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The fighter aircraft equipment cooling system provides the electronic equipment w/ a supply of cooling air to extend component life by preventing over heats.
0 - 35 degrees = Depending of Aircraft Altitude
PURPOSE EQUIPMENT COOLING
Two methods of equipment cooling ?:
Forced Air & Free Convection.
- used to cool the forward electronic equipment bay.
+ Radar Package
- used on the equipment that generates excessive heat.
+ this system “forces” cold air directly into the components.
- The size of the component determines the amount of cold air.
+ The system is designed to maintain an ideal discharge temp.
from the components of 140 degrees F.
Forced Air Equipment Cooling System
- controls the flow of cold air to the electronic equipment bay & the radar package.
*COLD AIR VALVE*
+ butterfly type valve
- requires power and servo air to CLOSE.
+ Loss of power or servo air, the valve spring loads to the OPEN pos.
- controlled by the equipment cooling s/c
+ modulates the cooling airflow to the electronic equipment to maintain the desired cooling rate.
Equipment Cooling Modulating Valve
- a temperature sensitive electronic unit installed in the equipment cooling air supply duct.
+ monitors the temperature of the air entering the electronic fay.
- sensor/controller receives a “sample” portion of the cold air.
+ It maintains the correct temperature in the bay by controlling the equipment cooling modulating valve & priority valve.
Electronic Equipment Cooling Sensor/Controller
3 Essential components in the Sensor/Controller?
Heating Element, Valve Control Sensor,& Low Flow Sensor.
- heats the air and simulates the head load of rate equipment to be cooled.
- simulated equipment that needs to cool
: controls the equipment cooling modulating valve and priority valve.
- Maintained : 140 degrees @ Exit Temp.
Valve Control Sensor
- monitors pressure and energizes the environmental control really which illuminates an equipment hot light.
- Senses Air pressure for 65 sec. energized (directs power) to ECR (Environmental Control Relay)
- Controls Equip Hot Light
(Hot light is a signal to ‘Turn-off non essential equipment)
Low Flow Sensor
- when closed, it provides added restriction to cabin airflow to increase equipment-cooling airflow during conditions when callable cooling capacity is marginal.
+ controlled by the electronic equipment sensor/controller.
- butterfly type valve
+ servo air actuated CLOSED
- spring-loaded OPEN.
- controls the flow of cooling air to the radar and is controlled by the Radar Mode switch.
*NOT CONTROLLED BY S/C*
+COLD AIR VALVE
-butterfly type valve
+ pneumatically actuated CLOSED
- spring loaded OPEN.
+ de-energized open
- CANNOT BE CLOSED IN FLIGHT.
Radar Cooling Shutoff Valve
- used on components that do not generate excessive heat.
+ Non-Essential Equipment
- done in the lower aft equipment bay.
- The air source is at the outlet of the expansion turbine.
+ Cools Low Aft Equip Bay.
- Cold Air Taped from expansion turbine outlet
Free Convection Cooling System
- supplies servo air to actuate the lower equipment bay cold air shutoff valve to provide cooling airflow to the compartment.
+ Hot Air Valve
- normally OPEN.
+ electrically actuated CLOSED
- located in the lower aft avionics compartment.
+ controlled by the EDC S/C & the lower equipment bay solenoid relay.
Lower Equipment Bay Servo Air Solenoid Valve
- regulates the supply of cooling air to the lower aft equipment bay.
+ Hot Air Valve
+ butterfly type valve
- pneumatically actuated OPEN
+ spring-loaded CLOSED.
- The lower equipment bay servo air SOLENOID valve controls the cold air SOV in response to input by the BRAIN.
+ Controls airflow to Low Equip.
Lower Equipment Bay Cold Air Shutoff Valve
- directs bay temperature signals to the EDC S/C for operation of the cold air shutoff valve.
- located inside the lower equipment bay.
+ resistance type sensor
Lower Equipment Bay Temperature Sensor
- plug type relay
+ located on the air conditioning matrix assembly.
- energized by the BRAIN to send a valve close signal to the servo air solenoid valve in turn,
+ closes the cold air shutoff valve.
- Directs to close lower equipment by servo air solenoid valve
Lower Equipment Bay Solenoid Relay
- provides a connection/disconnection port for application of a ground air conditioning cart.
- cannot be used to connect external bleed air
- used only as a connection for the ground air conditioning cart.
+ External ac’n can be accomplished ONLY during ground operations.
- incorporates a check valve that prevents the loss of electronic equipment cooling air ducting normal system operation in FLT & on the GND.
+ Ground cooling receptacle Check Valve
Ground Cooling Receptacle
- Lower equipment bay temp sensor temperature sends temperature signals to the EDC S/C.
When lower bay temp. reach 140 degrees to 150 degrees F.