10/12 Rule 74.13: 1

VENTURA COUNTY AIR POLLUTION CONTROL DISTRICT

RULE 74.13 - AEROSPACE ASSEMBLY AND COMPONENT MANUFACTURING 

OPERATIONS

(Adopted 4/15/86, Revised 10/13/87, 1/22/91, 9/10/96, 11/11/03, 09/11/12)

A. Applicability

This rule is applicable to the manufacturing, assembling, coating, masking, bonding, paint 

stripping, and surface cleaning of aerospace components and the cleanup of equipment 

associated with these operations. Where Rule 74.12, Surface Coating of Metal Parts and 

Products, applies to the coating or cleaning of metal parts, including but not limited to 

tooling operations, this rule shall not apply.

B. Requirements

1. Aerospace Coatings and Adhesives: No person shall apply to any aerospace 

component, any coating, or adhesive with an ROC content in excess of the 

following limits, as applied:

Limits

Grams of ROC Per Liter, or Pounds per Gallon

of Coating (or Adhesive), Less Water and 

Exempt Organic Compounds

COATING or ADHESIVE Grams per Liter Pounds per Gallon

Adhesion Promoter 850 7.1

Adhesives

 Non-Structural 250 2.1

 Structural

 Autoclavable 50 0.4

 Nonautoclavable 850 7.1

Adhesive Bonding Primers 780 6.5

Antichafe Coating 600 5.0

Barrier Coatings 420 3.5

Clear Topcoat 520 4.3

Conformal Coating 750 6.3

Dry Lubricative Materials

 Fastener Manufacturing 250 2.1

 Nonfastener Manufacturing 880 7.3

Electric/Radiation Effect Coatings 800 6.7

Fastener Sealants 675 5.6

Fire Resistant Coatings

 Civilian (Interior) 650 5.4
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COATING or ADHESIVE Grams per Liter Pounds per Gallon

Flight Test Coatings Used on Missiles

 or Single-Use Target Craft 420 3.5

 All Others 600 5.0

Fuel Tank Coatings 420 3.5

Fuel Tank Adhesives 620 5.2

High Temperature Coating 850 7.1

Impact Resistant Coating 420 3.5

Maskants - Chemical Milling 250 2.1

Optical Anti-Reflective Coating 700 5.8

Pretreatment Coatings 780 6.5

Primers Not Resistant

 To Phosphate Esters 350 2.9

Phosphate Ester-

 Resistant Primers 350 2.9

Rain Erosion-Resistant Coating 420 3.5

Scale Inhibitor 880 7.3

Sealant 600 5.0

Solid Film Lubricants

 Fastener Manufacturing 250 2.1

Solid Film Lubricants 

 Fastener Installation 880 7.3

 Nonfastener Manufacturing 880 7.3

Space Vehicle Coatings

 Electrostatic Discharge Protection 800 6.7

 Other Space Vehicle Coatings 1000 8.3

 Space Vehicle Adhesives 800 6.7

Temporary Protective Coatings 250 2.1

Topcoats 420 3.5

Unicoats (Self-Priming Topcoats) 420 3.5

Wing Coating 420 3.5

Wire Coatings

 Electronic 420 3.5

 Anti-Wicking 420 3.5

 Pre-Bonding Etching 420 3.5

 Phosphate Ester Resistant Ink 925 7.7

2. Solvent Cleaning:

a. Solvent Cleaning: No person shall use a solvent for solvent cleaning, or 

engine gas path cleaning excluding stripping coatings or cleaning coating 

application equipment unless:

1) The solvent contains less than 200 grams of ROC per liter of 

material, as applied, or 
10/12 Rule 74.13: 3

2) The ROC composite partial pressure of the solvent is less than or 

equal to 25 mm Hg at a temperature of 20o C.

b. Coating Application Equipment Cleaning:

 

No person shall use materials containing ROC for the cleaning of 

equipment used in coating operations unless an enclosed system or 

enclosed gun washer is used according to the manufacturer's 

recommendations and is closed when not in use.

