Robinsons R66 - 97-13 LRU Installation - GRS 77 H AHRS

97-13 LRU Installation – GRS 77H AHRS
Refer to R66 Illustrated Parts Catalog (IPC) Figure 97-9.
A. Description
The Garmin GRS 77H Attitude and Heading Reference System (AHRS) provides aircraft
attitude information to the G500H EFIS system. The GRS 77H interfaces with both
the GDC 74H Air Data Computer and the GMU 44 magnetometer. The GRS 77H
also utilizes GPS data forwarded from the GDU 620. Actual attitude and heading
information is sent to the GDU 620 using an ARINC 429 digital interface.
B. Schematic
Refer to MM 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 at
panel.
2. Hinge left seat forward and remove F950-3 cover assembly.
3. Disconnect airframe harness from GRS 77H AHRS at connectors.
4. Loosen thumbscrews securing AHRS to F950-1 support assembly. Carefully
remove AHRS from under left seat.
D. Installation
1. Turn battery & avionics switches off and pull out EFIS (5 amp) circuit breaker at
panel.
2. Place GRS 77H AHRS on F950-1 support assembly and tighten thumbscrews.
Verify security.
3. Connect airframe harness to GRS 77H AHRS at connectors.
4. Push in EFIS circuit breaker (5 amp) at panel. Turn battery & avionics switches on.
NOTE
System configuration and/or software loading may be required.
5. Perform appropriate functional checks per Garmin G500H Instructions for Continued
Airworthiness. Turn battery & avionics switches off.
6. Install F950-3 cover assembly and hinge left seat back.
MAY 2015 Chapter 97 Avionics Page 97.3