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Boeing 747 > Air Systems > Flashcards

Air Systems Flashcards

1
Q

How many temperature zones?

A

7 temperature zones:

Passenger:

  • flight deck
  • upper deck
  • main deck zones A - E

Freighter:

  • flight deck
  • upper deck
  • crew rest
  • fwd and aft main deck
  • fwd and aft lower lobe cargo deck
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2
Q

How many packs and controllers?

A
  • 3 identical packs
  • 2 identical pack temperature controllers (PTCs) - A and B

*pack valves are controlled electrically by PTC and open via bleed air pressure

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3
Q

How many channels for each Pack Temperature Controller (PTC)

A
  • 3 channels
  • 1 channel for each pack
  • PTCs alternate after touchdown or if a fault is detected
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4
Q

How many flow rates does each pack have?

A

Normal and High

  • Normal flow during cruise reduces fuel consumption by approximately 0.3%
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5
Q

How is conditioned air distributed through the cabin?

A

Flow rate and operation determined by:

  • phase of flight
  • number of pack operations
  • position of lower lobe cargo conditioned air flow rate selector (freight)
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6
Q

Trim Air Switch On

A
  • master trim air valve open
  • zone trim valves operate automatically
  • system provides hot bleed air to the zone duct condition air through zone trim valves
    • zone trim air valves modulated by ZTCs (zone trim controllers)
  • trim air to the lower cargo lobe (FWD&AFT) not controlled by Master Trim Air Valve
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7
Q

How is the cargo compartment heated?

A

FWD Compartment:
- from heated air exhausted from the electrical and electronic (E and E) compartment

Aft Compartment:

  • bleed air from center section of bleed air duct
  • thermal switch opens and closes temperature control valve
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8
Q

How are flight deck equipment and electrical equipment cooled?

A
  • internal fans and valves directed cool cabin air from lower fuselage into the equipment racks
  • warm exhaust air is either:
    • directed to the FWD Cargo compartment
    • recirculated in a closed loop through the E and E compartment
    • ducted overboard
  • on the ground when ambient temps are moderate or high warm air is exhausted overboard
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9
Q

How is the cabin pressurized?

A
  • 2 outflow valves in the rear of the cabin operate in parallel to regulate the discharge of conditioned cabin air
  • 2 cabin controllers (A and B) control both outflow valves
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10
Q

What are the different modes during automatic operation of the pressurization system?

A

In Flight:
Climb mode - cabin altitude increases on a schedule determined by airplane climb rate and flight plan cruise altitude (from FMS)
* cabin altitude controller assumes 39,000’ if cruise altitude is not available from FMS
Cruise mode - controls cabin altitude to a maximum of 8,000’
Descent mode - entered at T/D or initial descent of 1,000’ from cruise; controls cabin altitude to slightly below planned landing altitude (from FMS or MAN selection)
* cabin altitude controller assumes landing elevation of 2,000’ if FMS or MAN landing altitude is unavailable

Ground:
Takeoff - small positive pressurization is provided just prior to rotation
Landing - outflow valves open to depressurize aircraft

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11
Q

How many pressure relief valves?

A
  • 2 positive pressure relief valves (9.4 PSI)
  • negative pressure relief valves on each cargo door (number depends on aircraft) - relieve existing differential pressure when doors are open
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12
Q

Bleed Air Sources

A
  • APU
  • ground source
  • engine (IP or HP)
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13
Q

What is bleed air used for?

A
  • air conditioning
  • pressurization
  • engine starting
  • wing and nacelle anti-ice
  • leading edge flaps
  • aft cargo heat
  • cargo smoke detection
  • air driven hydraulic demand pumps
  • potable water pressurization
  • hydraulic reservoir pressurization
  • thrust reversers
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14
Q

Sources of Engine Bleed Air

A
  • Intermediate Pressure (IP) section - used during high power setting operations
  • High Pressure (HP) section - used during descent and low power setting operations
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15
Q

When does engine bleed valve close?