No person shall use materials containing ROC for the cleaning of coating 

application equipment unless:

1) An enclosed gun washer or "low emission spray gun cleaner" that 

has been approved in writing by the APCO is properly used for 

spray equipment cleaning, and 

2) The ROC composite partial pressure of solvent cleaner used is less 

than 5 mm Hg at 20oC, or the ROC content of the solvent cleaner 

is 25 grams per liter (0.21 lb/gal) or less (Effective Dec 1, 2012).

3. Coating Strippers: No person shall use a coating stripper unless it contains less 

than 300 grams of ROC per liter, as applied, or unless its ROC composite partial 

pressure is 9.5 mm Hg or less at 20 oC.

4. Storage of ROC Containing Materials: All ROC-containing materials including, 

but not limited to, surface coatings, cleanup solvents, or surface preparation 

materials shall be stored in closed containers which are nonabsorbent and do not 

leak. These storage containers shall be closed except when filling or emptying.

5. Coating Transfer Efficiency: No person shall apply coatings except by using 

properly operated coating application devices and by using:

a. Electrostatic application operated at a minimum of 60 kV,

b. Flow coat application,

c. Dip coat application,

d. Hand application methods,

e. High volume, low pressure spraying (HVLP): If a spray gun is used, the 

end user shall demonstrate that the spray gun meets the definition of 

HVLP in design and use. HVLP equipment shall be identified by either 
10/12 Rule 74.13: 4

test air cap measurements or an inlet pressure measurement that, when 

used with specifications published by the manufacturer that reference the 

corresponding spray nozzle size, establishes that the gun is being operated 

as specified in Subsection G.27.

f. Alternative Application Method: Any other alternative method that 

achieves a transfer efficiency equivalent to, or higher than one of the 

application methods listed in Subsections B.5.a, B.5.b, B.5.c, B.5.d, or 

B.5.e. Written approval of the APCO shall be obtained for each 

alternative method prior to use.

6. Add-on Control Equipment Option: A person may comply with provisions of 

Subsection B.1 or Subsection B.2 by using air pollution control equipment 

provided that:

a. The combined capture and control efficiency reduces emissions by at least 

85 percent by weight, and 

b. Written approval for such equipment in the form of an Authority to 

Construct and Permit to Operate is received from the APCO.

7. Prohibition of Solicitation: No person shall solicit, specify or require any other 

person to use in the District any coating, adhesive, solvent, spray equipment, or 

control equipment that does not meet the limits or requirements of this rule.

8. Coating Compliance Statement: The manufacturer of coatings subject to this rule 

shall designate on product labels or data sheets, the ROC content or the Volatile 

Organic Compounds (VOC) content of coatings including coating reducers and 

catalysts, as supplied. This designation shall include recommendations regarding 

thinning, reducing, or mixing with any other ROC containing materials, and 

express the coating ROC or VOC content on an as applied basis when used in 

accordance with the manufacturer's recommendations. All letters and numbers 

used to designate ROC or VOC content on product labels shall be visible and 

legible.

9. Liquid Cleaning Material Compliance Statement: The manufacturer of liquid 

cleaning materials used in coating operations shall designate on product labels or 

data sheets the ROC content and ROC Composite Partial Pressure of cleaning 

materials as supplied. This designation shall include recommendations regarding 

mixing with any other ROC containing materials, and express the cleaning 

material ROC content when used in accordance with the manufacturer's 

recommendations. All letters and numbers used to designate ROC or VOC 

content on product labels shall be visible and legible.
10/12 Rule 74.13: 5

10. Low-Solids Adhesives, Coatings, Primers or Sealant: The appropriate ROC limits 

in Subsection B.1 shall be expressed in grams of ROC per liter of material as 

defined in Subsection G.30.

C. Exemptions

1. This rule, except section B.7, shall not apply to any stationary source that emits 

less than 200 pounds of ROC in every rolling period of 12 consecutive calendar 

months from aerospace assembly and component manufacturing operations. 

Emissions from cold cleaners, vapor degreasers, and aerosol products, shall not be 

included in this determination.

Any person claiming this exemption shall provide operational records, data and 

calculations, as determined by the APCO to be necessary, to substantiate this 

claim.

2. Subsection B.1 of this rule shall not apply to any one coating or adhesive 

provided:

a. No complying coating or adhesive is available, and

b. Any coating with separate formulations used in volumes of less than 20 

gallons in any calendar year at a stationary coating source provided that the 

total usage of all noncomplying coatings (excluding noncomplying 

adhesives) has not exceeded 200 gallons annually, or

c. Any adhesive with separate formulations used in volumes of less than 10 

gallons in any calendar year at a stationary coating source.

