Instruction Manual

Page 5-76 G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air
Revision 9 190-00915-01
5.16 GDC 74B/GDC 7400 Troubleshooting
5.16.1 Air Data Common Problems
Symptom Recommended Action
Altitude shown on PFD is different
than standby altimeter
• Perform a pitot/static leak and accuracy check per Section 7.6 of
this manual.
• Determine which instrument is outside limits and replace.
Note: The GDC 74B may be field adjusted per Garmin Service
Advisory 0720. Both units may individually be in spec but
show a difference in altitude. If the GDC 74B cannot be
adjusted within the limits per Garmin Service Advisory 0720,
replace the unit.
Note: The GDC 74B and GDC 7400 software/configuration for the
200/B200 contains error correction at 19,000 feet and above.
The standby altimeter does not contain any correction.
GDC 74B Configuration file
does not load.
• Replace GDC 74B configuration module.
9 If problem persists, replace GDC 74B configuration module wire
harness.
5.16.2 GDC 74B/GDC 7400 Alerts
Failure Message Cause Solutions
MANIFEST – GDC1 software
mismatch Communication halted.
The system has detected an
incorrect software version loaded
in the specified GDC.
•
Load correct software version.
See Section 3.9 for the Software
Load Procedure.
MANIFEST – GDC2 software
mismatch Communication halted.