A
  • ground cart is supplying air
  • bleed over temperature
  • bleed over pressure
  • loss of bleed source
  • bleed duct leak
  • engine fire switch pulled
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16
Q

What opens the start valve during engine start?

A

For Autostart:

  • Engine Start switch arms the start valve
  • EEC opens start fable when Fuel Control switch to RUN

For Manual start:
- Engine Start switch opens the start valve

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17
Q

How many sections of the Bleed System?

A
  • 3 sections (Left, Center, and Right) separated by 2 isolation valves (Left and Right)
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18
Q

When is APU RUNNING displayed on EICAS

A

APU N1 95% or greater

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19
Q

Primary use for APU Bleed

A
  • engine starting

- pack operation on the ground (air conditioning)

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20
Q

Where are check valves located in the Bleed system?

A
  • APU supply duct
  • Ground Supply duct
  • IP section
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21
Q

What causes Pressure Regulating Valve (PRV) to close?

A
  • bleed air overheat
  • start valve failed to closed
  • engine bleed HP valve failed open
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22
Q

Under what conditions would High Pressure (HP) air be used?

A
  • Descent

- Other low power setting operations

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23
Q

Under what conditions would Intermediate Pressure (IP) air be used?

A

High Power Settings

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24
Q

The Engine Bleed Air Switches control which valves by system logic, when bleed air pressure is available?

A
  • Engine bleed air valve
  • Pressure Regulating Valve (PRV)
  • HP bleed valve
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25
Q

Describe the general function of the Pressure Regulating Valve

A

The PRV limits bleed air pressure to prevent damage to ducting and equipment downstream.

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26
Q

With the HP valve failed open and the respective bleed air switch OFF will nacelle anti-ice be available?

A

No

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27
Q

An Engine Bleed Air System (SYS) FAULT light indicates what?

A
  • Bleed air overheat
  • Bleed air overpressure
  • HP bleed valve open when commanded closed
  • PRV open when commanded closed
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28
Q

What does a bleed duct Isolation (ISLN) VALVE light indicate (amber)?

A

Isolation valve position disagrees with switch position

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29
Q

What happens if the engine start valve fails to close?

A
  • Bleed air is isolated from the engine starter (protects the starter)
  • The PRV remains closed
  • The engine bleed air valve remains closed
  • Nacelle anti-ice and thrust reverse are not available for the respective engine
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30
Q

What 2 valves close in the engine if a bleed are overheat is detected?

A
  • PRV

- HP valve

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31
Q

What conditions in the engine bleed air system would prevent nacelle anti-ice operation when the bleed air switch is ON?

A
  • The PRV has failed closed, or
  • The PRV has been closed due to a bleed air overheat (Fan Pre-cooler not working), or
  • The start valve is not closed
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32
Q

How would you isolate a bleed air duct section in the event of a bleed duct leak is detected?

A
  • Close the respective isolation valve

- Close the engine bleed air valves

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33
Q

Do we normally operate with the Isolation Valves open or closed?

A

Open

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34
Q

If the center duct is isolated how is temperature controlled in all temperature zones?

A
  • All temperature zones operate in backup temperature control mode
  • Trim air is unavailable
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35
Q

With a left or right duct isolated how would the leading edge flaps extend on the affected side and what EICAS Advisory message would display?

A
  • The respective LEF would operate in secondary mode (electric)
  • FLAPS PRIMARY (until LEF extended)
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36
Q

How does an isolated left or right duct affect the hydraulic systems?

A

The respective hydraulic demand pump 1 or 4 is turned off

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37
Q

What two systems use engine bleed air downstream in the engine prior to the engine bleed valve?

A
  • Nacelle anti-ice

- Thrust reverse

38
Q

How are the engine bleed air valves actuated and when do they open for forward flow?

A
  • The bleed air valves are pressure activated

- They remain closed until engine bleed air pressure causes forward flow

39
Q

Which areas does each pack receive bleed air from?

