TM 1-1500-204-23-11
F, whichever is lower. Do not exceed
10 F per minute ramp rate.
(j)
Upon reaching the speciied temper-
Support removed core areas, exposed core,
ature, hold for the minimum time as
and core edges to prevent the vacuum bag
shown on igure 6-9. If a moisture
from damaging or crushing the core. DO
indicator has been utilized, hold at dry-
NOT exceed the speciied drying temperature
ing temperature until no moisture is
or part damage may result.
present.
(a) Perform NDI of part to determine loca-
(k) Cool to room temperature at a rate not
tion of water in the core. If liquid water
to exceed 10 F per minute.
has been detected in the honeycomb
sandwich assembly, proceed with step
(l)
Disassemble vacuum bag, heat blanket,
(b). Otherwise proceed to step (e).
and thermocouples.
(b) Remove paint in the patch bond area as
(m) Reinspect area using NDI to determine
described in paragraph 6-1. The paint
if water has been removed or if it has
should be removed from an area larger
migrated to another location.
than the repair area.
(n) If water has been removed from the
(c) If the part has water in a nonrepara-
assembly, proceed to repair steps. Oth-
ble zone, as deined in the system spe-
erwise, continue drying until all moisture
ciic technical manual, refer to the oven
has been eliminated.
method or use a heat module and tent
as described in paragraph 6-6.
(o) If water has migrated as a result of the
drying process or if the previous proce-
(d) If the part has water in a reparable zone,
dures prove unsuccessful and the water
as deined in the system speciic tech-
is still in a repairable zone, remove the
nical manual, drill holes through skin in
skin from the area containing water.
the area containing water. Use a 0.125
Remove the skin cautiously to minimize
inch diameter carbide drill bit. For each
damage to the core underneath. After
square inch of water accumulation drill
skin removal, repeat the process start-
two holes.
ing at step (d).
(e) Machine and prepare the repair joint as
(p) If holes were drilled in skin, seal holes
described in the appropriate repair sec-
with liquid adhesive and bond an exter-
tion.
nal patch over the drilled holes using
(f)
Layup heat blanket, thermocouples,
and vacuum bag as described in para-
(q) If the skin was removed and/or the core
graph 6-18 over the area containing
damaged, repair skin and core in accor-
water.
dance with paragraph 7-5.
(g) Apply 20 to 30 inches of mercury vac-
(5) Other Local Heat Sources. A quartz lamp
uum to the vacuum bag.
and hot-air module are two other heat sources. These
two sources are least effective in drying and must
(h) After a good vacuum seal is made,
be used in conjunction with a process controller to
at the far end of the bag and farthest
control temperature.
away from the vacuum source, induce
a seal leak. This seal leak provides air
(a) Quartz Lamps. Quartz lamps may be
movement through the bag, drawing
used as a heat source, but the drying time must
the moisture out. A vacuum level of 10
be extended to ensure moisture removal. Follow the
to 16 inch mercury should be utilized.
procedures in paragraph 6-6e; however, do not use
If available, insert a moisture desiccant
the iberglass breather and vacuum bag.
indicator between the vacuum source
and the vacuum bag.
(b) Hot Air Module. A hot air module or heat
(i)
Heat the part to 20 F less than the
gun may also be used as a heat source for drying
part service temperature or 180 (10)
composites. A vacuum bag and heat entrapment tent
6-16
