# Boeing Alert Service Bulletin 747-25A3640: No revision named

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- Document: [Boeing Alert Service Bulletin 747-25A3640](https://openairdocs.org/service-documents/boeing/747-25a3640.md)
- Title as filed: Boeing Service Bulletin
- Pages: 26
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## Text

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### Page 1

Commercial 
Airplanes
747
Service Bulletin
ALERT
Number: 747-25A3640
Original Issue: January 08, 2014
ATA System: 2551
SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Main
Equipment Center Drip Shield Repair
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 2014 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and
Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in
connection with this document unless provided in writing by Boeing.
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Table of Contents
Summary ...................................................... 5
1. PLANNING INFORMATION ........................................ 9
A. Effectivity ................................................ 9
1. Airplanes ............................................. 9
2. Spares Affected ........................................ 1 1
B. Concurrent Requirements ...................................... 1 1
C. Reason ................................................ 1 2
D. Description .............................................. 1 2
E. Compliance .............................................. 1 3
F. Approval ............................................... 1 3
G. Manpower .............................................. 1 3
H. Weight and Balance Changes .................................... 1 3
I. Electrical Load Data ......................................... 1 4
J. References .............................................. 1 4
1. Existing Data: ......................................... 1 4
2. Data Supplied with this Service Bulletin: ........................... 1 4
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 1 4
K. Publications Affected ........................................ 1 4
L. Interchangeability and Intermixability of Parts ........................... 1 4
M. Software Accomplishment Summary ................................ 1 5
2. MATERIAL INFORMATION ........................................ 1 7
A. Material - Price and Availability ................................... 1 7
B. Industry Support Information .................................... 1 7
C. Parts Necessary for Each Airplane ................................. 1 7
1. Kits/Parts ............................................ 1 7
2. Parts and Materials Supplied by the Operator ........................ 1 7
3. Parts Modified and Reidentified ................................ 1 7
4. Parts Removed and Not Replaced .............................. 1 7
D. Parts Necessary to Change Spares ................................. 1 7
E. Special Tooling - Price and Availability ............................... 1 8
F. Special Tooling Necessary to do this Service Bulletin ....................... 1 8
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 1 9
A. GENERAL INFORMATION ..................................... 1 9
B. WORK INSTRUCTIONS ....................................... 2 0
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION ..... 2 1
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Commercial 
Airplanes
747
Service Bulletin
ALERT
SummaryNumber: 747-25A3640Original Issue: January 08, 2014
ATA System: 2551
SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Main
Equipment Center Drip Shield Repair
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
CONCURRENT REQUIREMENTS
Refer to Paragraph 1.B., Concurrent Requirements.
BACKGROUND
This service bulletin will reduce the possibility of water penetration into the main equipment center (MEC).
Cracking of the MEC drip shield has allowed water to drip past the MEC drip shield and through the exhaust
plenum into the MEC. Water penetration into the MEC could result in an electrical short and potential loss of
several functions essential for safe flight.
Cracking in the MEC drip shield and exhaust plenum have each been identified as part of the leak path into the
MEC. Multiple operators have reported a cracked MEC drip shield. These cracks can allow water to penetrate
the MEC drip shield and enter the MEC.
This service bulletin is related to service bulletin 747-25A3588 which includes repairs of drip shield cracks,
stiffens the drip shield top surface, and installs a fiberglass reinforcing overcoat to the top and sides of the drip
shield. Boeing has received reports of additional cracking of the drip shield which is not mitigated by SB