A
  • Pack 1 from left pneumatic manifold
  • Pack 2 from center pneumatic manifold
  • Pack 3 from right pneumatic manifold
  • can receive bleed air from any engine with isolation valves open
40
Q

How is the pneumatic manifold decided?

A
  • 3 sections decided by two isolation valves
  • left manifold section supplied by ENG 1 and ENG 2
  • center manifold section supplied by APU or Ground Air
  • right manifold section supplied by ENG 3 and ENG 4
41
Q

Temperature range with temp selectors

A

Upper Deck: 18ºC (65ºF) - 29ºC (85ºF)
Main Deck: 4ºC (40ºF) - 29ºC (85ºF)
FWD/AFT Lower Lobe: 4ºC (40ºF) - 29ºC (85ºF)

42
Q

When is High Flow selected?

A
  • Manually via HI FLOW switch (PACKS HIGH FLOW memo)
  • Automatically by:
    • position of Lower Lobe Cargo Conditioned Air Flow Rate selector
    • phase of flight (Hi on the ground, climb, and descent)
    • number of operation packs
  • Automatically when packs shut down or fail
  • normal flow at FMC Cruise altitude or VNAV PATH
43
Q

Ventilated areas

A
  • Lavs
  • Galley
  • Flight Deck crew rest
  • supernumerary seat gaspers
  • two ventilations fans (primary and back up) for galley and lavs
44
Q

What happens when you turn the Pack Control Selector Off

A
  • closes associated Pack Valve
  • resets Pack Fault Protection
  • extinguishes SYS FAULT Light
  • Pack 1, 2, or 3 OFF memo
45
Q

How do you know which Pack Temp Controller is in operation?

A

Displayed on ECS synoptic display

46
Q

How are pack valves controlled?

A
  • Pack Control Selector to NORM, A, or B
  • electrically signals valve to open
  • bleed air pressure opens pack valve
47
Q

Benefits of Normal Flow rate

A
  • minimize bleed air demand

- reduce engine fuel consumption by 0.3%

48
Q

Pack system SYS FAULT Light

A
  • PTC/other system Fault

- pack overheat

49
Q

What happens if both PTCs A and B fail?

A
  • Packs will operate in backup mode

- pack overheat protection continues

50
Q

Equipment Cooling selector NORM (On ground, Warm Ambient Temp)

A

Equipment Supply Valve - Open
Supply Fan ——> electrical equipment
Exhaust Air ——> Ground Exhaust Valve (Open)
Inboard Exhaust Valve - Closed

51
Q

E and E exhaust routing depends on

A
  • routing depends on:
    • ambient temp
    • lower lobe cargo conditioned air flow rate selector (LLCCAF)
    • forward lower lobe cargo temp selector
52
Q

Equipments Cooling selector NORM (On ground, Cold Ambient Temp)

A 
Flight Config:
Equipment Supply Valve - Open
Supply Fan ——> electrical equipment 
Exhaust Air ——> Inboard Exhaust Valve (Open)——> FWD Cargo
Ground Exhaust Valve - Closed
53
Q

What E and E configuration is automatically selected with one engine running on each wing?

A

Flight Configuration

*allows for cabin pressurization

54
Q

EQUIP COOLING selector STBY

A

Manually selects Flight Configuration

55
Q

EQUIP COOLING: NORM
One or more engine running on each wing
LLCR selector: OFF, AFT LOW, AFT HIGH, or 10ºC or higher selected

A
  • Flight Config Open Loop

Equipment Supply Valve - Open
Supply Fan ——> electrical equipment
Exhaust Air ——> Inboard Exhaust Valve (Open)——> FWD Cargo
Ground Exhaust Valve - Closed

56
Q

EQUIP COOLING: NORM
One or more engine running on each wing
LLCR selector: FWD LOW, BOTH LOW, FWD HIGH, or 10ºC or less selected

A

Flight (Closed Loop)

Flight Deck Equipment Cooling Source Valve - Closed Loop (no conditioned air)
Equipment Supply Valve -Closed (No Cabin Air)
Supply Fan ——> electrical equipment
Exhaust Air ——> Bypass Valve (Open)
Ground Exhaust Valve - Closed
Inboard Exhaust Valve - Closed

57
Q

EQUIP COOLING EICAS message

A

E and E Cooling System not properly configured

58
Q

Single fault detected in E and E system?

