190-01007-A1
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Rev. 5
Page 4-3
4.4 Visual Inspection
Conduct a visual check of the GTN unit, switches, GMA 35 (if installed), and their wiring harnesses to
ensure continued installation integrity.
1. Inspect the GTN unit(s) and GMA 35 for security of attachment, including visual inspection of
mounting racks and other supporting structure attaching the racks to aircraft instrument panel.
Verify the countersunk fastener heads are in full contact with unit mounting rack holes. Re-torque
to 8.5-9.5 in-lbs if required.
2. Inspect for signs of corrosion.
3. Inspect all switches, knobs, and buttons for damage.
4. Inspect condition of wiring, shield terminations, routing, and attachment/clamping.
5. Check the fan intake slots on the sides and bottom of the GTN unit’s bezel for dust, dirt, or
obstructions. Clean as needed.
6. Conduct a visual check of the GPS/WAAS antenna cable overbraid if installed.
7. Conduct a visual check of the WXR cable overbraid if installed.
Test Lightning
Protection
The GTN #1 main power input and NAV power input will have a
TVS located at the LRU, for
IFR
non-metallic aircraft only
. The
TVS must be replaced in accordance with Section 4.6.1.
Conduct a visual check of the GPS/WAAS antenna cable
overbraid in accordance with Section 4.7
Conduct a visual check of the WXR cable overbraid in
accordance with Section 4.8 if installed.
After a
suspected or
actual
lightning
strike
Visual Inspection
The GTN unit, GMA 35 (if installed), switches, and wiring
harnesses should be inspected to ensure continued integrity of the
installation. These items must be inspected in accordance with
Section 4.4.
12 Calendar
Months
Item
Description/Procedure
Interval
