Air Systems

Question 1

The airplane is divided into __________ temperature zones:

Answer 1

Seven, The flight deck and six cabin zones.

Question 2

The Air system provides

Answer 2

1. Automatic Pack control,
2. Zone temperature control,
3. Cabin air recirculation,
4. Fault detection, and
5. Overheat protection.

Question 3

The packs are controlled by

Answer 3

two identical pack controllers.

If a controller fails, pack control switches automatically to the other controller.

Question 4

Pack output is automatically increased during high pack demand periods (to compensate for a failed pack or recirculation fan).

Answer 4

Fail

Question 5

Pack output is limited during high bleed air demand periods (such as for gear retraction during takeoff).
This situation ensures adequate bleed air remains available to the Air Demand hydraulic pumps in the Center hydraulic system.

Answer 5

Pack output is limited during high bleed air demand periods (such as for gear retraction during takeoff).
This situation ensures adequate bleed air remains available to the Air Demand hydraulic pumps in the Center hydraulic system.

Question 6

When a source of conditioned air is available, it may be used to supply conditioned air directly to the cabin distribution system, eliminating the need for pack operation.
When using conditioned air, the packs and the Lower recirculation fans should be turned off.

Answer 6

When a source of conditioned air is available, it may be used to supply conditioned air directly to the cabin distribution system, eliminating the need for pack operation.
When using conditioned air, the packs and the Lower recirculation fans should be turned off.

Question 7

Bleed air is provided to the system through one of two Pack Control Shutoff Valves.
When the pack is off, both valves are closed.

Answer 7

Bleed air is provided to the system through one of two Pack Control Shutoff Valves.
When the pack is off, both valves are closed.

Question 8

When the pack is on and the aircraft is below approximately 26,000’ the upper valve opens and the bleed air enters the pack.
When the aircraft climbs above 26,000’, the lower valve opens and the upper valve closes. This action causes all bleed air to flow through the Ozone Converter.

Answer 8

When the pack is on and the aircraft is below approximately 26,000’ the upper valve opens and the bleed air enters the pack.
When the aircraft climbs above 26,000’, the lower valve opens and the upper valve closes. This action causes all bleed air to flow through the Ozone Converter.

Question 9

The Economy Cooling Valve opens and bleed air flows through the Economy Cooling Check Valve and through the Economy Cooling Valve to Turbine 2.
Therefore, the Economy Cooling mode reduces the air flow through the compressor and Turbine 1. This situation reduces engine fuel consumption by reducing the pneumatic pressure required for normal pack flow.

Answer 9

The Economy Cooling Valve opens and bleed air flows through the Economy Cooling Check Valve and through the Economy Cooling Valve to Turbine 2.
Therefore, the Economy Cooling mode reduces the air flow through the compressor and Turbine 1. This situation reduces engine fuel consumption by reducing the pneumatic pressure required for normal pack flow.

Question 10

In the Economy Cooling Mode, the Cabin Temperature Controller modulates the turbine bypass valve and ram air doors to control the pack output air temperature.
Standard operation of the pack resumes automatically when the conditions for Economy Cooling are no longer in effect.

Answer 10

In the Economy Cooling Mode, the Cabin Temperature Controller modulates the turbine bypass valve and ram air doors to control the pack output air temperature.
Standard operation of the pack resumes automatically when the conditions for Economy Cooling are no longer in effect.

Question 11

Pack control, fault detection, and overheat protection are all automatic.
When an overheat or other significant pack fault is detected, the pack automatically shuts down.
The EICAS advisory message PACK (L, R) is displayed.
The appropriate Non-normal checklist will attempt to restore pack operation by directing the crew to press the AIR CONDITIONING RESET switch.

Answer 11

Pack control, fault detection, and overheat protection are all automatic.
When an overheat or other significant pack fault is detected, the pack automatically shuts down.
The EICAS advisory message PACK (L, R) is displayed.
The appropriate Non-normal checklist will attempt to restore pack operation by directing the crew to press the AIR CONDITIONING RESET switch.

Question 12

For certain internal malfunctions, a pack automatically enters the standby cooling mode.
The Standby Cooling Mode while considered a non-normal condition, operates much like the Economy Cooling mode

Answer 12

For certain internal malfunctions, a pack automatically enters the standby cooling mode.
The Standby Cooling Mode while considered a non-normal condition, operates much like the Economy Cooling mode

Question 13

During standby cooling mode operation, the EICAS advisory message PACK MODE (L, R) is displayed, and STBY COOLING is displayed in amber on the Air Synoptic.

Answer 13

During standby cooling mode operation, the EICAS advisory message PACK MODE (L, R) is displayed, and STBY COOLING is displayed in amber on the Air Synoptic.

