TM 1-1500-204-23-11
part contour over the ilm and tape
in place on the part surface.
(d) Fabricate Replacement Core.
DO NOT use oil or oil based materials
as NDI couplants on advanced composite
Determine part core density and
1
components. Use only water or water based
ribbon direction by referring to the
materials. Disbonds may result and loss of
system speciic technical manual.
structural integrity may occur.
2
Select a replacement core mate-
(b) Deine Damage. Deine both the depth
rial speciied in the system speciic
and extent of the damage using NDI
technical manual. If no core is
according to paragraph 5-2 and the sys-
speciied, use core of the same or
tem speciic technical manual.
higher density and the same mate-
rial. Ensure that it is thicker than
Lay out the damage as described
1
the maximum depth of the core
in paragraph 6-4. Use a circular
cavity. If a core splice exists in the
coniguration.
area being repaired (as indicated
by the presence of core splice
Remove NDI couplant by wiping
2
material), select the higher density
with clean, water moistened cloth.
core section to be the replacement
core.
(c) Remove Damage.
Fabricate a template containing the
3
Remove skin damage along the
1
damage cutout shape using Mylar.
damage layout line as described
Mark the part core ribbon direction
in paragraph 6-4. If damage is
on the Mylar.
through both skins, remove the
damage so that both skins have
the same size and shape damage
cleanup hole.
Core ribbon direction must be maintained
Remove the damaged core as
2
within 2 degree. Incorrect alignment of core
described in paragraph 6-4. See
ribbon result in reduced strength and loss of
igure 7-15, View B.
structural integrity may occur.
4
Orient the template on the replace-
ment core. Match the replacement
core ribbon direction on the tem-
DO NOT sand into laminate when remov-
plate. Using a core slicer and
ing paint. When working on a carbon iber
slicing along the cell axis, cut the
laminate, a black colored dust on the sand-
replacement core to the damage
paper indicates that sanding into the laminate
cutout shape using the template as
occurred and carbon iber is being removed.
a guide as described in paragraph
If this occurs, the sanding process should
6-13. Trim the sides of the core
be stopped immediately. A loss of structural
plug to a loose it; approximately
integrity may occur if ibers are exposed or
1/8 inch smaller than the routed
damaged.
cavity. Trim the plug height so the
top of the plug sits approximately
Remove paint from skin in
3
1/8 to 1/4 inch higher than the level
the repair area by sanding as
of the original mold line. The core
described in paragraph 6-1.
will compress and set during cure
thereby requiring the extra height.
Vacuum the repair area and then
4
wipe with clean wiping cloth to
Carefully insert the replacement
5
remove sanding dust.
core into the cavity to check the it.
If damage is through both skins,
Align the ribbon direction with the
5
cover the hole on the lower skin
part ribbon direction. Use a vac-
with release ilm and tape in place.
uum to remove any dust remaining
Apply a metal plate formed to the
on the core plug.
7-26