747-25A3588. The reported additional cracking occurs at the lower radius of the MEC drip shield, adjacent to
the floor beams.
This service bulletin will install a fiberglass reinforcing overcoat to the lower radius area of the MEC drip shield
to prevent cracking. This will help prevent water intrusion into the MEC.
Boeing Service Related Problem (SRP) 747-SRP-25-0318 is related to this service bulletin.
This table is provided to operators for planning purposes only. Refer to the applicable sections for more
information.
ReferenceAffectedPlanning Data
Paragraph 1.A.2., Spares AffectedNoSpares Affected
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ReferenceAffectedPlanning Data
Paragraph 1.E., Compliance and Paragraph
1.F., Approval
YesAD Related
Paragraph 1.H., Weight and Balance ChangesNoWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedNoPublications Affected
Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsNoKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
YesOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION (PRR 85901-128RS)
Gain access to MEC drip shield. Clean MEC drip shield. Install a fiberglass reinforcing overcoat. Close access.
EFFECTIVITY
747-400/400F Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes.
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Boeing recommends that the change given in this service bulletin be done within 24 months after the original
issue date of this service bulletin.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the repair procedures given in this service bulletin.
MANPOWER
Elapsed HoursTotal Task HoursAirplanes
9.0036.00All Airplanes
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
Operator Supplied Parts/Materials.
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BOEING SERVICE BULLETIN 747-25A3640
ALERT  ALERT
Refer to Paragraph 2.A., Material - Price and Availability.
000
GAIN ACCESS TO MEC DRIP SHIELD.
CLEAN MEC DRIP SHIELD.
STA  INSTALL A FIBERGLASS
460  REINFORCING OVERCOAT.
CLOSE ACCESS.
2272772
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Commercial 
Airplanes
747
Service Bulletin
ALERT
Number: 747-25A3640
Original Issue: January 08, 2014
ATA System: 2551
SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Main
Equipment Center Drip Shield Repair
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index D6-30300 Part 3 for Airplane Variable Number, Line Number, and
Serial Number data.
This service bulletin is for the airplane(s) shown below. Refer to PRR 85901-128RS for data about
this change.
DESCRIPTIONCONFIGURATIONGROUP
747-400F or 747-400 BCF airplanes.-1
747-400F or 747-400 BCF airplanes which have not accomplished
747-25A3588.
1
747-400F or 747-400 BCF airplanes which have accomplished
747-25A3588.
2
747-400 BCF airplanes that have had the intent of 747-25A3588
incorporated on the airplane during BCF modification.
-2
Airplane Models:
747-400, 747-400F
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GroupVariable Number
1RL401 - RL403
1RL411 - RL436
1RL451 - RL456
1RL461 - RL462
1RL471 - RL481
1RL491 - RL492
1RL501 - RL502
1RL511 - RL516
1RL521 - RL522
1RL531 - RL534
1RL551
1RL561
1RL563 - RL568
1RL571 - RL572
1RL576 - RL577
1RL579
1RL581 - RL586
1RL651 - RL655
1RL671 - RL675
1RL681 - RL684
1RL751 - RL752
1RM128
1RM851 - RM859
1RM861 - RM862
1RM871 - RM899
1RM901 - RM906
1RM911
1RR701
1RR721 - RR724
1RR746 - RR748
1RR851 - RR856
1RR861 - RR862
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GroupVariable Number
1RR951 - RR952
1RT021 - RT022
1RT031 - RT033
2RT061
1RT071 - RT072
1RT101
1RT161
1RT164
1RT456
1RT501
1RT506 - RT510
1RT513
1RT516
1RT518 - RT520
1RT524
1RT526
1RT528
2RT530
1RT572 - RT579
1RT642
1RT655 - RT657
2RT691 - RT692
1RT751 - RT752
1RT781 - RT782
1RT837
1RT967
2. Spares Affected
None.
B. Concurrent Requirements
Group 1, Configuration 1:
The service bulletin listed below must be done before or at the same time as this service bulletin:
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DescriptionService BulletinCompany
Main Equipment Center Drip Shield Repair747-25A3588 Original Issue, Revision 1,
Revision 2, or Revision 3.
The Boeing Compa-
ny
Group 1, Configuration 2; Group 2:
None.
C. Reason
This service bulletin will reduce the possibility of water penetration into the main equipment center
(MEC). Cracking of the MEC drip shield has allowed water to drip past the MEC drip shield and through
the exhaust plenum into the MEC. Water penetration into the MEC could result in an electrical short
and potential loss of several functions essential for safe flight.
Cracking in the MEC drip shield and exhaust plenum have each been identified as part of the leak path
into the MEC. Multiple operators have reported a cracked MEC drip shield. These cracks can allow
water to penetrate the MEC drip shield and enter the MEC.
