*
Through the ADIRU and SAARU for status messages.
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PITOT AND STATIC (AIR DATA SENSORS) -ANGLE-OF-ATTACK PROBE HEAT -FUNCTIONAL DESCRIPTION
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PITOT AND STATIC (AIR DATA SENSORS) -TOTAL AIR TEMPERATURE PROBE HEAT -GENERAL DESCRIPTION
Purpose
The heaters in the TAT probe keep ice off of the probe so its data is reliable.
General Description
There is one TAT probe on the left side of the nose. The probe has an electrical connector and a connector for air. The air is from the air supply distribution system.
Ambient air temperature is measured by the sensing elements. To make sure the sensing elements have a sufficient amount of ambient air flow near them for correct temperature sensing, the probe has an ejector tube and a flow of air from the air supply distribution system.
A small amount of air from the air supply distribution system flows through the ejector tube, this makes a vacuum near the sensing elements. The vacuum makes ambient air flow near the sensing elements and then out of the probe near the base.
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PITOT AND STATIC (AIR DATA SENSORS) -TOTAL AIR TEMPERATURE PROBE HEAT -FUNCTIONAL DESCRIPTION
General
An ELMS electronics unit in the P110 left power management panel supplies control and indications for the TAT probe heat system.
Functional Description
Power for the TAT heater comes through the TAT probe heater relay. The ELMS electronics unit supplies the ground signal to energize the relay.
The relay supplies power to the heater when the airplane is in the air. The heater does not receive power when the airplane is on the ground.
The TAT current sensor supplies current information to the ELMS electronics unit. The ELMS electronics unit supplies the TAT probe heat fault status to the AIMS.
The ELMS electronics units receives the air/ground information from the weight on wheels (WOW) card.
Indications
There are status and maintenance messages if there are failures of the probe heater circuits.
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PITOT AND STATIC (AIR DATA SENSORS) -ENGINE PROBE HEAT -GENERAL DESCRIPTION
Purpose
The heaters in the engine P2/T2 probes keep ice off of the probes so their data is reliable.
General Description
There is a P2/T2 probe at the 12:00 position on the lip of each engine inlet cowl. The probes are interchangeable.
Each probe has a pressure line connector. They also have two electrical connectors. One of these connectors is for power to heat the probe. The other is for air data.
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PITOT AND STATIC (AIR DATA SENSORS) -ENGINE PROBE HEAT -FUNCTIONAL DESCRIPTION
General
The left and right engine P2/T2 probe heat systems are similar. The left and right electronic engine controls (EECs) supply engine probe heat control and indications. Each EEC has two channels, A and B. Only one channel gives control of the probe heater at a time. The other probe heater gives backup control.
Functional Description
Power for the heater comes through the engine relay unit (ERU). The ERU has an electric switch that it uses to give power to the probe. The control signal to energize the switch comes from channels A and B in the EEC. Channels A and B energize the switch when N1 speed is greater than 8.6 percent.
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