Any person claiming this exemption shall demonstrate the lack of an available 

coating or adhesive to the APCO on an annual basis.

3. The provisions of Subsection B.2.a of this rule shall not apply to the cleaning of 

aerospace assembly and subassembly surfaces that are exposed to strong oxidizers 

or reducers such as nitrogen tetroxide, liquid oxygen or hydrazine. 

4. The provisions of Subsection B.5 shall not apply to the application of coatings 

that contain less than 20 grams of ROC per liter of coating less water and less 

exempt organic compounds.

5. This rule shall not apply to aerosol coating products.

6. This rule shall not apply to solvent cleaning conducted inside of a degreaser. 

Solvent cleaning inside of a degreaser shall be subject to the requirements of Rule 

74.6 or Rule 74.6.1, as applicable.
10/12 Rule 74.13: 6

D. Recordkeeping

1. Any person subject to this rule shall:

a. Maintain a current list of all coatings and adhesives that provides all 

information necessary to evaluate compliance, including the following, as 

applicable:

1) The name and manufacturer of each coating and adhesive and any 

catalysts and reducers used with each coating or adhesive

2) Mix ratio of components used

3) ROC content , as applied (Less Water and Exempt Organic 

Compounds except for Low-Solids Coatings or Adhesives, which 

are expressed as Grams of ROC per liter of Material)

4) Category from Subsection B.1

b. Maintain records which show the following for each ROC containing 

material used for cleanup, including equipment cleaning, and each ROC 

containing material used for solvent cleaning:

1) Type

2) ROC content in grams per liter of material

3) Composite ROC partial pressure of organic solvent (where 

applicable)

c. Maintain records of the monthly volume of each complying coating, 

adhesive, and ROC-containing liquid used for solvent cleaning or 

stripping, and daily volume of each noncompliant coating , adhesive, 

stripper, or cleaning solvent. Any person claiming the coating or adhesive 

small-use exemption in Subsection C.2 shall maintain records of each 

exempt coating or adhesive used on a monthly basis.

d. Any person using an emission control system as a means of complying 

with this rule shall maintain daily records of key system operating and 

maintenance procedures which will demonstrate continuous operation and 

compliance of the emission control device during periods of emission 

producing activities. 

2. Any person subject to this rule shall record any coating or adhesive intended for 

use in any of the specialty categories listed below. This record shall be available 

for review and shall include the manufacturer name, product ID number, specialty 

category, ROC limit as applied, and information to support that the specialty 

coating or adhesive has been specified for the intended application.
10/12 Rule 74.13: 7

Adhesion Promoter Coating Antichafe Coating

Electric/Radiation Effect Coating Fuel Tank Adhesive

High Temperature Coating Optical Anti-Reflective Coating

3. Such records shall be maintained for a minimum of two (2) years and shall be 

available for inspection by the APCO. A longer period of time for record 

retention may be specified by a permit condition.

E. Test Methods

1. Coating ROC content and solvent ROC content shall be determined using EPA 

Reference Method 24 or its constituent methods. The ROC content of coatings or 

solvents containing exempt organic compounds shall be determined by CARB 

Test Method 432.

2. The solid content of pretreatment coatings shall be determined using ASTM 

Method D2369-95, “Standard Test for Volatile Content of Coatings.” The acid 

content of pretreatment coatings shall be determined using ASTM Method 

D1639-90(1996)e1, Standard Test Method for Acid Value of Organic Coating 

Material.”

3. The test method for determining the fire resistance of an interior coating shall be 

Federal Aviation Administration required Ohio State University Heat Release, 

Fire and Burn Tests.

4. ROC composite pressure of a solvent or stripper shall be calculated using a widely 

accepted published source such as: Boublik, T., V. Fried and E. Hala, "The Vapor 

Pressure of Pure Substances," Elsevier Scientific Publishing Co., New York 

(1973), Perry's Chemical Engineer's Handbook, McGraw-Hill Book Company, 

CRC Handbook of Chemistry and Physics, Chemical Rubber Publishing 

Company (1986-87), and Lange's Handbook of Chemistry, John A. Dean, editor, 

McGraw-Hill Book Company (1985). The true vapor pressure of a component in 

a solvent mix may be determined by ASTM Method D2879-97, “Test Method for 

Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature 

of Liquids by Isoteniscope.” The ROC composite pressure of a solvent mix 

consisting entirely of ROC may be determined by ASTM Method D2879-97.

