A/C -SUPPLEMENTAL HEATING -DOOR AREA HEATERS -FUNCTIONAL DESCRIPTION
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A/C -SUPPLEMENTAL HEATING -GALLEY AND FLIGHT DECK HEATERS -FUNCTIONAL DESCRIPTION
General
The enable signals for the galley heaters and the foot and shoulder heaters for the captain and first officer come from the ECSMCs in the system card files. At card file power up, the right ECSMC gives primary control and the left gives backup control. The primary and backup controls change cards at each air-ground transition.
See the air conditioning section for more information about the ECSMC (SECTION 21-00).
The ELMS has circuits that the ECSMCs use to enable the forward and aft galley and flight deck heaters. The enable signal for the heaters shown goes to the left power management panel. A switch in the ELMS electronics (ELEX) unit supplies a ground to energize the related heater relay. Each relay supplies power to the related heater.
Galley Heaters
The galley heaters get power if the left or right pack is on.
Each galley complex contains a heater control. This control sets the level of heat for the heater. In the OFF position, the switch disconnects the control input to the heater. This stops the heater.
Flight Deck Heaters
The captain and first officer both have a heater control for the related foot and shoulder heaters. These heaters get power when the airplane is in the air.
The foot heater selector sets the voltage for high or low power operation. The foot heaters have overtemperature protection. A control thermostat in each foot heater closes the circuit at approximately 70F (21C) and opens the circuit at approximately 80F (27C).
The shoulder heater control sets the level of heat. In the OFF position, the switch disconnects the control input to the heater. This stops the heater.
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A/C -SUPPLEMENTAL HEATING -GALLEY AND FLIGHT DECK HEATERS -FUNCTIONAL DESCRIPTION
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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
AIR CONDITIONING -COOLING -INTRODUCTION
General
The cooling system includes these two subsystems:
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Pack flow control
*
Pack cooling and mix manifold temperature control.
Pack Flow Control
These are the functions of the pack flow control system:
*
Pack air on/off control
*
Ozone control bypass
*
Pack air flow regulation.
The pack air on/off control function controls the rate that the pack starts and stops. The ozone control bypass function controls when the ozone removal system operates. The pack air flow regulation function controls the quantity of air that goes into the airplane. See the pack flow control section for more information about the pack flow control system (SECTION 21-51).
Pack Cooling And Mix Manifold Temperature Control
Two air conditioning packs decrease the temperature of air from the pneumatic system.
The mix manifold temperature control function adjusts the pack outlet air temperature. This function keeps the distribution air temperature equal to a reference temperature set by the zone temperature control system. See the pack cooling and mix manifold temperature control section for more information about the pack (SECTION 21-52). See the zone temperature control and indication section for more information about temperature control for the mix manifold (SECTION 21-61).
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777 AIRCRAFT MAINTENANCE MANUAL
AIR CONDITIONING -COOLING -INTRODUCTION
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AIR CONDITIONING -COOLING -GENERAL DESCRIPTION -CONTROL
CTC Functions
The CTCs control air flow into the air conditioning packs and control the mix manifold temperature. Two identical control channels in each CTC give redundancy.
With the APU off and the pack switches in AUTO, the CTCs use flow schedule data from the ASCPCs to control pack air flow. If the APU supplies air to the packs, the CTCs tell the APUC the amount of air necessary. Then, the CTCs do not use the flow schedule from the ASCPCs.
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