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Page 7-10
G1000 System Maintenance Manual
Rev. A
190-00903-00
GRS Software
New GRS 77 Configuration Module Installed:
If the GRS 77 configuration module was replaced, no software loading is required. Calibration
procedure A1, B, and D is required.
Original GMU 44 Reinstalled:
If the original GMU 44 is reinstalled, no software loading is required. This does not include
units that were returned for repair as their software and configuration files are deleted during the
repair testing process.
Original GMU 44s Installed in Opposite Locations for Troubleshooting:
No software loading is required if the original GMU units are installed in opposite locations
(GMU #1 and GMU #2 in opposite unit racks) for troubleshooting. However, the Magnetometer
Calibration Procedure is required.
New or Repaired GMU 44 Installed:
If a new or repaired GMU 44 is installed, load the following file after removing the
Supplemental Database cards from the bottom slots of each display. Note which card was
removed from the MFD so it may be identified later for reinsertion in the MFD when software
and configuration loading is complete. It contains a FliteChart or Chartview database which is
only used by the MFD. Reinstall all the cards after the software and configuration file loads are
complete.
GMU Software
GRS/GMU Calibration
System Software for certain VLJ aircraft allows valid outputs from the AHRS, prior to
completion of the AHRS and magnetometer calibration procedures, as long as the GRS 77 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 77, 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 44 that is removed and/or replaced requires a magnetometer calibration.
There are six calibration procedures available:
Pitch/Roll Offset (Procedure A1)
a.
Pitch/Roll Offset, Manual Entry (Procedure A2)
b.
Magnetometer Calibration, (Procedure B)
