SOW Attachment C_HC-144 Vendor Composite Repair Guidnace Reference updated 9 24 2020.docx

Attachment C 200002.D

DRAFT

(09-24-20)

1 GENERAL COMPOSITE REPAIR REFERENCES

REFERENCES:

AFTO TO 1-1-690

HC-144 000ACL.0

SRM-100 Nose Radome CMM

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NONE

CONSUMABLES:

NONE

A. Due to limited access to OEM publications and information restrictions available to vendors, the USCG desires to have all MRS general aerospace composite repairs performed IAW General Advanced Composite Repair Processes Manual TO 1-1-690.

B. The applicable Authorized Chemical List (ACL) shall be referenced as required and utilized for all composite repairs:

HC-144 000ACL.0

2 CONDUCTIVE COATINGS

REFERENCES:

ALC DRAWING 1100-11-1

AFTO TO 1-1-690

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NONE

CONSUMABLES:

10P2-3/EC-110, MIL-SPEC BMS10-21 TYPE III, Conductive Coating A. All composite panels not containing wire screen/mesh shall include conductive coating P/N 10P2-3/EC-110, MIL-SPEC BMS10-21 Type III as a part of the finish process.

3 PRIMER

REFERENCES:

ALC DRAWING 1100-11-1

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NONE

CONSUMABLES:

MIL-PRF-23377, TYPE 1, CLASS C2, Epoxy Primer MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer A. All bare metal shall be primed using epoxy primer MIL-PRF-23377, TYPE I, CLASS C2.

B. Composite panels shall be primed using epoxy primer MIL-PRF-23377, TYPE I, CLASS N.

4 SEALANT

REFERENCES:

ALC DRAWING 1100-11-1

HC-144 000ACL.0

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NONE

CONSUMABLES:

PR-1782, Polysulfide Sealant A. All Polysulfide Resin sealant shall be non-chromate and meet the specs of PR-1782.

5 FINISH WASHERS

REFERENCES:

CGTO 1C-144A-4

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NAS1169-DD-10L Aluminum Finnish Washer

CONSUMABLES:

NONE

A. Finish washers shall be P/N NAS1169-DD-10L and reamed to fastener fit as required.

6 TOP COVER MODIFICATION

REFERENCES:

AFTO TO 1-1-690

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NONE

CONSUMABLES:

MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer EA9394, Epoxy Paste Adhesive 7781 Fiberglass 120 Fiberglass Acetone Isopropyl Alcohol Aluminum Oxide 180 and 280 Grit Abrasive A. Top Cover P/N 35-22817-0003 may require repair and/or modification/alteration due to a hot air system clamp orientation as follows:

The Top Cover is considered secondary structure and is not FCBS according to EOM SRM.

• This alteration to the Top Cover restores the finishes using repair concepts equivalent to the USCG requirements and industry standards IAW General Advanced Composite Repair Processes Manual TO 1-1-690.

• This alteration uses materials equivalent to HC-144 000ACL.0.

• The repair does not appreciably affect the weight, balance, structural strength, performance, flight characteristics or other qualities affecting the aircraft airworthiness.

• FAR 43 Appendix A states that major repairs are: “Repairs to the following parts of an airframe and repairs of the following types involving the strengthening, reinforcing splicing and manufacturing of primary structural members or their replacement, when replacement is by fabrication such as riveting or welding, are airframe major repairs.”

• Since this alteration is accomplished to secondary structure, this MOD is considered minor.

7 REPLACING BONDED WASHERS (Without Mesh)

REFERENCES:

AFTO TO 1-1-690

HC-144 000ACL.0

TOOL/TEST EQUIPMENT:

NONE

EXPENDABLES:

NAS1169-DD-10L Aluminum Finnish Washer

CONSUMABLES:

MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer 10P2-3/EC-110, MIL-SPEC BMS10-21 TYPE III, Conductive Coating ALODINE 1200S, Conversion Coating HYSOL 9309.3NA, Epoxy Paste Adhesive

Acetone Isopropyl Alcohol Aluminum Oxide 180 and 280 Grit Abrasive

A. REPLACE WASHERS WITHOUT MESH

1. Clean parts per AFTO 1-1-690.

2. Remove paint with aluminum oxide paper 180-grit or finer.

3. If required, repair damaged composite per AFTO 1-1-690

4. Remove all washers from panel.

5. Prep back sides of washers by abrasive blasting using aluminum oxide media.

6. Apply Alodine 1200S to back side of washer after washer prep.

NOTE: Complete final reaming of washer diameter to .261 (-.004 or +.001) and apply Alodine 1200S to hole per manufacturer’s instructions.

