Figure 4-24.Gun blast area corrosion points.
preservative coatings are not used on jet aircraft
landing gear wheels. During inspections, maintenance
personnel should pay particular attention to the
Magnesium wheels, especially around bolt
heads, lugs, and wheel well areas
Exposed metal tubing, especially at nuts and
ferrules, and under clamps and identification
Exposed connectors, such as indicator switches
and other electrical equipment
Crevices between stiffeners, ribs, and lower skin
surfaces, which are typical water and debris traps
Water Entrapment Areas
Aircraft have drains installed in areas where water
may collect. However, these drains may not be
effective either because of improper location or
because they are plugged by sealants, fasteners, dirt,
grease, and debris. Daily inspection of drains is a
standard requirement, especially aboard ship.
Q57. Cockpit fasteners should be touched up with
what color paint?
Q58. In water entrapment areas of an aircraft, drains
are required to be inspected how often?
Wing Fold, Flap, and Speed
Flap and speed brake recesses are potential
corrosion problem areas because they are normally
closed when on the ground. Dirt and water may collect
and go unnoticed. Wing fold areas contain
complicated shapes and assemblies that are difficult to
cover with a protective paint coating or preservative
film; thus, corrosion is present. Wing fold areas are
extra vulnerable to salt spray when wings are folded
aboard ship. To thoroughly inspect this area,
maintenance personnel should use a mirror to check
the back sides of tubing and fittings. Also, they should
pay particular attention to aluminum alloy, wing lock
fittings (such as those used in some current aircraft
External Skin Areas
Most external aircraft surfaces are ordinarily
covered with protective paint coatings and are readily
visible or available for inspection and maintenance.
Even here, certain types of configurations or
combinations of materials can cause trouble under
shipboard operating conditions and require special
Magnesium skin, when painted over, is not visibly
different from any other painted metal surface.
Magnesium surfaces are identified in the applicable
structural repair manual. When an aircraft contains