more than one loop)
• single Loop for 14th Stage. ( one source one loop)

Question 6

What does the DUCT MON loop A/B test do?

Answer 6

It tests the continuity of the individual 10th stage loops A and B to ensure they are not shorted to ground.

Note that if “1” of the loops had a short it can be placed on MEL. Not both.

Question 7

How is pack pressure and out put divided through out the CRJ-200?

Answer 7

• Right Pack- 70% cabin and 30% to distribution manifold. Cabin exhaust air is routed under the floor boards to the out flow valves.
• Left Pack -70% flight compartment and 30% to distribution manifold. Flight compartment exhaust air is routed through the avionics bay to the out flow valves.

Question 8

What pressure does the 10th stage system regulate the packs to?

Single pack OPPS?

Answer 8

30PSI for dual packs

41PSI for single pack

Question 9

The cargo fan supplies what kinda of air to the cargo compartment?

Answer 9

Re-circulated cabin exhaust air

Note- if the temperate exceeds 35^c the fan shuts down and a yellow caution message on ED2 is displayed.

Question 10

How are the Out Fow Valves operated?

Answer 10

Out Flow Valves are operated by a jet pump driven by the 10th Stage air.

• Auto Mode- left valve is master and right is slave and both respond to electronic inputs.
• Manual Mode- right is master and valves respond to pneumatic imputes.

Question 11

With the PAX signs in “AUTO”. When will the seatbelt and no smoking signs automatically turn on

Answer 11

CPAM will turn on the PAX signs at 10,000 feet if the switch is in auto.

Question 12

If the cabin depressurizes or if the PACKS are left off, at what cabin altitude will the oxogen masks auto deploy?

Answer 12

14,000

Question 13

When does the “FAULT” light illuminate on the cabin press panel

Answer 13

Only when both cabin pressure controllers have failed.

Question 14

What happens when the guarded EMER DEPRESS switch light is selected?

Answer 14

Both outflow valves open to depressurize the cabin. The altitude limiters will attempt to prevent the cabin from rising above 14,250 +- 750 feet.

Question 15

How does the MAN ALT switch work?

Answer 15

In the UP position it allows the outflow valves to open and cabin ALT to climb at the rate selected by the MAN RATE knob

In the DOWN position it allows the outflow valves to close and the cabin alt to descend at a rate selected by the MAN RATE knob.

The man rate knob range is 50-3,000 +/- 1,000 fpm.