Question 14

In the standby cooling mode, the pack automatically shuts down at lower altitudes and higher outside air temperatures when ambient conditions do not permit standby cooling.
The pack automatically restarts when altitude and outside air temperatures are suitable for the standby cooling mode.

Answer 14

In the standby cooling mode, the pack automatically shuts down at lower altitudes and higher outside air temperatures when ambient conditions do not permit standby cooling.
The pack automatically restarts when altitude and outside air temperatures are suitable for the standby cooling mode.

Question 15

If both packs are in standby cooling mode, or if one pack is inoperative and the other pack is in standby cooling mode, then the packs operate continuously, regardless of altitude or outside air temperature, to maintain cabin pressurization.
Decreased pack cooling capacity may result in warm flight deck or cabin temperatures at lower altitudes.

Answer 15

Pressurization is priority

Question 16

With dual cabin temperature controller failures, or with a loss of all normal electrical power, the air supply and cabin pressurization controllers control the pack flow control valves.
The pack flow rate is modulated to keep pack outlet temperature between 40° and 110°F.
All flight deck temperature controls are disabled except the PACK switches.

Answer 16

With dual cabin temperature controller failures, or with a loss of all normal electrical power, the air supply and cabin pressurization controllers control the pack flow control valves.
The pack flow rate is modulated to keep pack outlet temperature between 40° and 110°F.
All flight deck temperature controls are disabled except the PACK switches.

Question 17

The flight deck receives 100% fresh conditioned air from the left pack only, and is maintained at a slightly higher pressure than the passenger cabin.
This prevents smoke from entering the flight deck.

Answer 17

The flight deck receives 100% fresh conditioned air from the left pack only, and is maintained at a slightly higher pressure than the passenger cabin.
This prevents smoke from entering the flight deck.

Question 18

Recirculation fans add to cabin ventilation, permitting the packs to be operated at reduced flow.
Air moves from the passenger cabin to the lower deck, where it is either exhausted overboard through outflow valves or is drawn into the lower recirculation system.

Answer 18

Recirculation fans add to cabin ventilation, permitting the packs to be operated at reduced flow.
Air moves from the passenger cabin to the lower deck, where it is either exhausted overboard through outflow valves or is drawn into the lower recirculation system.

Question 19

Air from the lower recirculation fans is mixed with pack air before entering the supply ducts.
Air from the upper recirculation fans feeds into the supply ducts directly.
The recirculation fans can be turned off for several minutes to provide a more rapid exchange of air.

Answer 19

Air from the lower recirculation fans is mixed with pack air before entering the supply ducts.
Air from the upper recirculation fans feeds into the supply ducts directly.
The recirculation fans can be turned off for several minutes to provide a more rapid exchange of air.

Question 20

Selecting one or more RECIRCULATION FAN switches OFF displays the EICAS memo message RECIRC FANS OFF.
The associated pack will operate in high flow, and approximately one percent fuel consumption increase occurs for each fan switch turned OFF.
Note: High flow in this situation will be inhibited during single engine operations.

Answer 20

Selecting one or more RECIRCULATION FAN switches OFF displays the EICAS memo message RECIRC FANS OFF.
The associated pack will operate in high flow, and approximately one percent fuel consumption increase occurs for each fan switch turned OFF.
Note: High flow in this situation will be inhibited during single engine operations.

Question 21

using the CABIN TEMP control. The flight attendants can use the Cabin Services System to further adjust the temperature in any passenger cabin zone (+/-10°F, within the limits of 65° to 85°F). The temperature of the zone requiring the coolest temperature controls the pack outlet temperature. With the loss of inputs from the flight deck or cabin temperature controls, the packs maintain a cabin temperature of 75°F.

Answer 21

using the CABIN TEMP control. The flight attendants can use the Cabin Services System to further adjust the temperature in any passenger cabin zone (+/-10°F, within the limits of 65° to 85°F). The temperature of the zone requiring the coolest temperature controls the pack outlet temperature. With the loss of inputs from the flight deck or cabin temperature controls, the packs maintain a cabin temperature of 75°F.

Question 22

The flight deck temperature selector sets and maintains the flight deck temperature as selected to between 65° and 85°F.
The flight deck temperature can be controlled manually by setting the flight deck temperature selector to the manual mode.
In this case the crew must manually adjust the Flight Deck Trim Air Valve to control the temperature.

Answer 22

The flight deck temperature selector sets and maintains the flight deck temperature as selected to between 65° and 85°F.
The flight deck temperature can be controlled manually by setting the flight deck temperature selector to the manual mode.
In this case the crew must manually adjust the Flight Deck Trim Air Valve to control the temperature.

