Gila River Indian Community (GRIC) TIP Development Source Specific Emission Limitations 

### & Standards Technical Support Document

June 10,2002 Version

Section 7,Rule 

### 6.0-Aerospace Manufacturing andRework Operations

1.0 Introduction and Source ~escri~tion'
Aerospace manufacturing and rework operations include all manufacturing facilities that produce an aerospace vehicle or component and all facilities that rework or repair these aerospace products. An aerospace vehicle or componentis defined as, but not limited to, any fabricated part, processed part, assembly ofparts, or completed unit of any 

### aircraft including,but not limited to, airplanes, helicopters,missiles, rockets, and space vehicles. 

### In additionto manufacturing and rework facilities, some shops may specialize in providing a service, such as chemical milling, rather than actually producing a component
or assembly. 

### In general, aerospacemanufacturing and rework facilities

### are covered by the SIC codes listed in Table 1 

### - 1. However, facilities classifiedunder other SIC codes may meet the definitionof an aerospace manufacturing or rework facility. Table 1-2 lists the products included in aircraft, aircraft engines, and space vehicle and missile categories.

TABLE 1 

### - 1. AEROSPACE MANUFACTURING SIC CODES



### 1 3721 

### I Aircraft 

### I SIC Code 3720 Description Aircraft and Parts

3724 3 728 Aircraft Engines and~n~ine Parts Aircraft Parts and Eaui~ment 3760 3761 Guided Missiles, Space Vehicles, and Parts Guided Missiles and S~ace Vehicles 3764 3769

Aerospace facilitiesmay be divided into four market segments: commercial original equipment manufacturers (OEM), commercial rework facilities, military OEM's, and military rework facilities. The commercial OEM segment ofthe market includes the manufacture of commercial aircraft as well as the production of business and private 

### SpacePropulsion Units and Parts SwaceVehicle Eaui~ment 4512 458 1 971 1

1 "Control ofVolatile Organic Compound Emissions fiom Coating Operations at AerospaceManufacturing and Rework Operations", Emission StandardsDivision, U.S. Environmental Protection Agency, December 1997. Air Transportation, Scheduled Aqorts, Flying Fields, and Services National Securitvaircraft. The military 

### OEM segment ofthe marketincludes military installationsand defense contractors that manufacture aircraft,missiles, rockets, satellites, and spacecraft. Rework facilities,both commercial and military, may rework many ofthe above end products.Table 1-2. 

### Listing ofProducts Included 

### in the Aerospace Industry 

# I Category Products

Reconnaissance ResearchlTest Bed Military Fixed-Wing Aircraft Attack Bombers 

### Cargo/Transport/Refueling Early Warning ElectronicWarfare

Commercial Fixed-Wing

Tiltrotor Training Training Utility Narrow Body Turbofans Aircraft

Rotary-Wing Aircraft Wide Body Turbofans Turboprops Naval Scout/Attack

Turboprop Reciprocating Engine-Powered Business & General Aviation

Gas Turbine Engines Unmanned Aerial Vehicles and Transport Utility Aircraft Turbofan



# I Drones 

# 1 1

Missiles Air-to-Air Air-to-Surface Anti-Armor SpaceLaunchVehicles

Anti-Ballistic Anti-Shi~ Manned Systems Unmanned Svstems



## I Anti-Submarine

Based on information f?om the Federal Aviation Administrationand the U.S. Department of Commerce Bureau ofthe Census, there are an estimated 2,869 aerospace facilities. 

### Of thisnumber, 1,3 95 produce or rework commercial products, and 1,474produce orreworkmilitary products. The combined VOC emissions from these facilities are estimated to be over 213,000 megagramslyear (Mdyr) (234,000 tonslyr).



### In addition to these facilities, there are numerous subcontractorsthat manufacture or rework aerospace vehicles or components. The subcontractorsmay work directly for the OEM or rework facilities, or indirectly through first line subcontractors. Because most of these subcon~ctors perform various types ofwork, they are often classifiedunder nonaerospace SIC codes. Consequently, an estimate ofthe number of subcontractors cannot be made. One company alone, however, employs the services of over 5,000 subcontracl~rs.
Aerospace manufacturing facilitiesand rework operations typically are located in or near industrial centers in areas ofmedium to high population density. Aerospace manufacturingfacilities range in size from small shops that produce a single aerospace component, such as propellers, to large corporationsthatproduce the entire aircraft. Aerospace rework facilities, however, are usually large facilitiesthat must be able to rework or repair every facet of several models of large commercial or military aircraft.
The hours of operation at aerospace manufacturing and rework facilities may vary greatly due to theproduction backlog at each facility. The hours of operationmay range 

