Installation Instructions

190-01007-A3 GTN 6XX/7XX AML STC Installation Manual
Rev. 4 Page 3-35
3.6.8.1 Attaching Bonding Strap to Tubular Structure
A tab may be welded to the tubular structure, or a conductive clamp may be used with the following
limitations. Complete the installation using the following procedures along with the guidance in
AC 43.13-2B, Acceptable Methods, Techniques, and Practices - Aircraft Alterations, AC 43.13-1B,
Acceptable Methods, Techniques, and Practices – Aircraft Inspection and Repair, and aircraft
make/model specific structural repair documentation, as indicated.
If a gusset or tab on the tubular structure suitable for attaching the bonding strap is not available, add a
new tab as follows:
1. Match the aircraft tube structure material with a tab of minimum dimensions 1.5"L x 1.5"W x
0.0.063"T.
2. Weld the tab to the tube.
3. Drill a 5/16-inch hole in the tab.
4. After assembly and bonding check, apply corrosion protection. Apply zinc chromate primer that
meets FED STD TT-P-1757, or epoxy primer that meets MIL-P-23377, or other corrosion
protection methods listed in the aircraft’s maintenance manual.
If using an electrical bonding clamp, the install must be in accordance with AC 43.13-1B Chapter 11 and
the following criteria:
• The AN735 conductive clamp must not be installed in lightning zone 1A, 1B, or 2B.
• Use cadmium plated steel clamp, nut, and washers. Only AN735-6 and larger diameter clamps
are permitted.
• Select location to minimize the presence of moisture and allow for easy inspection.
• Remove 0.38” square inches of finish on the tubular frame to ensure required contact surface.
• After assembly and bonding check, prime airframe tube and clamp in accordance with the
approved maintenance manual or MIL-PRF-85285 Type I, Color to suit (36081 Flat Gray
Preferable) Coating: Polyurethane, Aircraft And Support Equipment, or MIL-PRF-23377 Type I,
Class N, Primer Coatings: Epoxy, High-Solids.