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  1. - 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
    Primary & Secondary Air-to-Air Heat Exchanger
  2. *Fighter engine bleed win can have temperatures as high as 1100 degrees F*
  3. -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
    Primary heat exchanger
  4. -reduces the temperature of the air discharged from the compressor section of the cooling air turbine compressor. 

    -temperature is generally below 300 degrees F
    Secondary heat exchanger
  5. - 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.

    Cooling Air Turbine Compressor
  6. - 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
    expansion turbine
  7. - 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
  8. - 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”.
    Air Foil System
  9. - 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
    Regenerative Heat Exchanger
  10. - 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.
    Water Separator
  11. 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.
  12. - 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
    Internal Bypass Valve
  13. - used to prevent freezing and icing of the water separator.


    + 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)
    Water Separator Anti-Ice Modulating Valve
  14. Warm air is used for:
    - Cockpit sys & Anti Icing
  15. - 475 degrees - Shuts Off AC SYS. - High Stage to use Low-stage
    Cutback Mode
  16. Ram Air is used for: ?
    - Equipment Cool - Cockpit Ventilation
    Signal Procedure
  18. - 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.
    Water Separator Discharge Temperature Sensor
  19. - controls the flow of hot bleed air into the warm air manifold. 


    + 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
    400 Degree Hot Air Control Set Valve
  20. - 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
    400 Degree Warm Air Sensor/Controller
  21. - 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
    Cold Air Check Valve
  22. - 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.
    Ram Air System
    + 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.
    Ram Air Shutoff Valve
  24. Prevents a reverse flow on conditioned air in the event of Ram Air Shutoff valve failure.
    Ram Air Check Valve
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