Question 23

Flight crew shoulder heat is provided by electric elements in the side window air diffusers.
The foot heaters have electric heating elements only, with no airflow.
Both are available in flight only.

Answer 23

Flight crew shoulder heat is provided by electric elements in the side window air diffusers.
The foot heaters have electric heating elements only, with no airflow.
Both are available in flight only.

Question 24

Two ventilation fans, a primary and a backup, draw air from the galleys and lavatories.
The fans operate automatically.
If the primary fan fails, the backup fan automatically operates.
Conditioned air is provided to the galleys from the air distribution system

Answer 24

Two ventilation fans, a primary and a backup, draw air from the galleys and lavatories.
The fans operate automatically.
If the primary fan fails, the backup fan automatically operates.
Conditioned air is provided to the galleys from the air distribution system

Question 25

The aft and bulk cargo compartments each have independent bleed air heating systems. An insulated curtain separates the two compartments.
With the CARGO TEMPERATURE selector set to LOW or HIGH, the associated cargo heat shutoff valve opens and the temperature control valve (located downstream) opens and closes depending on the temperature in the compartment.

Answer 25

The aft and bulk cargo compartments each have independent bleed air heating systems. An insulated curtain separates the two compartments.
With the CARGO TEMPERATURE selector set to LOW or HIGH, the associated cargo heat shutoff valve opens and the temperature control valve (located downstream) opens and closes depending on the temperature in the compartment.

Question 26

The lavatory/galley vent fans draw air across temperature sensors in each compartment.
If both vent fans fail, cargo heat fails.

Answer 26

The lavatory/galley vent fans draw air across temperature sensors in each compartment.
If both vent fans fail, cargo heat fails.

Question 27

With the CARGO TEMPERATURE selector set to LOW and TAT less than 45°F, the respective temperature control valve opens. The compartment temperature is maintained between 40° and 50°F.
With the CARGO TEMPERATURE selector set to HIGH and TAT less than 70°F, the respective temperature control valve opens. The compartment temperature is maintained between 65° and 75°F.

Answer 27

With the CARGO TEMPERATURE selector set to LOW and TAT less than 45°F, the respective temperature control valve opens. The compartment temperature is maintained between 40° and 50°F.
With the CARGO TEMPERATURE selector set to HIGH and TAT less than 70°F, the respective temperature control valve opens. The compartment temperature is maintained between 65° and 75°F.

Question 28

Selecting the HIGH setting on the BULK CARGO TEMPERATURE selector turns on the bulk ventilation fan, which is provided for animal carriage.

Answer 28

Selecting the HIGH setting on the BULK CARGO TEMPERATURE selector turns on the bulk ventilation fan, which is provided for animal carriage.

Question 29

The system has automatic overheat protection.
When an automatic overheat shutdown occurs, cargo heat to the related compartment cannot be restored in flight.
The EICAS advisory message CARGO HEAT (AFT or BULK) notifies the flight crew if a shutdown occurs or if a selector is off.

Answer 29

The system has automatic overheat protection.
When an automatic overheat shutdown occurs, cargo heat to the related compartment cannot be restored in flight.
The EICAS advisory message CARGO HEAT (AFT or BULK) notifies the flight crew if a shutdown occurs or if a selector is off.

Question 30

On the ground, if the forward equipment cooling system is inoperative, the EICAS advisory message EQUIP COOLING is displayed and the ground crew call horn in the nose gear wheel well is activated.

Answer 30

On the ground, if the forward equipment cooling system is inoperative, the EICAS advisory message EQUIP COOLING is displayed and the ground crew call horn in the nose gear wheel well is activated.

Question 31

A vent fan provides forward equipment ventilation.
This fan extracts hot air, created as a result of normal equipment cooling operations, from the E&E bay and the flight deck overhead panels.
This air is then discharged into the forward cargo compartment to provide forward cargo heating.

Answer 31

A vent fan provides forward equipment ventilation.
This fan extracts hot air, created as a result of normal equipment cooling operations, from the E&E bay and the flight deck overhead panels.
This air is then discharged into the forward cargo compartment to provide forward cargo heating.

Question 32

In flight, smoke evacuation of the flight deck and equipment cooling of the lower forward pressurized section is provided by the equipment cooling system override mode.

Answer 32

In flight, smoke evacuation of the flight deck and equipment cooling of the lower forward pressurized section is provided by the equipment cooling system override mode.

Question 33

In the override mode, all supply and vent fans turn off, the smoke/override valve opens, and cabin pressure differential is used to reverse the airflow.
This action pulls the air (and smoke if present) through the system and equipment and discharges it overboard.