### from 8 hours (or less) per day, 5 days per week, to 24 hours per day, 7 days per week.
Aerospace manufacturing and rework operations typically consist of the following basic operations: materials receiving, machining and mechanical processing, coating application, chemical milling, heat treating, cleaning, metal processing and finishing, coating removal (depainting), composite processing, and testing. Many aerospace manufacturing and rework facilitiesmay employ all ofthese processes in their operations, 

### as with 

### an OEM facilitythat produces the entire aerospacevehicle. However,

an aerospace facility may only employ a subset ofthese operations, as with a facility that produces a single component or assembly or a facility that provides a service such as chemical milling. Ofthese operations, coating application and solvent cleaning arethe significant sources ofVOC emissions and are the focus of this rule. Other emissions fiom these facilities are addressedby other regulations including emissionsfiom chrome plating (40 CFR 63 SubpartN), emissions from degreasing and solvent cleaning (Section 

### V1.D -VOC Requirements), and emissions fiom combustion sources. Emissions from aircraft engine testing are not specifically regulated anywhere in the United States.
The following subsections provide a description and background on 

### the coating operations and solvent cleaning operations that are the focus ofthis rule.

1.1 Coating Application Operations
A coating is a material that is applied to the surface of a 

### part to form a decorative, protective, or functional solid film. The most common coatings arethe broad categories ofnonspecialized primers and topcoats that are regulated for major sources under the Aerospace NESHAP (i.e., 40 CFR 63 Subpart GG). There are also numerous specialtycoatings that provide additional performance characteristics, such as temperature, fluid, andlor fire resistance, flexibility, substrate compatibility, antireflection, temporary protection or marking, sealing, adhesively joining substrates,enhanced corrosion protection, or compatibilitywith a space environment. Each material is different because it must meet individualperformance standards particular to a specificdesign. The quality ofthe coatings is criticalto the airworthiness and safety of the finalproduct. Aerospace vehicle manufacturing is strictly controlled by the Federd Aviation Administration, the Department ofDefense, and specific customerrequirements. Industry specifications for coatings are dictated by these requirements. Such specificationsare often difficultto change, requiring long time periods to test and approve new formulations and alternatives.

Most aerospace coatings are solvent-borne, which contain a mixture of organic solvents, many of which are VOCs. The most commonVOC solvents

### used in coatings aretoluene, xyleae, methyl ethyl ketone, and methyl isobutyl ketone. The VOC content of a coating

can differ significantly for the various coating categories.
Sealing - Sealants, predominately composed ofpolysulfide, are applied throughoutthe aerospace vehicle structure primarily to seal out moisture and contaminantsto prevent corrosion, such as on faying (i-e., closely or tightly fitting) surfaces, inside holes and slots, and around installed fasteners. They are also used to seal fuel 

### tanks and pressurized components. Sealants are applied using tubes, spatulas,brushes, rollers, or spray guns. Sealants 

### are often stored frozen and thawed before use, and many 

### are two-component mixtures that cure after mixing. Typically, a sealantis applied before assembly or fastener installation, and the excess is squeezed out or extruded from between the parts as the assembly is completed. This ensures a moisture-tight seal between the parts. Adhesive Bonding -
Adhesive bonding involves joining together two or more metal or nonmetal components. This process is typically performed when thejoints being formed are essentialto the structural integrity of the aerospace vehicle or component. Bonding surfaces are typically roughened mechanically or etched chemically to provide increased surface area for bonding and then treated chemicallyto provide a stable corrosion-resistantoxide layer. The surfaces arethen thinly coated withan adhesive bonding primer to promote adhesion and protect from subsequent corrosion. Structural adhesives are applied as either a thin film or as a paste. The parts arejoined together and cured either at ambient temperature, in an oven, or in an autoclave to cure the adhesive and provide a permanent bond between the components.

Nonstructural adhesives are used to bond materials that are not criticalto the structural integrity ofthe aerospace vehicle or component, such as gaskets around windows and carpeting or to nonstructurally joined components. These adhesives are applied using tubes, brushes, and spray guns.

