Garmin G1000 Maintenance Manual page 142

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7.5.1 GRS/GMU Calibration
System software for certain aircraft allows valid outputs from the AHRS prior to completion of
the AHRS and magnetometer calibration procedures, as long as the GRS can definitively
determine that the aircraft is not moving. This gives a technician the ability to perform functional
tests during aircraft assembly that require valid AHRS outputs. Additionally, a "CALIBRATE
AHRS/MAG" message will be displayed on the PFD until a successful magnetic calibration has
been completed.
The criteria used by the AHRS to determine the aircraft is moving are as follows:
1. If valid GPS data is available and each component of 3D GPS velocity is less than 4 knots,
the aircraft is considered "not moving" and attitude/heading will become valid.
2. If valid 3D GPS data is not available, but valid true airspeed is less than 30 knots, the
aircraft is considered "not moving" and attitude/heading will become valid.
3. If both 3D GPS and true airspeed are unavailable, attitude/heading will not become valid.
No configuration is required for the GRS, unless the mounting bolts that secure the mounting
rack are loosened. If the mounting bolts are loosened a new post-installation calibration is
required. Any GMU that is removed and/or replaced requires a magnetometer calibration.
There are six calibration procedures available:
a. Pitch/Roll Offset (Procedure A1)
b. Pitch/Roll Offset, Manual Entry (Procedure A2)
c. Magnetometer Calibration, (Procedure B)
d. Heading Offset Compensation, (Procedure C)
e. Engine Run-Up Vibration Test, (Procedure D)
Magnetometer Interference Test, (Procedure E)
f.
Procedures A2 and C are not required and should not be performed on certain aircraft.
When ready to perform the procedures, shut both PFDs and MFD off by pulling the circuit
breakers. Restart all displays in configuration mode. Follow the steps given for each procedure
on-screen at the GRS/GMU CALIBRATION page. Note that the CALIBRATE command cannot
be selected and activated until the installer acknowledges all required steps have been carried
out by pressing the ENT key on each step.
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Rev. B
NOTE
G1000 System Maintenance Manual
190-00907-00