Z-P403_REV_-__DOC_1_approved_OEMimages.pdf

2017-12-19

PCO LETTER REQUEST

A-10 TLPS

Legacy VI 12/19/2017

Contract/Delivery Order Number: FA8202-15-D-0001

Program Manager: Edie Messina

Letter Number: A10-CDM-0001-E-17-0083

Date of Letter: 11/14/2017

CDRL Number: A129

Document Title:

A-10 Aircraft Process Specification for the Application of Epoxy-Polyamide Primer per MIL-PRF-23377

Document/ Drawing Number: Z-P403

NOT APPROVED (See comment below)

X APPROVED

APPROVED Subject to inclusion of attached comments

OTHER (please identify below)

Notes:

Program Manager Signature and Date:

X

MESSINA.CARRI

E.E.1023771388

Digitally signed by

MESSINA.CARRIE.E.1023771388

Date: 2017.12.21 13:26:15 -07'00'

CAGE 77751 Z-P403

24 October 2017

Data contained on this sheet is subject to the restrictions on the title page of this document.

ii

TABLE OF REVISIONS

Revision Changes Reason for Change Approved

Original 10/24/2017

New document – M. Kassinger iii

TABLE OF CONTENTS

TABLE OF REVISIONS ....................................................................................................... i

1.0 SCOPE

2.0 APPLICABLE DOCUMENTS

2.1 Government Documents

2.2 Non-Government Documents

3.0 REQUIREMENTS

3.1 Materials

3.2 Equipment

4.0 PROCEDURE

4.1 Surface Preparation

4.2 Primer Preparation

4.3 Primer Application

5.0 QUALITY ASSURANCE

6.0 STORAGE

1.0 SCOPE

This specification establishes the procedures for the application of epoxy-polyamide primer per MIL-PRF-23377 on interior and exterior surfaces of A-10 aircraft.

2.0 APPLICABLE DOCUMENTS

The following documents of the issue in effect on the effective date of contract shall form part of this specification. In the event of conflict between the contractual documents referenced herein and the requirements of this specification, the contractual documents referenced herein shall govern.

2.1 Government Documents

2.1.1 Federal

TT-N-95 Naphtha; Aliphatic

2.1.2 Military

MIL-DTL-5541 Chemical Conversion Coatings on Aluminum and Aluminum Alloys

MIL-DTL-18264 Finishes, Organic, Weapons Systems, Application and Control of

MIL-PRF-23377 Primer Coatings: Epoxy, High-Solids

MIL-T-81772 Thinner, Aircraft Coating

TO 1A-10C-23 Technical Manual, Corrosion Control, USAF Series A-10C Aircraft

2.2 Non-Government Documents

2.2.1 Industry

AMS 3819 Cloths, Cleaning, for Aircraft Primary and Secondary Structural Surfaces

ASTM D740 Standard Specification for Methyl Ethyl Ketone

ASTM D1153 Standard Specification for Methyl Isobutyl Ketone

2.2.2 A-10 Program

Z-P801 Storage, Handling, Shipping

3.0 REQUIREMENTS

3.1 Materials

3.1.1 Primer

Primer, epoxy-polyamide, MIL-PRF-23377 Ty. I or Ty. II, Cl. C2

3.1.2 Thinners

Thinner (epoxy grade), MIL-T-81772 Ty. II

3.1.3 Pretreatments

Chemical conversion coating, MIL-DTL-5541 PreKote® SP surface pretreatment Pantheon Chemical

225 West Deer Valley Road Phoenix, AZ 85027-2126 PantheonChemical.com

3.1.4 Solvents

Methyl ethyl ketone, ASTM D740 Any source Methyl isobutyl ketone, ASTM D1153 Any source Aliphatic naphtha, TT-N-95 Ty. II NOTE: Each batch of aliphatic naphtha shall successfully pass the acrylic crazing test outlined in TT-N-95, Section 4.3.7.