### 1.2 Solvent Cleaning Operations
Cleaning agents for hand-wipe, flush, and spray equipment cleaning consist of solvents such as methyl ethyl ketone, methyl isobutyl ketone, toluene, various solventblends, or alkalinematerials.
Hand-Wipe and Flush Cleaning - Aerospace components are cleaned frequently during manufacturing to remove contaminants such as dirt, grease, and oil, and to prepare the components for the next operation. Cleaning is typicallyperformed by a hand wiping process using a wide variety of cleaning solvents. Assemblies and parts 

### with concealed or inaccessible areas may be flush-cleaned by passing the cleaning agent over, into, or through the part. The cleaning agent is then drained from thepart and the procedure is repeated as many times as necessary to ensure the required cleanliness.
Spray Gun and Coating Line Cleaning - Spray guns and coating lines used to apply the various 'coatings used at aerospace facilitiesmust be cleaned when switchinghm one coating to another and when they are not going to be immediately reused. Spray guns can be cleaned either manually or with enclosed spray gun cleaners. Manual cleaning involves disassemblingthe 

### gun and placing the parts in a vat containingan appropriate cleaning solvent. The residual paint is brushed or wiped offthe parts. After reassembling,the cleaning solventmay be sprayed through the 

### gun for a 

### fd cleaning, Paint hoseslcoating lines are cleaned by passing the cleaning solvent through the linesuntil all coating residue isremoved. Enclosed spray gun cleaners are self-containedunits that pump the cleaning solvent through the gun within a closed chamber. After the cleaning cycle is complete, the 

### guns areremoved from the chamber and typically undergo somemanual cleaningto remove coating residue from areasnot exposed to the cleaning solvent, such 

### asthe sealsunder the atomizing cap.


### 2.0 GRIC Source Profile

Two sources currently located and operating on GRIC land comprise the aerospace manufacturingand rework source category. Those sources 

### are: Honeywell (formerly Allied Signal) AMTI (Advanced Material Technologies, Inc.)
Honeywell

This facility is an aircraft engine and auxiliary power unit (APU) test facility. Units tested include Turbofan, Turboshaft,and Turbojet engines. JP8 and Jet A helsare stored and used in testing. There are 5 open test cells and 3 enclosed test cells. Multiple portable generatorsare used forpower. Emissions from this facility occur from internalhe1combustion in the test engines and diesel powered generators, JP8, Jet A, and diesel he1storage and loading, and minor VOC material usage.

This facility refurbishes jet engineparts 

### (APU). Major process operations include metal stripping, fluoride cleaning, pressure treatment of castings, coating operations, grit blasting, and electroplating. Emissions fiom this source are associatedwith combustion emissions from powder coating operations 

### (3 gas-fired aluminizing furnaces), gas and solvent cleaningprocesses (VOC), grit blasting 

### (PM), vapor degreasing (TCE), masking (TCE), and acid processes 

### in the electroplatingoperations. PM fiom grit blasting is controlled in a dust hog bag filter. A 16,000 cfin (cubic feed per minute) caustic scrubber installed in 1997 controls acid gas emissions from the electroplating operations.



### 3.0 

### Technical Review 

### -EmissionsUnits, Pollutants,and Control ~echnolo~ies~

3.1 

### Emissions Units and Pollutants

Various activities at aerospace manufacturing and rework facilities result in emissions. 

### In general, these emissions can be divided into two categories. The first category represents doseemission-producing activities that are general in nature and not necessarily related specificallyto the aerospace industry. Emission sources that Ml in this category include combustion sources (i.e., heaters, boilers, curing ovens, diesel generators, etc), certain solvent cleaning operations (i-e.,vapor degreasersand cold cleaners),metal plating operations, and abrasive blasting operations. These nonaerospace specific emission sources are not addressed by this rule.

The second category of air emissions from aerospace manufacturing and rework facilities

are thosethat are more specificto the aerospace industry. 

### Air emissions, primarily volatile organic compounds (VOCs), result mainly fiom the sealing, painting, depainting, bonding, finishing applicationprocesses including material storage, mixing, applications, drying, and cleaning. These emissions 

### are composed mainly of organic solventswhich are used as carriersfor the paint or sealantand as chemical coating removers. Most aerospace coatiqgs are solvent-based, which contain 

### a mixture oforganic solvents, many of which are VOCs. The most common VOC solvents used 

### in coatings are toluene, xylene, methyl ethyl ketone, and methyl isobutyl ketone. The most common VOC solvent used for coatingremoval is methylene chloride. The VOC content ranges differ for the various coatingcategories.