This service bulletin is related to service bulletin 747-25A3588 which includes repairs of drip shield
cracks, stiffens the drip shield top surface, and installs a fiberglass reinforcing overcoat to the top and
sides of the drip shield. Boeing has received reports of additional cracking of the drip shield which is
not mitigated by SB 747-25A3588. The reported additional cracking occurs at the lower radius of the
MEC drip shield, adjacent to the floor beams.
This service bulletin will install a fiberglass reinforcing overcoat to the lower radius area of the MEC
drip shield to prevent cracking. This will help prevent water intrusion into the MEC.
Boeing Service Related Problem (SRP) 747-SRP-25-0318 is related to this service bulletin.
D. Description
Gain access to MEC drip shield. Clean MEC drip shield. Install a fiberglass reinforcing overcoat. Close
access.
The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
117, 118747-400, 747-400F
Group 2:
Affected Maintenance Zones
ZoneModel
117, 118747-400
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E. Compliance
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this
service bulletin mandatory.
Boeing recommends that the change given in this service bulletin be done within 24 months after the
original issue date of this service bulletin.
F. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified
in this service bulletin comply with the applicable regulations and are FAA approved, as well as European
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on
the airplane in its original Boeing delivery configuration or as modified by other approved Boeing
changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
G. Manpower
The table below shows an estimate of the task hours necessary to do this change for each airplane.
This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator
task hour data if necessary. The estimate does not include lost time. These are some examples of lost
time:
 Time to adjust to the workplace
 Time to schedule the work
 Time to inspect the work
 Time to cure the materials
 Time to make the parts
 Time to find the tools.
Elapsed HoursTask HoursNumber of PersonsTask
2.5010.004Open Access
4.0016.004FIGURE 1
2.5010.004Close Access
9.0036.00TOTAL FOR EACH AIRPLANE
Group 1, Configuration 1:
This estimate does not include the task hour data given in the service bulletin(s) in Paragraph 1.B.,
Concurrent Requirements.
H. Weight and Balance Changes
None.
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I. Electrical Load Data
Not applicable.
J. References
1. Existing Data:
a. Engineering Change Memo PRR 85901-128RS
b. Boeing Service Bulletin 747-25A3588
c. Boeing Service Related Problem (SRP) 747-SRP-25-0318
d. Service Bulletin Index D6-30300
e. Standard Overhaul Practices Manual (SOPM) 20-30-03, 20-50-01, 20-50-19
f. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19
g. 747-400 Aircraft Maintenance Manual (AMM) 25-57-01, 25-57-04, 25-57-06, 25-58-01,
25-58-02, 53-21-02
h. 747-400 Structural Repair Manual (SRM) 51-70-06
i. 747-400F Structural Repair Manual (SRM) 51-70-06
2. Data Supplied with this Service Bulletin:
None.
3. Installation Drawings Used in the Preparation of this Service Bulletin:
None.
K. Publications Affected
1. Publications:
None.
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
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M. Software Accomplishment Summary
Not affected.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each
Airplane . As an alternative, operators can purchase the parts from Boeing Spares. This service bulletin
does not show the Boeing price and supply data.
B. Industry Support Information
Boeing warranty remedies are not available for the repair procedures given in this service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
The following parts or materials are necessary to do the change in this service bulletin. Parts and
materials in the manuals given in Paragraph 1.J., References, can also be necessary. Examine
operator part and material supply to make sure all necessary parts and materials are available.
NotesNameQTYPart Number /
Specification
(a)SEALANT1 Qt.BMS 5-95, Type I,
Class B
(a)EPOXY RESIN1 Qt.BMS 8-201, Type
III or Type IV
(a)FIBERGLASS CLOTH1 RollBMS 9-3, Type H,
H-2, or H-3, Class
7
(a) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS)
for supplier data.
3. Parts Modified and Reidentified
None.
4. Parts Removed and Not Replaced
None.
D. Parts Necessary to Change Spares
None.
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E. Special Tooling - Price and Availability
None.
F. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance
and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator tool supply to make sure all necessary tools are available.