Shell Chemical Company PO Box 2463 Houston, TX 77252-2463 Part No. ShellSol W HT

MACH-DYNAMICS

494 Main Street Susquehanna, PA 18847-7979

Methyl propyl ketone (MPK), technical grade [90.0% by wt. min. MPK/10.0% by

wt. max. MIBK]

Eastman Chemical Company PO Box 431 Kingsport, TN 37662-0431

Methyl propyl ketone (MPK), ultra high purity [99.5% by wt. min. MPK/0.5% by wt.

max. MIBK]

Eastman Chemical Company PO Box 431 Kingsport, TN 37662-0431 http://pantheonchemical.com/

3.1.5 Wipers

Cloths, per AMS 3819 Class 1, Grade A, Form 1 e.g., Rymplecloth #301, 100% purified cotton

Any source suggested sources:

1) American Fiber and Finishing, Inc.

225 North Depot Street Albemarle, NC 28001-3914

2) John R. Lyman Company 60 Depot Street Chicopee, MA 01013-1251

3.1.6 Abrasives

Abrasive paper, 320-grit or finer Any source 3M Scotch-Brite™ Hand Pad 7447, or equivalent

Any source

3.1.7 Miscellaneous

3M No. 250 pressure-sensitive masking tape

Any source

Clean, white cotton gloves* Any source White cotton glove, style L31M-105 American Glove Company

98 Alpine Street Lyerly, GA 30730-3087

Thin mill gloves (nitrile), Ansell #92-600 ANE92-600-6.5-Small ANE92-600-7.5-Medium ANE92-600-8.5-Large ANE92-600-9.5-Extra Large

Suggested source of supply:

Airgas Safety 2355 Workman Mill Road City of Industry, CA 90601-1459

Nitrile exam glove, 55082-55084, powder free, textured, purple

Kimberly-Clark Professional 1400 Holcomb Bridge Road Roswell, GA 30076-2190

Distilled water Any source

* Materials shall contain less than 0.75% oil by acetone extraction and less than 1.2% oil by water extraction. Laundered materials shall not be used.

3.2 Equipment

3.2.1 Application Equipment

Equipment used for the application of the primer, e.g., spray guns and accessories, shall be compatible with the materials being applied and capable of properly delivering the primer to the surfaces requiring coating. They shall be kept clean between uses.

3.2.2 Miscellaneous

Red Devil paint shaker, or equivalent Any source 4-1/2-pound rubber-covered roller Any source No. 4 Ford cup Any source

3.2.3 Facilities and Equipment

Facilities and equipment shall be capable of producing primer coatings that meet MIL-

DTL-18264.

4.0 PROCEDURE

4.1 Surface Preparation

Unless otherwise specified, metal surfaces must be cleaned and pretreated prior to priming, as follows:

4.1.1 Masking

Prior to surface cleaning, chemical treatment or painting, areas such as canopies, windshields, radomes and transparent light covers shall be suitably masked. On canopies or windshields, tape shall be applied to the frames adjacent to the transparent areas but shall not contact the plastic or glass. All exposed portions of actuated rods passing through hydraulic seals shall be protected from any material application during cleaning or finishing to prevent damage to seals. All other areas requiring protection shall be masked. Any residue left by masking shall be removed with suitable solvents.

CAUTION: Do not use solvents containing ketones or toluene on plastics. Use only aliphatic naphtha, TT-N-95 Ty. II.

4.1.2 Cleaning

Surfaces that are not clean will produce poor paint adhesion, with subsequent paint loss, leaving the metal unprotected from corrosive conditions. Therefore, removal of grease, oil, and other gross surface contaminants shall be accomplished by wiping with a clean rag dampened with an appropriate solvent per Section 3.1.4. Do not allow solvent to dry on surfaces. Wipe clean with a clean, dry rag.

NOTE: Particular attention should be given to fasteners and other areas where residues may become entrapped.

