Volume 2-757

57-00-01

Page 1
OCT 01/00

CORROSION PREVENTION MANUAL
WINGS

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Volume 2-757

57-00-01

Page 2
OCT 01/00

CORROSION PREVENTIONMANUAL
OUTER WING

1. General

A. The outer wing consists of the primary wing structure, fixed outer skin and

support structures for main landing gear and flight control systems. The

deployment of flight control surfaces exposes front and rear spars to

inclement weather ground contaminants and thrust reverser soot. Spar chords

are particularly susceptible to corrosion at fasteners common to the chord

and web.

B. Overboard  drains are the open hole type since the wing is a non pressurized
area. Ref. 57-20-02, Fig. 1 for drain hole location.

2.  Corrosion Prevention

A. Following cleaning of suspected areas, a thorough inspection as described in

Volume 1, 20-20-00 is effective to ensure that protective finishes provided
during manufacture remain intact.

B. Inspect  web and chord interfaces for cracked or missing paint and for
appearance of dark material at the interface. If dark material is present,
the removal of spar cord fasteners is required to confirm corrosion.

C. Where corrosion exists (noticeable bulges of the skin or white deposits of
corrosion products at fastener heads or joint edges), refer to Structural
Repair Manual for details of corrosion removal.

D. For minor corrosion, to minimize the downtime of the airplane, the corrosion
products should be cleaned off, followed by the application of a corrosion
inhibiting compound into the affected area to retard the corrosion process

(Ref Volume 1, 20-60-00). The finish system should be restored at the first
opportunity consistent with the maintenance schedule.

E. Prevention Treatment

(1)At first  opportunity consistent with scheduled maintenance activity,
corrosion prevention treatment should be accomplished in and around the
primary wing structure, on flight control and MLG support structures and
on fixed outer skins.

(2)Drain Holes

(a) Make periodic  inspections of drain holes. Use a pipe cleaner or thin
wooden dowel to remove debris and contaminants from drain holes.

(3)Upper and Lower Inspar Skins-Apply BMS 10-79, type 3 primer and BMS
10-100 (Aeroflex G12E25) coating where repair or replacement of finish
is required (Ref SL 20-6 and 51-7). The BMS 10-100 coating is chemically
compatible with the Corogard that is on some airplanes. But the two
coatings have slight differences in color and finish.

(4)Do not apply  corrosion inhibiting compounds near engines, cowling, or
other areas of high temperature, or where firewall sealant is used. The
　
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