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Page 5-114
G1000 System Maintenance Manual
Rev. A
190-00903-00
5.2 CALIBRATION
PROCEDURES
5.2.1 GDC 74B Calibration Procedure
This procedure discusses the use of the GDC 74B Field Calibration Utility (software; P/N T06-
A0156-00) to adjust the calibration of GDC 74B LRUs that have failed the 14 CFR Part 43
Appendix E tests due to altitude drift or have failed the ICA limits for RVSM certification.
Both the GDC 74B Field Calibration Utility and the GDC 74B Field Calibration Instructions
(190-00303-82) can be downloaded from the dealer resource section of the Garmin website at
www.garmin.com. First download the GDC 74B Field Calibration Instructions Document, then
follow the steps listed in that document to download and run the GDC 74B Field Calibration
Tool.
5.2.1.1 Limitations
The following limitations should be noted:
a.
These procedures should be performed at room temperature on the bench and not in the
aircraft.
b.
The Field Calibration Utility should only be used to correct errors due to altitude drift. If the
drift is greater than the limits defined in the utility at any of the test points, the utility will not
allow the calibration to continue and the GDC 74B must be returned to Garmin.
c.
If the GDC 74B unit does not pass 14 CFR Part 43 Appendix E and the RVSM limits for
ICA that apply to the GDC 74B after the calibration utility has been run, the GDC 74B unit
should be returned to Garmin.
5.2.1.2 Required
Equipment
The following equipment is required to perform calibration.
a.
GDC 74B LRU
b.
Power supply capable of producing 14/28V at 500mA)
c.
PC with a Serial Port or serial port adapter
d.
Pressure control system capable of generating the correct static pressures for zero feet,
11,000 feet, 30,000 feet, and 41,000 feet.
NOTE
Field calibration of GDC 74B requires a pressure control system with
altitude accuracy equal to or better than ±5 feet at sea level, ±15 feet at
30,000 feet, and ±15 feet at 41,000 feet. The pressure control system must
control altitude automatically.
e.
Fabricate a cable built to interface a GDC 74B to a PC Serial Port (see Figure 2-33). The
cable is not available from Garmin.
