TM 1-1500-204-23-11
If multiple stacked patches are
7
required, stack the largest patch
on the part surface followed by
increasingly smaller size patches.
Pressure must be applied to adhesive within
See paragraph 7-5. Repeat scrim
the pot life of the resin. For ambient temper-
cloth and adhesive application for
atures in excess of 90 F, decrease this time
each stacked patch applied. Tape
by 50%. An unsatisfactory repair will result
in place with lash breaker tape.
if the resin gels before adequate pressure is
applied and may result in loss of structural
integrity. Select a heat blanket (if required)
and all necessary vacuum bag materials prior
to mixing resin.
Reduced strength will result if the incorrect
mix ratio is used, if an excessive amount of
air is introduced into the resin during mixing,
or if mixing is inadequate and may result in
loss of structural integrity.
Cut a piece of scrim cloth 1/4 inch
1
larger than the patch if required.
Figure 7-5. Layup of Stacked Patches and
Prepare approximately 50 grams
2
Adhesive
of adhesive for patch bond as
described in paragraph 6-17.
(o) Bond patch.
Apply a thin layer of adhesive on
3
Layup the vacuum bag and heat
1
the part surface using a spatula and
blanket as described in paragraph
adhesive comb per paragraph 7-6.
6-18, Vacuum Bagging. If a heat
Adhesive shall extend a minimum
blanket is not used to cure the
of 1/4 inch beyond patch periphery.
adhesive, omit heat blanket, cop-
per sheet and heat blanket control
Apply the scrim cloth to adhesive
4
thermocouple from layup.
on the part surface if required.
NOTE
The bond surface of the patch is the lat
Failure to properly cure adhesive in accor-
surface not containing the taper.
dance with the speciied cure cycle will result in
reduced repair strength may not be detectable
Apply a thin layer of adhesive on
5
by visual or nondestructive inspection. This
the bond surface of the patch using
may result in loss of structural integrity.
a spatula and adhesive comb per
Cure adhesive as described in
2
paragraph 6-19, using the cure
cycle from the system speciic tech-
nical manual.
Part to patch alignment must be main-
tained within 2 degrees. Fabricated com-
Disassemble the vacuum bag (and
3
posite patches are orientation sensitive from
heat blanket if used).
a strength standpoint. Incorrect alignment
of part and patch during layup will result in
(p) NDI Patch Bond(s).
reduced strength and loss of structural integrity
may occur.
1
Visually inspect adhesive squeeze
out at patch edge as described in
Apply bond side of patch containing
6
adhesive on part surface contain-
ing scrim cloth/adhesive. Ensure
Perform NDI of patch to skin and
2
patch is aligned on part to maintain
patch to iller bond areas to verify
minimum patch overlap.
bondline integrity.
