TUB SHELL (FUSELAGE) INSPECTION PANELS, MODIFICATION
TUB SHELL (FUSELAGE) INSPECTION PANELS, MODIFICATIONTO INSTALL 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
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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
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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
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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每A每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每S每5059
AMS 5517J
(Boeing Spec RM007058)
26 X 51 in.
(66.0 X 129.6 cm)
MDHI or Commercial
Receptacle, Quarter Turn (2) HS4427每3
Camloc Number 5R2每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每6
Camloc Number 5S15每5
24 MDHI or Commercial
Screw, Machine, Pan Head (3) MS27039C1每08 24 MDHI or Commercial
Washer, Retaining, Quarter Turn
(4)
HS4429每2 24 MDHI or Commercial
Epoxy Primer MIL每P每23377, Type 1,
Class1 or Equivalent
(Boeing Spec RM012212)
AR Commercial
Screw, Machine, Pan Head NAS603每8P 6 MDHI or Commercial
Washer, Flat AN960JD10L 6 MDHI or Commercial
Washer, Flat AN960每10L 6 MDHI or Commercial
Washer, Lock每Spring MS35338每43 6 MDHI or Commercial
Nut, Self Locking MS21042L3 3 MDHI or Commercial
Jumper Assembly, Electrical
Bonding (5)
MS25083每5BB16
or
M83413/8每A016BB
3 MDHI or Commercial
Jumper Assembly, Electrical
Bonding, Quick Disconnect (5)
MS25083每3BB16
or
M83413/8每D016BB
3 MDHI or Commercial
TB900.003R1*
900FG000006 REV. A
DATE: 15 MARCH 2002
PAGE 4 OF 32
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REPLACEMENT PARTS/SUPPLIES (Cont.)
Nomenclature Source Qty. Part No.
Chemical Film Iridite 14每2 AR Richardson Company
Allied每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每7823
Sealant, Fuel Resistant MIL每S每8802, Type 2, Class
B1/2
AR Coast Proseal
Compton, CA.
Epoxy Resin, Structural
HMS 16每1115 T3
Redux 501
(Boeing Spec RM011312)
AR Ciba每Geigy Corp.
E. Lansing, MI.
(800) 367每8793
Epoxy Fairing Compound
HMS 16每1068 CL6
RP1257每3
or
EA960F
AR
AR
Ciba每Geigy Corp.
E. Lansing, MI.
(800) 367每8793
Dexter Adhesives
Pittsburgh, CA.
(510) 458每8217
Filler, Epoxy Adhesive,
Non每sagging
HMS 16每1069 CL12
EA9321
(Boeing Spec RM010246)
or
BR 95
AR
AR
Dexter Adhesives
Pittsburgh, CA.
(510) 458每8217
Cytec Inc.
Havre De Grace, MD
(410) 939每1910
Plain Weave Graphite Fabric,
5.6 oz./sq. yd.
Fiberite W每5每322 3 sq. yd.
(2.5 sq. M)
Fiberite Corp.
Greenville, TX
(903) 457每8500
Fabric, E Glass HMS 16每1267/1601
MIL每C每9084 T3 C2
1.5 sq. yd.
(1.25 sq. M)
MDHI or Commercial
Shielding, Expanded Aluminum
Foil
HMS 16每1255 Type 1
(Boeing Spec RM012757)
1.5 sq. yd.
(1.25 sq. M)
MDHI or Commercial
Fluorosilicone Release
Compound
REN RP 79每2
or Equivalent
1 Ciba每Geigy Corp.
E. Lansing, MI.
(800) 367每8793
TB900.003R1*
900FG000006 REV. A
DATE: 15 MARCH 2002
PAGE 5 OF 32
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REPLACEMENT PARTS/SUPPLIES (Cont.)
Nomenclature Source Qty. Part No.
Primer Uroprime 1320S or
Equivalent
AR Dupont Co.
Lionville, PA
(800) 338每7668
Topcoat To Match Aircraft AR Commercial
Strip, Silicone Rubber MIL每R每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每1118 T1 C1
Silastic 732 (White)
(Boeing Spec RM002212)
or
RTV 157 (Black)
(Boeing Spec RM011172)
AR Dow Corning
Midland, MI
(517) 496每5900
General Electric Co.
Waterford, NY
(518) 237每3330
Respirator, Safety Glasses,
Gloves, etc.
AR Commercial
Vacuum Pump Capable of
Supplying 20每29 inches HG
(63每91 kPa)
1 Commercial
Vacuum Bagging Materials AR Commercial
Tape, Flashbreaker HMS 20每1267/1520, /1521,
/1522, /1650, /1693
(Boeing Spec 2.0 in.
RM0154244
or Equivalent
AR Airtech International, INC
Carson, CA
(310) 603每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
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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:
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(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
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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
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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 501 100 151 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 0.280.02 oz. (7.94g0.57g) 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
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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
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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
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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
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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*
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DATE: 15 MARCH 2002
PAGE 14 OF 32
CAUTION
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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
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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*
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DATE: 15 MARCH 2002
PAGE 16 OF 32
NOTE:
CAUTION
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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
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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
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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 501 100 151 12 Minimum @ Room
Temperature Followed by
2 1/2 @ 180∼ F
10∼ F
(3). Impregnate doubler plies with 0.280.02 oz. (7.94g0.57g) 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
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(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
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CAUTION
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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
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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
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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
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TECHNICAL BULLETIN
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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
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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
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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每1257每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
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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−P−23377 primer and allow to dry.
TB900.003R1*
900FG000006 REV. A
DATE: 15 MARCH 2002
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CAUTION
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(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
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(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
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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
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Legend (Ref. Figure 8)
1. KEEL ATTACH CHANNEL
2. SCREW NAS603每8P
3. WASHER AN960JD10L
4. WASHER AN960每10L
5. WASHER MS35338每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:
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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*
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DATE: 15 MARCH 2002
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