EQUIPMENT COOLING

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

Two methods of equipment cooling ?:

- 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.

- 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.

- 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.

3 Essential components in the Sensor/Controller?

- 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.

- 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)

- 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.

- 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

- 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.

- 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.

- 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

- 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

- 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

- Lower equipment bay temp sensor temperature sends temperature signals to the EDC S/C.