FIGHTER PRESSURE SYS.

Hot, high-pressure is bled (extracted) from the compressor section of the aircraft’s engine.

high stage is used since the pressure here will be higher than from the low stage.

the low stage will supply the bleed air since the pressure & temp. will be sufficient the operate the Environmental Control System (ECS) on the acft.

SPRING LOADED CLOSED

SPRING LOADED OPEN

used to reg. pressure from there engine compressor section during low throttle settings.

+ Approx. 1100 degrees F @ MAX throttle settings
+ valve OPEN idle & low throttle 
+ electrically controlled by the Air Source SW. 
+ pneumatically (air) actuated OPEN.
+ spring actuated CLOSED.
+ regulates the output pressure to 50-65 PSIG.

used to regulate the pressure form the engine’s compressor section during high throttle settings. 

+ electrically controlled by the Air Source SW. 
+ pneumatically (air) actuated CLOSED.
+ spring actuated OPEN.
+ regulates the output pressure to 80-90 PSIG.

used to determine which stage of compression will be used to supply bleed air for ECS operation. 

+ located in the left main landing gear wheel well. 
+ senses & compares pressures @ low stage of
compression w/ pressures downstream of the 
variable Air Pressure Reg. SOV. (Change Over)

> When adequate pressure is available @ low stage of compression. 
IT will provide an electrical signal to the EDC S/C {THE BRAIN}

> The EDC S/C will signal the high stage bleed air regulator & SOV to close. <
> The closing of the high stage valve allows the low stage reg. & sob to begin reg’n the pressure from the engine’s compressor section <

prevents high stage air from entering the low stage duct system. 

+ located in the low stage bleed air duct. 

+ Allows Air to flow in one direction only!

used to operate the ECS. 

( COLD AIR VALVE )

+electrically controlled by the Air Source Switch. 
- pneumatically actuated CLOSED
+ spring - actuated OPEN 
- regulates output pressure btwn 25- 70 PSI. 
+ this output pressures used to operate the ECS. 

> The output pressure of the VAPR is controlled by the EDC C/T <

indicates a malfunction of either high or low stage bleed air pressure regulator & sov’s. 

+ POP-UP type indicator 

- RESET only after malfunction is repaired 

- a manual reset button located in the jot air duct down stream of the high & low stage of bleed air regulator & sov’s. 

+ if the sys. pressure reaches 95-103 PSIG for more than 20-60 sec. IT will extend.

converts pneumatic signals to electrical signals & vice vera. 

+ DIRECTLY controls the flow of serve air to operate the VAPR, therefore it controls the output pressure of the VAPR. 

+ responds to upstream bleed air pressure & electrical cabin airflow demand signals from the EDC S/C. 

- tells “BRAIN” how much air is in the system. 
+ gives and/or takes away servo air to/from VAPR

used to minimize sys. shutdowns caused by excessive bleed air temps. { 370 - 475 degrees F }

- does so by providing warm air manifold temp. signals to the EDC S/C 

> if temp. in the manifold reaches 475 degree F,  the EDC S/C will place the ECS in the cutback mode <

____________ & ______________ are the only temp. sensors that can actuate ‘CUTBACK MODE’.

high stage bleed air regulator & sov is energized CLOSED. Allowing the ECS to operate using lower pressure & lower temperature air form the low stage of compression.

increases the cooling efficacy of the heat exchangers when opened. 

- required when the aircraft is on the ground, during low airspeeds or during excessive temps @ high airspeeds. 

+ ‘The Brain’ is the controller   { RAM AIR - primary cooling }
+ is energized CLOSED & de-energized OPEN.
+ controlled by the EDC S/C during [normals operation]
> in response (FEEDS) to airspeeds inputs from CADC < aka MACH & ALTITUDE

Airspeeds decreased flow 160 knots the EDC S/C _____ the ejector SOV.

Airspeeds above 160 knots the EDC S/C will direct the ejector SOV to ____ in response to overheat signals from { 2 temp sensors _ & _ ?)

a low pressure area is created behind ejector nozzles.
- low pressure will draw +++ ram air over the heat exchanger to increase their cooling efficiency.

1) GND - 160 knots = OPEN

2) RE-OPENS - overheat condition - IN FLT.

ALL TEMP SENSORS EXCEPT ____ & ____ SENSORS, SEND SIGNALS TO THE BRAIN

monitors the compressor inlet duct temperature 

+ directs a signal to the EDC S/C for controlling ejector SOV & VAPR operations. 
+ minimizes sys. shutdowns 

> The EDC S/C will open the ejector SOV to increase ram airflow over the heat exchangers when compressor inlet temperatures increase above 400 degrees F. < 

(STAGE 1)                                     (RESET)
>  The ejector SOV will be closed when the compressor inlet temp decreases to 370 degrees F. or less (overheat protection) <

(STAGE 2)             (ACTIVE)
- If the compressor inlet temp climbs above 465 degrees F, the EDC S/C signals the EDC C/T to reduce the VAPR output.

* Reduced bleed airflow through the heat exchangers will reduce the _________. *

-monitors turbine inlet duct temperature.

