Gsu 75B, Grs 77, Or Grs 7800 And Gmu 44 Troubleshooting - Garmin G1000 Nxi System Maintenance Manual

GSU 75B, GRS 77, or GRS 7800 and GMU 44 Troubleshooting

AHRS Symptoms
Symptom
AHRS/ADAHRS does not complete
initialization
Attitude appears unstable
G1000 NXi System Maintenance Manual
King Air 300 Series
190-00716-N1
Recommended Action
•
Ensure that a cell phone or a device using cell phone technology is not turned
on (even in a monitoring state) in the cabin.
•
Ensure GPS has acquired at least four satellites, has a 3D navigation solution,
and a DOP of less than 5.0. This is particularly important if this issue appears
during ground operation only.
•
Calibrate the GSU75B, GRS 77, or GRS 7800.
•
Check GSU75B, GRS 77, or GRS 7800 configuration module wiring for
damage.
•
Check GSU75B, GRS 77, or GRS 7800 connector for bent pins.

If no damage can be found, replace GSU75B, GRS 77, or GRS 7800
configuration module.

If problem persists, replace the GSU75B, GRS 77, or GRS 7800.
•
Ensure that a cell phone or a device using cell phone technology is not turned
on (even in a monitoring state) in the cabin. (Wi-Fi and Bluetooth may be
operational)
GRS 77
•
Ensure the four mounting screws are tight. Finger tight is not sufficient, a
screwdriver must be used to verify.
GRS 7800
•
Ensure the hold down clamps are tight.
GSU 75B
•
Ensure the two mounting jack screws are tight.
•
Ensure mounting rack and airframe shelf are secure and all hardware and
brackets are present (CAUTION - do not loosen the mounting rack hardware to
the airframe shelf or the aircraft will need to be re-leveled and the PITCH/ROLL
OFFSET procedure performed).
•
Ensure the GSU 75B, GRS 77, or GRS 7800 connector is securely fastened
and proper strain relief is provided.
•
Remove the GSU 75B, GRS 77, or GRS 7800 connector and verify there are
no bent pins.
•
Replace the GSU 75B, GRS 77, or GRS 7800.
•
Contact Garmin for further troubleshooting if required.
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