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B777 CATHAY STUDY GUIDE > AIRCONDITIONING > Flashcards

AIRCONDITIONING Flashcards

1
Q

What types of air is provided to the cabin?

A

Fresh conditioned air and recirculated cabin air

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2
Q

How many zones are there in the pax compartment and in total?

A

6 in pax compartment labeled A - F
2 cargo (AFT and BULK)
F/D (Flight deck)

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3
Q

What sources can provide bleed air?

A
  1. Engines
  2. APU
  3. Ground source
    Conditioned air can also be connected on the ground directly to the conditioned air manifold
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4
Q

What is the purpose of the recirculation fans?

A

To recirculate cabin air. This allows the packs to operate at a reduced capacity which saves fuel

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5
Q

How is each pack controlled?

A

Each pack is controlled by two redundant channels in one of two controllers. If one channel fail in a controller, control of the repective pack is continued automatically by the redundant channel in that controller

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6
Q

What would cause pack output to automatically decrease?

A

When demand for bleed air is high like during gear retraction and during certain phases of flight to reduce fuel consumption

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7
Q

On the ground, which is noiser, one or two packs?

A

One pack

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8
Q

What is the difference between the EICAS message PACK L/R and PACK MODE L/R?

A

PACK L/R: Means that the pack is inoperative
PACK MODE L/R: Means that the pack is in stand-by cooling mode

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9
Q

How is cooling achived in stand-by cooling mode?

A

Bleed air is passed through the ram air heat exchanger only and bypassing the ACM in that pack.

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10
Q

When does a pack in stand-by cooling mode shut down?
When is the only time that it doesn’t shut down?

A

At lower altitudes and with high OAT when ambient conditions do not permit cooling. Pack restarts automatically when altitude and temperature permits

If both packs are in stand-by cooling mode or if one pack failed and the other one is in standby cooling mode, the pack valve doesn’t close at lower altitudes or higher temperatures. Reason for this is to be able to maintain cabin pressurization.

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11
Q

From where does the Flight deck receive fresh conditioned air?

A

From the left pack

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12
Q

What is the consequence of a RECIRC FAN being switched off?

A

The packs operates at full capacity which means more air is needed from the Engines and fuel consumption increases 0,7% for each fan that is OFF

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13
Q

How many trim air systems are there?

A

Two (Left and Right)

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14
Q

What provides air to the left and right trim air system?

A

Air from the respective Engine. Air is tapped off Before the heat exchanger and mixed into the conditioned air manifold to mix with cool conditioned air

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15
Q

What is the max and min Master temp selector range?

A

18 - 29 deg C

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16
Q

What is the flight attendants range for cabin temp control?

A

+- 6 deg C

17
Q

How can the flight deck temp be manually controlled?

A

By using the FLT DECK TEMP selector in the MAN setting

18
Q

Which zone controls the pack output temperature?

A

The zone that is requireing the coolest temp

19
Q

What is the default temp if control is lost?

A

24 deg C

20
Q

After a failiure of both cabin temp controllers, how is pack flow achieved?

A

By the ASCPC controllers
Pack flow is modulated to achieve a pack outlet temp of between 5 - 43 deg C

21
Q

Are the flight deck shoulder and foot warmers available on the ground?

A

No, only in flight

22
Q

Where are the Upper and Lower RECIRC fans drawing air from and where are they recirculating it to?

A

Upper: Draws air from the area above the pax compartment and recirculates it back to the zone ducts after the conditioned air manifold

Lower: Draws air from under the floor area and recirculates the air into the conditioned air manifold

23
Q

Describe the Equipment cooling normal operation

A

A supply fan draws air from the FWD cargo bay over temp and smoke sensors. Those sensors also detects fan failiures if no air is coming over them.
Air flows into the flight deck panels and Equipment racks from below.
Air is then drawn into the exhaust duct via a vent fan and back into the FWD cargo compartment.
There is another smoke detector after the vent fan to detect smoke from the avionics bay.

24
Q

How is temp controlled in the FWD cargo compartment?

A

By valves that opens and close to direct more air into the compartment for heating or to send the air overboard before it reaches the compartment

25
Q

How are the AFT and BULK cargo compartments heated?

A

With bleed air from the normal bleed air system

26
Q

What system draws air across the cargo temperature sensors?

A

The lavatory/galley vent fans

27
Q

How is the AFT and the BULK cargo heating affected by failiure of both the lavatory and galley vent fans?

A

The cargo heat shut-off valve closes and cargo heat is not provided

28
Q

What are the two temp settings for the AFT and BULK cargo compartments?

A

Low: 4 - 10 deg C
High: 18 - 24 deg C

29
Q

When does the BULK cargo ventilation fan operate?

A

When tempcontroller is set to high (18-24 deg C)

30
Q

What air heats the FWD cargo compartment?

A

Air from the Equipment cooling system

31
Q

How many supply cooling fans are there and why?

A

There are two. One is for back up

32
Q

What does the EICAS message EQUIP COOLING mean?

A

Equipment cooling has failed, means supply fan failure, low air flow, hot temperatures

33
Q

What does the EICAS message EQUIP COOLING OVRD mean?

A

System is in override mode, means smoke in the ducts, low airflow, system faults or arming FWD cargo fire arm switch

34
Q

What happens in the system when EQUIP COOLING OVRD message comes up?

A

Supply and vent fans stop
The override valves opens
FWD cargo heat valve closes
Air now flows into the Equipment area through differential pressure from the cabin and then over board via the override valve

35
Q

What is the expected temperature in the FWD cargo hold with a TAT of -13 deg C? Where would you find that information?

A

Around +15 deg C
Found in FCOM 2

36
Q

How can we determine the temperature in the fwd cargo compartment?

A

Temperatures can be predicted in the fwd compartment by a table in the DDG section

37
Q

What happens in the bulk cargo compartment when the temp setting is set to HIGH, apart from the temp increase? And what is the purpose of this?

A

When the bulk compartment is set to HIGH a ventilation fan starts to run to increase ventilation when animals are carried. The purpose of this vent fan is to reduce high levels of CO2 and humidity to build up.

38
Q

Where does the airflow for the Overhead Flight Crew Rest come from?

A

Directly from the left pack

B777 CATHAY STUDY GUIDE (24 decks)

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