### 3.2 Controls
The principal technique used by the aerospace industry to control VOC emissionsfiom coating application and cleaning isproduct substitution,which eliminates or reduces the generation of emissions. The emission reduction is obtained using less energy and producing less waste than using a control device to achievethe same emission reductions.The VOC emissions may be controlled by replacing products containing high concentrationsof VOCs 

### with ones that have reduced or eliminated VOCs. Different aerospace manufacturers use different processesto produce their product. Therefore, they typicallyhave different specificationsfor the coatings and cleaning solventsused on the components ofthe end products. Each individual facility must evaluate the ability of the new product to maintain standardsof quality and performance. 

### In addition, the potential overall environmental benefit ofthe reformulated products must be carefully evaluated.

A second major method of emissions control for the aerospacemanufacturing and rework industry sector is the use of improved equipment and applicationmethods. When combined 

### with reduced solvent coatings and cleaners,these additional changes are effective at addressing aerospace VOC emissions.
The following sections describethe available product substitutions for coatings and cleaning solvents and typically employed equipment changes. While alternative methods, such as control devices (carbon adsorbers, incinerators, etc.), are occasionally used to reduce emissions, they represent emission reductions that go beyond reasonably available control levels and are, therefore, not discussedbelow.
Coating Substitutions -
Waterborne and high solids materials are generally used for coating substitutions. Specialty coatings typically have relatively low usage, so reformulationof these coatings to lower VOC contents does not produce significant 

### air quality benefits nor is it economicallyfeasible for the paint suppliers. Paint suppliers and the aerospace industry generally have targeted high volume materials for reformulation efforts. Therefore, lower VOC formulations are not available for most ofthe low-volume speciahy coating categories.
Equipment Changes - The aerospace industry has implemented several equipment changes that directly reduce the level of VOC emissions. While there are equipment changes that effect emissions from everyprocess, the three changespredominantly used in the industty are high transfer efficiency spray guns, spray gun cleaners, and conventional high transfer efficiency methods. Each ofthese equipment changes is discussed below.
High TransferEfficiencySpray Guns

Emissions from spray coating operations can be reduced throughthe use of spraying systems with higher transfer efficiency. Transfer efficiency, expressed as a percentage,
can be defined as the ratio of coating solids actually applied to the surface ofthe component being coated to the total amount of solids released fromthe spray 

### gun. Spraying systems with a higher transfer efficiency can coat the same dace area using less coating. Therefore, the VOC emissions resulting from the use ofthis equipment arereduced compared to applyingthe same coatingwith conventional spray equipment. The transfer efficiency values reported in this section depend on coating sprayed, part configuration, spray booth air velocity, and other variables.

Most aerospace components

### are coated using manual spray equipmentutilizing conventional air spray or airless spraying technology. The following sections discuss 

### two types of high transfer coating application equipment generallyused in the aerospace industry for the application ofprimers and topcoats: high volume, low pressure (HVLP) and electrostatic. (Note that the use ofthese types ofhigh transfer efficiency for specialty coatings is limited.)

High Volume Low Pressure Sprav Guns 

### -High volume low pressure and electrostatic spraying systems are the primary high efficiency spray methods used by the industry. High volume low pressure spray guns use high volumes 

### [loto 

### 25 standard cubic feet per minute (scfin)] of low pressure 12to 10pounds per square inch gauge (psig)] air to deliver the paint. The lower air pressure creates a lower particle speed, resulting in a more controlled spray pattern 

### with less overspray and bounce back fkom the substrate, thus improving transfer efficiency.
High volume low pressure systemshave been in use in the United States for approximately 10 years. 

### In early systems, turbines were used to supply a high volume of low pressure air to the spray guns through large hoses. The second generation used compressed air 

### with an air regulator to maintainthe required low pressure. The third and cwrent generation of HVLP equipment uses restrictors 

### withinthe gun to reduce the atomizationpressure to a maximum of 10 psi at the 

### air cap.

One disadvantageof HVLP spray guns is that some very high solids coatings are difficult to atomize due to their higher viscosities. However, when a turbine is used, the temperature ofthe atomizing air increases which aids in reducing the viscosity ofthe coating. Other disadvantages ofHVLP spray guns are that they cannotbe used 

### with extension nozzles, and they may slow production rates because ofthe low fluid delivery rates.

It is estimated that HVLP equipment can be used to apply approximately 80 percent ofthe coating currently used 

### in the aerospace industry, includingprimers, waterborne coatings, and both single and two-component topcoats. As an example, a medium sized comerciaVrework facilityutilizing HVLP equipment in combination with high solids paints has had a reduction of 22 to 30 percent in coating usage for various aircraft types. The HVLP technology

### has proven easy to use and maintain. It alsoprovides high transfer efficiency and appears to be the preferred spray technology in the aerospace industry at thistime.

