Page 97.4 Chapter 97 Avionics APR 2019
97-13 LRU Installation – GRS 77H AHRS (continued)
E. Scheduled Maintenance and Inspections
Refer to Garmin G500H EFIS Maintenance Manual, Section 5 Periodic Maintenance.
NOTE
All factory-installed Garmin units are “on condition” and do not
require scheduled periodic maintenance. Units feature a BIT
(Built-In Test) function during each initial power-up that will
detect internal failure(s) and alert pilot.
NOTE
Refer to § 97-60 for avionics software information.
F. Special Maintenance and Inspections
1. Turn battery & avionics switches off. Open circuit breaker panel, hinge left seat
forward, and remove F950-3 cover assembly.
2. Inspect condition of and verify no obvious damage to Garmin GRS 77H AHRS,
circuit breaker, and wiring. Verify no loose, chafed, or broken wires or terminals.
Verify no evidence of arcing. Verify equipment security.
3. Secure circuit breaker panel. Perform ground checks per Part D steps 4 thru 6.
97-14 LRU Installation – GMU 44 Magnetometer
A. Description
The GMU 44 magnetometer senses the earth’s magnetic field. Data is sent to the
GRS 77H AHRS for processing to determine aircraft magnetic heading. This unit
receives power directly from the GRS 77H and communicates with the GRS 77H
using an RS-485 digital interface.
B. Schematic
Refer to Figure 98-11 for GRS 77H AHRS Installation electrical schematic.
C. Removal
1. Turn battery & avionics switches off and pull out EFIS (5 amp) circuit breaker on
circuit breaker panel.
2. Remove tailcone cowling per § 53-23.
3. Supporting GMU 44 magnetometer, remove hardware securing magnetometer to
F950-4 bracket.
4. Remove MS21919WDG12 clamp and disconnect magnetometer harness from
F951-1 harness assembly at connectors. Remove magnetometer.
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