5. The active and passive solvent losses from spray gun cleaning systems shall be 

determined using South Coast Air Quality Management District's "General Test 

Method for Determining Solvent Losses from Spray Gun Cleaning Systems" dated

October 3, 1989. The test solvent for this determination shall be any lacquer 

thinner with a minimum vapor pressure of 105 mm Hg at 20 oC. The minimum 

test temperature shall be 15 oC.
10/12 Rule 74.13: 8

6. Transfer efficiency shall be determined in accordance with the South Coast Air 

Quality Management District method entitled "Spray Equipment Transfer 

Efficiency Test Procedure for Equipment Users" (May 24, 1989). Spray 

equipment HVLP equivalency shall be determined by using South Coast AQMD’s 

“Guidelines for Demonstrating Equivalency with District Approved Transfer 

Efficient Spray Guns” (September 26, 2002).

7. The capture and control device efficiency of any air pollution control equipment 

shall be determined according to EPA's technical document, "Guidelines for 

Determining Capture Efficiency," January 9, 1995, and40 CFR 51, Appendix M, 

Methods 204-204F, as applicable:

Methods 204, Criteria for and Verification of a Permanent or Temporary Total Enclosure 

Method 204A, VOC content in Liquid Input Stream

Method 204B, VOC Emissions in Captured Stream

Method 204C, VOC Emissions in Captured Stream (Dilution Technique)

Method 204D, VOC Emissions in Un-captured Stream from Temporary Total Enclosure

Method 204E, VOC Emissions in Un-captured Stream from Building Enclosure, and

Method 204F, VOC Content in Liquid Input Streams (Distillation Approach)

The calculation of control device efficiency shall be determined only during 

periods of continuous coating operations and shall be averaged over the duration 

of the coating operation not to exceed 24 hours.

F. Violations

Failure to comply with any provision of this rule, including the requirement to maintain 

records, shall constitute a violation of this rule.

G. Definitions

1. "Adhesion Promoter": A primer used to promote wetting and form a chemical 

bond with the subsequently applied sealant or other elastomer. 

2. "Adhesive": A substance that is used to bond one surface to another surface by 

attachment.

3. "Adhesive Bonding Primer": A primer applied to aerospace componentsto 

increase adhesive or adhesive film bond strength.

4. "Aerosol Coating Product"; A pressurized coating product containing pigments or 

resins that dispenses product ingredients by means of a propellant, and is 

packaged in a disposable can for hand held application, or for use in specialized 

equipment for ground traffic/marking applications.
10/12 Rule 74.13: 9

5. "Aerospace Component": Any raw material, partial or completed fabricated part, 

assembly of parts, or completed unit of any aircraft, helicopter, missile, or space 

vehicle, including mockups and prototypes.

6. "Antichafe Coating": A coating applied to areas of moving aerospace components 

which may rub during normal operation.

7. "Anti-Wicking Wire Coating": The outer coating of a wire which prevents fluid 

wicking into the insulation of the wire.

8. "Barrier Coating": A coating applied in a thin film to fasteners to inhibit 

dissimilar metal corrosion and to prevent galling.

9. “Capture Efficiency”: The percentage of ROC used, emitted, evolved, or 

generated by the operation, that is collected and directed to an air pollution control 

device.

10. "Coating": A material which is applied to a surface and which forms a film in 

order to beautify and/or protect such surface.

11. "Conformal Coating": A coating applied to electrical conductors and circuit 

boards to protect them against electrical discharge damage and/or corrosion.

12. “Degreaser”: A container for solvent and articles being cleaned that includes a 

facility for draining solvent from surfaces such that the drained solvent is returned 

to the container.

13. "Dry Lubricative Coating": A coating consisting of lauric acid, cetyl alcohol, 

waxes, or other non-cross linked or resin-bound materials which act as a dry 

lubricant or protective coat.

