TM 1-1500-204-23-11
(f)
Cut one ply of non-porous release ilm
temperature/vacuum controller and
large enough to cover the aluminum
check for proper operation before plac-
caul sheet.
ing next to patch. Refer to paragraph
6-19f for operation of the controller.
(g) Cut a piece of breather material large
Thermocouple readings should approx-
enough to cover the caul sheet and
imate the ambient air temperature. If
reach the vacuum source.
the thermocouple reading does not,
replace thermocouple.
(h) Cut a piece of bagging ilm at least 2
inches past the edge of the caul sheet
(g) Mark the warp orientation and center
and the vacuum source.
lines on the non-porous release ilm out-
side the porous release ilm with a per-
(3) Tool Preparation.
manent marker. Extend the center lines
outside the repair ply stacking area to
assist in the alignment of each ply as the
patch is being fabricated.
Use only lash breaker tape under the vacuum
(h) Place a bead of vacuum bag sealant
bag to prevent contamination of laminate.
tape around the perimeter of the base
plate within the tape boundary line. Do
(a) Place at least four layers of breather
not remove the backing paper from the
material that are the same size as
vacuum bag sealant tape.
the caul sheet to act as insulation on
the base plate. If the double-vacuum
(4) DVD Wet Layup Procedure.
debulk tool is being used, this step can
be skipped as the insulation is already
incorporated into the tool.
(b) Place the heat blanket on top of the
Reduced strength will result if the incorrect
insulation. The heat blanket selected
mix ratio is used, if an excessive amount
must be large enough to maintain a
of air is introduced into the adhesive during
patch edge to heat blanket edge dis-
mixing, or if mixing is inadequate and may
tance of at least 1 inch (see igure 3-7).
result in loss of structural integrity.
(c) Cut an aluminum sheet the same size
Impregnating cloth must be completed within
as the heat blanket and center on top
40 minutes of mixing resin. Double vacuum
of the heat blanket. Tape to base plate
bag debulking must begin within 75 minutes
with a few pieces of tape. Cover the
of mixing resin. An unsatisfactory repair
aluminum caul sheet with non-porous
will result if the resin gels before adequate
release ilm and tape in place.
pressure is applied.
Select heat blanket
(if required) and all necessary vacuum bag
(d) Place the caul sheet on the heat blan-
materials prior to mixing resin.
ket.
Wear protective gloves when laying up and
(e) Tape one piece of porous release ilm
handling repair plies to prevent contamination
on the center of the non-porous release
of adhesive or repair plies.
ilm covered caul sheet.
Pressure must be applied to adhesive within
(f)
Use at least three thermocouples to
the pot life of the resin. For ambient temper-
monitor heat blanket temperature. All
atures in excess of 90 F, decrease this time
thermocouples must be taped to within
by 50%. An unsatisfactory repair will result
0.5 inch of the perimeter of the porous
if the resin gels before adequate pressure is
release ilm and electrically insulated
applied and may result in loss of structural
from the caul sheet using lash breaker
integrity. Select and prepare a heat blanket
tape. Connect thermocouples to the
7-106