Electrostatic Spray Guns -With electrostaticspray systems, atomized particles of coating acquire an electric charge 

### as they pass through a high voltage field at the end ofthe spray nozzle. This electric charge causes the particles to be attracted tothe parts being painted, which are electrically grounded. Although other substrates can be pretreated 

### with conductive coatings, this technology is primarily used for metal parts. The electrostatic effect can be utilized 

### in conjunction with air spray, airless, and air-assisted airless systemsto enhance the transfer efficiencies ofthese basic technologies. See Table 

### 3-1 for examples ofpercent reduction obtained at various facilities using electrostaticspray 

### guns or electrostaticspray 

### guns in combination with 

### HVLP spray guns.

Spray Gun Cleaning
Spray guns are typically cleaned at the end of every job, as well as between color changes. Manual cleaning of spray 

### guns involves disassemblingthe 

### gunand placing the parts 

### in a tray containingan appropriate cleaning solvent. The residual paint is brushed

or wiped offthe parts, then cleaning solventis sprayed through the gun after it is reassembled. Various methods are used to minimize the resulting emissionshm spray gun cleaning and 

### are discussed below.

Enclosed System -Enclosed spray gun cleaners are completely enclosed units that spray the cleaning solventthrough and over the spray gun. The enclosed unit eliminates most ofthe exposureof the cleaning solvent to the air, thereby greatly reducing the VOC emissions from evaporation.

Nonatomized Cleaning- Cleaning solventis placed 

### in the pressure pot and forced through the gun with the atomizingcap in place. No atomizing 

### air is used. The cleaning solvent hm the spray gun is directed into a vat, 

### dnun,or other waste container

### that is closed when not in use.

Disassembled S~rav Gun Cleaning -Manual cleaning with the components cleaned by hand in a vat, which is closed when not In

### use. Alternatively,the components are soaked in a vat, which is closed at all times except when components are being inserted or removed.
Atomizing Cleaning -Cleaning solvent is forced throughthe spray gun and the resulting atomized spray is directed into a waste containerthat is fitted witha device designed to capturethe atomized solvent emissions.

Conventional High TransferEfficiency Application Methods

Conventional high transfer efficiency applicationmethods for primers and topcoats include dip, roll, brush, and flow coating (use ofthese methods for specialty coatings is limited). These methods are discussedbelow.
Dip Coating -With dip coating application, parts are immersed into a tank of coating. The parts are then removed fiom the tank and held over it until the

excess coatingdripsback into the tank. Thismethod is simple and allows manydifferentparts to be coated with 

### high transfer efficiency. However, dip coating is limited to parts that can fit into the dip tank. Otherparts difficultto dip coat could include complex parts that would trap the coating, allowing unequal coating thickness
Roll Coating -

### In roll coating application, a series of mechanical rollers 

### are used to coat flat surfaces. This method achieves 

### high efficiency with 

### high rates of application and automation. However, roll coating is limited to flat parts.

Brush Coating -

### In brush coating application, brushes and hand rollers are used to apply the coatingmanually. This method is used with operations (e.g., touch-up and detailpainting) that cannot tolerate the overspray associated with spray gun application. For example, if a facility needs to paint only the tail section of an airplane, it may be easier to brush coat this 

### area 

### thanto mask the entire plane to protect the rest ofthe shell hm overspray. This applicationmethod typically involves high labor costs, increased production time, and poor coating thickness control.

Flow Coating - In flow coating application, the part is conveyed over a closed sink, and a pumped stream of coating gently flows over the surface ofthe part. The excess coating is drained intothe sink, filtered, and pumped to a holding tank for reuse. Flow coating is typically limited to flat sheets 

### and noncritical parts. Coating thickness isdifficultto control using flow coating.
Hand-Wipe Cleaner Substitutions -
Product substitutions forhand-wipe cleaningthat 

### areprevalent in the aerospace industry

can be classified as aqueous, semiaqueous, citrus-based, and reduced vapor pressure. Each category is discussed below.
Aqueous and Semi-aqueous
Aqueous and semi-aqueouscleaners contain water 

### as the base component rather than an organic solvent or mixture of solvents. Other components may include corrosion inhibitors, alkaIinitybuilders, and organic surfactants, dependingon the desired soil removal properties. Aqueous and semi-aqueous cleanershave been used in non-critical areas where strict cleanliness requirements do not have to be met, or where there are no confined spaces that may trap residues ofthe cleaner.
The advantages ofusing aqueous and semi-aqueous cleaning solvents includereduced VOC emissions. Disadvantages are increasedproduction time due to slowerevaporation rates, possible decreased efficiency, and possible increase in wastewater treatment requirements. 

