TM 1-1500-204-23-11
(r)
If applying the patch to sandwich struc-
ture, pot the core according to para-
DO NOT damage inner surface of opposite
(s) Disassemble the patch from the sub-
skin or internal structure during machining or
strate.
drilling.
(t)
Using a 2000 rpm drill motor, drill guide,
DO NOT center punch advanced composite.
and a 1/64 undersized HSS drill bit,
drill all the patch holes except for the
(j)
If applicable, remove any existing fas-
marked alignment holes. Deburr the
teners covered by the repair plate.
holes drilled.
Transfer the fastener hole locations
to the repair patch using the methods
(u) Using temporary fasteners in the align-
described in paragraph 7-7e.
ment holes, attach the patch onto the
(k) Using a center punch, mark the loca-
composite substrate.
tions on the metal patch that require
(v) Using a 2000 rpm drill motor, drill guide,
pilot holes.
and a full-sized drill reamer, match drill
(l)
Using a 2000-rpm drill motor, drill guide,
the patch/substrate combination.
and a No. 30 HSS drill bit and back-
(w) Remove the patch from the substrate.
ing plate, drill all the holes. Deburr the
holes.
(x) Using a 2000-rpm drill motor, drill guide,
and a 1/64-undersized HSS drill bit,
(m) On the drilled patch, mark one piloted
enlarge the alignment holes in the
hole in each of the patch corners. These
patch. Deburr the holes.
holes will be used as alignment holes for
aligning and match drilling the patch to
(y) Attach the patch onto the substrate
the structure.
with temporary fasteners using full-size
holes that are adjacent to each of the
(n) Place the patch onto the repair area in
alignment holes used.
its proper location and orientation and
mark the irst hole to be drilled.
(z) Using a 2000-rpm drill motor, drill guide,
and a full-sized drill reamer, match drill
(o) Remove patch and check to ensure fas-
the remaining holes in the patch/sub-
tener hole to edge of damage cleanup
strate combination.
meets the minimum requirement in the
system speciic technical manual. If any
(aa) Disassemble and deburr the remaining
fastener hole has less than the required
holes in the patch.
edge distance, repeat step (n) above,
relocating patch to obtain required edge
NOTE
distance.
Using a grip length gauge, determine fastener
(p) Using a 2000 rpm drill motor, drill guide,
grip length by gauging material thickness after
a straight-luted carbide drill reamer,
drilling holes full size.
and the patch holes as the template or
guide, pilot drill through the alignment
(ab) Place patch in place and measure the
holes into the composite substrate. Drill
fastener grip length required in each
the alignment holes in order to ensure
fastener hole.
accurate patch location and install tem-
porary fasteners in the holes as they are
(ac) Prime patch if required as speciied in
drilled to hold the patch irmly in place.
the system speciic technical manual
and paragraph 6-7.
(q) Complete drilling all the pilot holes
through the substrate using the patch
(ad) Remove paint from skin in the repair
pilot holes as the guide. If the drilling
area by sanding as described in para-
process begins to slow down or requires
more pressure, the drill reamer has
become dull. Stop and replace the drill
(ae) Seal the patch per paragraph 7-7g
reamer.
above.
7-56
