01 March 2005
PRESERVATION AND PACKAGING
9-1. PURPOSE. The materials, equipment, and
g. Whenever the corrosion protection system has
techniques described in this chapter are intended to
failed in service.
assist the avionic technician at the Intermediate
Maintenance Activity (IMA) in preserving, packaging,
handling, and shipping avionic equipment.
be used only where their application and maintenance
will not hamper circuit or component operation.
Components that do not require preservation are listed
9-2.1. GENERAL. Surfaces and components not
nonconductive film that acts to insulate two mating
n o r m a l l y conformal coated or painted need
preservation. Cleanliness and elimination of moisture
contacts will degrade operation of the relay. Each
are keys to avoiding corrosion. Since it is impossible
piece of avionic equipment should be inspected. With
to guarantee a dry, moisture-free environment,
the assistance of the applicable service directives,
preservation of equipment is essential. In today's
areas requiring preservation should be noted and
avionic systems, miniaturization has resulted in
preserved on a scheduled basis. The following items
microminiature circuits no longer than a pencil eraser.
may require preservation on a scheduled basis:
The slightest amount of corrosion can cause a whole
system to fail. Preservation has become an essential
a. Hinges and door latches.
part of the repair and maintenance of avionic systems.
9-2.2. WHY PRESERVE.
c. Shock mounts, rigid mounts, and associated
a. To protect nonmoving parts by filling air spaces,
displacing water, and providing coatings.
d. Any dissimilar metals not otherwise preserved.
b. To protect components such as hinges, control
e. Antenna mounts, brackets, hardware, and
c. To protect nonoperating or idle equipment.
f. Fasteners, screws, nuts, and bolts.
g. Terminal boards, bus bars, and junction boxes.
always be used:
h. Equipment lids on the interior or exterior of
a. After avionic cleaning.
equipment that are susceptible to moisture.
b. On avionic equipment prior to shipment.
i. Solder joints not otherwise conformal coated.
c. O n equipment or components that are
j. Unpainted mounting brackets, equipment racks,
nonoperating or idle (including those awaiting parts).
d. Whenever access is achieved to parts normally
k. Unpainted equipment covers, lids, and chassis.
inaccessible for inspection without disassembly and
l. External and internal surfaces of coaxial
e. Whenever paint films in difficult-to-protect areas
require additional preservation.
m. External surfaces of cooling system joints.
f. After immersion or exposure to fresh water, salt
n. Grounding straps and wires.
water, or fire extinguishing agents.