ADIRS -ANGLE OF ATTACK SENSOR
Electrical Connector
The angle of attack (AOA) sensor sends AOA data to the AIMS cabinet and receives heater power through the electrical connector.
Resolvers
There are two resolvers in each AOA sensor.
The AOA data from the two resolvers in the left AOA sensor goes to the left AIMS cabinet. The AOA data from the two resolvers in the right AOA sensor goes to the right AIMS cabinet.
AOA Heaters
There are two heaters in each AOA sensor, one from the case and one for the vane.
Installation
You install the AOA sensor from the outside of the airplane.
Training Information Point
There are two alignment pins on the AOA sensor. Make sure the pins fit in their holes when you install the AOA sensor.
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ADIRS -AOA SENSOR FUNCTIONAL DESCRIPTION
AOA Heaters
The case and the vane heaters in the angle of attack (AOA) sensors receive 115v ac from the power management panels for power.
AOA Measurement and Transmission
The resolvers in the left AOA sensor send the AOA to the left AIMS cabinet. The resolvers in the right AOA sensor send the AOA to the right AIMS cabinet.
The AIMS cabinets change the AOA sensor data to ARINC 629 format. The AOA sensor data goes to the left and right flight controls ARINC 629 buses.
The air data inertial reference unit (ADIRU) and the secondary attitude air data reference unit (SAARU) use AOA sensor data to calculate the corrected AOA.
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ADIRS -AOA SENSOR FUNCTIONAL DESCRIPTION
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ADIRS -ADM CONTROL OF AOA SENSOR HEAT
Functional Description
The angle of attack (AOA) sensor has two heaters, one for the AOA vane and one for the AOA case. Power for the heaters comes through the ground heat control relay or the air heat control relay.
The pitot air data modules (ADMs) control the relays.
There are two heat sensor relays, one for the vane heater and one for the case heater. The heat sensor relays supply a ground signal to the ADMs when the AOA heat is on.
Power goes through the ground heat control relay when both of these conditions are true:
*
The airplane is on the ground
*
Left or right engine is running.
Power goes through the air heat control relay when either of these conditions are true:
*
The airplane is in the air
*
CAS is more than 50 kts.
The primary flight computers (PFCs) are the source of air/ ground, engine running, and CAS inputs. If the PFCs are not valid, the inputs come from the autopilot flight director computers (AFDCs).
Training Information Point
The air AOA heat and ground AOA heat is 115v ac.
See the ice and rain protection chapter for information on how to do a test of the AOA sensor heat operation (CHAPTER 30).
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ADIRS -AIR DATA/ATTITUDE SOURCE SWITCH
General
The captain and first officer air data/attitude switches on the instrument source select panels control the source of attitude and air data that shows for the onside PFD and ND.
Air Data/Attitude Switch in the Normal Position
When the air data/attitude switches are in the normal position, the ADIRU is the source of attitude and air data for the captain and first officer PFDs and NDs. The ADIRU is the source for heading and track data.
Air Data/Attitude Switch in the Alternate (ALTN) Position
When the captain air data/attitude switch is in the ALTN position, the source for the captain displays is the SAARU for attitude and SAARU single channel (right) for air data. The ADIRU remains the source for heading and track data.
When the first officer air data/attitude switch is in the ALTN position, the sources for the first officer displays are the SAARU for attitude and the ADIRU single channel (left) for air data. The ADIRU remains the source for heading and track data.
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