Chapter 6.20 - Air Systems

Question 1

With a pack in AUTO when will it go to high flow?

Answer 1

With only one pack operating, operating pack regulates to high flow

• In flight, and
• With the flaps up

Question 2

When will the isolation valve open in the auto position?

Answer 2

• If either bleed air switch is positioned to OFF, or

- Either pack switch is positioned to OFF

Question 3

-700

When will the recirculation fan shut off when in the AUTO mode?

Answer 3

• Shuts down with both packs operating, and

- Either pack switch in HIGH

Question 4

-800/-900
When will the left recirculation fan shut off when in the AUTO mode?

The right fan?

Answer 4

In Flight
- Left fan shuts down if either pack switch is in HIGH
On the ground
- Left fan shuts down if both pack switches are in HIGH

In Flight
- Right fan shuts down if both pack switches are in HIGH
On the ground
- Right fan will not shut down regardless of pack switch position

Question 5

-800/-900

What will be the fixed temperatures of the packs if all temperature selectors are positioned OFF?

Answer 5

Left pack 75 degrees Fahrenheit and right pack 65 degrees Fahrenheit

Question 6

What does the DUAL BLEED light look at?

Answer 6

The isolation and APU valves and the engine bleed switches

Question 7

What will cause an amber DUAL BLEED light?

Answer 7

• APU bleed valve open, and
• Engine number 1 bleed air switch on, or
• Engine number 2 bleed air switch on, and
• APU bleed valve and isolation valve open

Question 8

When are the RAM DOOR FULL OPEN lights on?

Answer 8

• On the ground
• In the air with the trailing edge flaps down
• In the air whenever additional cooling is needed

Question 9

What causes an amber PACK light?

Answer 9

• Pack trip off, or

- Failure of both primary and standby pack controllers

Question 10

What causes an amber WING-BODY OVERHEAT light?

Answer 10

Overheat from bleed air duct leak in engine strut, or

• Inboard leading edge, or
• Air conditioning bay

For a left light,

• Keel beam, or
• APU bleed air duct as well

Question 11

What causes an amber BLEED TRIP OFF light?

Answer 11

• Excessive bleed air temperature, or

- Excessive bleed air pressure

Question 12

-700

What causes an amber DUCT OVERHEAT light?

Answer 12

Air in related duct exceeds temperature limit

Question 13

-800/-900

What causes an amber ZONE TEMP light?

Answer 13

CONT CAB

• Indicates a duct temperature overheat, or
• Failure of the flight deck primary and secondary temperature control

FWD CAB or AFT CAB
- Indicates duct temperature overheat

Question 14

What lights can be reset by the TRIP RESET switch?

Answer 14

If condition is corrected resets,

• BLEED TRIP OFF
• PACK
• DUCT OVERHEAT (-700)
• ZONE TEMP (-800/-900)

Question 15

How can the WING-BODY OVERHEAT light be reset?

Answer 15

Only by removing the bleed air source

Question 16

What occurs when the DUCT OVERHEAT (-700) / ZONE TEMP (-800/-900) light comes on?

PACK light?

BLEED TRIP OFF?

Answer 16

Air mix valves drive full cold

Pack valve closes
Air mix valves drive full cold

Bleed valve closes
Pack valve closes
Air mix valves drive full cold