TM 1-1500-204-23-11
(c) Remove NDI couplant by wiping with
left on the cotton tipped applicator
clean, water moistened wiping cloth.
or the wiping cloth. Allow the sol-
vent to evaporate for a minimum of
(d) Fabricate Mylar Template.
30 minutes. See paragraph 6-7 for
surface preparation steps.
1
Establish the centerline of the fas-
tener hole using reference points
Seal the backside of the fastener
4
and lines marked on the part as
hole by securing release ilm and
shown in igure 7-52, using a per-
an aluminum backup plate with
manent ink marking pen. Ensure
overlapped layers of lash breaker
the reference points are far enough
tape as shown in igure 7-53.
away from the fastener hole to not
be affected by the repair process.
Figure 7-53. Fastener Hole Sealing
Reduced strength will result if the incorrect
mix ratio is used, if an excessive amount
of air is introduced into the adhesive during
mixing, or if mixing is inadequate and may
result in loss of structural integrity.
Pressure must be applied to adhesive within
the pot life of the resin. For ambient temper-
Figure 7-52. Template Fabrication
atures in excess of 90 F, decrease this time
by 50%. An unsatisfactory repair will result
2
Transfer the hole centerline and
if the resin gels before adequate pressure is
the reference points to a piece of
applied and may result in loss of structural
Mylar. Use this Mylar as a guide in
integrity. Select and prepare a heat blanket
redrilling the fastener hole follow-
(if required) and all necessary vacuum bag
ing illing.
materials prior to mixing resin.
(e) Prepare Fastener Hole For Filler Appli-
Prepare a small quantity (30
5
cation.
grams) of adhesive/chopped iber
mixture per paragraph 6-17 with
1
Lightly sand countersink area using
mrF = 5 (5 parts by weight of
180 grit abrasive paper to remove
chopped iber). Ensure iber is
sealant, paint and other debris.
chopped to 1/4 inch or smaller.
Vacuum area to remove sanding
residue. See paragraph 6-3 for
(f)
Apply Filler.
paint removal steps.
Carefully apply the adhesive/iber
1
2
Dry the repair area to remove sub-
mixture into the fastener hole and
surface moisture using per para-
ill to the top. Apply mixture in lay-
ered amounts to avoid air entrap-
ment.
Clean fastener hole and counter-
3
sink area using a cotton tipped
Fair mixture with a spatula and
applicator, wiping cloth and solvent.
2
wipe off excess with clean, dry,
Thoroughly clean the area with
wiping cloth.
repeated wiping until no residue is