Only for PN’s: 35-22817-xxxx and 35-22839-xxxx **For PN’s 35-22839-xxxx, ream only upper aft washers and bottom aft OB washer.

7. Clean the faying surfaces with acetone.

8. Prepare Hysol 9309.3NA per manufacturer’s instructions.

9. Apply a thin layer of adhesive (Hysol 9309.3NA) on the two faying surfaces.

10. Install washers PN NAS1169-DD-10L.

11. Clamp the installed washers in place with just enough pressure to ensure it holds its position during the adhesive cure.

12. Remove excess adhesive by wiping with a clean cloth.

13. Cure adhesive per manufacturer’s instructions.

14. Remove clamping and remove excessive adhesive in countersink with scotch brite.

15. Apply Alodine 1200S to exposed washer metal.

16. Clean panel surface with acetone before refinishing.

8 REPLACE WAHSERS WITH MESH

REFERENCES:

HC-144 000ACL.0

CGTO 1C-144A-3

AFTO TO 1-1-690

TOOL/TEST EQUIPMENT:

Electrical Resistance Meter (Ohmmeter)

EXPENDABLES:

NAS1169-DD-10L Aluminum Finnish Washer RR-W-360A, Aluminum Wire Mesh

CONSUMABLES:

PR-1782, Polysulfide Sealant MIL-PRF-23377, TYPE 1, CLASS C2, Epoxy Primer MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer 10P2-3/EC-110, MIL-SPEC BMS10-21 TYPE III, Conductive Coating ALODINE 1200S, Conversion Coating EA9396, or EC-2216, Epoxy Paste Adhesive Acetone Isopropyl Alcohol Aluminum Oxide 180 and 280 Grit Abrasive

A. REPALCE WASHERS WITH MESH

1. Clean parts per AFTO 1-1-690.

2. Remove paint with aluminum oxide paper 180-grit or finer.

3. Remove washers from panel.

4. Pry up edges of mesh and peel from part.

5. Remove adhesive from area where mesh was removed by abrading with 180-grit paper.

6. If required, repair damaged composite per AFTO 1-1-690.

7. Cut replacement section of aluminum wire mesh (RR-W-360A).

8. Clean replacement aluminum wire mesh by abrading with 280-grit aluminum oxide abrasive paper until bright metallic luster appears (both sides).

9. Prepare Hysol EA 9396 or Epocast 50A per manufacturer’s instructions.

10. Apply a thin layer of mixed epoxy resin to repair area.

11. Press aluminum wire mesh into epoxy resin.

12. Vacuum bag and cure per manufacturer’s instructions.

Drill fastener holes in mesh to a diameter .192 (+.03/-0.00).

NOTE: Complete final reaming of mesh diameter to .261 (-.004 or +.001) and apply Alodine 1200S to hole per manufacturer’s instructions.

Only for PN’s: 35-13656-xxxx, 35-13659-xxxx, 35-13664-xxxx, 35-13666-xxxx, 35-22842-xxxx, 95-21160-xxxx **For PN’s 95-21160-xxxx ream all holes except for 4ea holes at core cutout.

13. In area of washer replacement lightly abrade the aluminum wire mesh with 180-grit aluminum oxide abrasive paper until a bright metallic luster appears.

14. Prep back sides of washers by abrasive blasting using aluminum oxide media.

15. Apply Alodine 1200S to back side of washer after washer prep.

9 COUNTERBORING KEVLAR ALLOWING CLEARANCE FOR FASTENER RETAINING LOCK RINGS

REFERENCES:

HC-144 000ACL.0

CGTO 1C-144A-3

AFTO TO 1-1-690

TOOL/TEST EQUIPMENT:

Piloted 10.5mm, Carbide Tip Counter bore Cutter

EXPENDABLES:

CA18203, Retaining Ring

CONSUMABLES:

PR-1782, Polysulfide Sealant MIL-PRF-23377, TYPE 1, CLASS C2, Epoxy Primer MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer 10P2-3/EC-110, MIL-SPEC BMS10-21 TYPE III, Conductive Coating EA9396, or EC-2216, Epoxy Paste Adhesive Acetone Isopropyl Alcohol Aluminum Oxide 180 and 280 Grit Abrasive

A. COUNTERBORING KEVLAR ALLOWING CLEARANCE FOR FASTENER RETAINING LOCK RINGS

1. Inspect the composite area surrounding the hole to be counterbored for damage.

2. Repair any damage found IAW AFTO 1-1-690. Redrill each hole as required.

3. Clean the area around the hole to be counterbored using isopropyl alcohol and wipe dry with a clean cloth.

4. Using a 10.5mm diameter counterbore, cut away the material surrounding the hole to a depth of approximately 0.8mm-1.1mm. A CA18203 lock ring should fit flush with, or slightly lower than the outer surface after counterboring. Use care not to bore through the outer skin layers. NOTE: Using a carbide or HSS counterbore is recommended. Positive rake angles and helix flutes can reduce fraying. High RPM and low feed rates should be used. Use a microstop when able for consistent depth over multiple counterbores.

