ODS-FREE AIRCRAFT COMPONENTS CLEANING - OVERVIEW
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| Overview: |
Chlorofluorocarbon (CFC) solvents, including MCF and CFC-113, are used extensively for cleaning metal, electronic, and precision parts during aircraft maintenance procedures. These solvents are also used in applications such as coatings, adhesives, lubricant carriers, and mold release agent carriers. However, CFC-113 and MCF are EPA Class I ozone-depleting substances (ODSs) and have been banned from production as of January 1, 1996. DoD policy is that CFCs and Halons can only be used for mission critical applications. Fortunately, numerous ODS-free alternatives are now available to replace CFC-113 and MCF. In many instances solvent use can even be reduced or eliminated Cleaning for aircraft maintenance can, for the most part, be divided into three categories: metal, electronics, and precision cleaning. Metal cleaning refers to the removal of oil or grease from metal parts during maintenance and repair procedures. Landing gear and control surfaces fall under metal cleaning. Electronics cleaning includes the removal of flux from soldered operations. Encompassing both metal and electronics cleaning, the term "precision cleaning" is not as much a function of the component being cleaned, as it is of the level of cleanliness required. Components typically requiring precision cleaning are those with close tolerances, complex geometries, or sensitive to contamination. There are aircraft components that fall into all three categories. The following suggestions are directed primarily at typical aircraft maintenance functions. Cleaning Applications The first step in eliminating the use of CFCs in aircraft maintenance is to characterize all cleaning steps. What parts need to be cleaned? What is the substrate and contaminant being cleaned? How clean does the part need to be? By identifying the cleaning needs, a proper alternative can be chosen. Certain materials are subject to corrosion, swelling, deformation, and damage to coatings and adhesives if the proper cleaning alternative is not chosen. Complexity of the part dictates whether vapor degreasing or aqueous cleaning should be used. Vapor degreasing works best for cleaning complex parts. Some cleaning steps may be identified that can be reduced, consolidated, or eliminated. Most aircraft cleaning falls into two general cleaning processes: cold cleaning and vapor degreasing. In cold cleaning processes, parts are cleaned by either immersion and soaking, spraying, or wiping with ambient temperature solvents. The vapor degreasing process uses a boiling solvent to effect cleaning. A volatile solvent such as CFC-113 or MCF is heated in a reservoir below a suspended part. Solvent vapors rise to the top of the cleaning vessel and are condensed into droplets. The solvent droplets fall onto the part, dissolving contaminants. As the droplets collect and fall, contaminants are carried off the part and into the solvent reservoir. Since the contaminants are generally low or non-volatile, solvent vapors remain essentially pure; effective cleaning is maintained despite the increasing contamination of the solvent reservoir. The following table lists cleaning operations and alternatives associated with aircraft maintenance:
DLA’s Environmental Catalog lists several aircraft cleaning products that do not contain chlorinated compounds, ODCs, HAPs and have low VOCs. |
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| Compliance Benefit: |
Use of ODS-free substances to clean aircraft components will help facilities meet the requirements under 40 CFR 82, Subpart D and Executive Order 12843 requiring federal agencies to maximize the use of safe alternatives to class I and class II ozone depleting substances, to the maximum extent practicable. In addition, the elimination of substances such as methyl chloroform and CFC-113 at the facility decreases the possibility that the facility would meet any of the reporting thresholds for those chemicals under 40 CFR 370 and EO 12856. Chemicals used as substitutions should be reviewed for SARA reporting issues. The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.
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| Materials Compatibility: |
Materials compatibility depends on the alternative solvent/procedure implemented. Considerations can include corrosion, damage to coatings and adhesives, and swelling and deformation (especially for organic substitutes: alcohols, ketones, ethers, chlorinated solvents, etc.). Testing will reveal damage.
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| Safety and Health: |
Organic Solvents can be extremely flammable/combustible. Use only in areas with good ventilation. Aliphatic hydrocarbons are also flammable and have low occupational exposure limits. Consult the MSDS of particular solvents to ensure that solvent is used properly and all necessary safety requirements (i.e., personal protective equipment, increased ventilation, fire fighting equipment) can be met. In addition, consult your local Industrial Health specialist, local health and safety personnel, and the SNAP comments prior to converting to any replacement product.
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| Benefits: |
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| Disadvantages: |
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| Economic Analysis: | Because
cleaning circumstances are so variable, the economic feasibility of substitute
processes and chemicals needs to be evaluated for each application prior
to conversion. |
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| Approving Authority: |
Approval is controlled locally and should be implemented only after engineering approval has been granted. Major claimant approval is not required.
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| NSN/MSDS: |
*There are multiple MSDSs for most NSNs. The MSDS (if shown above) is only meant to serve as an example.
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| Points of Contact: |
Civilian: EPA:
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| Vendors: |
PCI of America Golden Technology P-T Technologies,
Inc.
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| Sources: |
ICOLP Manual, Eliminating CFC-113 and Methyl Chloroform
in Aircraft Maintenance Procedures, 1993. |