A
  • system configure to closed loop mode
  • no EICAS message to alert crew
  • status page message for maintenance
59
Q

EQUIP COOLING OVRD

A
  • Flight Deck Equipment Cooling Source Valve - Closed
  • selected with both internal fans inoperative
  • cooling via reverse airflow from flight panels
  • Equip Supply valve - closed
  • ground exhaust valve - closed
  • Inboard exhaust valve - closed
  • Bypass valve - closed
  • Smoke/Override valve - open
  • differential pressure exhaust air overboard
60
Q

What is the source of bleed air for thrust reversers?

A
  • HP Bleed from respective engine

* HP is needed for thrust reverse operation

61
Q

How do the cabin altitude controllers calculate cabin pressurization schedule?

A
  • ambient pressure

- flight plan data from FMC

62
Q

When does the cabin altitude controller enter descent mode and what happens?

A
  • T/D
  • initial descent approx 1,000’ from cruise
  • controller decreases or increases cabin altitude to slightly below the FMC planned landing altitude in AUTO or the landing altitude set in MAN
  • The slight altitude difference assures a small positive pressurization at touchdown
63
Q

When is the protection of the cabin altitude limiter?

A

Closes both outflow valves if cabin altitude exceeds 11,000’

63
Q

What altitude is assumed by the cabin altitude controllers if landing altitude is not available from the FMC, and MAN is not selected?

A

2,000’

64
Q

What action would allow you to gain manual operation of the pressurization system?

A
  • Turn both Outflow Manual switches to ON

- Bypasses all automatic cabin altitude control functions

65
Q

Describe the cabin altitude controller CLIMB mode

A
  • cabin altitude increases on a schedule based on airplane climb rate and flight plan cruise altitude
  • FMC climb path planned level segment are included
  • Cabin altitude continues to increase during the level segment
66
Q

Is automatic PTC switch available with TRIM AIR off?

A
  • PTC A is automatically selected

- auto and manual selection of PTC B is inhibited, unless PTC A fails (inhibition will be removed)

67
Q

How is pack outlet temperature determined

A

The zone required the coolest temp control pack outlet temp

68
Q

Lower Lobe Cargo Conditioned Air Flow Rate - OFF

A

All lower lobe conditioned air is off

  • FWD and AFT Trim Air Valves closed
  • FWD and AFT Conditioned Air valves closed
69
Q

FAN AIR switch

A
  • turns on and off flight deck fan

- recirculated air in the cockpit

70
Q

Trim Air Off

A
  • Master Trim Air valve closes
  • Pack output temp to backup
  • PTC A selected (auto/mam selection of PTC B inhibited unless failure of A)
  • temp control of upper deck and crew rest areas inhibited
71
Q

ZONE RST SYS FAULT Light

A
  • ZTC fault or overheat in temp zone duct
  • Master trim air valve failed closed
  • TRIM AIR Switch OFF
  • master trim air valve closed and pack air continues to flow
72
Q

When is Trim Air unavailable to Flight Deck, Upper Deck, Crew Rest, and Main Deck areas (temp control reverts to back up mode)

A
  • TEMP ZONE EICAS Advisory
  • TRIM AIR OFF EICAS Advisory
  • Master Trim Air switch Off
  • center bleed duct isolated
73
Q

How is temperature modulated in backup mode

A
  • depends on which settings are avail to PTCs

Zone duct overheat:
* FLT DECK TEMP selector is operative - regulates all pack to an averages of 18ºC - 29ºC

Zone Controller fault:

  • FLT DECK TEMP selector failed; then
  • PACK outlet temp regulates to last flight deck temp set; or
  • average of 24ºC
74
Q

What happens when either pressure relief valve is open?