+ directs a signal to the EDC S/C for controlling  SOV, VAPR, & cutback mode operations. 
- prevents over-speed conditions 
- only has (CUTBACK)

> The EDC S/C will open the ejector SOV to increase ram airflow over the heat exchangers when turbine inlet temperature increases above 180 degrees F. <

> The ejector SOV will be closed when the turbine inlet temperature decreases to 180 degrees F or less (over heat protection).

225 degrees - STAGE 1 & 2 

280 degrees - CUT BACK MODE

Overheat Condition Stages:

Stage 1- Brain Opens EJT

Stage 2 - Brain closes VAPR through EDC C/T w/ 25 PSI.

Stage 3 - CUTBACK ‘Brain’ Shuts Down HIGH STAGE (to force use of low-stage)

- to compute the cabin airflow demand & provide an output signal (electrical) to the EDC converter/transducer to modulate the output pressure of the VAPR SOV (modulating bleed airflow) 

+an electronic digital controller
+ it receives & processes the following input signals: 

- Cabin airflow
- Cabin air supply inlet duct temperatures
- Compressor & turbine inlet temperature
- Total (ram air) temperature
- Available bleed air pressure
- CADC: airspeed & altitude
- Warm air manifold temperature sensor 

+ minimizes sys. shutdowns by monitoring temps during sys. operation of bleed air & ac sys’s. 
+ provides the ECS w/ over temp protection by controlling ejector SOV ops. 
+ operates the ECS in ‘cutback’ mode {during extreme sys. operating temps.}

-ejector valve 
- high/ low stage
- cutback mode
- AC/TEMP control functions

- a pneumatic connector that provides a connection for an external air source during ground operation & checkout of the ECS w/o starting the engine. 

+ located in the left man in wheel well & incorporates a dual check valve to prevent discharge of engine bleed air during flight & ground operation of the acft engines.

- a plug-in type replay located in the air conditioning matrix.

+ Shuts All AC Sys. Down 

+ energized during excessive temperature conditions to prevent damage to the aircraft. 
- energized replay will cause the sys. to shutdown by completing an electrical circuit to the solenoids of the 3 primary bleed air valves (low stage, high stage & VAPR). 

+the components used to energize the relay are:

-Hot Air Bypass Thermostatic SW  
-Turbine Inlet Thermostatic SW
- Cockpit Supply Thermostatic SW 
- Fuel Pressure Supply Thermostatic SW.

- located in the warm air manifold this is normally open thermostat limits maximum temperature in the manifold.

+ when it exceeds 510 degrees F, the thermostatic sw completes an electrical circuit to energize the air over-temperature relay ( shutting down the ECS )

located in the inlet duct of the turbine (expansion side), this switch is normally open. 

- When temperature increases 310(+10)degrees F, the thermostat closes
+ energizing the air over-temperature replay { shutting down the bleed air sys.}
- REOPENS when the temperature decreases to 270 degrees F
+ Bleed air system valves are re-reopened, restoring ECS operation.

- located in the cabin air supply inlet duct the cabin temperature thermostatic sw limits the maximum cabin temp.

+ will energize the air over-temp relay 
+ automatically shut down the bleed air sys.
+ sw is normally open
+ will close if temp in the duct reaches 200 degrees F.

- located in the right wheel well in the fuel tank pressurization line.

+ When temperature increases to 450 degrees F, the thermostat closes, energizing the air over-temperature relay & shuts down the bleed air sys. 
- The sw reopens when the temp decreases to 380 degrees F, allowing the 3 primary bleed air valves to re-open & restore ECS operation.

energizes the 3 primary bleed air valves closed 
& Ram Air Shutoff Valve open. (Requires air to close)

+ de-energizes the three primary bleed air valves open 
+ energizes the Ram Air Shutoff Valve closed.

normal air conditioning continues 
& the the solenoid on the Cabin Pressure Relief 
& Dump Valve is energized dumping cabin pressure.

energizes the 3 primary bleed air valves closed
de-energized the Ram Air SOV open
- ambient air enters to ventilate the cabin & the equipment compartments. 
+ The Relief & Dump Valve is also energized open allowing the ram air to vent from the cabin.

Where is the Source Servo Air System?

is used to actuate valves open or closed.

+ provides air signals to the air conditioning sys. valves.

Servo air opened & Spring loaded closed

SPRING LOADED OPEN & SERVO AIR CLOSED

+ filters the servo air prior to entering the servo air regulator valve 

+ done to ensure no particles enter the servo air system.

* Time Changed
* Phase Inspections 
[disposable wire mesh unit]

+ regulates the servo airflow into the system

Air pressure entering the Servo Air Regulator is between __ to __ PSIG.

Servo Air Regulator decreases the pressure to __ to __ PSIG.

If airflow is blocked, the Servo Air Regulator has an ____ ________ ______ setting of __ PSIG.

- constructed on INCONEL & STEEL 
- covered w/ insulation

- constructed w/ ALUMINUM ALLOY
- covered w/ insulation

- Used on HOT air ducts 
- Reusable E-seal gasket

COLD AIR DUCTS

WARM & COLD air ducts 

- used where high pressure or frequent removal is anticipated

Blue - low temp apps

Red - used on al apps.