time varies with temperature.
High temperatures shorten and low
temperatures lengthen curing time.
Artificial heat can be used to
speed curing, but care must be used to avoid damaging the sealant
Warm circulating air, not over 120 F
with too high a temperature.
(49 C), or infrared lamps placed 18 inches or more from the sealants
are satisfactory heat sources. If infrared lamps are used, adequate
ventilation must be available to carry away solvent fumes.
Some areas of airframe structures are sealed to prevent fuel fumes
from entering the aircraft's interior.
Pilot and crew compartments
are tightly sealed to permit controlled ventilation. The three kinds
of sealers in general use are rubber, sealing compound, and special
seals. Rubber seals are used when the seal is frequently broken for
repairs. Rubber seals are not repairable, and they must be replaced
anytime the seal is damaged.
Sealing compounds are used where the
seal is seldom broken except for structural maintenance or part
Special seals are used to pass cables, tubing,
plugs, couplings, and similar fittings are sealed to the bulkheads.
All seals of moving components are subject to wear and must be
Surfaces to be sealed must be clean, and only approved strippers and
cleaners can be used.
cleaner to pick up loose dirt, a stripper to remove the old seal, and
an approved solvent to scrub the repair area. Safety practices range
from protecting undamaged sealants and acrylic plastics from the
stripper to wearing protective clothing and goggles and using
Rubber seals must be applied immediately after a seal frame is
cleaned. A clean paint brush can be used to apply an even
coat of rubber cement. Rubber cement must be allowed to dry
to a sticky consistency before joining the seal to the metal.
Sealing compound can be applied directly from a tube or, if it