Installation Instructions

GTN 6XX/7XX AML STC Installation Manual 190-01007-A3
Page 3-10 Rev. 4
3.4 GTN/GMA 35 Location and Mounting
3.4.1 GTN Rack Installation
Use the dimensions shown in Figure A-4 (GTN 6XX) or Figure A-6 (GTN 7XX) to prepare the mounting
holes for the GTN 6XX or GTN 7XX unit. The GTN 6XX or GTN 7XX unit mounting rack itself may
also be used as a template for drilling the mounting holes.
1. The backplate of the rack may optionally be removed for ease of mounting in the aircraft panel.
To do so, remove the two #4-40 screws, tilt the backplate away from the tray, and then slide the
backplate to the side.
2. Figure A-9 shows outline dimensions for the aviation rack for the various GTN units. Install the
rack in a rectangular 6.320” x 4.600” hole (or gap between units) in the instrument panel (See
Figure A-10). The lower-front lip of the rack should be flush with, or extend slightly beyond, the
face of aircraft instrument panel.
NOTE
If the front lip of the mounting rack is behind the surface of the aircraft panel, the GTN
unit connectors may not fully engage.
3. Make sure that no screw heads or other obstructions prevent the unit from fully engaging in the
rack (see Section 5.3). Exercise caution when installing the rack into the instrument panel.
Deformation of the rack may make it difficult to install and remove the GTN.
4. Install the rack in the aircraft panel using six #6-32 flat head screws and six self-locking nuts. The
screws are inserted from the inside through the holes in the sides of the rack. Torque screws 12-
15 in-lbs.
5. Verify GTN/GMA rack is electrically bonded to aircraft structure or instrument panel as required
in Section 2.4.5.
6. If the backplate was previously removed (see Step 1), replace the backplate by positioning the
tabs on the backplate in the slots of the left side of the rack (viewing it from the cockpit) and
attaching it by replacing the two #4-40 screws. Torque 5 to 6 in-lbs.
3.4.2 GTN Unit Insertion and Removal
It may be necessary to insert the hex drive tool into the access hole and rotate the cam mechanism 90°
counterclockwise to ensure correct position prior to placing the unit in the rack. The GTN is installed in
the rack by sliding it straight in until it stops, about 1 inch short of the final position. A 3/32-inch hex
drive tool is then inserted into the access hole at the bottom of the unit face. Rotate the hex tool clockwise
while pressing on the left side of the bezel until the unit is firmly seated in the rack.
To remove the unit from the rack, insert the hex drive tool into the access hole on the unit face and rotate
counterclockwise until the unit is forced out about 3/8 inches and can be freely pulled from the rack.
Be sure not to over-tighten the unit into the rack. The application of hex drive tool torque exceeding
15 in-lbs can damage the locking mechanism.
NOTE
After installing a GTN unit, verify that the unit power-up self-test sequence is
successfully completed and no failure messages or configuration error messages are
annunciated. Section 5.7.1 outlines the power-up self-test sequence.