Instruction Manual

Page 5-70 G1000 / GFC 700 System Maintenance Manual - 300/B300 Series King Air
Revision 4 190-00716-01
Failure Message Cause Solutions
MAG VAR WARN – Large
magnetic variance. Verify all
course angles.
Magnetic variance value from
GMU 44 is not accurate.
• If flying near large radio towers or
other sources of possible
electromagnetic interference, the
condition should correct itself as the
aircraft leaves the area.
• If problem persists, run magnetic
interference check in Section 5.15.4
to check for magnetic interference in
the aircraft.
PIT MISCOMP
Difference in the pitch sensors is
greater than 5 degrees.
Perform Calibration Procedure A1: GRS
77 or GRS 7800 Pitch/Roll Offset
Calibration (reference Section 7).
ROL MISCOMP
Difference in the roll sensors is
greater than 6 degrees.
Perform Calibration Procedure A1: GRS
77 or GRS 7800 Pitch/Roll Offset
Calibration (reference Section 7).
5.15.3 GMU Alerts
Failure Message Cause Solutions
MANIFEST – GMU1 software
mismatch. Communication
halted.
The system has detected an
incorrect software version loaded
in the specified GMU 44.
Load the correct software version. See
Section 3.9 for the Software Load
Procedure.
MANIFEST – GMU2 software
mismatch. Communication
halted.
HDG FAULT – AHRS1
magnetometer fault has occurred
A fault has occurred in the
specified magnetometer; heading
will be flagged invalid.
• Check GMU 44/GRS 77 or GRS
7800 interconnect for faults.
9 Replace GMU 44.
9 If problem persists, replace
GRS 77 or GRS 7800.
HDG FAULT – AHRS2
magnetometer fault has occurred.
HDG MISCOMP
Difference in the heading sensors
is greater than 6 degrees.
Perform Calibration Procedure E:
Magnetometer Interference Test
(reference Section 5) and Procedure B:
GRS 77 or GRS 7800 and GMU 44
Magnetometer Calibration (reference
Section 7).