2. Corrosion Prevention

A. To find out if the airplane has aluminum collars in the elevators, examine
the elevators per SB 55-0009. This service bulletin also gives procedures
for regular inspections and applicable repairs.

Volume 2-757

55-20-01
Page 1
OCT 01/00

CORROSION PREVENTION MANUAL
ELEVATOR

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Volume 2-757

55-20-01

Page 2
OCT 01/00

CORROSION PREVENTIONMANUAL
VERTICAL STABILIZER

1. General

A. BMS 3-23, type 2 corrosion inhibiting compound is applied to the aft surface
of the rear spar, interior forward and aft torque boxes, forward surface of
the front and auxiliary spars and the interior surface of the leading edge.

B. Areas  of possible corrosion are the auxiliary, front, and rear spars, inte-rior of forward and aft torque boxes and leading edge interior surface.

2. Corrosion Prevention

A. Make periodic inspections (Ref Volume 1, 20-20-00) of the vertical stabi-lizer interior and exterior for evidence of corrosion.

B. If you find corrosion (bulges of the skin, or white deposits of corrosion
products at fastener heads or joint edges) refer to Structural Repair Manual
for corrosion removal.

C. For minor  corrosion, to reduce the downtime of the airplane, clean off the
corrosion products. Then apply corrosion inhibiting compound on the area.
Refer to Volume 1, 20-60-00 for how to apply corrosion inhibiting compound.

D. Prevention Treatment

(1)When the scheduled  maintenance work permits, do corrosion prevention
treatment on the vertical stabilizer.

(2)Apply BMS 3-23, type II corrosion inhibiting compound to the vertical
stabilizer-to-body attachments when the area is made accessible.

(3)The following application is for enhanced corrosion protection of verti-cal fin rear spar and rear spar cavity access panels, body-to-forward
torque box seal, fin tip, center forward and upper forward torque box
panels. Apply BMS 10-11, Type 1 primer to all removable fastener holes
including countersink and MIL-C-11796 Class 3 corrosion preventive com-pound to substructure in areas of holes only.

(4)
Apply BMS 10-79, type 3 primer followed by BMS 10-100 (Aeroflex G12E25)
coating when repair or replacement of the existing corrosion protection
is required (Ref SL 20-6). The BMS 10-100 coating is chemically compat-ible with Corogard, but the two coatings have slight differences in
color and finish.

E.  
Frequency of Application

(1) Regular inspection is required in areas which can get corrosion, and
should agree with the schedules in the Maintenance Planning Document.
　
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