5. 5. Remove any dust or debris with light compressed air or by vacuuming.

6. Mix and prepare EA9396, 50A or EC-2216 per the manufacturer’s recommended procedures.

7. Apply the adhesive to the counterbored area, ensuring complete coverage of all fibers. Wipe away any excess adhesive around the counterbore.

8. Allow the adhesive to cure per the manufacturer’s recommended instructions.

9. Using a 10.5mm diameter counterbore, cut away the cured adhesive filling the counterbored area. The depth of the cut should be slightly less, approximately 0.2mm, than the original counterbore in step 4. It is recommended to use a slower RPM for a less aggressive cut during this step. NOTE: Grinding stones may produce a smoother finish and may be used for this step instead of a counterbore. Using water while grinding may reduce fraying.

10. Wipe away any dust or debris using isopropyl alcohol.

11. Apply primer as required IAW ACE EO HC-144-005.

12. Inspect the counterbore for surface roughness or frayed Kelvar. If excessive irregularities exist, repeat steps 6-10. See Figure 1 below for examples.

Using a CA18203 lock ring, perform a final depth inspection of the counterbore. The lock ring should sit flush with, or slightly lower than the outer surface.

10 ARMPIT PANEL ACCESS DOOR MODIFICATION

REFERENCES:

HC-144 000ACL.0

ALC Drawing 1100-53-14

AFTO TO 1-1-690

TOOL/TEST EQUIPMENT:

Piloted 10.5mm, Carbide Tip Counter bore Cutter 1100-53-14-3 Flange Template

EXPENDABLES:

CA18203, Retaining Ring CA18112-2TS Stud CA18157 Receptacle, Livelock GSC-21-95204-011 Skyflex Seal Tape MS20426AD3-xx Rivet NAS1169DD10L Washer

CONSUMABLES:

EA9396 Epoxy Paste Adhesive EA9394 Epoxy Paste Adhesive T20 Glass Bubbles EA9309.3NA Epoxy Paste Adhesive 7781 Fiberglass Alodine 1200S GSC-21-95204-011 Skyflex Seal Tape RTV-732 Silicone Sealant Acetone Isopropyl Alcohol MIL-PRF-23377, TYPE 1, CLASS N, Epoxy Primer 10P2-3/EC-110, MIL-SPEC BMS10-21 TYPE III, Conductive Coating Aluminum Oxide and 220 - 320 Grit Abrasive

A. REINFORCE ACCESS PANEL

NOTE: This procedure may require support tooling (splash molds created via standard aviation tooling/pattern procedure). Use tool PN AC-HC144-T-01-LH or AC-HC144-T-01-RH. Utilize locally created Mylar stencils to help establish dimensions.

1. Use Mylar stencils Ref ALC Drawing 1100-53-14 to establish where plunge cuts into core should begin on back of panel and verify with inspector. Using grinding and sanding techniques, remove core from indicated area. **Ensure honeycomb intended to be beveled is not removed.**

2. Bevel all exposed vertical faces of exposed honeycomb approximately 1” in the indicated direction per ALC Drawing 1100-53-14.

3. Prep layup area for fiberglass installation.

4. Cut a piece of 7781 fiberglass sufficiently large enough to create 6 plies to cover the location for the access panel and the exposed core. Overlap by ≥.25”.

5. Lay the dry fabric on top of a sheet of bagging film.

6. Mix EA9396 resin per the manufacturer’s data.

7. Add resin to the top of the fabric and squeegee it through. Be sure to fully impregnate the fabric. Squeegee excess resin outward.

8. Place the reinforcement plies in the intended area while minimizing bridging. First ply will terminate approximately at end of exposed core and begin of ≥.25” with subsequent plies.

9. Install a vacuum bag and evacuate to a minimum of 23” Hg.

10. Allow the resin to cure per the manufacturer’s data.

11. After the resin cures, remove all equipment and materials. Sand the area smooth with 220 – 320 grit sandpaper.

12. Clean all sanding dust using an acetone or isopropyl alcohol. Dry with a clean, lint-free cloth.

B. PREP and CUT ACCESS PANEL

1. Ensure panel is sufficiently supported prior to performing modification.

2. Vacuum panel to remove dust and debris. Wipe the surface with a lint-free cloth and acetone or isopropyl alcohol.

3. Measure and mark the cutout area for the access panel using dimensions per ALC Drawing 1100-53-14. Corners should have approximately 3 inch radius.

