15.1.2 Perform Air Systems Operations and Procedures

Question 1

How many packs are there?

How many pack controllers?

Answer 1

2 packs

2 identical controllers

Question 2

How is the pack temperature output controlled?

Answer 2

The packs will attempt to satisfy:

• the compartment requiring the coolest air, then
• add hot trim air (bleed) to control the other compartments

Question 3

What happens when any pack control system fault or pack outlet overheat is detected?

Answer 3

• Pack INOP light illuminates and

- EICAS advisory L or R PACK TEMP displays

Question 4

Pack output is limited during?

Answer 4

High bleed air demand periods such as:

• Main cargo fire suppression system is activated,
• Engine inoperative,
• Landing,
• Takeoff.

Question 5

Will the pack shut down for an automatic system control fault or pack outlet overheat?

Answer 5

No. It continues to run in an uncontrolled, degraded condition requiring crew action

Question 6

For an internal pack overheat, does the pack completely shut down? What indication will you see?

Answer 6

Yes. You will see:

• PACK OFF light
• Pack INOP light (in the same switch)
• EICAS PACK OFF and
• EICAS PACK TEMP.

Question 7

What does it mean if the pack INOP light remains illuminated after selecting STBY?

Answer 7

The fault is a pack overheat. After the pack has cooled, you may attempt to reset.

Question 8

Assuming no system faults, on touchdown the cabin altitude controller directs the outflow valve to:

Answer 8

The fully open position

Question 9

The engine BLEED light illuminates and the EICAS advisory message >L or R ENG HPSOV< displays when the:

Answer 9

Engine high pressure valve is open when commanded closed

Question 10

Which valves are normally commanded to close when the Engine Bleed switch is selected OFF?

Answer 10

• Engine bleed air valve,
• PRV (Pressure Relief Valve),
• HP bleed valve.