TUB SHELL (FUSELAGE) INSPECTION PANELS, MODIFICATION

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TUB SHELL (FUSELAGE) INSPECTION PANELS, MODIFICATION TO INSTALL

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TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. * Supersedes Technical Bulletetin TB900−003, dated 11 November 1997. Revised to correct material manufacture errors. TUB SHELL (FUSELAGE) INSPECTION PANELS, MODIFICATION TO INSTALL 1. PLANNING INFORMATION A. Aircraft Affected: All McDonnell Douglas Helicopter Systems (MDHS) MD900 helicopters. B. Assembly/Components Affected By This Bulletin: Fuselage tub shell assembly 900F2307019. C. Reason: Installation of access panels in fuselage tub shell eliminates the requirement to remove the cabin floor for inspections. D. Description: (Ref. Figure 1) Procedures in this Bulletin provide owners and operators with procedures to add three (3) access panels to the fuselage tub assembly. These access panels provide a means of inspecting the outboard side of the keel beams, heat defog system tubing and fire detection cable, vapor shroud components forward of station 230.50, area wire harness installations, and structural components under the cabin floor and outboard of the keel beams. These access panels will also provide some limited access for minor maintenance tasks. The owner or operator has the option of installing either a graphite/epoxy or a stainless steel inner doubler, using seal in place sealant or rubber seal, and quarter turn fasteners or screws. This modification is separated into three parts to allow the operator the option of installing any of the three access doors as separate maintenance tasks. The operator may also elect to install only one, two, or all three doors. There are no limitations as to door installation sequence. Part A installs the access door to the right side of the aircraft at fuselage station 213.5. Part B installs the access door to the left side of the aircraft at fuselage station 213.5. Part C installs the access door to the left side of the aircraft at fuselage station 172.0. E. Compliance At owner/operator option. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 1 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. WL 106 FLOOR STA 155.5 FRAME WL 106 FLOOR STA 155.5 FRAME STA 230.5 FRAME EXISTING FUEL DRAIN ACCESS PANEL NEW ACCESS PANEL NEW ACCESS PANEL NEW ACCESS PANEL STA 230.5 FRAME 9B53.068 160 180 190 200 210 220 220 200 210 180 190 160 Figure 1. Access Panel Locations TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 2 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. F. Requirements of Accomplishment: This modification is only to be accomplished by persons qualified in composite repair at a properly equipped facility. G. Classification: Compliance with this Bulletin is a major alteration. H. FAA Approval: The technical design aspects of this Bulletin are FAA Approved. I. Manpower: The man−hour estimation is based on a non−modified aircraft with a standard interior. If being accomplished as a stand alone maintenance function, twenty (20) man−hours for each panel. If being accomplished in conjunction with other maintenance that requires access to the modification area, nineteen (19) man−hours for each panel. J. Interchangeability: None K. Warranty Policy: N/A L. Tooling: N/A M. Weight and Balance: Part A 1.0 pound (0.454 Kg) for graphite/epoxy inner doubler and 1.6 pound (0.726 Kg) for stainless steel inner doubler at FS 213.5, BL 30.4, WL 92.9. Part B 1.0 pound (0.454 Kg) for graphite/epoxy inner doubler and 1.6 pound (0.726 Kg) for stainless steel inner doubler at FS 213.5, BL −30.4, WL 92.9. Part C 1.0 pound (0.454 Kg) for graphite/epoxy inner doubler and 1.6 pound (0.726 Kg) for stainless steel inner doubler at FS 172.0, BL −30.4, WL 92.9. N. Electrical Load Data: N/A O. Other Publications Affected: N/A P. Disposition of Parts Removed N/A Q. Points of Contact For further assistance, contact your local MDHI Field Service Representative (refer to the latest revision of the !At Your Service" handbook for address and telephone numbers) or contact the Field Service Department at MDHI, Mesa, Arizona. Telephone 1−800−388−3378 or (480) 346−6387. DATAFAX: (480) 346−6813. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 3 OF 32 NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. R. Required Supplies and Equipment: The parts and supplies listed are for installation of all three access doors. If the operator is installing less than three, adjust the quantities accordingly. REPLACEMENT PARTS/SUPPLIES Nomenclature Part No. Qty. Source Aluminum Sheet, 2024T3 0.040 in. (1.02 mm), Aluminum Clad QQ–A–250/5 T3 (Boeing Spec RM000160) 24 X 24 in. (61 X 61 cm) MDHI or Commercial Stainless Steel Sheet, 301 Cres, 1/4 Hard, 2B, 0.025 in (0.64 mm) (1) MIL–S–5059 AMS 5517J (Boeing Spec RM007058) 26 X 51 in. (66.0 X 129.6 cm) MDHI or Commercial Receptacle, Quarter Turn (2) HS4427–3 Camloc Number 5R2–3 24 MDHI or Commercial Nutplate (2) MS21060L3 24 MDHI or Commercial Rivet, Blind, Nonstructural, 100 Degree Flush MS20605R3W2 48 MDHI or Commercial Stud Fastener, Quarter Turn (3) HS4437–6 Camloc Number 5S15–5 24 MDHI or Commercial Screw, Machine, Pan Head (3) MS27039C1–08 24 MDHI or Commercial Washer, Retaining, Quarter Turn (4) HS4429–2 24 MDHI or Commercial Epoxy Primer MIL–P–23377, Type 1, Class1 or Equivalent (Boeing Spec RM012212) AR Commercial Screw, Machine, Pan Head NAS603–8P 6 MDHI or Commercial Washer, Flat AN960JD10L 6 MDHI or Commercial Washer, Flat AN960–10L 6 MDHI or Commercial Washer, Lock–Spring MS35338–43 6 MDHI or Commercial Nut, Self Locking MS21042L3 3 MDHI or Commercial Jumper Assembly, Electrical Bonding (5) MS25083–5BB16 or M83413/8–A016BB 3 MDHI or Commercial Jumper Assembly, Electrical Bonding, Quick Disconnect (5) MS25083–3BB16 or M83413/8–D016BB 3 MDHI or Commercial TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 4 OF 32 NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. REPLACEMENT PARTS/SUPPLIES (Cont.) Nomenclature Source Qty. Part No. Chemical Film Iridite 14–2 AR Richardson Company Allied–Kelite Products Division 2400 E. Devon Ave. Des Plains, IL. Solvent, Blended Desoclean 45 or Equivalent AR DeSoto Aerospace Coatings, Inc. Berkeley, CA. (818) 549–7823 Sealant, Fuel Resistant MIL–S–8802, Type 2, Class B1/2 AR Coast Proseal Compton, CA. Epoxy Resin, Structural HMS 16–1115 T3 Redux 501 (Boeing Spec RM011312) AR Ciba–Geigy Corp. E. Lansing, MI. (800) 367–8793 Epoxy Fairing Compound HMS 16–1068 CL6 RP1257–3 or EA960F AR AR Ciba–Geigy Corp. E. Lansing, MI. (800) 367–8793 Dexter Adhesives Pittsburgh, CA. (510) 458–8217 Filler, Epoxy Adhesive, Non–sagging HMS 16–1069 CL12 EA9321 (Boeing Spec RM010246) or BR 95 AR AR Dexter Adhesives Pittsburgh, CA. (510) 458–8217 Cytec Inc. Havre De Grace, MD (410) 939–1910 Plain Weave Graphite Fabric, 5.6 oz./sq. yd. Fiberite W–5–322 3 sq. yd. (2.5 sq. M) Fiberite Corp. Greenville, TX (903) 457–8500 Fabric, E Glass HMS 16–1267/1601 MIL–C–9084 T3 C2 1.5 sq. yd. (1.25 sq. M) MDHI or Commercial Shielding, Expanded Aluminum Foil HMS 16–1255 Type 1 (Boeing Spec RM012757) 1.5 sq. yd. (1.25 sq. M) MDHI or Commercial Fluorosilicone Release Compound REN RP 79–2 or Equivalent 1 Ciba–Geigy Corp. E. Lansing, MI. (800) 367–8793 TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 5 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. REPLACEMENT PARTS/SUPPLIES (Cont.) Nomenclature Source Qty. Part No. Primer Uroprime 1320S or Equivalent AR Dupont Co. Lionville, PA (800) 338–7668 Topcoat To Match Aircraft AR Commercial Strip, Silicone Rubber MIL–R–6130 T2, GR A, SOFT 0.125 X 1.0 in. (3.18 X 25.4 mm) 90 in. (228.6 cm) Commercial Adhesive/Sealant, Silicone HMS 16–1118 T1 C1 Silastic 732 (White) (Boeing Spec RM002212) or RTV 157 (Black) (Boeing Spec RM011172) AR Dow Corning Midland, MI (517) 496–5900 General Electric Co. Waterford, NY (518) 237–3330 Respirator, Safety Glasses, Gloves, etc. AR Commercial Vacuum Pump Capable of Supplying 20–29 inches HG (63–91 kPa) 1 Commercial Vacuum Bagging Materials AR Commercial Tape, Flashbreaker HMS 20–1267/1520, /1521, /1522, /1650, /1693 (Boeing Spec 2.0 in. RM0154244 or Equivalent AR Airtech International, INC Carson, CA (310) 603–9683 Gram Scale For Weighing Epoxy 1 Commercial Mixing Cups, Mixing Sticks, Plastic Squeegee, etc. AR Commercial 90 Degree High Speed Die Grinder 1 Commercial Rotary File, Two (2) and Three (3) Inch Sanding Mandrils, and Sanding Disks (180 Grit and Finer) AR Commercial Drill Motor 1 Commercial TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 6 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. REPLACEMENT PARTS/SUPPLIES (Cont.) Nomenclature Source Qty. Part No. Drum Sander, 1 and 2 Inch (2.5 and 5cm) Diameter (180 Grit and Finer) 1 Commercial Drill, High Speed Number Forty (40) 2 Commercial Drill, Dagger Number Forty (40) 2 Commercial Drill, High Speed Number Two (2) 2 Commercial Drill, High Speed Number Eight (8) 1 Commercial Drill, Dagger Number Two (2) 2 Commercial Sandpaper, Non Aluminum Oxide 180 Grit and Finer AR Commercial NOTES: (1) Either graphite/epoxy or stainless steel is required for inner doublers. (2) Either quarter turn receptacles or nutplates are required for panel attachment. (3) Either quarter turn fasteners or screws are required for panel attachment. (4) Retaining washer is not required if screws are used for panel attachment. (5) Either bonding jumper may be used. 2. ACCOMPLISHMENT INSTRUCTIONS Accomplishment instructions are for one access panel installation, and are applicable to all three access panel locations A. Access Modification Area Either the left outboard cabin floor panel (AL 165), or right outboard cabin floor panel (AR 165) may be removed individually without defueling the aircraft. (1). Remove left outboard cabin floor panel (AL 165), or right outboard cabin floor panel (AR 165) (Ref. CSP−900RMM−2 Section 06−00−00). B. Mark Access Panel Locations. (Ref. Figure 2 and Figure 3) (1). Fabricate access hole outer skin cutout template from any suitable stable material to the cutout dimensions. (2). Mark FS 172.0 on the inside and outside of the Tub Assembly, LH only. (3). Mark FS 213.5 on the inside and outside of the Tub Assembly, LH and RH. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 7 OF 32 NOTE: NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. (4). Measure down from the upper edge of the fuselage tub skin at WL 106.00 13.2 inches (33.53 cm) and mark WL reference on fuselage skin. (5). Align the template center with the station and waterline mark, and tape into position. Mark with reference marks outside area of doubler ply installation. (6). Using the template, mark the location of the panel cutout. C. Prepare Outer Graphite/Epoxy Laminates For Doubler Ply Installation
Do not sand into or expose Astrostrike expanded aluminum foil lightening protecA tion. A layer of primer must remain to insulate the expanded aluminum foil from the graphite/epoxy to prevent corrosion.
Around the outer edges of the doubler installation, carefully sand 1.5 inches (3.81 cm) of the surface to expose the Astrostrike expanded aluminum foil lightening protecA tion. This is required to ensure electrical continuity of the foil.
Do not sand into or expose graphite/epoxy fibers.