Answer 33

In the override mode, all supply and vent fans turn off, the smoke/override valve opens, and cabin pressure differential is used to reverse the airflow.
This action pulls the air (and smoke if present) through the system and equipment and discharges it overboard.

Question 34

This mode is selected automatically if any of these conditions occur:
· If smoke is detected in the equipment cooling or equipment ventilation ducts; · Both supply fans fail in the forward equipment cooling system; · Low flow is detected in flight.
This mode is manually selected if:
· Commanded by the equipment cooling switch; or - If the Forward Cargo Fire Protection system is armed.

Answer 34

This mode is selected automatically if any of these conditions occur:
· If smoke is detected in the equipment cooling or equipment ventilation ducts; · Both supply fans fail in the forward equipment cooling system; · Low flow is detected in flight.
This mode is manually selected if:
· Commanded by the equipment cooling switch; or - If the Forward Cargo Fire Protection system is armed.

Question 35

Aft equipment cooling is part of the lavatory and galley ventilation system.
It provides draw-through cooling and ventilation for:
· The aft equipment racks and passenger cabin overhead equipment racks
· Passenger cabin videotape and computer equipment, and
· The lavatories and galleys.

Answer 35

Aft equipment cooling is part of the lavatory and galley ventilation system.
It provides draw-through cooling and ventilation for:
· The aft equipment racks and passenger cabin overhead equipment racks
· Passenger cabin videotape and computer equipment, and
· The lavatories and galleys.

Question 36

Cabin pressurization is controlled by adjusting the discharge of conditioned cabin air through the outflow valves.
The maximum cabin differential pressure is shown on this frame, and a schedule for cabin vs. aircraft altitude is also displayed. Make a mental note of these values.

Answer 36

Cabin pressurization is controlled by adjusting the discharge of conditioned cabin air through the outflow valves.
The maximum cabin differential pressure is shown on this frame, and a schedule for cabin vs. aircraft altitude is also displayed. Make a mental note of these values.

Question 37

Maximum cabin differential

Answer 37

9.1

Question 38

Maximum differential pressure for take off and landing

Answer 38

0.11 psi

Question 39

In the automatic mode, the pressurization system uses ambient pressure from the Air Data Inertial Reference Unit (ADIRU) in conjunction with flight plan data from the FMC to calculate the cabin pressurization schedule.
This provides a comfortable cabin climb to cruise altitude.

Answer 39

In the automatic mode, the pressurization system uses ambient pressure from the Air Data Inertial Reference Unit (ADIRU) in conjunction with flight plan data from the FMC to calculate the cabin pressurization schedule.
This provides a comfortable cabin climb to cruise altitude.

Question 40

When maximum cabin differential pressure is reached, cabin climb rate becomes a function of airplane climb rate, while maintaining the maximum differential pressure.
This results in a cabin altitude of 8,000 feet at the maximum certified operating altitude.

Answer 40

When maximum cabin differential pressure is reached, cabin climb rate becomes a function of airplane climb rate, while maintaining the maximum differential pressure.
This results in a cabin altitude of 8,000 feet at the maximum certified operating altitude.

Question 41

During descent, cabin altitude decreases to slightly below the FMC planned landing altitude. This ensures that the airplane lands pressurized.
Landing altitude barometric pressure correction comes from the Captain’s altimeter setting.

Answer 41

During descent, cabin altitude decreases to slightly below the FMC planned landing altitude. This ensures that the airplane lands pressurized.
Landing altitude barometric pressure correction comes from the Captain’s altimeter setting.

Question 42

The Landing altitude can be manually set using the LANDING ALTITUDE selector.
Landing field selection limits are 2,000 feet below sea level to 14,000 feet above sea level.

Answer 42

The Landing altitude can be manually set using the LANDING ALTITUDE selector.
Landing field selection limits are 2,000 feet below sea level to 14,000 feet above sea level.

Question 43

With a sudden loss of cabin pressurization, the outflow valves will close immediately in an attempt to control the cabin pressure. During or after descent, when the aircraft and cabin altitudes are approximately equal, the outflow valves open to protect the aircraft against negative pressure differentials. It is important that the flight crew NOT attempt to manually close the outflow valves during the descent. Now, let’s answer some questions . . .

Answer 43

With a sudden loss of cabin pressurization, the outflow valves will close immediately in an attempt to control the cabin pressure. During or after descent, when the aircraft and cabin altitudes are approximately equal, the outflow valves open to protect the aircraft against negative pressure differentials. It is important that the flight crew NOT attempt to manually close the outflow valves during the descent. Now, let’s answer some questions . . .