Garmin G1000 Nxi System Maintenance Manual page 172

Invalid Data Field
HDG FAIL
G1000 NXi System Maintenance Manual
King Air 300 Series
190-00716-N1
Associate
d LRU(s)
•
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
•
The GMU 44 magnetometers located in the tail cone are
vulnerable to magnetized rudder torque tube lower fittings
and control rod ends. This magnetism may be caused by
an improperly functioning aircraft static discharge system
which is dependent on static dischargers (wicks) and
electrical bonding of the static dischargers and surrounding
structure. The bonding straps on the elevators and rudder
should be visually inspected to verify they are not missing,
broken or frayed. Refer to the King Air 300 Series
Maintenance Manual, chapter 23-60-00, to verify the
following items are within specification:
1. The resistance from the tip to the base of each static
discharger
2. The resistance between the base of each static
discharger and the surface to which it is attached
GSU 75B,
3. The resistance between the elevators/rudder and the
GRS 77, or
airplane structure
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.
GMU 44
•
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 GSU 75B, GRS 77, or GRS 7800 and GMU 44
connectors are secure.
•
Check the wiring and any inline connectors between the
GSU/GRS and GMU for faults.
•
Recalibrate the GMU 44,
•
Load configuration files to the PFD1, PFD2, GIA1, and
GIA2

If problem persists replace the GMU 44.

If problem persists, replace the GSU 75B, GRS 77, or
GRS 7800.
GSU 75B,
GRS 77, or
•
GRS 7800
If this message persists longer than five minutes, perform
AHRS calibration procedures as described in Section 7.10.
&
GMU 44
Solution
Page 159
Revision 1