Do not use aluminum oxide abrasives on graphite/epoxy materials. Protective Equipment (1). Prepare outer skins for bonding by light sanding to remove gloss and topcoat using 180 grit sandpaper or nylon pad. Solvent Cleaner (C429) (2). Clean area with Desoclean 45 or equivalent blended solvent and allow to air dry for at least fifteen (15) minutes. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 8 OF 32 NOTE: CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 900.. 9B53.075 5.5 IN (13.97 cm) TYP 0.50 IN R (12.7 mm) TYP 2.75 IN (6.99 cm) 2.75 IN (6.99 cm) WL REFERENCE ALIGNMENT MARK C L FS 172.0 AND FS 213.5 ALIGNMENT MARK 1.00 IN (2.54 cm) Figure 2. Access Hole Outer Skin Cutout Template TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 9 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. D. Prepare Outer Doubler Plies (Ref. Table 1 and Figure 3) Prepare and install doubler plies at only one outer location at a time. (1). Cut enough doubler ply material to fabricate the required doublers with an additional 1.0 inch (2.54cm) outside dimension on each doubler. Adhesive, Epoxy Paste (C409) Do not machine mix epoxy as it will cause air to be included in the epoxy which will reduce its strength. (2). Mix epoxy thoroughly by weight in accordance with Table 1. Table 1. Epoxy Resin Mix and Cure Material Mix Ratio Cure in Hours Part A Part B Redux 501 100 15
1 12 Minimum @ Room Temperature Followed by 2
1/2 @ 180° F
10° F Do not impregnate Astrostrike expanded aluminum foil with epoxy. Sufficient epoxy is included in the other doubler plies to ensure an adequate bond. (3). Impregnate doubler plies with 0.28
0.02 oz. (7.94g
0.57g) epoxy resin per sq. ft. (929 sq. cm) of fabric. (a). Mark a piece of nonporous release film, approximately 3.00 inches (7.62 cm) larger circumference than the doubler ply with the finished dimension of the doubler ply. (b). Brush a thin coat of epoxy resin, the size of the doubler ply, onto the nonporous release film on the opposite side from the dimensional mark of the doubler ply. (c). Place the doubler ply onto the epoxy resin, apply another thin coat of resin, and cover with another piece of nonporous release film. (d). Using a plastic squeegee, carefully work the resin into the fabric. Work excess resin outboard of the fabric. (4). Cut the doubler ply and nonporous release film to the finished dimension marked on the nonporous release film. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 10 OF 32 CAUTION CAUTION NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. E. Install Outer Doubler Plies (Ref. Figure 3) (1). Brush a very thin coat of epoxy onto the aircraft skin over the entire area of the doubler installation. (2). Remove nonporous release film from both sides of smallest doubler ply and place centered on access panel location on aircraft skin. On the outside of the fuselage install the smaller fiberglass ply between the outer layer of graphite fabric and the expanded aluminum foil. (3). Continue installing plies on aircraft skin in order (smallest to largest). When using the elevated temperature cure, it is necessary to monitor the temperature with a calibrated thermocouple. (4). Cure doubler installation. (a). Install peel ply, bleeder ply, nonporous release film, thermocouple, breather cloth, heat pad, vacuum bag sealing putty, vacuum bag, and vacuum port. (b). Apply 20.29 inches HG (63.91 kPa) to vacuum bag and maintain a minimum of 20 inches HG (63 kPa) during cure. (c). Cure per Table 1. Protective Equipment (5). Clean up excess resin with 180 grit (or finer) sandpaper. Solvent Cleaner (C429) (6). Wipe surfaces with Desoclean 45 or equivalent. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 11 OF 32 CAUTION CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 4X 0.50 IN RAD (12.7 mm) VIEW LOOKING INBOARD RH LH OPPOSITE FS 172.00 OR FS 213.50 FS 230.50 FS 213.50 5.50 IN (13.97 cm) FS 169.25 OR 210.75 OR 216.25 900F2307001 9B53.074.1 PLY ORIENTATION 4 3 2 1 0 / 90 + / .45 0 / 90 + / .45 VIEW LOOKING DOWN RH LH OPPOSITE FS 186.00 0° +45° 90° .45° VIEW LOOKING UP 6 5 OPTIONAL OPTIONAL 0.50 RAD (8 PL) CL EXISTING ACCESS PANEL BONDING JUMPER ATTACHMENT 7 (8 PL) FS 172.0 7 (8 PL) 0.75 IN TYP (19.1 mm) Figure 3. Access Panel Installation (Sheet 1 of 2) TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 12 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 4.75 IN (6) (12.07 cm) 13.20 IN (33.53 cm) TRUE 1.5 IN (3.81 cm) 900F2307001 9B53.074.2 2.00 IN (2) (5.08 cm) 1.75 IN (1) (4.45 cm) 4.25 IN (5) (10.16 cm) 3.25 IN (4) (7.62 cm) 2.25 IN (3) (5.72 cm) 5.50 IN (16.51 cm) TRUE 4 3 2 1 1.00 IN (2.54 cm) TYP KEELBEAM REFERENCE 3.00 IN (7.62 cm) (PARALLEL TO AIRCRAFT SKIN) 5 0.25 IN (6.35 mm) ROTATED 90° CW 1.75 IN (4.45 cm) 2.00 IN (5.08 cm) 2.25 IN (5.72 cm) 4.00 IN (10.16 cm) WL REFERENCE TOP EDGE OF BONDED TUB SKIN 5 6 2.5 IN (6.35 cm) 2.00 IN (2) (5.08 cm) 1.75 IN (1) (4.45 cm) 4.25 IN (5) (10.16 cm) 3.25 IN (4) (7.62 cm) 2.25 IN (3) (5.72 cm) 1.00 IN (2.54 cm) ROTATED 90° CW 4.75 IN (6) (12.07 cm) GRAPHITE/EPOXY DOUBLER STAINLESS STEEL DOUBLER 8 (0.025 IN) Figure 3. Access Panel Installation (Sheet 2 of 2) TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 13 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Legend (Ref. Figure 3) 1. PLAIN WEAVE GRAPHITE FABRIC 2. PLAIN WEAVE GRAPHITE FABRIC 3. PLAIN WEAVE GRAPHITE FABRIC 4. PLAIN WEAVE GRAPHITE FABRIC 5. FABRIC, E GLASS 6. SHIELDING, EXPANDED ALUMINUM FOIL 7. QUARTER TURN RECEPTACLE OR NUTPLATE 8. STAINLESS STEEL DOUBLER F. Remove The Graphite/Epoxy Plies and Core Material. (Ref. Figure 2, Figure 3, and Figure 4) (1). Using the outside skin cutout template, mark the outside of the aircraft skin with the area to be cut out for panel installation.
