CORROSION PREVENTION MANUAL
FUSELAGE -SECTION 43
1. General
A. Section 43 extends from stations 440 to 900. The upper lobe contains the
passenger compartment with left and right passenger doors and windows. The
lower lobe houses the electrical/electronics compartment and forward cargo
compartment. Access to the electrical/electronics compartment during ground
servicing is through a door aft of the nose gear wheel well doors. An in-
flight access door is also provided. The forward cargo compartment door is
approximately 42.5 by 55 inches and located on the right side of the fuse-lage. The forward section of the wing/body fairing attaches to section 43.
B. All non-aluminum fasteners which penetrate the exterior skin are installed
with wet sealant. A coat of sprayable sealant is applied to the inboard
flange of stringer 10 and above. A coat of BMS 3-23, type II corrosion
inhibiting compound is applied to all structure within 2 inches of the body
skin, and the body skin, from stations 654 to 766. On airplanes line number
241 and on, per PRR 54133, this compound extends the full length of Section
43, and also includes the upper surface of the passenger floor.
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 deterio-rated. Refer to 53-30-02, Fig. 1 for lower lobe structure.
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 53-30-03, Fig. 1 for
valve location.
E. The corrosion protective finish for the structure surrounding the No. 1
cargo and No. 2 passenger 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 10-11, type II, white enamel is applied around
the doors. A coat of BMS 3-23 is applied except on the door assembly and
door opening (Ref 53-30-04, Fig. 1).
(1)The primary corrosion area is under the door sill, floor panels, floor
beams and doubters or triplers at door openings. Contaminants are
tracked in by passengers, crew members, cargo and service personnel or
by driven rain/snow when door is opened.
(2)Corrosion can also occur under the latch fitting for the electrical/ 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 防腐手册 CORROSION PREVENTION MANUAL(26)