14. "Electric- or Radiation-Effect Coating": An electric-effect coating is electrically 

conductive. A radiation-effect coating helps in the prevention of radar detection.

15. "Electronic Wire Coating": The outer electrical insulation coating applied to tape 

insulation of a wire specifically formulated to smooth and fill edges.

16. "Electrostatic Application": A sufficient charging of atomized paint droplets to 

cause deposition principally by electrostatic attraction. This application shall be 

operated at a minimum 60 KV.

17. "Exempt Organic Compounds": As defined in Rule 2, of these rules. 
10/12 Rule 74.13: 10

18. "Fire Resistant Coating - Civilian (Interior)": A cabin interior coating that passes 

Federal Aviation Administration standards using the Ohio State University Heat 

Release, Fire and Burn Tests.

19. "Flight Test Coating": A coating applied to an aircraft prior to flight testing to 

protect the aircraft from corrosion and to provide required marking during flight 

test evaluation.

20. "Fuel Tank Adhesive": An adhesive used to bond components exposed to fuel 

and which must be compatible with fuel tank coatings.

21. "Fuel Tank Coating": A coating applied to the interior of a fuel tank or areas of 

an aircraft that are continuously wetted by fuel to protect it from corrosion and/or 

bacterial growth.

22. "Grams of ROC per liter of Coating, less water and exempt organic compounds": 

The weight of ROC per combined volume of ROC and coating solids, calculated 

using the following equation:

Grams of ROC per Liter of Coating 

Less Water and Exempt Organic Compound= Ws - Ww - Wes

 Vm - Vw - Ves

Where: Ws = Weight of volatile compounds (grams)

Ww = Weight of water (grams)

Wes = Weight of exempt organic compounds (grams)

Vm = Volume of material (liters)

Vw = Volume of water (liters)

Ves = Volume of exempt organic compounds (liters)

23. "Grams of ROC per Liter of Material": The weight of ROC per volume of 

material calculated as follows: 

Grams of ROC per Liter of Material = Ws - Ww - Wes

Vm 

Where: Ws = Weight of volatile compounds (grams)

Ww = Weight of water (grams)

Wes = Weight of exempt organic compounds (grams)

Vm = Volume of material (liters)

24. "Gun Washer": Electrically or pneumatically operated system that is designed to 

clean spray application equipment while enclosed. A gun washer may also be 
10/12 Rule 74.13: 11

considered a gun cleaning system that consists of spraying solvent into an 

enclosed container using a snug fitting.

25. "Hand Application Methods": The application of coatings, sealants, or adhesives, 

by nonmechanical hand-held equipment including but not limited to paint brushes, 

hand rollers, caulking guns, trowels, spatulas, syringe daubers, rags and sponges.

26. "High Temperature Coating": A coating that must withstand temperatures of 

more than 350oF.

27. "High Volume Low Pressure Application (HVLP)": Equipment used to apply 

coatings by means of a spray gun designed to be operated and operated between 

0.1 and 10 psig air pressure measured dynamically at the center of the air cap and 

at the air horns.

28. "Impact Resistant Coating": A flexible coating that protects aerospace 

components, such as aircraft landing gear, and landing gear compartments, and 

other surfaces subject to abrasive impacts from runway debris.

29. "Low emission spray gun cleaner": Any properly used spray equipment cleanup 

device which has passive solvent losses of no more than 0.6 grams per hour and 

has active solvent losses of no more than 15 grams per operating cycle as defined 

by the test method in Subsection E.5.

30. “Low-Solids Adhesive, Coating, Primer or Sealant”: An adhesive, coating, 

primer, or sealant that has less than one pound of solids per gallon of material

(120 grams of solids per liter of material). Such solids are the non-volatiles 

remaining after a sample is heated at 110o

C for one hour.

31. "Maskant for Chemical Milling": A coating applied directly to an aerospace 

component to protect surface areas when chemical milling such component.

32. "Non-Structural Adhesive": An adhesive that bonds non-load carrying aircraft 

components in noncritical applications.

33. "Optical Anti-Reflective Coating": A coating with a low reflectance in the 

infrared and visible wavelength range and is used for anti-reflection on or near 

optical and laser hardware.

