screws are not torqued correctly, the plastic panel may
fail while the aircraft is undergoing normal taxiing and
flight operations.
When you remove a plastic panel, there may be
several different lengths of screws to be removed. You
will save a lot of time by acquiring the habit of keeping
screws separated. An easy way to do this is to draw a
diagram of the panel on cardboard. Puncture each
screw hole, with an awl, through the cardboard. As each
screw is removed from the panel, it is installed in its
respective position on the cardboard. This is done with
each screw as it is removed.
During installation of the panel, remove each screw
from the cardboard and reinstall it in the same hole
from which it was removed until all of the screws are
reinstalled. If any screws or other fasteners are
damaged during removal or reinstallation, the part
replaced must be the same part number as the damaged
part. Some fasteners are required to be of nonmagnetic
Figure 5-6.--Typical sighting dome attachment.
material because of their location near compasses and
other instruments. The specific part number for each
Since plastic expands and contracts three times as
fastener can be found in the Illustrated Parts
much as metal, suitable allowances for dimensional
Breakdown (IPB) for the aircraft.
changes with temperature must be made. Minimum
clearances between the frame and plastic are listed in
Q5-1. What are cracks and small surface fissures in
Fabrication, Maintenance and Repair of Transparent
transparent plastic materials called?
Plastics, NAVAIR 01-1A-12, or the applicable MIM.
Q5-2. What should you use to clean excessive
Clearances should be equally divided on all sides.
masking paper adhesive residue from plastic?
Screw torquing procedures should be in
Q5-3. What is normally used to measure scratches
accordance with the applicable MIM. Plastic panels
on plastic materials?
should not be installed under unnatural stresses. Each
screw must be torqued, as specified in the MIM, to
Q5-4. To sand out scratches in transparent plastic,
enable it to carry its portion of the load. If a plastic
what is the maximum coarse number of
panel is installed in a binding or twisted position and
abrasive paper that you may use?
Q5-5. What substance is often applied to the buffing
wheel in place of, or in addition to, a buffing
compound that acts similar to wax to fill
hairline scratches and provides a high gloss
to plastic surfaces?
Q5-6. How many times greater will plastics expand
and contract as compared to metal?
REPAIRING REINFORCED PLASTIC
This section covers the materials and procedures to
be used in repairing reinforced plastic and sandwich
construction components. The procedures discussed
are general in nature. When actually repairing
reinforced plastic and/or sandwich construction
components, refer to the applicable maintenance
instruction manual or structural repair manual.
Figure 5-7.--Typical loop edge attachment.
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