LIQUID COOLANT SYSTEM:
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- to inform maintenance personnel of potential problem.
+ receives signals from various acft sys’s.
+ If fault occurs, will trip direct indication.
+ functions like a caution panel.
Avionics Status Panel (ASP)
- the component that holds liquid coolant for the system.
+ a line replaceable unit.
+ includes sub-components: reservoir, the fill/refill potentiometer, the piston, & the pump.
Liquid Coolant System (LCS) Pump Assembly
- used to store the liquid coolant & can contain up to 100 cubic inches of liquid coolant.
- a wiper type unit, which provides a signal to the Avionics Status Panel, & turns ‘on’ the fill/refill light when the system loses 20 cubic inches or more of coolant.
- is designed to maintain constant pressure and flow throughout the system anytime the system is operating.
+ is driven by a three-phase 115VAC motor.
+ delivers 5.25 gallons of liquid coolant per minute 100 psi.
- removes heat from the liquid coolant.
+ located in the avionics cooling air ducting.
+ liquid-to-air type
+ can be bypassed if the liquid is cool.
- controls the temperature of the liquid coolant.
- will open or close depending upon the coolant.
- temp of liquid determines whether it will bypass or flow to the heat exchanger.
Thermal Pilot Valve
- when open, provides a path of lesser resistance for coolant flow.
+ when closed: the coolant must flow through the heat exchanger.
+ spring loaded poppet valve.
- are installed in the liquid coolant system to sense the temperature of the coolant.
+ turns on warning light @ & sends signal to ASP. If the liquid is too hot to cool the radar unit 140 - 160 degrees F.
+ 2 sensors are located bwtn. pilot valve & the low pressure sw the other btwn the filter delta sw & the pump.
Over temperature Sensor
- ill complete an electrical circuit and trip an ASP indicator.
+ indicates that the pressure in the sys. is low.
+ sends signals to ASP w/ low or no pressure.
Low Pressure SW
+ Protects radar unit from high pressures
+ spring loaded to the closed position.
+ Liquid will flow to the ball of the bypass valve during sys. op. but spring will hold valve closed.
- if system pressure gets too high, it pushes against the ball & overrides spring tension. causing high pressure liquid to bypass the radar liquid unit to return to the pump.
Delta System By-pass Valve
+ Removes dirt, contaminants etc.
+ Two ways - of telling if the its dirty:
1)Mechanical pop-up indicator will extend
2) Delta pressure SW will send a signal to the ASP.
+ protects the reservoir from high pressure
+ allows you to drain the liquid & bleed air out of sys.
+ located just off the reservoir.
Bleed/Overboard Expansion Relief Valve
- is used to energy the solenoid shutoff valve closed.
2 POS: NORMAL & TEST.
+ located on the pump assembly
+ maximum time held @ test pos. is 6.5 mins w/o ac.
+ w/ ac applied = min of 15 mins.
+ four drops or > liquid coolant escape within a 15 min. period. pump/reservoir must be replaced.
- is energized or de-energized by a test sw. on the pump assembly.
+ Norms Pos : de-energized
+ when test sw is in TEST POS, it is energized CLOSED. (makes coolant go thru H.E.)
Solenoid Shutoff Valve
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