### In addition, aqueous cleaners may not be applicableto all aerospaceparts, especially those components that have small confined spaces where the cleaner residues cannot be adequatelyremoved.Citrus-Based
Citrus-based terpenes such as d-limonene are the primary componentsin many alternative cleaning solutions. While these solutionshave high VOC contents, their vapor pressure is very low, leading to reduced evaporation rates. These cleaners have been found to be effective in some cleaning operations except for cleaning prior to adhesive bonding. Some disadvantagesinclude possible worker sensitivity, VOC emissions, lack ofrinseability in water, and increased production time due to slower evaporation rates.

Reduced Vapor Pressure
Reduced vapor pressure cleaning solventshave a maximum VOC composite vapor pressure of 45 millimeters of mercury (mrnHg) at 

### 20°C. Cleaning solvent emissions 

### are reduced because their lower vapor pressure leads to reduced evaporation rates. These cleaners are effective

### in many cleaning operations except for some limited operations such as cleaning oxygen systems.



### 4.0 Regulatory Review

4.1 TribalPrograms/Rules

A review of U.S. tribal 

### air quality programs was performed to definethe baseline of existing tribal rules and source specific standards. This review was conducted jointly between RTP and the GRIC. At the time ofthis review, no tribal programs or rules were identified that specificallypertained to the AerospaceManufacturing and Rework source category.

4.2 Federal Programs and Regulations

There are a number of Federal NSPS and NESHAP regulations that are potentially applicable to non-aerospace specific activitiesthat may occur at aerospacemanufacturing and rework facilities (i.e., 40 CFR 60 Subpart

### D, 40 CFR 60 Subpart

### K, 40 CFR 63 Subpart

### T, and 40 CFR 63 SubpartN among others).

In additionto these non-aerospace specific regulations, there is a promulgated NESHAP standard (Subpart GG) specifically applicableto major aerospace manufacturingand rework facilities2 and a NESHAP standard currently being developedtoregulate emissions fiom aircraft and rocket engine testing activities. As well, EPA has developed Control Technique Guidelines (CTG) for aerospace manufacturing and rework facilities. Most existing SIPregulations governing aerospacemanufacturing and rework are based
on EPAYs CTG. The CTG also serves as the basis is the ruledefined 

### in Section 5 ofthis

2 The term "major" in this context means a potentially affected source that has the potential to emit more than 10tons per yea.of any singlehazardous air pollutant or 25 tons per year of any combination of hazardous air pollutants.document. Tables 4- 1 and 4-2 summarize the key emission limits and work practice standards found in Subpart GGand the Aerospace CTG respectively.

Table 4- Equipment I process Unit Cleaning Operations 1 Housekeeping Measures 40 CFR 63.744(a)

Cleaning Operations / Hand-wipe Cleaning 40 CFR 63.744(b) 

# . 40 

### CFR 63

## sub^ Pollutant I Parameter HAP & VOC

HAP & VOC 

### ~rt GG Summary Emission Limit I Standard (Units)

Place solvent laden cloth in enclosed containers.

Store fresh and spent solvent

### in closed containers.
Conduct handling and transfer of cleaning solvents in a manner to minimize spills. Cleaning solventsmust meet one of the following requirements:
Aqueous: Cleaning solvents in which water is the primary ingredient.
Hydrocarbon-based: Cleaners that are composedofphotochemically reactive hydrocarbons andlor oxygenatedhydrocarbonsand have a 

### maximum vapor pressure of 7 

### mm Hg at 20 OC (3.75 

### in. &I20 and 68 OF). These cleaners also contain

no 

### HAP.

Have a composite vapor pressure of 45 mm Hg (24.1 

### in. H20)or less at 20 OC (68 OF); or

Demonstrate that the volume of hand-wipe solvents used in cleaning operations has been reduced by at least 60% from a baseline adjusted

Spray Gun cleaning 40 CFR 63.744(c) Cleaning Operations /

- or their equivalent: Enclosed system.; Nonatomized cleaning; Disassembled spray gun HAP & VOC

cleaning; for production. Use one or more ofthe techniques,Table 4-1. 

