Instruction Manual

G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air Page 2-7
190-00915-01 Revision 8
2.1.10 GRS 77 Attitude & Heading Reference System (2)
The Garmin GRS 77 AHRS units provide attitude and heading information to the G1000 system. The units,
mounted in the nose equipment bay, contain advanced tilt sensors, accelerometers, and rate sensors. The
unit interfaces with the GDC 74B/GDC 7400 and GMU44 Magnetometer and utilizes GPS signals from the
GIA 63Ws. Actual attitude and heading information is sent using ARINC 429 digital interface to both GDU
1040As and GIA 63Ws. The GRS 77 interfaces with and provides power to the GMU 44 Magnetometer.
The GRS 77 supplies attitude and heading information directly to the PFDs, MFD, and GIAs.
GRS 1 receives primary electrical power from the Essential Bus and a secondary power supply from the
Dual Fed No. 1 Bus. GRS 2 receives electrical power from Dual Fed No. 2 bus.
Figure 2-10, AHRS
2.1.11 GMU 44 Magnetometer (2)
The GMU 44 provides horizontal and vertical magnetic field information to the GRS 77 AHRS. This allows
heading to be calculated and provides assistance during AHRS alignment. The GMU 44 units are mounted
in the tailcone or in the horizontal stabilizer. The units receive power directly from the GRS 77 units and
communicate with the GRS 77 units via RS-485 digital interface.
Figure 2-11, Magnetometer