Gdc 74A; Equipment Description - Garmin G900X Installation And Maintenance Manual

6

GDC 74A

6.1 Equipment Description

The Garmin GDC 74A Air Data Computer is a remote mounted device that provides air data for flight
instrumentation. The system measures aircraft static and impact pressure information from pressure
transducers and raw air temperature from an outside temperature probe. Using the raw data from the
appropriate sensors, the unit computes pressure altitude, vertical speed, airspeed values, air temperature
information and density altitude. Aircraft specific configuration parameters are stored in an external
configuration module to make the GDC 74A a Line Replaceable Unit (LRU).
The system provides pitot-static and temperature derived air data to the GIA 63W Integrated Avionics
Unit and the GDU 1040 Primary Flight Displays.
The GDC 74A provides the following information in ARINC 429 format:
•
Air Temperature (total air temperature, outside/static air temperature)
•
Corrected Static Pressure
•
Density Altitude
•
Impact Pressure Uncorrected
•
Indicated Airspeed
•
Mach Number
•
Pressure altitude
•
Total Pressure
•
True Airspeed
•
Vertical Speed
G900X/G950 Installation and Maintenance Manual – GDC 74A
190-00719-00
Page 6-1
Revision D