34. "Phosphate Ester Resistant Wire Ink Coating": A coating that is used for surface 

identification or mark on aerospace wire or cable which inhibits the corrosion 

caused by contact with phosphate ester type hydraulic fluids.

35. "Pretreatment Coating": A coating which contains no more than 12 percent solids 

by weight, and at least one-half percent acid, by weight, to provide surface 
10/12 Rule 74.13: 12

etching, and is applied directly to metal surfaces to provide corrosion resistance, 

adhesion and ease of stripping.

36. "Primer": A coating applied directly to an aerospace component for purposes of 

corrosion prevention, protection from the environment, functional fluid resistance 

and adhesion of subsequent coatings.

37. "Rain Erosion Resistant Coating": A coating that protects leading edges, flaps, 

stabilizers, and engine inlet lips against erosion caused by rain during flight.

38. "Reactive Organic Compounds (ROC)": As defined in Rule 2.

39. ROC Composite Partial Pressure": The sum of the partial pressures of the 

compounds defined as ROCs. ROC composite partial pressure is calculated as 

follows:

( )( )

( ) PP

W VP

MW

W

MW

W

MW

W

MW

c

i i

i i

n

w

w

e

e e

n i

i i

n = 



 



 + 



 



 + 



 





=

= =

∑

∑ ∑

1

1 1

Where:

Wi = Weight of the "i"th ROC compound, in grams

Ww = Weight of water, in grams

We = Weight of the "e"th exempt organic compound, in grams

MWi = Molecular weight of the "i"th ROC compound, in g/(g-mole)

MWw = Molecular weight of water, in g/(g-mole)

MWe = Molecular weight of the "e"th exempt compound, in g/(g-mole)

PPc = ROC composite partial pressure at 20 C, in mm Hg 

VPi = Vapor pressure of the "i"th ROC compound at 20 C, in mm Hg.

40. "Scale Inhibitor": A coating that is applied to the surface of a part prior to

thermal processing to inhibit the formation of tenacious scale.

41. "Sealant": A viscous semisolid material that fills voids in order to seal out water, 

fuel, and other liquids and solids, and in some cases air movement.

42. "Solid Film Lubricant": A very thin coating consisting of a binder system 

containing as its chief pigment material one or more of the following: 

molybdenum disulfide, graphite, polytetrafluoroethylene (PTFE) or other solids 

that act as a dry lubricant between faying surfaces.

43. "Space Vehicle Coating": A coating applied to vehicles designed to travel beyond 

earth's atmosphere, including but not limited to, rocket or satellite coatings.
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44. "Stripper": A volatile liquid applied to remove a maskant for chemical 

processing, cured or dried paint, cured or dried paint residue or temporary 

protective coating.

45. "Structural Adhesive - Autoclavable": An adhesive used to bond load-carrying 

aircraft components and is cured by heat and pressure in an autoclave.

46. "Structural Adhesive - Nonautoclavable": An adhesive cured under ambient 

conditions and is used to bond load-carrying aircraft components or other critical 

functions, such as nonstructural bonding near engines.

47. “Solvent Cleaning”: The use of solvent to remove loosely held uncured adhesive, 

uncured ink, uncured coating, uncured resin, or other contaminants which include, 

but are not limited to, dirt, soil, lubricants, coolant, moisture, grease, and 

fingerprints from parts, products, tools, machinery, equipment, or general work 

areas.

48. "Temporary Protective Coating": A coating applied to an aerospace component to 

protect it from mechanical and environmental damage during manufacturing or 

shipping.

49. "Topcoat": A coating applied over a primer for purposes such as appearance, 

identification, or protection.

50. "Transfer Efficiency": The ratio of the weight or volume of coating solids 

adhering to the part being coated to the weight or volume of coating solids used in 

the application process, expressed as a percentage.

51. "Unicoat": A coating that is applied directly to an aerospace component for 

purposes of corrosion protection, environmental protection and functional fluid 

resistance that is not subsequently topcoated. A unicoat is used in lieu of the 

application of a primer and a topcoat.

52. "Wing Coating": A coating that is corrosion resistant and is resilient enough to 

withstand the flexing of wings.

53. "Wire Prebonding Etchant": A nonadditive surface treatment process to provide 

bondability of aerospace wire coatings to the underlying insulation layer.