Cleaned parts shall be handled only by personnel wearing clean cotton or nitrile gloves.

4.1.2.1 Water-Break Test

All surfaces to be painted shall be subjected to a water-break test, in which a mist of distilled water shall be atomized on the surface. If the water droplets tend to coalesce into large lenses lasting for 25 seconds without a sudden flashout, then the surface shall have passed the water-break test. If, on the other hand, the water gathers into droplets within 25 seconds, i.e., the surface shows a water-break, then the surface fails the test. If the water forms a continuous film by flashing out suddenly over a large area, that is evidence of an impurity on the surface, and the surface fails the test. Any surfaces failing the water-break test require recleaning and retesting.

4.1.3 Surface Treatment

Detail parts or assemblies including the entire aircraft are to be finished in accordance with drawing requirements, unless other contractual A-10 Engineering documentation is authorized by the SPO. After solvent cleaning these surfaces, they shall be primed in accordance with the applicable drawing requirement, unless otherwise specified.

NOTE: At Hill AFB only, in lieu of applying MIL-DTL-5541 Cl. 2 conversion coating, surfaces may be pretreated with PreKote® SP as directed within TO 1A-10C- 23.

4.2 Primer Preparation

The primer is supplied in kit form; the two components of which are admixed first prior to application, per the manufacturer’s instructions.

NOTE: Some manufacturers supply three components, the third being a thinner.

4.2.1 Mixing

4.2.1.1 Thoroughly mix or stir each component of the kit prior to and after admixing. Mix in a paint shaker per 3.2.2 or if not available, use a paddle, removing any excess material from the paddle. Ensure that the temperature of each component is within the manufacturer’s recommendations. See the manufacturer’s technical data sheet for additional instructions.

4.2.1.2 After sufficient agitation, separately pour each component into a suitable container of sufficient capacity. The base shall be poured into the empty container, followed by the curing solution, while stirring constantly. Mix only sufficient material for a 4-hour period.

NOTE: Components from one manufacturer shall not be mixed with components of another manufacturer.

4.2.1.3 Using a no. 4 Ford cup, verify that the viscosity of the primer meets MIL-PRF-23377 and the manufacturer’s recommendations. Test viscosity under ambient laboratory conditions (65° to 100°F). If thinning is necessary for production, use either thinner specified in 3.1.2 or the thinner component supplied by the manufacturer.

CAUTION: Do not add thinner if that addition will raise the VOC content to greater than 340 g/l (2.8 lb./gal.) in accordance with MIL-PRF-23377. Consult manufacturer if required.

4.2.1.4 If required per the manufacturer’s instructions, ensure that the minimum induction time is met prior to application.

NOTE: Not all primers require induction.

4.2.1.5 A log shall be maintained that will include primer manufacturer, manufacturer product number, batch number, viscosity and work life.

4.3 Primer Application

4.3.1 Equipment used for the application of the primer, e.g., spray guns and accessories, shall be suitable for their purpose and shall be cleaned as required with appropriate solvents as soon as work is complete.

4.3.2 Spray one wet crosscoat of primer to a dry film thickness of 0.6 to 0.9 mil, except that in difficult joint designs or locations this value may be exceeded. Crosscoating of the primer provides superior corrosion protection. Keep the spray gun moving to avoid thick films of the primer.

4.3.3 Allow the primer to air dry for five (5) hours minimum prior to applying a topcoat.

Consult manufacturer’s technical data sheet for guidance on use of accelerated curing.

4.3.4 Reactivation of Primer

To ensure proper adhesion, primer that exceeds the maximum timeframe until topcoat, as specified by the manufacturer, shall be scuff sanded with 320-grit or finer aluminum oxide or sandpaper followed by solvent wiping with an appropriate solvent per Section 3.1.4. The dry scuff sanding shall not result in the exposure of bare substrate. There shall be no gouging of the surface of rivets and other protuberances and edges of faying surfaces with the sandpaper because it removes the primer and exposes bare metal. In areas to be reactivated, after scuff sanding and solvent wiping, spray a mist coat to 0.2 to 0.5 mil dry film thickness to obtain a total coating dry film thickness of 0.6 to 0.9 mil of primer.

