Garmin GTN6XX User Manual
190-01007-A1
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Rev. 7
Page 4-6
4.5.3 GMA 35 (Metallic or Tube/Fabric Aircraft)
A bonding check is required for the GMA 35. Perform an electrical bonding check as follows:
A bonding check is required for the GMA 35. Perform an electrical bonding check as follows:
1. Gain access to the GMA 35 by removing the GTN 7XX.
2.
2.
Remove the GMA unit from the mounting rack.
3. Remove backplate assembly from the rack.
NOTE
The GTN 7XX backplate assembly must be removed from the GTN rack prior to
performing Step 4.
performing Step 4.
4. Measure the resistance between the mounting rack and nearby exposed portion of aircraft metallic
structure and verify it is less than or equal to 10 milliohms.
NOTE
A bonding test failure may occur if a fastener is not secured to the specified torque value.
For installations that use screws in lieu of rivets to secure the rack to surrounding
structure, verify that the screws are torqued to the appropriate value before proceeding to
remove the rack. See Section 4.4 for torque values.
For installations that use screws in lieu of rivets to secure the rack to surrounding
structure, verify that the screws are torqued to the appropriate value before proceeding to
remove the rack. See Section 4.4 for torque values.
In the event of bonding test failure, remove the GMA 35 rack and clean the attachment points with a
bonding brush at both the GMA rack and the aircraft attachment points. Re-verify the resistance between
the mounting rack and nearby exposed portion of aircraft metallic structure and ensure that the resistance is
less than or equal to 2.5 milliohms.
bonding brush at both the GMA rack and the aircraft attachment points. Re-verify the resistance between
the mounting rack and nearby exposed portion of aircraft metallic structure and ensure that the resistance is
less than or equal to 2.5 milliohms.
5. Reinstall the backplate assembly and reinstall the GMA unit in the mounting rack.
4.5.4 GMA 35 (Composite Aircraft)
1. Gain access to the GMA 35 by removing the GTN 7XX.
2. Remove the GMA unit from the mounting rack.
3. Remove the backplate assembly from the rack.
2. Remove the GMA unit from the mounting rack.
3. Remove the backplate assembly from the rack.
NOTE
The GTN 7XX backplate assembly must be removed from the GTN rack prior to
performing Step 4.
performing Step 4.
4. Measure the resistance between the mounting rack and the instrument panel, and verify it is less
than or equal to 10 milliohms.