TM 1-1500-204-23-11
h
Using an acid brush, brush on a
vacuum integrity test should be performed to ensure
bead of adhesive around the sup-
there are no vacuum leaks in the part that would
port patch, inside the perimeter
degrade the repair. The vacuum integrity check is
of the 2 sided tape. Use enough
sometimes performed in conjunction with a thermal
resin so that visible squeeze out
survey. Follow these steps to perform a vacuum
will occur when the patch is pulled
integrity test:
into place. All internal compo-
nents of the backside seal must
(1) Facilities, Equipment and Materials. the
be coated in adhesive to minimize
following items are required to perform the vac-
FOD potential.
uum integrity test: Solvent, Wiping cloths, Abrasive
mats, distilled water, breather material, adhesive tape,
Insert the patch through the hole,
i
breather material, vacuum bag material, vacuum, vac-
and pull it up against the under-
uum port bases, vacuum ittings, thermocouples and
side of the repair area skin, apply-
heat blanket (as needed for thermal survey).
ing as much pressure as possible
without pulling the wire off. Look
(2) Vacuum Integrity Test Procedure. Follow
for squeeze out around the cutout
these steps to perform a vacuum integrity test.
edge. Tape the wire to the base
laminate.
(a) Solvent clean the surface area to be
tested for vacuum integrity with an
Place a piece of release ilm over
j
approved solvent.
the repair area
(b) If the surface is metallic, obtain water,
Attach a minimum of three thermo-
k
break-free surface by scrubbing the
couples with lash breaker tape no
repair area with abrasive mats to
further than inch from the patch
remove any oxides and contaminants.
border. Do not place thermocou-
Using distilled water, check for water,
ples directly on the patch as they
break-free condition. Repeat scrub-
will leave a mark during cure.
bing process as needed to reach water,
break-free condition.
l
Place a heat blanket 2 inches larger
than the patch on top and heat
(c) If there are no obvious leak paths, such
the base laminate/support patch
as loose fasteners, rivets or open joints,
area according to paragraph 6-19
continue with this procedure.
using the cure cycle noted system
speciic technical manual or recom-
(d) Place breather material over the repair
mended by the resin manufacturer
area and tape into place. Place two
per engineering disposition..
vacuum port bases in opposite corners
and run vacuum sealant tape around
Remove the tape and wire coil.
m
the repair area perimeter. Cut a piece
Sand the support patch lightly with
of vacuum bagging ilm to it the repair
abrasive paper or cloth and clean
area and install the ilm. If a thermal sur-
thoroughly with solvent. Allow to
vey is to be performed concurrently, the
air dry.
thermocouples and heat blanket would
be installed at this stage.
Apply vacuum bag and perform
n
leak check per paragraph 6-18e.
(e) Install self-sealing vacuum ittings to the
vacuum port bases. Attach a vacuum
Install outer moldline patch and
o
gauge to one vacuum port and a vac-
iller plies according to the system
uum source to the other and draw a vac-
speciic technical manual.
uum in the bag.
f. Vacuum Integrity Test. Vacuum leaks are
(f)
Listen for any obvious leaks in the vac-
checked for after all paint and other coatings have
uum arrangement and seal.
been removed and a backside seal has been installed,
if needed. Before the inal repair is attempted, a
6-65