### 40 

### CFR 63 Sub~art 

### GG Summarv Equipment I

Cleaning Operations I Flush Cleaning 40 CFR 63.744(d) 

### HAP & VOC Pollutant I Parameter

vapor capture. Empty the used cleaning solvent Emission Limit I Standard (Units)
Atomizing cleaning with

each time aerospaceparts or assemblies, or components of a coating unit (with the exception of spray guns) are 

### flushcleaned into an enclosed container or collection system that is kept closed when not in use or into a system with eauivalent emission control. Primer and Topcoat Uncontrolled Coatings 

### - Primers 40 CFR 63.745(c) HAP & VOC Organic 

### HAP emissions from primers shall be limitedto an organic 

### HAP content level of no more than: 350 g/L (2.9 lblgal) of primer (less water) 

### as applied or 540 

### g/L (4.5 lblgal) of primer (less water) 

### as applied for general aviation rework facilities.

VOC emissions from primers shall be limited to a VOC content level of

no more than: 350 

### g/L(2.9 lblgal) of primer (less water and exempt solvents) as applied or 540 g/L(4.5 lblgal) ofprimer (less water and exempt solvents) 

### as applied for general aviationrework facilities.Process Unit Primer and Topcoat Uncontrolled Coatings - Topcoats 40 CFR 63.745(c) Table 4-1. 40 

### CFR 63 Subpart 

### GG Summary

Primer and Topcoat Coatings

# -Primers and Topcoats 40 CFR 63.745(d) Equipment 1 Parameter 

### HAP & VOC PollutantI 

# 1 Emission Limit I Standard (Units) 

# I

Organic HAP emissions fiom topcoats shallbe limitedto an organic 

### HAP content level ofno
more than: 420 g/L (3.5 lblgal) of coating (less water) as applied or 540 

### g/L (4.5 lblgal) of coating (less water) as applied for general aviation rework facilities.

I Organic 

### HAP emissions ikom selfpriming topcoats shall be limitedto
an organic

### HAP content level of no

more 

### than: 420 g/L (3.5 Iblgal) of self-priming topcoat (less water) as applied or 540 g/L (4.5 lblgal) of self-priming topcoat (less water) as applied for general aviation rework facilities.

VOC emissions

### hm topcoats shall be limitedto a VOC contentlevel of

no more 

### than: 420 g/L (3.5 Iblgal) of coating (less water and exempt solvents) as applied or 540 

### g/L (4.5 Iblgal) of coating (less water and exempt solvents)as applied for general aviation rework facilities.

VOC emissions 

### hm self-priming topcoats shall be limitedto a VOC content level of no more than: 420 g/L (3.5 Iblgal) of self-priming topcoat (less water and exempt solvents) as applied or 540 g/L (4.5 lblgal) of self-primingtopcoat (less water) as applied for general aviation rework facilities. Each control system shall reduce the operation's organicHAP and VOC emissionsto the atmosphereby 81 %
or greater, taking into account cahe and destruction or removal efficiencies.Table 4-1. 40 

### CFR 63 Subpart 

### GG Summary

Application Methods 40 CFR 63 63.745(f) Equipment 

### I Process Unit Primer and Topcoat primers and topcoats (including selftopcoats) shallbe applied using one or more ofthe approved application techniques listed 

### in 40 CFR 63.745(f)(l). Pollutant 

### 1 

# I Emission Limit 

### I Standard (Units)

All application devices used to apply primers or topcoats (including selfpriming topcoats) shall be operated accordingto company procedures, local specified operating procedures, andfor the manufacturer' s specifications,whichever is most stringent, at 

### all times. Equipment modified by the facility shall maintain a transfer efficiency equivalent to HVLP and electrostatic spray applicationtechniques. Parameter 

### HAP & VOC For non-exempt applications, allProcess Unit Primer and Topcoat Inorganic 

### HAP Emjssions Existing Sources Table 4-1. 40 

### CFR 63 Subpart GG Summary

Non-exempt application Equipment 

### 1

methods 40 CFR 63.745(g) Pollutant 

### 1 

# I Emission Limit 

### I Standard (Units) Parameter Inorganic

### HAP Apply these coatings in a booth or hangar in which 

### air flow is directed downward onto or across the part or assembly being coated and exhausted through one or more outlets.

