Technical data

13773-001
20-10
Page 14 30 Nov 2000
Sealant which does not wet properly or which is difficult to extrude from the
sealing gun must be discarded. Sealant should never be applied at temper-
atures below 60° F (15.5° C) or to a structure that is below 60° F (15.5° C).
Sealed structures must be handled with care and should never be moved
until sealant has achieved a tack-free surface. Pressure testing, if required,
must never be performed, until all sealant has cured.
(d) Apply injection seal by injecting cavity with sealant from one end until sealant emerges
from the other.
(e) Remove excess sealant with a fairing tool and smooth ends of seal.
(f) Fair out extruded sealant to leave a smooth fillet along joint.
(g) Inspect seal for poor adhesion and evidence of air bubbles. Evidence of air bubbles is
cause to rework the seal.
(h) Allow seal to cure.
(3) Repairing Fillet Seals
Fillet seals are used in the integral fuel tank along the intersection of the wing skin ribs, along the
intersection of the wing skin and the spar and aft shear web, around fasteners and fitting pro-
truding into the tank. Fillet seals are also used around the firewall perimeter, and other places
where weather, fume, or dust intrusion must be prevented and to seal wetted areas. Fillet seals
produce a smooth junction. All joints, joggles, voids, and fasteners in wet areas must be fillet
sealed. Fillets laid on intersecting joints must be joined together to produce a continuous seal.
(a) If not already accomplished, remove all sealant from damaged seal with cutting tools and
suitable scrapers as described in paragraph A. - “Preparation for Sealing.”
Note: The injection channel must be cleared all the way through as trapped air will
prevent complete filling of the channel. A pipe cleaner or hooked wire may
be used to clear sealant debris from inside the seal channel.
(b) Refinish damaged surface.
CAUTION: After thoroughly cleaning surfaces to be sealed, wear clean, white, cotton
gloves to prevent contaminating the surfaces to be sealed.
Use care in selecting solvent. Do not use acetone to clean acrylic. Use only
isopropyl alcohol for solvent cleaning acrylic surfaces.
(c) Solvent clean channel to be sealed using pipe cleaners. The channel should be cleaned at
least twice and all reside removed. Dry channel using pipe cleaners.
CAUTION: Sealant which does not wet properly or which is difficult to extrude from the
sealing gun must be discarded. Sealant should never be applied at temper-
atures below 60° F (15.5° C) or to a structure that is below 60° F (15.5° C).
Handle sealed structures carefully and do not move until sealant is tack-
free. Pressure testing, if required, must never be performed, until all sealant
has cured. Sealant must never be applied after usable application time.
(d) Use the extrusion gun to lay a bead along joint. Point the extrusion gun into the seam and
maintain it nearly perpendicular to the line of travel. A bead of sealant shall precede the
extrusion gun nozzle tip. and work out all entrapped air with a small paddle.