is used to determine when drying is complete. This
drying temperature and time should be
procedure can only be used when the part can be
recorded either using the thermocou-
removed from the aircraft and an oven large enough
ples applied to the part and a tempera-
to hold the part is available. Perform the following
ture recording device (preferred) or the
procedure for drying composite parts in an oven.
oven temperature recorder. If neither
of the recorders are available, temper-
(a) Ensure damaged material and paint
ature recordings should be made man-
has been removed in preparation for
ually at 15 minute intervals.
the bonded repair. The paint should be
removed from an area larger than the
(h) Cool to room temperature at a rate not
to exceed 10 °F per minute.
(b) Machine and prepare the repair joint as
Disassemble the vacuum bag and
described in the appropriate repair sec-
remove the thermocouples.
Inspect the part to determine the mois-
(c) Attach thermocouples to the part in the
ture/water entry point. If the entry point
can be determined, seal the area with
liquid adhesive. Refer to the system
(d) A vacuum bag may or may not be used.
speciic technical manual and cure as
If one is not utilized, proceed to step (g),
otherwise continue with step (e).
(3) Removal of Water From Honeycomb Core-
(e) Place two plies of iberglass cloth
. Water present in the honeycomb core, either visually
breather over the drying area to provide
apparent or detected by x-ray, must be removed to
a moisture escape path.
prevent corrosion of metallic core or moisture related
degradation of nonmetallic core. Areas containing
Install a vacuum bag over the area to be
water will appear lighter than adjacent areas in an x-ray
ilm. However, the presence of cured liquid adhesive
vacuum bagging information. Apply 20
from a previous disbond or delamination repair can
to 30 inches of mercury vacuum to the
give a similar appearance. If the water indication is in
vacuum bag. After a good vacuum seal
proximity to a previous repair, obtain assistance from
is made, at the far end of the bag and
an NDI technician to determine if water is present.
farthest away from the vacuum source,
Water must be removed prior to using a cure temper-
induce a seal leak. This seal leak pro-
ature of 200 °F or higher. Generally, water removal is
vides air movement through the bag
performed at a lower temperature than the laminate
drawing the moisture out. A vacuum
drying temperature to prevent damage to the honey-
level of 10 to 16 inch mercury should be
comb sandwich assemblies due to steam pressure.
utilized. If available, insert a moisture
Selection of the procedure to use is dependent upon
indicator between the vacuum source
availability of equipment and materials, whether the
and the vacuum bag.
part can be removed from the aircraft and whether
the water is located in a repairable area.
(g) Put the part in the oven and ramp the
heat to the speciied drying tempera-
(4) Heat Blanket, Oven or Hot Air Module
ture. Heat the part to 20 °F less than the
Method. This procedure uses any heat source to
part service temperature or 180 (±10)
°F, whichever is lower. Upon reach-
locally heat the water in the assembly causing it to
ing the speciied temperature, hold for
egress out of the part. It is the easiest method to
the minimum amount of time shown in
use and is effective only when the moisture in the
area being heated has an open path to the vacuum
tor shows no moisture present. The