(5)Protect surfaces, joints and seams adjacent to rework areas from chemi-cal paint strippers, corrosion removers, and surface treatments.

Volume 1

20-40-00
Page 5 OCT 01/01
5. Cleaning, General

A. Prior to paint stripping and corrosion removal, if the corroded area or part
is soiled by grease, dirt or other foreign material, the area should be
cleaned. For general cleaning procedures refer to Chapter 51 of the Mainte-nance Manual. Special cleaning procedures may be required in some cases and
will be outlined in Volume 2. Precautions necessary when working with clean-ing chemicals are noted in par. 2.

6. Paint Removal

A. For general procedures, refer to Chapter 51 of the Maintenance Manual. For
special removal procedures, refer to the appropriate sections of Volume 2.
For safety precautions when you use paint removal chemicals, refer to par.

2. above.

7. Corrosion Removal Procedures

A. General. Corrosion can be removed by mechanical or chemical procedures.
Examples of mechanical procedures are hand sanding with abrasive paper or
metal wool, power sanding or buffing with abrasive mats, grinding wheels or
rubber mats, and abrasive blasting, which includes abrasive blasting with
glass beads. The selections decision is different for different metals, dif-ferent amounts of corrosion or the access to the area or part. In most cor-rosion removal operations, the mechanical procedures are recommended. The
chemicals used in the chemical removal procedure can also cause corrosion
and must not be permitted to flow into joints or seams or on highly stressed
steel parts.

B. If the area of corrosion includes or is near fasteners, remove the fasteners
before you start to remove the corrosion. There could be corrosion under the
fastener heads or in the holes. Corrosion removal around such fasteners
without fastener removal will not stop the corrosion under the fasteners

(Fig. 8). Also, metal from the fastener heads will be rubbed into the adja-cent metal surface during the corrosion removal procedure, and can cause
subsequent galvanic corrosion.

C. Blending Repaired Areas. After corrosion removal, blend all depressions
with the adjacent surface to keep stress concentrations to a minimum.

(1)Remove rough edges and all corrosion from the damaged area. Make selec-tion of the applicable abrasive from Fig. 3.

(2)Repair depressions to make smooth, elliptical blend-outs as shown in
Fig. 4. In areas with multiple pits close together, remove the material
in between to keep surface irregularities or waviness to a minimum (Fig.
5).

(3)In areas where sufficient clearance does not permit the elliptical shape
as specified in Fig. 4 and 5, blend as nearly as possible to these
　
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