Environmental Control System (ECS)

Question 1

How many Air conditioning packs are there?

Answer 1

2

Question 2

Where does the left pack provide bleed air to?

Answer 2

Flight deck and last 4 rows

Question 3

Where does the right pack provide bleed air to?

Answer 3

The cabin and cargo areas

Question 4

What does the RECIRC FAN switch do when positioned to on?

Answer 4

Air is filtered and re-circulated into the flight deck and cabin for greater efficiency.

Question 5

On the ground, if actual cabin temperature differs from selected temperature in flight deck by more than __ degrees, the ACSC will increase pack flow to decrease the time for pull up/down.

Answer 5

10 degrees

Question 6

Outflow valves are controlled by ___. One for each cabin pressure controller (CPC) and one that will react during manual pressurization.

Answer 6

3 DC motors

Question 7

What two computers control all aspects of bleed air and air conditioning while in AUTO.

Answer 7

ACSC (Air conditioning system controller)

AILC (Anti ice leak controller)

Question 8

What is the key difference in AUTO and MANUAL temperature control?

Answer 8

Auto has protection, manual does not.

Question 9

What are the indications and what would happen you would see after pressing the EMER DEPRESS at FL250?

Answer 9

1. 8500 - Caution message
2. 10,000 - Warning message
3. 14,000 +/- 300 ft PAX O2 masks drop
4. 14,500 +/- 500 ft Cabin press is locked by limiter.

Max cabin altitude is set, auto or manual inputs overridden. Outflow valve driven open by manual DC motor. Active CPC is instructed to close outflow valve at cabin ALT of 14,500 +/- 500.

Question 10

How many pressure controllers are there? Are they always active?

Answer 10

2 CPCs (Cabin Pressure Controllers)

Only one is active at a time and they alternate.

Question 11

When do the CPCs change automatically?

Answer 11

Weight off wheels + 3 minutes, when one computer fails

Question 12

What happens when both CPCs fail?

Answer 12

Enters isobaric hold mode

Question 13

How can you manually change CPCs

Answer 13

Double press (PRESS CONT) button on the cabin pressure panel

Question 14

If the CPAM-like microprocessor should fail, which CPAM functions will be lost?

Answer 14

Passenger signs will not illuminate and O2 masks will not drop automatically

Question 15

Following a CPAM-microprocessor failure, which of the CPAM functions will still be functioning and which component will take over these functions?

Answer 15

One of the CPCs will take over and will take care of displaying the CABIN ALT caution and warning messages at 8500 and 10,000. Will also engage the cabin limiter mode as well at 14,500 +/-500.

Question 16

What is the maximum cabin altitude allowed by the outflow valves?

Answer 16

14,500 +/- 500 so 15,000.

Question 17

How would you cause the cabin pressure to INCREASE manually?

Answer 17

Set manual mode and push “down” on the switch.

Question 18

Why do we not need any sort of pressure regulating pack valve?

Answer 18

45 PSI is regulated by the PRSOVs and LCV

Question 19

How is Pack output regulated by the ACSC?

Answer 19

Temperature control valve and Ram air regulating valve

Question 20

In AUTO mode when will the Packs switch bleed air sources from APU to the engines?

Answer 20

Approach BIT/Takeoff BIT

Question 21

When you command warmer or colder air from the Pack, what process takes place to change the temperature of pack output air?

Answer 21

Temp control valve and ram air regulating valve actuate to control temp

Question 22

What malfunction will cause the PACK FAULT switchlight to illuminate?

Answer 22

Pack failure in AUTO mode

Question 23

Which cargo compartment is pressurized and air conditioned and where does the conditioned air come from?

Answer 23

Both are pressurized, aft only receives conditioned air from the recirculated cabin air on Pack 2 from an inlet SOV. If failed then it comes from the mixing manifold.

Question 24

What occurs automatically following a smoke or overheat detection in AFT cargo bay?

Answer 24

Heater will cut off and intake/exhaust SOVs close. EICAS message will display indicating AFT cargo fire.

Question 25

Describe the function of aircraft’s two safety valves:

Answer 25

Protect against negative pressurization and over-pressurization.

Question 26

When would you receive the message “DISPLAY COOL”?

Answer 26

CRT cooling fans have failed or air flow is too low.

Question 27

If the CRT cooling fans fail, what system takes its job?

Answer 27

The Air Conditioning system will take over after selecting STANDBY.

Question 28

Which computer controls the CRT fans?

Answer 28

ACSC

Question 29

From where does the Avionics rack receive cooling air?

Answer 29

CRT Exhaust conditioned air is pulled through by avionics fans.

Question 30

Describe the purpose of the ground valve and when it will open and close automatically:

Answer 30

60 seconds after landing the valve opens to dump CRT and avionic exhaust. It closes automatically when the main and galley doors close to prepare for takeoff pressurization.

Question 31

What is the difference between “OVBD COOL” caution message and “OVBD COOL FAIL” status message.

Answer 31

OVBD COOL = valve fails open
OVBD COOL FAIL = valve failed closed

Question 32

Can the aircraft be fully supported by 1 pack?

Answer 32

Yes, if single pack altitudes are followed.

Question 33

Will the aircraft depressurize with the ram air valve open?

Answer 33

No, check valve should hold pressure in.