4. Cut access panel out using jigsaw (or similar) and ensure minimal material loss.

C. CREATE ACCESS PANEL FLANGE

Note: This procedure may require support tooling (splash molds created via standard aviation tooling/pattern procedure). Use tool PN AC-HC144-T-01-LH or AC-HC144-T-01-RH. A prefabricated flange can be created using the tool and bonded to panel using EA9394. Otherwise, utilize the back of the panel as a pattern for creating flange.

Note: Access panel flange ply stack should be at minimum 150% of the thinnest section of the armpit panel solid laminate area.

Note: Ply orientation should complement the original armpit panel.

1. Cut a piece of 7781 fiberglass sufficiently large enough to create plies for the flange.

2. Lay the dry fabric on top of a sheet of bagging film.

3. Mix EA9396 resin per the manufacturer’s data.

4. Add resin to the top of the fabric and squeegee it through. Be sure to fully impregnate the fabric. Squeegee excess resin outward.

5. Cut 9 plies of 7781 fiberglass to create flange plies. The number of plies may be adjusted to achieve the 150% thickness requirement noted above.

6. Using support tooling, place the flange plies on the backside of the pattern (tool or panel).

7. Install a vacuum bag and evacuate to a minimum of 23” Hg.

8. Allow the resin to cure per the manufacturer’s data.

9. After the resin cures, remove all equipment and materials. Sand the area smooth with 220 – 320 grit sandpaper.

D. INSTALL FLANGE ON PANEL

1. Drill size .125” holes between each planned fastener location on the flange spaced approximately .25”-.75” from outer edge of flange. These will be used to secure flange to panel during curing.

2. Align flange in desired location on panel and pick up the same hole pattern on both flange and panel. Ensure to properly secure the flange throughout drilling process to avoid shifting/misalignment.

3. Apply EA9394 to both the flange and panel.

4. Place flange on panel and align hole locations. Use Cleco fasteners (or similar hardware) in drilled holes to secure flange to panel during curing process.

5. Clean all excess squeeze out of EA9394 before cure.

6. Create a fillet seal on the outer edge of the flange on the back face of the panel with EA9394.

7. Ensure the area of the flange exposed on the outer face of the panel (where the seal will be placed) is totally free of resin/debris.

8. Allow the resin to cure per the manufacturer’s data.

9. Fill holes created for Cleco fasteners with EA9396 and milled/chopped fiber.

10. After all resins cure, sand area smooth with 220 – 320 grit sandpaper.

E. DRILL FASTENER HOLES, ALIGN PANEL and INSTALL BONDED WASHERS

1. Using access panel template PN 1100-53-14-3, locate and drill holes for receptacles on the flange ONLY (not access panel) with size 11 drill bit utilizing a drill bushing.

2. 2. Line up the access panel in its proper location:

a. The maximum misalignment allowed between access panels and the surrounding skin surfaces (above or below) is 0.031 inches for straight edge and 0.059 inches for chamfered edge.

Note: Take the seal thickness into account when placing panel.

b. A minimum clearance of 0.039 inches must exist between an access panel and the surrounding skin to allow for removal and installation. The clearance must not exceed 0.118 inches.

Note: Edges of access panel may need to be trimmed to ensure proper fit.

3. After proper panel alignment, pick up fastener holes from flange to access panel with a size 11 drill bit. Drill holes and install Cleco fasteners (or similar) one at a time to minimize slippage and maintain required clearance.

4. Drill/expand receptacle hole sizes wide enough to install threaded barrels. Install barrels tight with receptacle to ensure alignment of panel and flange.

5. Locate and drill holes for receptacle rivet PN MS20426AD3-xx and install rivets with head of rivet on outboard face of flange.

6. Countersink outboard holes in access panel as required to accommodate NAS1169DD10L washers.

7. Install bonded washer PN NAS1169DD10L IAW STEPS 5 and 7.

8. Complete final reaming of washer diameter to .261 (-.004 or +.001) and apply Alodine 1200S to hole per manufacturer’s instructions.

F. COUNTERBORE as NEEDED

1. Counterbore and refinish all required holes IAW STEP 9.

G. ASSEMBLE

1. Install Skyflex Seal Tape PN GSC-21-95204-011 to the flange.

Note: It is permissible to use RTV-732 to securely bond the seal.

2. Install access panel using Stud PN CA18112-xTS and Retainer PN CA18203).

H. REFINISH

1. Refinish IAW STEPS 2 and 3.

I. QA FINAL and PART NUMBER /NSN CHANGE

1. QC will verify all alignment dimensions are correct.

2. When modification is complete, the part numbers and NSNs will be changed on the part tag and the 8130 to reflect the following:

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