Control the 

### air stream fiom this operation as follows: (i) For existing sources, the owner or operatormust choose one ofthe following:
(A) Before exhaustingit to the atmosphere,pass the 

### air stream through a dry particulate filter system certified using the methods described in$63.750(0)to meet or exceed the efficiency data points 

### in Tables 1and 2 of 65.745(g); or 

### (B) Before exhausting it to the atmosphere,pass the 

### air stream through a waterwash system that shall remain in operation during all coating application operations;or (C) Before exhaustingit to the atmosphere, pass the 

### air stream through an 

### airpollution control systemthat meets or exceeds the efficiency data points in Tables 1 and 2 of 65.745(g) and is approved 

### by the permitting authority.Table 

### 4-. Equipment I Process Unit Primer and Topcoat Inorganic HAP Emissions New Sources Non-exempt application methods 40 CFR 63.745(g)

Depainting Operations Non-HAP-Based Chemical Strippers Non-exempt applications 40 CFR 63.746(b) 

### 40 

### CFR 63 Subg Pollutant I Parameter Inorganic 

### HAP



### HAP rt GG Summary Emission Limit I Standard (Units)
Before exhausting it to the atmosphere, pass the 

### air stream through a dry particulate filter system certified using the methods describedin $63.750(0) to meet or exceed the efficiency 

### datapoints 

### in Tables 3 and 4 of 63.745(g); or

Before exhaustingit to the atmosphere, pass the 

### air stream through an 

### airpollution control systemthat meets or exceeds the efficiency

### datapoints in Tables 3 and 4 of 63.745(g) and is approved by the permitting authority. Each owner or operator of a new or existing aerospace depainting operation subjectto this subpart shall emit no organic HAP from chemical stripping formulationsand agents or chemical paint softeners.Process Unit Depainting Operations OrganicHAP-Based Chemical Strippers Non-exempt applications 40 CFR 63.746(c) Table 

### 4-1. 40 

### CFR 63 Subpart 

### GG Summary

Chemical Milling Maskant Application Operations Housekeeping 40 CFR 63.747(b) Equipment 

### 1 Parameter 

### HAP Pollutant/ 

# I Emission Limit 

### I Standard (Units) 

# I

HAP & VOC All organic 

### H&' emissions fiom the operation shall be reduced by the use of a control system. Each control systemthat was installed before the effective date shallreduce the operations' organic 

### HAP emissions to the atmosphere by 81 percent or greater, taking into account capture and destruction or removal efficiencies.

Each control system installed on or afterthe effective date shallreduce organic HAP emissions to the atmosphere by 95 percent or greater. Reduction shall take into account capture and destruction or removal efficiencies, and may take into account the volume of chemical stripperused relative to baseline levels (e-g., the 95percent efficiency may be achieved by controlling emissions at 81 percent efficiency with 

### a control system and using 74 percent less stripperthan in baseline applications). The baseline shall be calculated using data fiom 1996and 1997, which shallbe on a usage per aircraft or usage per square foot of surfacebasis. Conduct the handling and transfer of chemical milling maskants to or fiom containers, tanks, vats, vessels, and piping systems in such a manner that minimizes spills.Table 4-1. 40 

### CFR 63 Subn 

## 1 Equipment I 

# I Pollutant I

Uncontrolled Maskants 

# 1 Process Unit Chemical Milling Maskant
Non-exempt Operations 40 CFR 63.747(c) Parameter HAP & VOC

Chemical Milling Maskant Uncontrolled Maskants Control System Requirements 40 CFR 63.747(c)
Handling and Storage of Waste 40 CFR 53.748 

### HAP & VOC



### HAP art 

### GG Summary Emission Limit IStandard (Units)
Organic 

### HAP emissions fiom chemical milling maskants shall be limited to organic

### HAP content levels ofno more than 622 grams of organic HAP per liter (5.2 lblgal) of Type 

### I chemical milling maskant (less water) as applied, and no more than 160grams of organic

### HAP per liter (1-3lblgal) of Type 11 chemical milling maskant (less water) as applied.

VOC emissions from chemical milling maskants shall be limited to VOC content levels ofno more than 622 grams ofVOC per liter (5.2 lblgal) of Type 

### I chemical milling maskant (less water and exempt solvents) as applied, and no more than 160 grams ofVOC per liter (1.3 lblgal) ofType 

### I1 chemical milling maskant (less water and exempt solvents) as applied. Each control system shall reduce the operation's organic

### HAP and VOC emissions to the atmosphereby 8 1%

or greater, taking into account capture and destruction or removal efficiencies. Conductthe handling and transfer of waste to or fiom coi&ners, tanks, vats, vessels and piping systems in such a manner that minimizes spills.