1-1-24_Chemical Removers Highlighted_2018.pdf

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4.43 REMOVAL OF COATINGS.

4.44 REMOVAL OF SAE AMS-C-83231 AND SAE

AMS-C-83445 POLYURETHANE COATINGS AND

AMS3138A FLUOROCARBON ELASTOMERIC COAT-

INGS.

There are two methods of removal of organic finishing sys-tems; chemical and mechanical. Each method has its own set of procedures, precautions, restrictions, and limitations and therefore, each will be explained separately.

NOTE

User must gain specific System Program Office (SPO) or Equipment Item Manager approval for use of the coating removal materials and processes contained in this technical order.

4.44.1 Chemical Removers.

Handling and use of coating removal solvents re-quires precautions commensurate with their toxic-ity and flashpoint characteristics. Chemical remov-ers are toxic to skin, eyes, and respiratory tract.

Contact Bioenvironmental Engineering for deter-mination of need for and selection of proper per-sonal protective protection.

4.44.1.1 Radomes will be inspected for damages that pen-

etrate the face plies prior to application of any chemical coating removal agents. To prevent the solvent from entering the radome core, damages that penetrate the face plies will be covered with tape, Stock No. 7510-00-684-8803 or equivalent. The tape should extend approximately three inches beyond the edges of the damaged area. Do not at-tempt to remove the coating under the tape; this coating will be removed with the face ply when the damaged areas are repaired by hand sanding.

4.44.1.2 There are no USAF-approved specification re-

movers for these finish systems, however Methyl-ethyl- ke-tone, TT-M-261, and specific benzyl alcohol/hydrogen per-oxide based proprietary coating removers have been tested and found to be effective for removing radome coatings. The following benzyl/hydrogen peroxide alcohol removers are currently authorized for use on radomes:

P/N Manufacturer 9095 B&B Tritech

875 W. 20th St.

Hialeah, FL 33010-2310

AS 5050 Aero Solutions 8323 Woodcliff Blvd Selma, TX 78154

Desolift 5269 PPG Aerospace PRC-DeSoto 12780 San Fernando Rd.

Sylmar, CA 91342

E-2787 Cee-Bee™ Div., McGean-Rocho, Inc.

1314 Murphy Ave.

Atlanta, GA 30310-4004

4.44.1.3 Chemical removal of radome coatings shall be

accomplished by one of the following methods:

a. Using Methyl-ethyl-ketone (MEK), TT-M-261. Thor-oughly saturate the surface of the radome using a con-tinual stream of MEK. Perform the removal process by placing the radome over a locally constructed drip pan so that the solvent drain off may be caught and reap-plied to the radome coating. The drip pan should have a drain outlet and a means of positioning the radome so that the radome base will not be submerged in the solvent accumulated in the drip pan. Alternatively, the radome may be covered with absorbent, non- synthetic cloth saturated with MEK. The cloth may be covered with a suitable vapor-resistant material to prevent rapid solvent evaporation. Once the solvent has caused the coating to blister and soften, scrape the coatings from the radome surface using weapon system engineer ap-proved non-metallic scrapers, taking care not to dam-age the fiberglass epoxy skin. Maintain saturation of the radome surface throughout the scraping process.

Any residual coatings should be removed by hand sanding with 280 grit or finer abrasive paper taking care not to damage the radome surface.

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