Naval aviation depot aircraft maintenance operations have been identified as major contributors to the hazardous waste generated by the Navy. Previously, solvents classified as hazardous air pollutants (HAP), such as methyl ethyl ketone (MEK), were used for surface pre-cleaning prior to painting and for purging paint spray equipment. Hazardous chemical paint strippers such as methylene chloride currently are regulated by the Environmental Protection Agency (EPA) for use in stripping operations. Additionally, aircraft cleaning and corrosion-preventive compounds used in routine aircraft maintenance operations are high in volatile organic compounds (VOC). The EPA Clean Air Act and local Air Quality Management District rules restrict the use and disposal of these hazardous materials. In response to a strict regulatory environment, U.S. naval directives have prioritized reducing the usage of such materials.
The objectives of this project were to explore the development of low-VOC content and non-HAP maintenance products for use on naval aircraft and weapon platforms and to develop or identify products which would be evaluated with laboratory performance tests. The best materials were to be evaluated further for vapor pressure, odor, evaporation rate, safety, and cost.
Cleaners must be effective on a diverse combination of soils, from baked-on carbon to aircraft greases and lubricants. Corrosion-preventive compounds must protect various aircraft metals against the corrosive effects of sea water. Non-HAP paint strippers must be effective on a variety of naval paint systems. Procedure efficiency, effects on substrate surface, and hazardous waste generation were investigated in order to determine the best procedure for naval applic ations. The best alternative materials from these efforts were service demonstrated at a naval aviation depot and transitioned to fleet use through specification modification.
Initial testing to establish the technical feasibility of the low- VOC pre-paint cleaner was performed. Three initial prototype formulations were tested against various control solvents, including MEK, to measure their effectiveness in removing hydraulic fluid and their effects on organic coating adhesion. Military specification MIL-PRF-85570C was completed and issued on June 11, 1997. Type II of this specification became the no-VOC aircraft exterior cleaner and Type V the low-VOC wheel well cleaner. Qualification testing was completed for two Type II products and two Type V products. Qualification letters for these materials were issued on June 18, 1997. Federal specification TT-R-2918 was completed and issued on April 4, 1997 to specify non- HAP chemical strippers. Development of non-HAP paint purge solvent blend was completed. A new product was manufactured and then demonstrated in shop trials at the Jacksonville, FL, Cherry Point, NC, and North Island, CA, Naval Aviation Depots. Adhesion testing and humidity resistance testing of coatings following soiling and cleaning with low-VOC pre-paint cleaner candidate was completed. Results compared favorably to the MEK control. This project was completed in FY 1997.
The development of non-HAP, low-VOC maintenance chemicals would reduce the total amount of hazardous materials generated by naval maintenance facilities significantly. This technology effort was coordinated with commercial aerospace, chemical, and equipment manufacturers.