FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 3. Fiberglass and Plastics | 1. Repair of Light Load Laminate Structures | 3-4. Sample Bagging and Curing Process
9/8/98
AC 43.13-1B
(4) Small parts may be envelope bagged
(i.e., enclosing the entire part in the bag).
Larger parts with localized repairs can be
bagged by sealing the surface completely
around the repair areas with sealing tape and
applying the bagging material to the sealing
tape.
CAUTION: The whole panel must be
vacuum bagged to prevent delamina-
tion in sandwich skins when using an
oven or autoclave. Contoured parts
must be restrained with tooling to
prevent warpage.
b. When the heat for curing the repair
is provided by a heat blanket, the blanket can
be either inside or outside the vacuum bag.
However, the blanket should be covered to
minimize heat loss, and the blanket should be
separated from direct contact with most bag
ging materials by layers of fiberglass cloth.
cloth over the patch, extending beyond the
prepreg and the adhesive. Smooth to avoid
wrinkles.
(b) With the patch material in place,
place the end of the thermocouple wire next to
the edge of the prepreg. Tape the wire to the
structure inside the bag with heat-resistant
tape. The tape should not be in contact with
the prepreg or the adhesive.
(c) Place bleeder plies as shown, ex
tending 2 to 3 inches beyond the patch. The
number of bleeder plies needed will vary with
the type of resin and the resin content required.
(d) Place a layer of nonporous part
ing film over the bleeder plies, cut 1 inch
smaller than the bleeder plies. This layer is
intended to stop resin flow from bleeder plies
into breather plies while still providing an air
flow path when vacuum is applied.
(1) This will prevent localized over
heating that could damage the bag. It is some
times helpful to place a thin aluminum sheet
under the heating blanket to minimize local
ized heating. A thin rubber blanket can help
smooth the surface of the material being cured.
A pressure plate should be used when two or
more heat blankets are applied to the same re
pair.
(e) If a pressure plate is used, place it
over the previous separator ply. The plate is
frequently perforated with small holes to per
mit airflow to the breather plies. Bleeder plies
may be necessary when using a pressure plate.
NOTE: Pressure on the repair will be
reduced if the pressure plate does not
conform to the repair.
NOTE: Understanding that various
resins behave differently during cure,
the choice of bagging arrangements
will often vary with the material being
cured.
(2) The procedure for the bagging ar
rangement is as follows:
(a) Place a peel ply over the patch
material to provide a surface finish for subse
quent bonding or painting if not previously ac
complished. Place a layer of porous separator
(f) Place the heat blanket over the as
sembly, making sure it extends 3 to 4 inches
beyond the material to be cured.
(g) One or more thermocouples
should be in contact with the heat blanket to
monitor its temperature. Additional thermo
couples should be placed near the curing repair
to monitor the temperature of the curing resin.
(h) When using a heat blanket as the
heat source, four to six layers of fiberglass sur
face breather or the equivalent should be
Par 3-4
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