I A P 2 0 2 3 . 0 0 1 - A F M / I R I S T E X A N I I P A G E | 70
FOR SIMULATION USE ONLY – NOT A TRAINING AID
or HOT results in directional control of the heat exchanger bypass valve, resulting
in warmer or cooler inflow temperatures.
The temperature controller receives input from the cockpit temperature control
sensor located in the duct between the two cockpits, the TEMP CONTROL rheostat
position, and the cabin temperature sensor located on the rear pressure bulkhead.
These inputs result in an output signal from the controller to the heat exchanger
bypass valve to direct more or less bleed air through the heat exchanger as
necessary to achieve and maintain the selected temperature.
If the temperature controller detects a temperature in excess of 165 °F at the
cockpit temperature control sensor, it directs the heat exchanger bypass valve to
move to full closed, forcing maximum bleed air through the heat exchanger.
Power for the temperature controller is provided through a circuit breaker,
placarded CKPT TEMP, located on the generator bus circuit breaker panel in the
front cockpit.
The DEFOG switch, placarded DEFOG, ON, and OFF, is located on the centre console
in the front cockpit. Placing the switch to the ON position does three things:
(1) The defog valve is opened, increasing the bleed air supply
(2) The inflow valve is automatically set to high, further increasing the
amount of bleed air entering the cockpit, and
(3) The air conditioning compressor is automatically turned on to dry the air.
Additionally, an ejector downstream of the heat exchanger takes the high pressure
bleed air and passes it through a venturi. The resulting drop in static pressure
draws ambient cockpit air into the ECS ducting, further increasing the volume of air
available for defogging.
If the DEFOG switch is placed to OFF, the electrically controlled defog valve may
take up to 40 seconds to close. Operation of the canopy defog increases ITT for a
given PCL setting due to the higher bleed air load on the engine.
Adjust the PCL to maintain the ITT within limitations appropriate to the operation,
e.g., maximum climb when climbing or maximum cruise power for cruise flight.
Defog is typically required for short intervals during climb to, and cruise at, high
altitude and descents from high altitude into humid conditions.
A reduction in flaps UP climb performance of up to 47% may be observed with the
defog switch ON and the PCL retarded to maintain the ITT within limits.
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