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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL
PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,
METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE
DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
2. Obey all of the warnings and cautions given in the specified manual sections.
3. Unless shown differently, these dimensions and tolerances are used:
– Linear dimensions are in inches
– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus
or minus 0.03 inch
– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
– Angular tolerance is plus or minus 2 degrees
– Hole dimensions for standard solid rivets and fasteners are in Structural Repair
Manual (SRM) Chapter 51
– Torque Values:
— Values for structural fasteners are given in 747 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 747
Airplane Maintenance Manual (AMM).
— Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
— Values for engine maintenance tasks are included in Chapter 70 of 747
Airplane Maintenance Manual (AMM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
4. Use the approved fastener, process and material substitutions in accordance with
SRM Chapter 51.
5. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,
and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.
6. The necessary conditions for selection of clamp type and size are included in SWPM
20-10-12. If any wire bundle support clamp specified in this service bulletin does not
make a correct fit on the wire bundle, refer to SWPM 20-10-12 as an accepted
procedure to select a clamp that fits correctly.
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7. If the length of any fastener specified in this service bulletin does not meet installation
standards given in SRM Chapter 51, then a fastener of the same specification, or
an approved substitute, with a length which meets the installation standards given
in SRM Chapter 51 may be used. In addition, washers may be installed for fastener
grip length in accordance with SRM Chapter 51. Refer to SOPM 20-50-01 for alternate
full threaded fasteners (screws) needed for installation in this service bulletin.
8. These work instructions refer to procedures included in other Boeing documents.
When the words "refer to" are used and the operator has an accepted alternative
procedure, the accepted alternative procedure can be used. When the words "in
accordance with" are included in the instruction, the procedure in the Boeing document
must be used.
9. If it is necessary to remove more parts for access, you can remove those parts. If
you can get access without removing identified parts, it is not necessary to remove
all of the identified parts. Jacking and shoring limitations must be observed.
10. Where the work instructions include installation of a kept part, a new or serviceable
part with the same part number can be installed as an alternative to the kept part.
11. If shading is used, shaded areas in Figures are to separate the non-critical and
non-authoritative information from the critical and authoritative information.
12. Some steps in the Work Instructions are identified as Required for Compliance (RC).
If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps
identified as RC must be done to comply with the AD. Alternative procedures for
steps not identified with RC can be used if the RC steps can still be done as specified,
and the airplane can be put back in a serviceable condition. An Alternative Method
of Compliance (AMOC) is not necessary for deviations to steps that are not identified
as RC.
B. WORK INSTRUCTIONS
1. Remove cargo handling equipment between STA 440 and STA 460 and LBL 55 and RBL 55. Refer
to 747-400 AMM 25-57-01, 747-400 AMM 25-57-04, 747-400 AMM 25-57-06, 747-400 AMM
25-58-01, and 747-400 AMM 25-58-02 as an accepted procedure.
2. Remove main deck floor panels between STA 440 and STA 460 and LBL 55 and RBL 55. Refer
to 747-400 AMM 53-21-02 as an accepted procedure.
3. RC- Install a fiberglass reinforcing overcoat on the main equipment center (MEC) drip shield in
accordance with FIGURE 1.
4. Install main deck floor panels between STA 440 and STA 460 and LBL 55 and RBL 55. Refer to
747-400 AMM 53-21-02 as an accepted procedure.
5. Install cargo handling equipment between STA 440 and STA 460 and LBL 55 and RBL 55. Refer
to 747-400 AMM 25-57-01, 747-400 AMM 25-57-04, 747-400 AMM 25-57-06, 747-400 AMM
25-58-01, and 747-400 AMM 25-58-02 as an accepted procedure.
6. Put the airplane back to a serviceable condition.
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Work - See page 1 for details.
Original Issue: January 08, 2014
747-25A3640
20 of 26
BOEING SERVICE BULLETIN 747-25A3640
ALERTALERT

