Garmin GTN 6 series Maintenance Manual - page 67
190-01007-B1
GTN 6XX/7XX Part 27 AML STC Maintenance Manual
Rev. 1
Page 6-3
6.2.9
Radar Altimeter
Original Radar Altimeter Reinstalled
No return-to-service procedures are required.
New, Repaired, or Exchanged Radar Altimeter Installed
Perform interface check in accordance with Section 6.3.9.
6.3 Configuration and Testing Procedures
6.3.1
GTN 6XX/7XX Configuration and Testing
This section covers the configuration and checkout procedures that must be completed when a GTN is
replaced with an equivalent unit. The steps provided in this section are only applicable for replacement of
an equivalent GTN unit (i.e. 750 for 750, 625 for 625 etc.). If wiring updates are needed or the
configuration module is being replaced simultaneously, refer to the GTN 6XX/7XX Part 27 AML STC
Installation Manual (P/N 190-01007-B3) for installation instructions.
6.3.1.1
COM Configuration Page (GTN 635/650/750 Only)
Select the COM Configuration page from the GTN Setup page. These values are set at the factory and
rarely require calibration.
To enable or disable the COM radio, touch the COM key to toggle between enabled and disabled. The
COM radio defaults to the enabled state.
Review the COM configuration settings on the GTN and compare them against the GTN Configuration
Log that is retained with the rotorcraft permanent record. A blank copy of the GTN Configuration Log
form may be found in Appendix A of this document. If any of the settings differ from the checkout log,
update the settings to the correct value. For information regarding individual settings, refer to the
GTN 6XX/7XX Part 27 AML STC Installation Manual (P/N 190-01007-B3).
6.3.1.2
Enabled Features
Refer to Section 3.3.4 for instructions on feature enablement. If the configuration module is not replaced,
the enabled features will be retained upon replacing the GTN.
6.3.2
GTN Ground Checks
Ground checks of the GTN require the GTN to be powered up in configuration mode as described in
Section 3.3.
6.3.2.1
Connector Engagement Check
Prior to configuration and checkout of the GTN, the connector engagement should be checked as described
below:
1. Remove power from the GTN.
2. Slide the GTN straight into the rack until it stops about 1 inch short of the fully seated position.
3. Insert a 3/32-inch hex drive into the unit retention mechanism access hole at the bottom of the unit
face and rotate the tool clockwise while pressing the bezel until the unit is firmly seated in the
rack.
4. With the GTN seated, reapply power.
5. Again, insert the hex drive into the unit retention mechanism access hole. Rotate the tool counter-
clockwise to back out the retention mechanism. Ensure that three (3) complete revolutions of the
Allen screw can be performed without red ‘X’ indication or loss of power to the GTN.