Use care not to damage any graphite/epoxy skin surfaces.
Protect the surrounding structural components from tool contact with suitable shieldA ing (e.g. stainless steel sheet).
Do not use aluminum oxide abrasives on graphite/epoxy materials. When cutting graphite/epoxy, leave an excess of 0.1 to 0.2 inch (2.5 to 5mm) material to be removed at a later step. Protective Equipment (2). Using a 90° high−speed die grinder with a rotary file, remove the outer layer of graphA ite/epoxy, honeycomb core, and inner layer of graphite/epoxy. (3). Fabricate access panel from aluminum sheet and roll to match fuselage contour. Do not drill holes at this time. (4). Using the access panel as a template, mark the final dimension of the epoxy filler. (5). Using a 90° high−speed die grinder with a rotary file, remove the inner layer of graphA ite/epoxy. (6). Carefully remove the honeycomb core. Remove core 1.0 inch (2.54 cm) beyond edge of inner graphite/epoxy laminates. (7). Using a 90° high−speed die grinder with a two (2) and three (3) inch disk sander attachment and 180 grit (or finer) disks, carefully remove any remaining honeycomb core (it is not necessary to remove all of the old epoxy used to bond the honeycomb core). TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 14 OF 32 CAUTION NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 900.. 9B53.073 7.0 IN (17.78 cm) TYP 0.50 IN RADIUS (12.7 mm) TYP SEAL REFERENCE 1.0 IN (2.54 cm) TYP 2.0 IN (5.08 cm) 1.5 IN (3.81 cm) BONDING JUMPER ATTACH 1.00 IN (2.54 cm) 0.40 IN (10.16 mm) TYP REFERENCE 0.40 IN (10.16 mm) TYP C L C L Figure 4. Access Panel TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 15 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. G. Fill Core Cavity With Filler. (Ref. Figure 5) Protective Equipment Drill all 0.063 inch (1.60mm) holes in inner graphite/epoxy laminate only. (1). Drill three (3) each 0.063 inch (1.60mm) holes at forward and aft edges of filler perimeter (adjacent to and in from outer mark to allow filler to completely fill cavity). (2). Drill two (2) each 0.063 inch (1.60mm) holes at outboard/upper edge of filler perimeter (adjacent to and in from outer mark to allow filler to completely fill cavity). (3). Vacuum area thoroughly and remove any loose core, chips, and dust. Solvent Cleaner (C429) (4). Wipe surfaces with Desoclean 45 or equivalent and allow to air dry for a minimum of fifteen (15) minutes. (5). Prepare epoxy filler and fill cavity. (Ref. Table 2) Adhesive, Epoxy (C411) Do not machine mix epoxy as it will cause air to be included in the epoxy which will reduce its strength. (a). Mix epoxy thoroughly by weight in accordance with Table 2. Start filling cavity at the bottom and tape the edge with flashbreaker release tape as the cavity fills up. As epoxy begins to extrude from the 0.063 inch (1.60mm) holes, tape holes closed to prevent epoxy from escaping the filled area. (b). Using a tongue depressor or equivalent, completely fill cavity and ensure that epoxy extrudes from all eight (8) 0.063 inch (1.60mm) holes. If using the elevated temperature cure, it is necessary to monitor the temperature with a calibrated thermocouple. (6). Cure filler in accordance with Table 2. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 16 OF 32 NOTE: CAUTION NOTE: CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Table 2. Epoxy Filler Mix and Cure Material Mix Ratio Cure in Hours Part A Part B EA 9321 2 1 24 @ Room Temperature or 2 @ 160° F
10° F BR 95 3 1 24 @ Room Temperature or 2 @ 160° F
10° F 0.063 IN (1.60 mm) TYPICAL HOLE LOCATION FOR EPOXY EXTRUSION 9B53.071 EPOXY FILLER Figure 5. Cross Section of Filler and Hole Relationship TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 17 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. H. Complete access holes (Ref. Figure 6) Protective Equipment (1). Using a drill motor and drum sander, remove the remaining portion of the outer layer of graphite/epoxy. (2). Fabricate the inner graphite/epoxy cutout template from any suitable stable material to the cutout dimensions. (3). Using the template, mark the final dimension of the inner layer or graphite/epoxy. (4). Using a drill motor and drum sander, chamfer inner graphite/epoxy and filler 45° . (5). Finish hole with 320 grit sandpaper. I. Prepare Inner Graphite/Epoxy Laminates For Doubler Installation Solvent Cleaner (C429) Protective Equipment
Do not sand into or expose graphite/epoxy fibers.