A

Pack 2 will automatically shutdown to assist in relieving cabin pressure

75
Q

What is supplied by the Right Bleed Manifold?

A
  • LE Flaps
  • HYD 3 and 4 Reservoir Press
  • Wing Anti-Ice
  • # 4 Hydraulic Demand pump
  • Pack 3
76
Q

What is supplied by the Center Bleed Manifold?

A
  • Trim Air
  • Aft Cargo Heat
  • Pack 2
  • Cargo Smoke Detectoin
  • Lower Lobe Cargo Air Con Trim Air
77
Q

What is supplied by the left bleed manifold?

A
  • LE Flaps
  • HYD 1 and 2 Reservoir Press
  • Wing Anti-Ice
  • # 1 Hydraulic Demand pump
  • Pack 1
78
Q

When is Bleed Air unavailable for thrust reverser operation with the Engine Bleed Air switch ON?

A
  • PRV failed closed
  • PRV closed due to bleed air overheat
  • start valve is not closed
79
Q

Purpose of the fan air precooler

A

Regulates Bleed air temperature

80
Q

What does the PRV protect with the start valve open?

A

Protects the engine compressor sections from reveres air flow during engine start

81
Q

LLCCAFR switch FWD LOW or AFT LOW

A

FWD LOW:

  • Pack 3 hi flow
  • Pack 1 and 2 normal flow
  • 2/3 of PACK 3 airflow to FWD lower lobe

AFT LOW:

  • Pack 2 hi flow
  • Pack 1 and 3 normal flow
  • 2/3 of PACK 2 airflow to AFT lower lobe
82
Q

LLCCARF BOTH LOW, FWD HIGH, or AFT HIGH

A
  • All PACKS HI

Both LOW: 2/3 of PACK 2 ad 2/3 of PACK 3 to respective lower lobes
FWD HI: All of PACK 3 flow to FWD lower lobe
AFT Hi: All of PACK 2 flow to AFT lower lobe

83
Q

Where is the temperature controlled for the Upper Deck and Crew Rest Area

A

Cabin Temperature Panel on the Lav Wall

84
Q

When do the positive pressure relief valve open? Can they be be closed?

A
  • open if cabin pressure becomes excessive
  • pack 2 shuts down to assist in relieving excess cabin pressure
  • part of the valve will close when cabin press is no longer excessive
85
Q

When do the negative pressure relief valves open?

A
  • located on side, fwd, and aft cargo doors
  • open when airplane cabin pressure is slightly less than outside air pressure
  • open to relieve any existing pressure when cargo door is unlatched
86
Q

Does the deck fan operate in flight?

A
  • operates on the ground only to recirculate air in the flight deck
87
Q

Functions of the Zone Temperature Controller

A

Controls commanded temperature by:

  • setting the cold pack outlet temperature
  • modulating trim air to selected zones by positioning zone trim air valves
88
Q

How is temp controlled when AFT or LWR Lobe in back up mode?

A
  • if FWD/AFT LWR Lobe Cargo Temp selector available to PTC, pack three/two outlet temp regulated to achieve the temp set by the selector, or
  • if FWD/AFT LWR Lobe Cargo Temp selector unavailable to PTC, pack three/two outlet temp regulated to achieve the cargo temp sensed at time backup mode initiated, or
  • if FWD/AFT LWR Lobe cargo temp unavailable to PTC, pack three/two outlet temp controlled to the pack outlet temp sensed at time backup mode initiated
89
Q

How can you attempt to restore zone temp control and clear back up mode?

A

FLT DECK, UPPER DECK, CREW REST, FWD MAIN, AFT MAIN: push ZONE RST switch

LWR FWD/AFT Cargo Lobe: associated Temp controller from AUTO to MAN or MAN to AUTO; also LLCCAFR selector to OFF

90
Q

AFT Cargo TEMP light

A
  • AFT cargo compartment temp excessive

- overheat shutoff valve closes

Boeing 747 (21 decks)

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