### Page 21 (OCR)

BOEING SERVICE BULLETIN 747-25A3640
ALERT  ALERT
000
STA
460
STA
440
2272788
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 1 OF 6)
Original Issue: January 08, 2014
Export Controlled ECCN: 9E991 - BOEING  747-25A3640
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  21 of 26

### Page 22

FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 2 OF 6)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: January 08, 2014
747-25A3640
22 of 26
BOEING SERVICE BULLETIN 747-25A3640
ALERTALERT

### Page 23 (OCR)

BOEING SERVICE BULLETIN 747-25A3640
ALERT  ALERT
FIBERGLASS
• SEALANT
LOWER
FLOOR BEAM
CHORD
FIBERGLASS
SEALANT
LOWER
FLOOR BEAM
CHORD
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 3 OF 6)
Original Issue: January 08, 2014
PROPRIETARY - Copyright © Unpublished  Export Controlled ECCN: 9E991 - BOEING  747-25A3640
Work - See page 1 for details.  23 of 26

### Page 24 (OCR)

BOEING SERVICE BULLETIN 747-25A3640
ALERT  ALERT
275
LOWER
FWD  FLOOR BEAM
CHORD
A-A
453
2.75
2.25
FWD  LOWER  FLOOR BEAM  2273299
B-B  CHORD
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 4 OF 6)
Original Issue: January 08, 2014
Export Controlled ECCN: 9E991 - BOEING  PROPRIETARY - Copyright © Unpublished  747-25A3640
Work - See page 1 for details.  24 of 26

### Page 25

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for each airplane.
More DataQtyIdentificationNameTaskStep
Solvent clean, refer
to SOPM 20-30-03
as an accepted pro-
cedure. Only area to
be covered by fiber-
glass cloth needs to
be cleaned.
--MEC DRIP SHIELDClean1
Abrasive clean, refer
to SOPM 20-30-03
as an accepted pro-
cedure. Only area to
be covered by fiber-
glass cloth needs to
be cleaned.
--MEC DRIP SHIELDClean2
Solvent clean, refer
to SOPM 20-30-03
as an accepted pro-
cedure. Only area to
be covered by fiber-
glass cloth needs to
be cleaned.
--MEC DRIP SHIELDClean3
(a) (c)-BMS 9-3, TYPE H, H-2
OR H-3, CLASS 7
FIBERGLASS CLOTHCut4
(b)-BMS 8-201, TYPE III
OR IV
EPOXY RESINPrepare5
Make sure that fiber-
glass cloth is in-
stalled flush against
the lower floor beam
chord as shown. (c)
-BMS 9-3, TYPE H, H-2
OR H-3, CLASS 7
FIBERGLASS CLOTHInstall (New)6
Bond using BMS 8-
201 Type III or Type
IV. Refer to 747-
400F SRM 51-70-06
or 747-400 SRM 51-
70-06 as an accept-
ed procedure. (d)
-BMS 8-201, TYPE III
OR IV
EPOXY RESINApply
Refer to SOPM 20-
50-19 as an accept-
ed procedure.
-BMS 5-95, TYPE I,
CLASS B
SEALANTApply7
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 5 OF 6)
Export Controlled ECCN: 9E991 - BOEING
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Work - See page 1 for details.
Original Issue: January 08, 2014
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ALERTALERT

### Page 26

More DataQtyIdentificationNameTaskStep
Make sure that fiber-
glass cloth is in-
stalled flush against
the lower floor beam
chord as shown. (c)
-BMS 9-3, TYPE H, H-2
OR H-3, CLASS 7
FIBERGLASS CLOTHInstall (New)8
Bond using BMS 8-
201 Type III or Type
IV. Refer to 747-
400F SRM 51-70-06
or 747-400 SRM 51-
70-06 as an accept-
ed procedure. (d)
-BMS 8-201, TYPE III
OR IV
EPOXY RESINApply
Refer to SOPM 20-
50-19 as an accept-
ed procedure.
-BMS 5-95, TYPE I,
CLASS B
SEALANTApply9
(a) Cut fiberglass cloth in sections as required. All seams shall overlap 2 inches minimum, including sheet-
to-sheet and sheet-to-beam.
(b) Prepare epoxy laminating resin in sufficient quantity. Work in small batches consistent with working life
of resin.
(c) Two layers of fiberglass cloth are required.
(d) Apply mixed resin and cloth using squeegee or similar tool.
FIGURE 1: MEC DRIP SHIELD FIBERGLASS REINFORCING OVERCOAT INSTALLATION
(SHEET 6 OF 6)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: January 08, 2014
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26 of 26
BOEING SERVICE BULLETIN 747-25A3640
ALERTALERT

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