AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -INTRODUCTION
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -HEAT VALVES
Purpose
The aft and bulk cargo heat valves control the amount of air added from the pneumatic system to heat these compartments. Each cargo compartment has two heat valves that do these functions:
*
Shutoff
*
Temperature control.
Physical Description
The aft and bulk cargo heat valves have these parts:
*
Relief valve
*
Flow assembly
*
Electrical solenoid valve
*
Optical switch assembly
*
Actuator assembly.
Location
The aft and bulk cargo heat valves are in the left side wall where the aft and bulk cargo compartments come together.
Functional Description
With no power to the solenoid valve, the butterfly valve (not shown) in the flow assembly is closed. When the solenoid gets power and pneumatic air is available to the valve, the butterfly valve will fully open.
The optical switch assembly tells the ECSMC when the valve is completely open or closed.
Training Information Point
The aft and bulk cargo heat valves are all the same.
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -HEAT VALVES
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -TEMPERATURE SENSORS
Purpose
The aft and bulk cargo compartment temperature sensors monitor the temperature in the related compartment. The ECS miscellaneous cards (ECSMCs) use these temperatures to control the amount of heat added to the cargo compartments.
Physical Description
These sensors are a single element thermistor type of sensor. These sensors have a threaded housing with an electrical connection.
Location
The aft cargo compartment temperature sensor is on the left side wall of the aft cargo compartment (STA 1659). The bulk cargo compartment temperature sensor is on the right side wall of the bulk cargo compartment (STA 1984).
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -TEMPERATURE SENSORS
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -TEMPERATURE SELECTORS
Purpose
The cargo temperature selectors give manual control of the aft and bulk cargo compartment temperatures. Each cargo compartment has a selector on the cargo temperature select panel.
Location
The cargo temperature selector panel is on the P61 overhead maintenance panel.
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -TEMPERATURE SELECTORS
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777 AIRCRAFT MAINTENANCE MANUAL
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AIR CONDITIONING -AFT AND BULK CARGO COMPARTMENT HEATING -FUNCTIONAL DESCRIPTION
General
The aft and bulk cargo temperature selectors set the temperature range for these compartments.
Each cargo compartment has two heat valves that do these functions:
*
Shutoff
*
Temperature control.
Valve Open
The open signal for the aft cargo heat valves comes from the left environmental control system miscellaneous card (ECSMC) in the left system card file. The open signal for the bulk cargo heat valves comes from the right ECSMC in the right system card file.
An open signal for the aft cargo heat valves goes to the left power management panel. An open signal for the bulk cargo heat valves goes to the right power management panel. Switches in the electrical load management system (ELMS) electronics (ELEX) unit supply a ground to energize the related cargo heat shutoff valve relay and cargo heat temperature control relay. These relays apply power to the open solenoid on the related valve.
EFFECTIVITY
BEJ ALL
When the heat valves are enabled, the shutoff valve is open. The temperature control valve cycles open and closed to keep the temperature in the cargo compartment to within 5F (3C) of the selected temperature.
Indication
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