Technical data

13773-001
20-10
Page 1730 Nov 2000
(f) Work out all entrapped air and remove excess sealant with a fairing tool. Fair out extruded
sealant to leave a smooth fillet along joint and at ends.The tool should be pressed against
the sealant and moved parallel to the bead.
(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
(4) Fastener Sealing in Wet and Non-Wet Areas
The following procedure is used primarily for sealing bolts, nuts, and domed nutplates in wet
areas with MIL-S-8802 Class B fuel tank sealant. However, this procedure is also applicable to
bolt sealing with RTV 736 sealant in non-wet areas, such as the firewall.
(a) If not already accomplished remove all sealant from damaged seal with cutting tools and
suitable hardwood or plastic scrapers as described in paragraph A. - “Preparation for
Sealing.”
(b) Ensure that fastener is properly installed and torqued.
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 area to be sealed. The fastener and surrounding area should be cleaned at
least twice and all residue removed. (Refer to 20-30)
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 extrusion gun or spatula to apply sealant around the base and over the fastener. If
necessary, the sealant may be worked with a tool so that the sealant has a minimum thick-
ness as specified.
Note: Sealant must be applied so that it provides an airtight seal. Ensure that
folds, laps, and entrapped air are not created during the process. The fillet
can be moved slightly to insure that the highest portion of the fillet is over
the edge of the structure.
(e) Work out all entrapped air and remove excess sealant with a fairing tool.
(f) Inspect seal for poor adhesion and evidence of air bubbles. Evidence of air bubbles is
cause to rework the seal.
(g) Allow seal to cure.
(5) Tube Fitting Seals in Fuel Tank Bulkheads
Bulkhead tube fittings installed in fuel tank bulkheads with the bulkhead nut on the wet side of
the bulkhead, shall be sealed by applying sealant to the threaded area of the fitting prior to
installing the bulkhead nut and o-ring. Bulkhead fittings which are installed with the nut on the
dry side of the tank bulkhead shall be fillet sealed only.