FIGHTER AC SYS.

- dual system to provide partially cooled air for use in the air conditioning and equipment cooling systems. 

+ Air to Air type ( Bleed Air to Ram Air ) 
+ First Stage of Cooling

*Fighter engine bleed win can have temperatures as high as 1100 degrees F*

-is used to supply to the warm air manifold and servo air system*
-airflow is normally above 300 degrees F* (370 Degrees Ideally) 

- Air used for/from IT : 

1) Compressor 
2) War Air Manifold 
3) Servo Air Systems

-reduces the temperature of the air discharged from the compressor section of the cooling air turbine compressor. 

-temperature is generally below 300 degrees F

- an air cycle unit used to refrigerate the bleed air after it has passed through the heat exchangers.

- consists of expansion turbine and a compressor  { used to super cool bleed air }
- a shaft that is supported by an airfoil lubrication sys. connects the expansion turbine and a compressor.
- entire unit of responsible for supplying cold air to the A/C system for cabin temperature control and electronic equipment cooling.
- utilizes an airfoil system in place of an oil lub. sys.

*FINAL STAGE OF COOLING*

- quickly compresses the air then discharges it into a larger opening allowing the air to quickly expands.

1) Driving Force 
2) Expand Bleed Air to Drop Temp.
3) Mechanical Energy to Electrical Energy.

-actually reduces the temperature of the air to the freezing point or below

- driven by a shaft connected to the expansion turbine. 

- provides a workload on the expansion turbine.
- workload prevents the turbine from spinning too fast or over-speeding. 
- also used to increase the pressure and temperature of the air flowing 
  from the primary heat exchanger. 

- expansion wheel 

- cooling by rapid expansion

- uses a thin layer of air to support the shaft that connects the expansion turbine and compressor and requires no lubrication. This principles if referred to as “Air Bearings”.

- provides additional cooling of the bleed air by using cold air extracted from the outlet side of the expansion turbine and water from the water separator. 

*RAM AIR is PRIMARY cooling of Bleed Air. *

- water is drawn from the water separator by a venturi. 
- works best at low altitudes due to the higher moisture content in the air at lower altitudes. ( because of more moisture ) 

+ increases cool efficiency

- prevents fogging or snowing in the cabin.

+removes 80% to 85% of the moisture from the conditioned air. 
+located in the cold air supply duct and is downstream of the expansion turbine. 
+ consists of two parts: coalesced and a by-pass valve.

a cylindrically shaped metal grid covered by a Dacron Fabric sleeve.

1) Condenses Moisture
2) Forms Water Droplets 
3)Acts as Filter

- Elastic bands sewn into each end of the sleeve holds it in-place. 
- Air is forced to flow throughout the sleeve, which will condense the moisture
and allow it to be separated for use in the regenerative heat exchanger. 
- also collects oil & dust from engine bleed air.

- will prevent the loss of cold airflow should the water separator become frozen or clogged. 

- if the water separator should freeze, IT will be forced open and the air will flow through its center.
- This prevents a loss of cold air. 

+ Opens @ 7 PSID

- used to prevent freezing and icing of the water separator.

{COLD AIR VALVE}

+ pneumatically OPENED (servo air) 
+ spring CLOSED.
+ controlled by the EDC S/C 
+ modulates to control the temperature of the air at the water separator outlet.

@ 27,000 - 35 degrees F

- 31,000 ^ 0 degrees 

27,000 --- 31,000 temp = Proportional w/ Altitude 


* Water separator outlet air temperature is determined by the aircraft altitude. *
* Higher the altitude the less moisture in the air * 
* The EDC S/C adjusts the temperature in response to altitude signals from the Air Data Computer (CADC) (MACH & ALTITUDE)

Warm air is used for:

- 475 degrees - Shuts Off AC SYS. - High Stage to use Low-stage

Ram Air is used for: ?

***SENSOR > CONTROLLER > VALVE***

- used to sense the water separator outlet temperature and supply air temperature signals to the EDC S/C. 

+ EDC S/C utilizes the temperature signals from the water separator temperature sensor and altitude signals from the CADC to determine the position of the water separator anti-ice modulating valve. 

Hot Air Components - used to maintain the temperature in the warm air manifold at a nominal 370 degrees F for water separator anti-ice & cabin temperature control. 

+ the set consists of a 400 degrees F hot air control valve and a 400 degrees F warm air sensor/controller.

- controls the flow of hot bleed air into the warm air manifold. 

{HOT AIR VALVE}

+ spring loaded CLOSED 
+ pneumatically actuated (servo air) OPENED. 
- modulates in response to servo air signals from the warm air sensor/controller. 
+ can be checked through the use of a built-in push-to-test button.
- valve has an indicator for visual indication of the valve position. 

>Pressing the test button in half way will went servo air from the control chamber of the hot air control valve causing the valve to close.<
- Indicator Built Into Valve -
> The increased pressure will override the spring tension and valve will open. <
- Test Push - All the way - Valve will open

- used to sense the temperature of the air in the warm air manifold and control the opening and closing of the 400 degree F hot air control valve.

+ Controls Hot Air Control Valve 
- Maintains Warm Air Manifold @ 370 Degrees

- is installed in the cabin air supply duct, directly behind the cabin. The check valve is used to prevent a reverse flow to air from the cabin back into the ducting during normal system operation. 

+ if the air source should fail, IT will prevent rapid loss of cabin pressure ( IN COCKPIT ) by trapping the air inside the cabin. 

- Prevents Reverse Flow of Air When Cabin is Pressurized 
- Prevents Rapid Loss of Cabin Pressure when air source fails 
- Traps air in Cabin Air Supply Duct

- Emergency ventilation of the cabin is provided if the air conditioning system fails. 

- pilot will place the air source switch to RAM. 
- will allow ambient air to flow into the cabin and electronic equipment bays. 
- This is accomplished through the Ram Air Shutoff Valve.

(COLD AIR VALVE)
+ electrically controlled by the air source sw. 
+ pneumatically actuated (servo air) CLOSED
- spring-loaded OPEN
+ When opened ram air is allowed flow from the ram air inlets into the cabin and electronic equipment cooling bays & cockpit.

Prevents a reverse flow on conditioned air in the event of Ram Air Shutoff valve failure.