The reference pressure regulators set control pressure to a fixed value. The regulators are in series with each other. The torque motors regulate the control pressure to values less than the reference pressure regulators.
The heater makes sure the controller does not freeze.
Training Information Point
The mounting bolt hole pattern on the HPFAC helps install it correctly. Three pneumatic line connectors are of different sizes on the HPFAC. This makes sure you connect the lines correctly. Two electrical connectors are of different sizes to help install the HPFAC correctly.
The filter is line replaceable.
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ENGINE AIR SUPPLY SYSTEM -HIGH PRESSURE AND FAN AIR CONTROLLER
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ENGINE AIR SUPPLY -HIGH PRESSURE AND FAN AIR CONTROLLER -FUNCTIONAL DESCRIPTION
Functional Description
The high pressure and fan air controller (HPFAC) sets the pressure of the control air for the HPSOV and the FAMV. The HPFAC uses two pressure regulators and two torque motors to set control air pressure. The torque motors are in parallel with each other and in series with the regulators.
Two regulators in series give an accurate control air pressure, at a fixed value. The fixed value gives these functions:
*
Pneumatic and backup modes of operation for the HPSOV (HPSOV regulates to approximately 55 psig)
*
Pneumatic and backup modes of operation for the FAMV (FAMV goes fully open)
*
Protection for the HPSOV and FAMV actuators by setting the maximum pressure limit of the control air.
The primary mode of the ASCPC uses the torque motors to change the position of the HPSOV and FAMV. The torque motors change the amount of control air to the valves.
The torque motor for the HPSOV is set to supply maximum control air pressure to the HPSOV when it gets no current. When the ASCPC sends current to the torque motor, the flapper moves to let control air pressure vent to ambient. The amount of air that vents has a relation to the amount of current that goes to the torque motor. This is an example: If the ASCPC wants to close the HPSOV, it supplies full current to the torque motor. This sets the position of the flapper in the torque motor to stop supply air and vent control air pressure. A spring in the HPSOV (not shown) and duct pressure downstream of HPSOV move the valve closed.
The torque motor for the FAMV is set to stop control air pressure to the FAMV when it gets no current. When the ASCPC sends current to the torque motor, the flapper moves to let control air pressure go to the actuator of the FAMV. The amount of control air pressure given to the actuator has a relation to the amount of current that goes to the torque motor. This is an example: if the ASCPC wants to close the FAMV, it supplies full current to the torque motor. This sets the position of the flapper in the torque motor to let supply air flow through the regulators and to the actuator for the FAMV.
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ENGINE AIR SUPPLY -HIGH PRESSURE AND FAN AIR CONTROLLER -FUNCTIONAL DESCRIPTION
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ENGINE AIR SUPPLY SYSTEM -CONTROLLER AIR COOLER
Purpose
The controller air cooler (CAC) decreases the temperature of the engine bleed air (HP15) that goes to these controllers:
*
EAI controller
*
Pressure regulating and shutoff valve controller (PRSOVC)
*
High pressure and fan air controller (HPFAC).
See the engine anti-ice (EAI) section for more information on the EAI controller (SECTION 30-21).
Physical Description
The controller air cooler is an air-to-air heat exchanger. It has three pneumatic line connectors, two high pressure and one low pressure (fan air).
Location
The controller air cooler is on the right side of the engine core at the 2:30 position. The cooler is forward of the main fuel supply line.
Functional Description
Hot air from the high stage compressor section and cool fan air flows through the controller air cooler. The cool air carries heat away from the hot air. This decreases the temperature of the hot air.
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ENGINE AIR SUPPLY SYSTEM -DUCT VENT VALVE 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 气源 Pneumatic(11)
