AIR CONDITIONING -PACK FLOW CONTROL -FLOW CONTROL AND SHUTOFF VALVES
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AIR CONDITIONING -PACK FLOW CONTROL -FLOW SENSOR
Purpose
The pack flow sensor supplies two types of air pressure information, pack inlet and pack inlet differential to the related CTC and ASCPC. The controllers use the pressure information to help calculate the rate of air flow from the pneumatic system into the airplane.
Physical Description
There are two pack flow sensors, one for each air conditioning pack/trim air system. Each sensor has these parts:
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High pressure (inlet) line (2)
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Inlet pressure sensor
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Differential pressure sensor (2)
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Electrical connector (3)
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Bracket (pressure sensor attachment)
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Titanium body
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Low pressure (venturi) line (2).
The titanium body is in the shape of a venturi. The pressure sensors attach to a bracket that attaches to the body. The pressure sensors use lines to connect to the body.
Location
The pack flow sensors are in the aft part of the left and right ECS bays. You get access through these blowout doors:
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195QL left pack flow sensor
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196QR right pack flow sensor.
Functional Description
The CTC differential pressure sensor gives an output in proportion to the pressure difference across the venturi part of the pack flow sensors body. The inlet pressure sensor gives an output in proportion to the pack inlet air pressure. These outputs go to the CTC.
Power for the CTC differential pressure sensor and inlet pressure sensor comes from the power management panel that supplies the pack.
The ASCPC differential pressure sensor is the same as the CTC
differential pressure sensor. pressure information and gives pressure sensor. The ASCPC power to gets its differential differential
Training Information Point
The pack flow sensor is an LRU. The individual inlet and differential pressure sensors are not LRUs.
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AIR CONDITIONING -PACK FLOW CONTROL -FLOW SENSOR
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AIR CONDITIONING -PACK FLOW CONTROL -PRIMARY HEAT EXCHANGER INLET TEMPERATURE SENSOR
General
The primary heat exchanger (PRI HX) inlet temperature sensor monitors the PRI HX inlet temperature.
Temperature data goes to the cabin temperature controller (CTC). It uses the data with data from the flow sensor to calculate pack mass air flow.
See the zone temperature control and indication section for more information about the CTC (SECTION 21-61).
Physical Description
The sensor is a single element resistance temperature device (RTD). Threads on the sensor connect it to the boss in the duct. The sensor electrical connector is also threaded.
Training Information Point
This sensor is interchangeable with the other high temperature sensors in the pack.
See the pack cooling and mix manifold temperature control section for more information about sensors on the pack (SECTION 21-52).
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AIR CONDITIONING -PACK FLOW CONTROL -PRIMARY HEAT EXCHANGER INLET TEMPERATURE SENSOR
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777 AIRCRAFT MAINTENANCE MANUAL
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AIR CONDITIONING -PACK FLOW CONTROL -FUNCTIONAL DESCRIPTION -PACK FLOW SCHEDULES
General
The air supply cabin pressure controller (ASCPC) sets the flow schedule (limit) that the cabin temperature controllers (CTC) use to control air flow into the airplane, (packs and trim air). See the trim air pressure regulation and shutoff control section for more information about the trim air control (SECTION 21-62). Flow schedule 1 gives the largest air flow to the air conditioning packs and is the usual flow schedule.
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