Installation Instructions

190-01007-A3 GTN 6XX/7XX AML STC Installation Manual
Rev. 4 Page B-7
B.5 Fabrication of Instrument Panel
Given the age of the aircraft and the number and type of past avionics rack modifications, it may not be
possible to reuse the existing instrument panel. For example, removal and replacement of the mounting
rails may create a scenario where the rivet holes in the instrument panel have been enlarged too much to
repair. Under certain conditions, it may be possible to fabricate an identical instrument panel to allow
installation of the GTN 6XX/7XX.
Instrument panel must not be a part of aircraft primary structure to make modifications for this STC.
Modifications that affect instrument panel structure are not approved through this STC and require
separate review and approval.
If the existing instrument panel is replaced with a new instrument panel, the new panel must comply with
the following requirements:
• Material must be the same thickness and type as the original instrument panel (with a minimum
thickness of 0.062”)
• Use sheet metal techniques (bend radius, fillets, etc.) appropriate to the material type and
thickness – refer to AC 43.13-1B, Chapter 4, Section 4 (Metal Repair Procedures).
• The original mounting locations, shape, form, and/or bends shall not be modified from the
original design.
• Bends in the material must not exceed the minimum bend radius specification of the material
used.
• OEM processes may allow for tighter bends (e.g. a “soft” material is formed then heat treated to
increase hardness.”
• Panels shall not be combined (i.e. an original two-piece panel cannot be combined to create a
single-piece panel). Likewise, panels shall not be split (e.g. creating a two-piece panel from a
single-piece panel.
• Movement or consolidation of instruments, gauges, annunciators, placards, lighting, etc. is
beyond the scope of this STC and will require separate approval.
• Instrument panels are often more than a single piece of aluminum: they are an assembly with
other brackets and components permanently or semi-permanently attached to the main panel. For
example, angles may have been riveted to create attach points for other pieces of equipment (e.g.
“rails” for the radio rack) or they may be used to resist bending of the panel due to weight and
center of gravity of the instruments; brackets or channels may exist to create additional attach
points to the aircraft. The new instrument panel must not alter the design of the instrument panel
assembly features from the original design. These features must be duplicated in the new panel
structure.
• The only intended difference between the new and the old instrument panel assembly is the
installation of the GTN 6XX/7XX which should occur in the location of the existing radio stack.
Every other feature of the panel, including aspects of the structure invisible to the pilot, must be
duplicated. Modification of the instrument panel that will not comply with these requirements is
not approved under this STC. MIL-P-23377, or other corrosion protection method listed in the
aircraft’s maintenance manual. Consider the finish paint for the instrument panel when choosing
corrosion protection to ensure compatibility.