Installation Instructions

GTN 6XX/7XX AML STC Installation Manual 190-01007-A3
Page 3-34 Rev. 4
3.6.8 Instrument Panel Bonding Procedure
If the instrument panel is electrically isolated from the aircraft structure, additional bonding may also be
required for the installation. A copper bonding strap with cross sectional area greater than 0.016 sq inches
(approx 20816 circular mils) is required. A 7/16-inch or wider QQ-B-575B (24120 circular mils)
overbraid meets this requirement. The strap length should be as short as possible and must not exceed six
inches in length. The installation shall be such that it avoids the bonding strap looping back on itself.
Refer to Section 2.3.2.5 for hardware specifications. Complete the installation using the following
procedure 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.
Construct a bonding strap by attaching 5/16-inch inside diameter terminal lugs to both ends of the
overbraid.
Prepare the bonding strap installation on the instrument panel with following procedure:
1. Drill a 5/16-inch hole in the instrument panel.
2. Drill a 5/16-inch hole in an existing structure, gusset, or tab of minimum dimensions 1.5"L x
1.5"W x 0.063"T on the aircraft structure; or refer to Section 3.6.8.1 for guidance on attaching the
bonding strap to tubular structure.
3. The bonding strap must be electrically bonded to the instrument panel and to the gusset or tab via
a spot face at least 0.125” larger in diameter than the bonding strap terminal lug and washer.
Install the bonding strap with the following procedure:
1. Secure one end of the bonding strap to the instrument panel with a 5/16-inch bolt, washers, and
nut in accordance with bonding requirements in Section 2.4.5. The washers must seat fully
against the panel, without overhang or interference from other hardware.
2. Secure the other end of the bonding strap to the tab with a 5/16-inch bolt and nut in accordance
with bonding requirements in Section 2.4.5. The washers must seat fully against the tab, without
overhang or interference from other hardware.