System Maintenance Manual

Page 3-24 G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air
Revision F 190-00682-01
The GRS 77 and GDC 74B configuration modules function differently than the rest of the system. The
GDC 74B’s configuration file is loaded directly to GDC internal memory. A copy of the file is stored in
the GDC configuration module.
The GRS 77 configuration module does not store any configuration settings. Instead, it stores calibration
data recorded during installation calibration procedures.
GRS 77 Config Module
(located in GRS backshell connector)
Stores a copy of AHRS / magnetometer
calibration values that are recorded upon
completion of post-installation calibration
procedures.
GDC 74B Config Module
(located in GDC backshell connector)
Stores a copy of the GDC 74B configuration
file
GRS 77 AHRS
The GRS stores calibration data internally.
The GRS 77 also stores factory calibration data internally.
Should internal memory or the configuration module fail, AHRS
output data flags invalid.
GRS Internal Memory
Contains internal sensor calibration data
that is not installation-specific. Data is
stored from factory calibrations.
GDC 74B
The GDC 74B stores GDC configuration file internally.
The GDC 74B also stores factory calibration data internally.
Should internal memory or the configuration module fail, loss
of some or all air data outputs will result.
GDC Internal Memory
Contains internal sensor calibration data
that is not installation-specific. Data is
stored from factory calibrations.
Figure 3-16. GRS/GDC Configuration Settings Storage