Typical airframe "panels" are constructed from either 2024-T3 or 7075-T6 aluminium alloy. They are usually coated or clad with pure aluminiun for enhanced corrosion protection.<br><br>The thickness of the panels depends on the type of aircraft the kind of structure and the structural loads it must withstand. Common thicknesses range from 0.025 in. - .2 inches.<br><br>To prevent corrosion, most structure has a surface conversion treatment applied. These are either alodine or irridite. Irridite can not be used on structure that requires electrical grounding,instrument panels for examlpe; it is not a good conducter.<br><br>Final finish is usually a chromate primer and a top coat, although some fuselages are left unpainted.<br><br>Hope this helps, <p>Nigel Waterhouse<br><a href=mailto:n_a_waterhouse@hotmail.com>n_a_waterhouse@hotmail.com</a><br><a href= > </a><br>A licensed aircraft mechanic and graduate engineer. Attended university in England and graduated in 1996. Currenty,living in British Columbia,Canada, working as a design engineer responsible for aircraft mods and STC's.