Do not use aluminum oxide abrasives on graphite/epoxy materials. (1). Prepare inner skins for bonding by light sanding to remove gloss using 180 grit sandpaA per or nylon pad. (2). Clean area with Desoclean 45 or equivalent blended solvent and allow to air dry for at least fifteen (15) minutes. J. If Using Graphite/Epoxy Laminates, Prepare Inner Doubler Plies (Ref. Figure 3 and Table 3) Prepare and install doubler plies at only one inner location at a time. Inner doubler plies are installed in strips with full width overlap in each corner. (1). Cut enough doubler ply material to fabricate the required doublers with an additional 1.0 inch (2.54cm) outside dimension on each doubler. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 18 OF 32 CAUTION CAUTION NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Adhesive, Epoxy Paste (C409) Do not machine mix epoxy as it will cause air to be included in the epoxy which will reduce its strength. (2). Mix epoxy thoroughly by weight in accordance with Table 3. Table 3. Epoxy Resin Mix and Cure Material Mix Ratio Cure in Hours Part A Part B Redux 501 100 15
1 12 Minimum @ Room Temperature Followed by 2
1/2 @ 180° F
10° F (3). Impregnate doubler plies with 0.28
0.02 oz. (7.94g
0.57g) epoxy resin per sq. ft. (929 sq. cm) of fabric. (a). Mark a piece of nonporous release film, approximately 3.00 inches (7.62 cm) larger circumference than the doubler ply with the finished dimension of the doubler ply. (b). Brush a thin coat of epoxy resin, the size of the doubler ply, onto the nonporous release film on the opposite side from the dimensional mark of the doubler ply. (c). Place the doubler ply onto the epoxy resin, apply another thin coat of resin, and cover with another piece of nonporous release film. (d). Using a plastic squeegee, carefully work the resin into the fabric. Work excess resin outboard of the fabric. (4). Cut the doubler ply and nonporous release film to the finished dimension marked on the nonporous release film. K. Install Inner Doubler Plies (Ref. Figure 3) (1). Brush a very thin coat of epoxy onto the aircraft skin over the entire area of the doubler installation. (2). Remove nonporous release film from both sides of smallest doubler ply and place centered on access panel location on aircraft skin. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 19 OF 32 CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. (3). Continue installing plies on aircraft skin in order (smallest to largest). When using the elevated temperature cure, it is necessary to monitor the temperature with a calibrated thermocouple. (4). Cure doubler installation. (a). Install peel ply, bleeder ply, nonporous release film, thermocouple, and suitable caul plate. (b). Apply clamps to ensure adequate compacting of plies during cure. (c). Cure per Table 3. Protective Equipment (5). Clean up excess resin with 180 grit (or finer) sandpaper. Solvent Cleaner (C429) (6). Wipe surfaces with Desoclean 45 or equivalent. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 20 OF 32 CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 900.. 