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where corroded DU has been handled or stored.
(6) DU waste will be disposed of IAW AFI 40-201
and shipped IAW applicable Federal regulations (10 CFR
& 49 CFR).
For further information or, in the event of a potential DU
overexposure, contact your local Bioenvironmental Engineering
(BEE) office or Medical Treatment Facility for
urgent care.
For more information on DU safety contact the AFIERA
Radiation Surveillance Division through the ESOH Service
Center 1-888-232-ESOH or DSN 240-5454.
Depleted Uranium (DU)
Counterweight Safety
3-20
TO 00-105E-9
3-21
3.5 COMPOSITE MATERIAL HAZARDS. The mishap
responder’s primary duties do not provide an opportunity
to learn about composite system or materials associated
with aerospace vehicles. This paragraph contains
introductory information that will aid with a familiarization
of composite systems pertinent to a mishap scenario.
Information in subparagraph a and b can be used to identify
composite debris among the wreckage and provides
a common language that will help with communication
consistency for all response types.
a. BASICS OF COMPOSITES. Knowing how a composite
part is made will help explain what happens to it
when it becomes damaged. A Photo Gallery located in
3.5d has been provided in this section to enhance understanding.
(1) SYSTEM OF MATERIALS. Composites are a SYSTEM
of two or more different materials. Most common
for aircraft manufacturing are man made fibers surrounded
by a matrix. The matrix is a resin or plastic material.
During the manufacturing process the resin chemically
bonds to the fiber and each adjacent layer of material.
The resin seals and holds thousands of fibers in
place. Without the fiber the resin would be a solid chunk
of plastic material. Without the resin the fiber behaves
similar to thread used for making clothes or hair found in
a hairbrush. (Photo 1)
(2) INTERMEDIATE MATERIAL.
(a) “PREPREG”. Different manufacturing processes
are used to make or repair aircraft parts and different
material forms are used for each process. One common
material form is the “prepreg”. “Prepreg” is a fibrous material
that has been coated or pre-impregnated with a
tacky or viscous resin. It is received from the materials
manufacturer in a ready-to-use state.
(b) “PREGREG” TYPES. “Prepreg” is identified by the
fiber direction. Fibers are oriented in a parallel fashion
for the unidirectional “prepreg” and are weaved into various
interlacing patterns for the woven “prepreg”. The roving
“prepreg” is a collection of fiber bundles and is delivered
just like a spool of thread. The unidirectional and
the woven “prepreg” is received as a sheet of material
wound around a cardboard spool for storage and handling
purposes. Because the spool resembles a roll of
tape, the material is sometimes referred to as a “prepreg”
tape. (Photos 2 thru 8)
(3) BUILDING THE COMPOSITE PART. To obtain a
specific shape, one way of building a composite is by
stacking multiple layers of “prepreg” (resin-coated fibers)
material around a tool that has the desired shape. The
layers of “prepreg” material is produced by cutting the
desired size from the spool much like cutting textile fabric
used to make clothing. The layers are stacked until
the desired thickness is reached. (Photos 9 and 10)
To become a solid part the matrix solidifies during a cure
cycle. During the cure, the resin chemically attached to
each fiber within a layer and between the layers. After
cure, the tool is removed and the “prepreg” material now
has a permanent shape. The layers are not distinguishable
from one another and the part appears to be homogenous.
The bulk solid part is considered to be chemically
and biologically inert to the touch.
(4) FINISHED FORM TYPES. There are several different
types of parts made by layering of materials that
can be found at a mishap scene. The solid laminate, the
sandwich laminate and the filament wound laminate will
be identifiable among the damage debris.
(a) SOLID LAMINATE. The cured part is called a laminate.
The laminate can have various forms but the solid
laminate is usually referenced to a flat or slightly curved
form. This type of laminate is used to make aircraft skins,
panels, and doors. Ribs, stiffeners, and spars are other
composite applications made by layering of materials.
(Photos 11 and 12)
(b) SANDWICH LAMINATE. To reduce the weight of
　
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