4.3.4 Rework and Touch-Up of Localized Areas

If primer is removed or otherwise damaged, the part shall be submitted for Material Review Board action.

5.0 QUALITY ASSURANCE

5.1 Epoxy-polyamide primer components shall be certified by the manufacturer as meeting the requirements of MIL-PRF-23377.

5.2 Usage of primer shall be tracked and logged in order to ensure that it is within its shelf life. Material that has exceeded its shelf life shall be discarded.

5.3 To ensure that application conditions are within the primer manufacturer’s recommendations, a daily log shall be maintained for recording temperature and relative humidity.

5.4 Regular and frequent thickness measurements shall be made on cured primer with an eddy current-type gauge or equivalent in order to ensure that the coatings meet the requirements of MIL-PRF-23377, or A-10 Engineering documentation, as applicable.

5.5 Primer coatings applied to a vertical surface shall not sag, run, or streak. The dried film shall have a smooth, uniform surface free of grit, seeds, craters, blisters, and other irregularities. No orange peel (wavy appearance) shall be evident when viewed from six feet away.

5.6 Adhesion Testing

In conformance with MIL-DTL-18264 requirements, at a minimum, wet tape adhesion tests on the complete exterior finish shall be conducted on the completed coating after drying for a period of at least 48 hours whenever a new supplier furnishes materials used in the production process, whenever evidence occurs of deterioration in the quality of the finish, or whenever a change of process or sequence is effected. The tests shall be in accordance with Section 5.6.1.

5.6.1 Wet Tape Testing

Quality Assurance shall select, at random, a representative number of topcoated parts to be wet tape tested as follows: A piece of cloth or plastic shall be taped on the area under inspection. The test area shall be kept soaked for not less than 24 hours with tap or distilled water. The test areas shall have a minimum diameter of 3 inches. Remove the wet cloth and blot up the surface water. Immediately thereafter, apply a 1-inch strip of 3M no. 250 pressure-sensitive masking tape (only newly manufactured tape, i.e., no older than six months, shall be used), adhesive side down. Press the tape down, using two passes of a 4-1/2-pound rubber-covered roller or employ firm pressure with the hand. Remove the tape in one abrupt motion and examine the tested area for any paint damage, such as removal of paint at one of the layers of the finish system or removal of the entire system from the base metal. At the option of Quality Assurance, witness test panels shall be prepared along with the production part.

Scratch wet tape adhesion tests shall be conducted on these panels. The scratch wet tape adhesion test is identical to the wet tape adhesion test except that 2-inch-long and 1-inch-apart parallel scratches joined at each end by an inverted V shall be scribed down to base metal with a suitable stylus prior to water immersion. Removable inspection plates or access doors when available and depending on aircraft configuration may be used in place of witness test panels for these tests.

5.6.2 Dry tape testing may be accomplished at the discretion of Quality Assurance. Allow the topcoated substrate to dry a minimum of 48 hours. Apply a one-inch-wide strip of 3M no. 250 pressure-sensitive masking tape with the adhesive side down on the painted surface. Using finger pressure, firmly and evenly press the tape against the surface of the coating. Remove the tape with one quick motion and examine the surface for damage to the intercoat (between polyurethane topcoat and primer) or surface adhesion. If paint shows lack of adhesion, it shall be removed and reapplied, or repaired, and re-inspected.

6.0 STORAGE

6.1 Storage Stability

Storage stability shall be in accordance with manufacturers’ technical data sheet.

6.2 Detail parts shall be stored in accordance with A-10 specification Z-P801 so as to prevent damage and soiling.