Electrical Bonding Test; Gtn Xi Bonding Check (Metallic Or Tube-And-Fabric Aircraft); Gtn Xi Bonding Check (Composite Aircraft) - Garmin GTN Xi Series Maintenance Manual

4.5 Electrical Bonding Test

4.5.1

GTN Xi Bonding Check (Metallic or Tube-and-Fabric Aircraft)

NOTE
If the GMA 35 is installed (GTN 7XX Xi only), it must be removed from its rack and the
GMA 35 backplate assembly must be removed prior to performing step 3. When a
GMA 35 bonding check is planned, perform the GMA 35 bonding check prior to
re-installing the GTN Xi backplate assembly to the rack.
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 the surrounding
structure, verify that the screws are torqued to the appropriate value before proceeding to
remove the rack. Refer to Section 4.4 for torque values.
Perform an electrical bonding check as follows:
1. Remove the GTN Xi unit from the mounting rack.
2. Remove the backplate assembly from the rack.
3. Measure the resistance between the mounting rack and nearby exposed portion of aircraft metallic
structure and verify it is less than or equal to 5 mΩ.
In the event of bonding test failure, remove the GTN Xi rack, clean the attachment points with a bonding
brush at both the rack and the aircraft, and re-attach the rack to the rails in the panel. Measure 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 mΩ.
4. Re-install the backplate assembly and re-install the GTN Xi unit in the mounting rack.
4.5.2

GTN Xi Bonding Check (Composite Aircraft)

NOTE
If the GMA 35 is installed (GTN 7XX Xi only), it must be removed from its rack and the
GMA 35 backplate assembly must be removed prior to performing step 3. When a
GMA 35 bonding check is planned, perform the GMA 35 bonding check prior to
re-installing the GTN backplate assembly to the rack.
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. Refer to Section 4.4 for torque values.
Perform an electrical bonding check as follows:
1. Remove the GTN Xi unit from the mounting rack.
2. Remove the backplate assembly from the rack.
3. Measure the resistance between the mounting rack and the instrument panel, and verify that it is
less than or equal to 10 mΩ.
190-01007-C1
Rev. 1
GTN Xi Part 23 AML STC Maintenance Manual
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