9B53.070 7.5 IN (19.05 cm) TYP 0.50 IN R (12.7 mm) TYP 1.00 IN (2.54 cm) Figure 6. Inner Graphite/Epoxy Cutout Template TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 21 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. L. If Using Stainless Steel Inner Doubler (1). Install the inner fiberglass ply. (Ref. Procedure D. and E.) Fluorosilicone Compound (C222) Prior to covering access hole, coat access panel with mold release compound. (a). Using the access panel or other suitable material, cover outside of access hole. (b). Tape thoroughly with flashbreaker release tape and duct tape. (c). Prepare inner fiberglass doubler ply for installation. (d). Install inner fiberglass doubler ply. (e). After cure using a 90° die−grinder and rotary file, remove fiberglass doubler ply from inside of access hole (f). Finish with sandpaper 320 grit or finer. M. Fabricate and Install Stainless Steel Doubler (Ref. Figure 7) Protective Equipment (1). Cut doublers from stainless sheet and deburr. Doublers are installed with the overlap in the horizontal plane. (2). Roll doublers to match contour of aircraft skin. (3). Joggle doubler. (4). Prepare stainless doublers for bonding by light sanding to remove gloss using 180 grit sandpaper or nylon pad. Solvent Cleaner (C429) (5). Clean doublers with Desoclean 45 or equivalent blended solvent and allow to air dry for at least fifteen (15) minutes. Adhesive, Epoxy (C411) Do not machine mix epoxy as it will cause air to be included in the epoxy which will reduce its strength. (6). Mix epoxy thoroughly by weight in accordance with Table 4. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 22 OF 32 NOTE: NOTE: CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Table 4. Epoxy Filler Mix and Cure Material Mix Ratio Cure in Hours Part A Part B EA 9321 2 1 24 @ Room Temperature or 2 @ 160° F
10° F BR 95 3 1 24 @ Room Temperature or 2 @ 160° F
10° F (7). Brush a coat of epoxy onto the aircraft skin over the entire area of the doubler installaA tion. (8). Install the non−joggled doubler in the lower position and clamp to hold in place. (9). Brush a coat of epoxy onto the non−joggled doubler where the joggled doubler onerlays it. (10). Install the joggled doubler in the upper position and clamp in place. (11). Add sufficient clamps to ensure an adequate bond. (12). Clean up squeeze out and cure per Table 4. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 23 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. CL 2.50 IN (6.35 cm) 8.125 IN (20.64 cm) 2.50 IN (6.35 cm) 2.50 IN (6.35 cm) 7.25 IN (31.12 cm) 12.25 IN (31.12 cm) 9B53.088 JOGGLE 4.0 IN (10.16 cm) 2.0 IN (5.08 cm) Figure 7. Stainless Steel Doubler (Sheet 1 of 2) TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 24 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. CL 2.50 IN (6.35 cm) 8.125 IN (20.64 cm) 2.50 IN (6.35 cm) 2.50 IN (6.35 cm) 7.25 IN (31.12 cm) 12.25 IN (31.12 cm) 9B53.087 2.0 IN (5.08 cm) Figure 7. Stainless Steel Doubler (Sheet 2 of 2) TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 25 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. N. Fill and Fair Area (Ref. Table 5) Adhesive, Epoxy (C405) Do not machine mix epoxy as it will cause air to be included in the epoxy which will reduce its strength. (1). Mix epoxy fairing compound thoroughly by weight in accordance with Table 5. Table 5. Epoxy Fairing Compound Mix and Cure Material Mix Ratio Cure in Hours Part A Part B EA 960F 2 1 24 @ Room Temperature or 2 @ 160° F
10° F RP–1257–3 1 1 24 @ Room Temperature or 2 @ 160° F
10° F
If using the elevated temperature cure, it is necessary to monitor the temperature with a calibrated thermocouple.
Maximum thickness of fairing compound, primer, and top coat shall not exceed 7 mils in thickness. (2). Fill and fair doubler edges using epoxy fairing compound. (3). Cure epoxy fairing compound in accordance with Table 5.
Do not sand into or expose Astrostrike expanded aluminum foil lightening protecA tion.
Do not sand into or expose graphite/epoxy fibers.
