All the sealing compounds covered by this specification are intended for
use as multi-purpose aircraft structure and fuel tanks sealants with rapid
ambient and low temperature curing capabilities without sacrificing
application life. As an example, cure time at any given application time for
these materials is approximately 80% less when compared to a two component
polysulfide fuel tank sealant. These sealants give "fly-away" capability in 2
to 3 hours when cured at temperatures of at least 75° F. When cured as low
as 40° F, these sealants provide a 4 hour "fly-away" capability when using
¼ application time material (see 1.2.3). They will also cure at lower
temperatures for example 20° F (−5° C) at proportionately longer
periods of time. These sealants will also cure rapidly in low humidity desert
environments. Type II materials are intended as protection for metal and
dissimilar parts against corrosion.
Type I, grade A-1 sealants can be cured at elevated temperatures
immediately after application and are suitable for composite co-cure bonding
procedures in manufacture and repair processes. Direct heat at temperatures of
up to 350° F (176° C) can be applied by heat gun or blanket
immediately after sealant application.
These sealing compounds are for use in areas that may be subjected to long
term service temperatures of −85°F to +285°F (−55°C to
+140°c) and short term exposures in the +400°F (+204°C) to
+420° F (+216°C).
These materials have outstanding resistance to mercaptans present in fuels
and also can withstand heating in a confined structural configuration.
The sealing compounds have a minimum shelf life of 12 months when stored
at temperatures below 80°F. In addition, the 12 month shelf life can be
extended by storage at refrigeration temperature (approximately 40° F).
The sealing compounds furnished under this specification are to be used
with the manufacturer's recommended primer to obtain optimum results of
adhesion to all surfaces.
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