System Maintenance Manual

Page 5-76 G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air
Revision G 190-00682-01
5.16 GDC 74B Troubleshooting
5.16.1 Air Data Common Problems
Symptom Recommended Action
Altitude is different than standby
altimeter
• Perform a pitot/static check per Section 7.6 of this manual. Allow
the GDC to warm up for fifteen minutes before checking
accuracy, per Garmin Service Advisory 0606.
• Determine which instrument is outside limits and replace. The
GDC may be field adjusted per Garmin Service Advisory 0720.
Note: Both units may individually be in spec but show a
difference in altitude. Do not return the GDC to Garmin for
service if not outside limits.
GDC Config file does not load.
• Replace GDC config module.
√ If problem persists, replace GDC config module wire harness.
5.16.2 GDC 74B Alerts
Failure Message Cause Solutions
MANIFEST – GDC1 software
mismatch Communication halted.
The system has detected an
incorrect software version loaded
in the specified GDC 74B.
• Load correct software version.
See Section 3.9 for the Software
Load Procedure.
MANIFEST – GDC2 software
mismatch Communication halted.