Do not use aluminum oxide abrasives on graphite/epoxy materials. Protective Equipment (4). Sand area lightly with 320 grit sandpaper. Solvent Cleaner (C429) (5). Wipe surfaces with Desoclean 45 or equivalent. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 26 OF 32 CAUTION CAUTION CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Maximum thickness of fairing compound, primer, and top coat shall not exceed 7 mils in thickness. (6). Repeat fill and fair as necessary to provide a smooth contour and fair modification into fuselage skin. O. Install Receptacles or Nutplates (Ref. Figure 3 and Figure 4) (1). Locate holes in access panel and drill to number forty (40). (2). Using access panel as a template locate the quarter turn receptacle or nutplate center holes and drill to number forty (40). (3). Enlarge quarter turn fastener or screw holes in aircraft skin to number two (2) drill. (4). Using the receptacle or nutplate as a guide drill the receptacle fastener holes to a number forty (40). (5). Countersink fastener holes 100° and deburr all holes. Primer (C310) (6). Install receptacles or nutplates with MS20605 rivets. Install rivets wet with primer (C310). P. Complete Access Panel (Ref. Figure 3) (1). Finish fastener holes. (a). Enlarge quarter turn fastener holes in access panel to number two (2) drill. Deburr holes. (b). Enlarge screw holes in access panel to number eight (8) drill. Deburr holes. (2). Locate bonding jumper attach hole. (3). Drill hole to a number eight (8). Deburr hole. Chemical Coating (C233) (4). Treat aluminum with iridite. (5). Mask area of bonding jumper attachment with tape. Primer (C310) (6). Prime panel with MIL−−23377 primer and allow to dry. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 27 OF 32 CAUTION TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. (7). If using the quarter turn fasteners, assemble the access panel, HS4437 stud, and HS4429 retaining washer. Silicone Compound (C221) (8). Install panel seal. (a). If using rubber seal, install seal MIL−R−6130 onto access panel with silicone adhesive/sealer HMS 16−1118. Fluorosilicone Compound (C222) (b). If using form in place seal, spray fuselage around access hole with mould release compound and allow to dry for fifteen minutes. Sealant, Fuel Resistant (C216) (c). If using form in place seal, place a 0.250 in. (6.35 mm) bead of sealant around periphery of panel, and install panel. Clean up excess sealant. (9). Attach bonding jumper to access panel with attaching hardware. Q. Attach Electrical Bonding Jumper (Ref. Figure 8) (1). Locate existing hole on aft flange of keel attach channel approximately 2.0 inches (5.08cm) from the bottom and 0.75 inches (19.05mm) outboard from keel beam surface. Protective Equipment (2). Enlarge screw hole to a number eight (8). Deburr hole. (3). Remove all paint and surface treatment from the faying surfaces between the keel attach channel and bonding jumper attaching hardware. Chemical Coating (C233) (4). Treat exposed aluminum with iridite. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 28 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. (5). Attach bonding jumper from access panel to keel attach channel with attaching hardware. Sealant, Fuel Resistant (C216) (6). Environmentally seal all hardware at both ends of bonding jumper with sealant MIL−S−8802. (7). Perform an electrical bond test class L (Ref. CSP900−RMM−2 Section 20−50−00). TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 29 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. 900F7307629.101.b.b 9B53.069 FS 181.000 REF FS 205.230 REF 1 1 4 3 2 7 6 VIEW LOOKING INBOARD 1 REF 5 Figure 8. Electrical Bonding Jumper Attachment (RH Shown LH Opposite) TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 30 OF 32 TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Legend (Ref. Figure 8) 1. KEEL ATTACH CHANNEL 2. SCREW NAS603–8P 3. WASHER AN960JD10L 4. WASHER AN960–10L 5. WASHER MS35338–43 6. NUT MS21042L3 7. BONDING JUMPER MS25083 R. Touch Up Paint Maximum thickness of fairing compound, primer, and top coat shall not exceed 7 mils in thickness. (1). Touch up all exposed surfaces with primer Uroprime 1320S or equivalent. (2). Touch up topcoat to match aircraft. S. Close All Removed Panels (1). Install left outboard cabin floor panel (AL 165), or right outboard cabin floor panel (AR 165) (Ref. CSP−900RMM−2 Section 06−00−00). (2). Record compliance to this Bulletin in the Compliance Record section of the helicopter Log Book. If installing less than all three panels, record compliance as part A, B, or C to designate at which location access panel has been installed. TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 31 OF 32 CAUTION NOTE: TECHNICAL BULLETIN Copyright 1999 by MD Helicopters Inc. This document may be reproduced and distributed provided no fee is charged, the text is not modified, and this copyright notice is included. Inspection Access Panel Installation Parts Request Form: Please fill in the following information and return to MDHS for parts/supplies required for compliance. This form may be faxed to MDHS Warranty and Repair Department at (602) 891−3952. Aircraft Ser. No.: Aircraft Total Time: Date: Parts Required: Part Ser. No. (if required): Ship to: TB900.003R1* 900FG000006 REV. A DATE: 15 MARCH 2002 PAGE 32 OF 32