Visual Inspection; Electrical Bonding Maintenance Check; Table 3-2 Electrical Bonding Maintenance Requirements; Aluminum Foil Tape (Non-Metallic Aircraft Only) - Garmin GI 275 Maintenance Manual

3.4 Visual Inspection

Operation of the GI 275 system is not permitted unless an inspection, as described in this section, has been
completed within the preceding 12 calendar months. Conduct the following visual inspection of the GI 275
system LRUs and associated wiring harnesses to ensure installation integrity:
1. Inspect all units for security of attachment, including visual inspection of brackets and other
supporting structure attaching all units to the airframe.
2. Inspect all switches, annunciators, knobs, and buttons for legibility.
3. Visually inspect each unit's wiring (including electrical bonding straps), overbraid, and connectors
for chafing, deterioration, damage, or wear.
4. Visually check for any signs of corrosion.
3.4.1

Aluminum Foil Tape (Non-metallic Aircraft Only)

Any aluminum foil tape used in the GI 275 installation for grounding of a GEA 24 or GEA 110 (refer to
Appendix A of this document) must be inspected every 12 calendar months. The inspection must verify
that the foil tape is not torn, damaged, or showing signs of corrosion. If any of these conditions are found,
the tape must be replaced in accordance with Section 4 of GI 275 Part 23 AML STC Installation Manual.

3.5 Electrical Bonding Maintenance Check

GI 275 LRU electrical bonding must be checked every 2,000 flight hours or 10 years, whichever occurs
first. During the check, any cables normally attached to the LRU must be disconnected from the LRU.
Resistance must be measured from a bare metal portion of the LRU to an airframe grounding location. The
airframe grounding location should be as close to the LRU as possible, unless otherwise noted in
Table 3-2. If the measured resistance is greater than applicable values in the table, bonding must be
improved to meet applicable requirements for a new installation in accordance with Section 4 of GI 275
Part 23 AML STC Installation Manual.

Table 3-2 Electrical Bonding Maintenance Requirements

LRU
GI 275 Base
GI 275 ADAHRS
GI 275 ADAHRS+AP
Engine Annunciator(s)
GEA 24
GEA 110
GTP 59
GMU 44B
GMU 11
GSB 15
190-02246-11
Rev. 1
Maintenance Requirement
5 mΩ (from unit to instrument panel)
20 mΩ (from unit to instrument panel)
5 mΩ (from unit to local structure)
Ω
5 m (or electrically isolated per Appendix D of GI 275 Part 23 AML
STC Installation Manual)
None, except when overbraid is required. Overbraid bond must meet
Ω.
5 m
5 mΩ (from unit to instrument panel or local structure)
GI 275 Part 23 AML STC Maintenance Manual
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