01 March 2005
gaskets with disassembly/ reassembly. Gaskets may
deteriorate via attack by operational chemicals,
corrosion, and wear. Therefore, inspection should
Compound, Corrosion Preventive
include the following.
a. Check for corrosion products, pitting of the
aluminum surface, or bulges in the sealant due to
corrosion beneath the gaskets.
b. Check the bonding of the gasket to the structure
to prevent moisture intrusion.
b. Carefully clean the area with Isopropyl Alcohol,
gasket or its electrical bond to the aircraft.
seals are available, install them in accordance with
aircraft maintenance instructions or bulletins. If
d. Check for wear and swelling of the gasket.
replacement seals are not available or do not exist,
spray the contacting surfaces with a light coating of
e. Check for compression set of the seal.
Water Displacing Corrosion Preventive Compound,
MIL-C-81309 Type II (Volume IV or V, Chapter 2) and
f. Insure maintenance procedures are being
followed (e.g. avoid solvents which can wash away
c. Inspect repairs and areas known to be chronic
g. Check for excessive bending and/or pulling of
electrical cables and shields.
7-6.3.1. (AF) Electronically Conductive, Corrosive
Inhibiting Sealant for EMI Suppression Applications.
7-6.3. EMI SHIELDING CORROSION REPAIR AND
Many electrically conductive sealants are available,
TREATMENT. Corrective maintenance of EMI gaskets
but most are not corrosion inhibiting and generate
depends on the type of gasket involved, size of the
galvanic corrosion at bond lines when contacting
damaged area, and degree/type of corrosion. EMI
aluminum and/or steel alloys in the presence of
gaskets are usually of either metal or conductive
moisture. SAE Specification AMS 3262 covers an
elastomer construction. Finger stock, mesh, and spiral
electrically conductive, corrosion inhibiting sealant
ribbon are examples of metal gaskets. Conductive
that can be used in EMI suppression applications
without causing a galvanic corrosion problem. This
particles (spheres, irregular shapes, fibers) in elastomer
material can be used to bond EMI gaskets to one of two
matrices. Oriented wire gaskets have characteristics
mating surfaces, to bond and seal two mating metal
of both categories. Since each type of EMI gasket has
surfaces fastened in a permanent joint, or to fillet seal
its own peculiarities, each will require special corrosion
the edges of a metal-to-metal lap or butt type joint
treatment/repair. The following "generic" gasket repair
procedure is outlined below for general guidance.
between all components. See Volume V, Chapter 2 for
Maintenance personnel should refer to the applicable
sealant ordering information. Application procedures
MIM (Navy), TO (Air Force), and/or TM (Army) for more
are as follows:
specific repair information.
a. If present, remove all paint and primer from all
a. When corrosion is observed, disassemble only
metal surfaces that will contact the sealant per TO
the affected area and remove the corrosion using the
1-1-8 procedures, and lightly abrade these surfaces
mildest available method.
with an Abrasive Mat, A-A-58054 Type I Grade B