(2)
BMS 10-11, type 1 and BMS 10-20 primers cannot be readily stripped with chemical strippers. However, it is not necessary to strip these epoxy base primers down to bare metal prior to application of finish coating.
C. Refer to Structural Repair Manual for limits concerning corrosion removal.
2. Inspection/Check
A. Check for steel fastener head rusting and for discoloration of adjacent anodized skin, indicating skin corrosion. If corrosion exists, accomplish repair per par. 3.
3. Approved Repairs
A. Rust and Corrosion Removal
506
Feb 15/79 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 51-21-131 Page 701
F85342
Skin and Fastener Corrosion Control Location 500
51-21-131Page 702 Figure 701 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 15/71
(1)
Equipment and Materials
(a)
Hardwood scraper
(b)
Solvent – Final Cleaning Prior to Fuel Tank Sealing (Series 93) (Ref AMM/SOPM 20-30-93)
(c)
Portable Blaster - Educ-O-Matic E10A, Clementina Ltd., San Francisco, California, or equivalent
(d)
Aluminum Oxide Grit - No. 154 (600-4F mesh)
(e)
Aluminum oxide paper or cloth, 240 grit
(f)
Magnifying glass (5 to 10X magnification)
(2)
Remove Rust and Corrosion
(a)
Remove previously applied corrosion preventive paint in corroded area (Ref 51-21-11, Paint Stripping).
(b)
Paint strippers per 51-21-11 will not remove BMS 10-11, type 1 or BMS 10-20 primers. If primer does not readily remove, lightly sand area immediately adjacent to corroded area to smoothly blend primer into base metal.
(c)
Remove previously applied fastener sealant with hardwood scraper and solvent, Series 93 (Ref AMM/SOPM 20-30-93).
(d)
Grit blast rusted fastener heads and limited surrounding skin area. If skin corrosion is noted, grit blast to remove corrosion to approved depth per Chapter 57 of the Structural Repair Manual. Avoid blasting of larger skin area than required to remove corrosion.
NOTE: Mask all openings to fuel tank to prevent entry of grit into tank. As an option, rust and corrosion may be removed with 240 grit aluminum oxide paper or cloth.
(e)
After removing rust and skin corrosion, inspect countersunk area surrounding fastener heads for corrosion, using a 5 to 10X magnifying glass.
(f)
If corrosion in the countersunk area is detected, remove the affected fasteners and remove the corrosion by approved method and to approved depth given in Chapter 57 of the Structural Repair Manual.
CAUTION: TO PREVENT SKIN SHIFTING, REMOVE ONLY ONE ROW OF RIVETS AT A TIME IN A MULTIPLE ROW FASTENER CONFIGURATION AND REPLACE THE FASTENERS BEFORE REMOVING THE NEXT ROW. IN A SINGLE ROW CONFIGURATION, REMOVE AND REINSTALL ALTERNATE FASTENERS.
May 01/98 51-21-131
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
B. Cleaning Skin Prior to Alodine Treatment
NOTE: Only areas where the skin or fasteners were exposed to base metal while removing rust and corrosion need be cleaned for alodine treatment.
(1)
Equipment and Materials
(a)
Solvent Alkaline Cleaner (Wyandotte Aerowash A, Cee Bee Alumiloy P, GMC 528B)
(b)
Water (no more than 150 ppm totally dissolved solids)
(c)
BMS 3-2, Type I Solvent (TT-N-95 naphtha or 100°F flash Stoddard solvent)
(d)
Soft-bristled brushes
(2)
Clean Skin
(a)
An effective Alodine treatment can be achieved only on a properly cleaned surface. It is therefore mandatory to follow the cleaning procedures exactly. 1) Solution preparation:
a) Prepare the cleaning solution by using one part, by volume, solvent alkaline cleaner to two parts water and five to six parts BMS 3-2, Type I solvent.
(b)
Environment
1) Park aircraft in shade and electrically ground. Refer to Chapter 20, Static Grounding.
(c) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 结构 STRUCTURES(27)
