Garmin G1000 NAV III Line Maintenance Manual page 13

G1000 Nav III Line Maintenance Manual
190-00352-00
GRS 77: The GRS 77 is an attitude, heading, and reference, or AHRS, unit that
provides aircraft attitude and flight characteristics information to the G1000
displays and GIAs. The unit contains advanced tilt sensors, accelerometers, and
rate sensors. In addition, the GRS 77 interfaces with both the GDC 74A Air Data
computer and the GMU 44 magnetometer. The GRS 77 also utilizes GPS signals
sent from the GIA. Actual attitude and heading information is sent using ARINC
429 digital interface to both GDU 104Xs and GIAs.
GMU 44: The GMU 44 magnetometer senses magnetic field information. Data is
sent to the GRS 77 ARHS for processing to determine aircraft magnetic heading.
This unit receives power directly from the GRS 77 and communicates with the
GRS 77 using RS-485 digital interface.
GDC 74A: The GDC 74A air data computer compiles information from the
pitot/static system and various outside air temperature (OAT) and angle of attack
(AOA) sensors. The GDC 74A is responsible to provide pressure altitude,
airspeed, vertical speed, and OAT information to the G1000 system. The GDC
74A communicates with the GIA 63/GIA 63W, GDU 104X, and GRS 77 using
ARINC 429 digital interface. Software and configuration settings are received
through RS-232 digital interface with the GIA 63/GIA 63W.
GEA 71: The GEA 71 is a microprocessor-based LRU that is responsible for
receiving/processing signals from engine and airframe sensors. Sensor examples
include engine temperature and pressure sensors as well as fuel measurement and
pressure sensors. The GEA 71 communicates directly with both GIAs using RS-
485 digital interface. The GEA 71 can serve aircraft from basic single-engine
platforms to sophisticated turbine propulsion systems. Software and configuration
settings are received through RS-232 digital interface with the GIA.
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