C. The stringers, frames and skins have been found susceptible to corrosion due
to moisture entrapment between the skin and insulation blankets. Corrosion
can readily start where protective finishes have been broken or deteriorated
(Ref 53-10-02, Fig. 1).
D. External drains are either leaf spring or plunger type drain valves which
close when the airplane is pressurized. Drain paths through the internal
structure lead to the external drain valves. Refer to 53-10-03, Fig. 1 for
valve location.
E. The nose gear wheel well is a rigid box structure consisting of a ceiling,
sidewalls, and end walls and is located in the forward fuselage. The nose
gear attachment fittings are located in the wheel well.
F. The nose gear wheel well has a corrosion protective finish that consists of
a chemical conversion coating (alodine) on clad aluminum parts, anodize sur-face treatment on non-clad parts, a coat of BMS 10-11, type I, primer and a
coat of BMS 10-11, type II, enamel. The wheel well structure is assembled
and installed with BMS 5-95 fay surface sealant. The entire pressure surface
of the wheel well has a coat of BMS 3-23 applied after assembly and painting
(Ref 53-10-04, Fig. 1).
(1)The surfaces inside the box structure are exposed to air contaminants
and runway splash which can cause corrosion.
Volume 2-757
53-10-01
Page 1 OCT 01/00
CORROSION PREVENTION MANUAL
FUSELAGE -SECTION 41
G. The corrosion protective finish for the structure surrounding the No. 1 pas-senger door opening consists of a chemical conversion coating (alodine) on
clad aluminum parts, anodize surface treatment for non-clad parts and a coat
of BMS 10-11, type I, primer. The doubters around the doors are installed
with fay surface sealant. All non-aluminum fasteners which penetrate the
exterior skin are installed with wet sealant. After assembly, a touchup coat
of BMS 10-11, type I, primer is applied to bare fasteners and a coat of BMS
3-23 is applied except on the door assembly and door opening (Ref 53-10-05,
Fig. 1).
(1)The primary corrosion area is under the door sill, floor panels, floor
beams and doubters or triplers at the door opening. Contaminants are
tracked in by passengers, crew members, cargo and service personnel or
by driven rain/snow when door is opened.
(2)
Insulation blankets are provided on cabin interiors for passenger com-fort and to minimize the condensation of warm cabin air on cold skins
and stringers. Corrosion has been experienced in areas where the blan-kets are not installed taut and wrap around stringers or contact the
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