____________________________________________________________________
Page 5-6
G1000 System Maintenance Manual
Rev. A
190-00903-00
Table 5-1. (continued)
Annunciation Associated
LRU
Recommended Actions
HDG FAIL
GRS 77 &
GMU 44
•
Check PFD1 Alert Window for PFD1/2, MFD or
GRS configuration, software or failed data path
error messages. Correct any errors before
proceeding.
•
Ensure metal objects (tool boxes, power carts,
etc.) are not interfering with the magnetometer
and aircraft is not in hangar, near other buildings,
parked over metal drainage culverts or on hard
surfaces that may contain steel reinforcements
•
Ensure that a cell phone or a device using cell
phone technology is not turned on (even in a
monitoring state) in the cabin.
•
Cycle power after moving aircraft away from metal
objects to determine if metal objects were the
source of the interference. Allow up to five
minutes for the heading to reinitialize.
•
Perform a Magnetometer Interference Test to
check for interference from onboard electrical
system components (e.g. NAV lights). Pay
particular attention to any new electrical devices
that have been installed since the aircraft was
new. Correct any discrepancies that do not allow
this test to pass before continuing.
•
Ensure GRS 77 and GMU 44 connectors are
secure.
•
Check the wiring and any inline connectors
between the GRS and GMU for faults.
•
Recalibrate the GMU 44.
•
Replace the GMU 44.
•
If problem persists, replace the GRS 77.
