Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-25A3613

Original Issue: June 22, 2012

ATA System: 2551

SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Aft Main

Equipment Center (MEC) Drip Shield Gutter 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.

ECCN: 9E991

BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET

Copyright © 2012 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Unpublished Work.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.

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BLANK PAGE
Table of Contents

Summary ...................................................... 5

1. PLANNING INFORMATION ........................................ 9

A. Effectivity ................................................ 9

1. Airplanes ............................................. 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 15

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 17

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 18

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

FIGURE 1: CARGO LINER SUPPORT REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

FIGURE 2: AFT MEC DRIP SHIELD GUTTER CLEANING AND PREPARATION FOR GENERAL VISUAL

INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

FIGURE 3: AFT MEC DRIP SHIELD GUTTER REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . 29

FIGURE 4: AFT MEC DRIP SHIELD GUTTER REINFORCEMENT . . . . . . . . . . . . . . . . . . . 32

FIGURE 5: CARGO LINER SUPPORT INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 36

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Commercial 

Airplanes 747

Service Bulletin

ALERT

Summary Number: 747-25A3613

Original Issue: June 22, 2012

ATA System: 2551

SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Aft Main

Equipment Center (MEC) Drip Shield Gutter 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

None.

BACKGROUND

This service bulletin will reduce the possibility of water penetration into the main equipment center (MEC).

Disbonded aft MEC drip shield gutters have allowed water to drip past the MEC drip shield and into the Wire

Integration Units (WIU). Water penetration into the WIUs could result in loss of flight critical systems.

An operator experienced water leaking from main deck cargo into the WIU. It flowed from the drip shield through

disbonded floor seams into the aft MEC drip shield gutter, then onto the WIU

Liquids can leak through the MEC drip shield due to disbonded aft MEC drip shield gutters resulting in water

intrusion into the WIU of the MEC. Disbonding can occur due to improper preparation of the drip shield/gutter

material, aging of materials, and/or poor workmanship.

This Service Bulletin does a general visual inspection of the aft MEC drip shield gutters for disbonded seams,

and repairs them if necessary. A reinforcing layer of fiberglass is applied over the seam in the aft MEC drip

shield gutter to ensure no future disbondments occur.

Boeing Service Related Problem (SRP) 747-SRP-25-0304 is related to this service bulletin

This table is provided to operators for planning purposes only. Refer to the applicable sections for more

information.

Planning Data Affected Reference

Spares Affected No Paragraph 1.A.2., Spares Affected

AD Related Yes Paragraph 1.E., Compliance

Weight and Balance Change Yes Paragraph 1.H., Weight and Balance Changes

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Planning Data Affected Reference

Electrical Load Changed No Paragraph 1.I., Electrical Load Data

Publications Affected No Paragraph 1.K., Publications Affected

Airplane Flight Operations Affected (Flight Crew No Paragraph 1.K., Publications Affected

Operations Manual and/or FAA Approved Airplane Flight Manual)

Kits/Parts Required No Paragraph 2.C.1., Kits/Parts

Paragraph 2.C.2., Parts and Materials Supplied

by the Operator

Operator Supplied Material Yes

Paragraph 2.F., Special Tooling Necessary to

do this Service Bulletin

Special Tooling Required No

ACTION (PRR 85901-117RS)

- Do a general visual inspection of the aft MEC drip shield gutters for disbonded seam, and repair if necessary.

- Add fiberglass reinforcement to aft MEC drip shield gutters.

EFFECTIVITY

747-400, 747-400D, 747-400F Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s).

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 inspection, change and/or repair 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 configuration changes, inspection, and/or repair procedures

given in this service bulletin.

MANPOWER

Airplanes Total Task Hours Elapsed Hours

Group 1 air- 10.65 6.15

planes

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

Refer to Paragraph 2.A., Material - Price and Availability.

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BLANK PAGE
Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-25A3613

Original Issue: June 22, 2012

ATA System: 2551

SUBJECT: EQUIPMENT/FURNISHINGS - Electrical/Electronic Equipment Centers - Aft Main

Equipment Center (MEC) Drip Shield Gutter 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 85901-117RS for data about

this change.

GROUP CONFIGURATION DESCRIPTION

747-400 passenger and freighter airplanes that have a two piece aft

MEC drip shield gutter

1 -

Airplane Models:

747-400, 747-400D, 747-400F

Variable Number Group

RF001 - RF006 1

RL401 - RL402 1

RL411 - RL418 1

RL651 - RL654 1

RM001 - RM007 1

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Variable Number Group

RM010 - RM013 1

RM021 - RM024 1

RM026 - RM030 1

RM036 - RM045 1

RM051 - RM053 1

RM071 1

RM081 - RM084 1

RM091 1

RM096 - RM097 1

RM116 - RM117 1

RM126 - RM127 1

RM129 - RM132 1

RM136 - RM147 1

RM156 - RM158 1

RM166 - RM177 1

RM191 - RM192 1

RM231 - RM233 1

RM241 - RM246 1

RM261 - RM264 1

RM316 - RM318 1

RM331 - RM333 1

RM341 1

RM351 - RM355 1

RM366 - RM367 1

RM401 - RM403 1

RM426 1

RM431 1

RM801 - RM803 1

RM811 - RM813 1

RM851 - RM858 1

RM861 1

RM871 - RM876 1

RM881 - RM886 1

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Variable Number Group

RM891 - RM899 1

RM901 - RM903 1

RM911 1

RR701 1

RR721 - RR724 1

RR746 - RR748 1

RR851 - RR856 1

RR861 - RR862 1

RR951 - RR952 1

RT001 - RT014 1

RT034 - RT035 1

RT041 - RT047 1

RT073 - RT074 1

RT101 - RT103 1

RT121 1

RT131 - RT137 1

RT151 - RT152 1

RT162 - RT163 1

RT165 - RT168 1

RT401 - RT412 1

RT431 - RT447 1

RT452 - RT455 1

RT457 - RT460 1

RT462 - RT469 1

RT471 - RT499 1

RT502 - RT505 1

RT511 - RT512 1

RT514 - RT515 1

RT517 1

RT521 - RT523 1

RT525 1

RT527 1

RT529 1

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Variable Number Group

RT531 - RT535 1

RT551 - RT568 1

RT571 1

RT580 - RT591 1

RT601 - RT614 1

RT616 - RT630 1

RT633 - RT634 1

RT636 - RT641 1

RT643 - RT654 1

RT672 - RT673 1

RT681 - RT682 1

RT691 - RT699 1

RT701 - RT704 1

RT711 - RT717 1

RT741 1

RT744 - RT750 1

RT753 - RT757 1

RT776 - RT777 1

RT783 - RT784 1

RT801 - RT803 1

RT811 - RT814 1

RT831 - RT835 1

RT861 - RT864 1

RT877 - RT880 1

RT931 - RT932 1

RT945 - RT949 1

RT951 - RT955 1

RT966 1

RU002 - RU006 1

RU016 - RU017 1

RU031 - RU032 1

RU051 - RU052 1

RU059 - RU062 1

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Variable Number Group

RU081 - RU083 1

RU101 - RU102 1

RU121 - RU132 1

RU803 1

RU805 1

RU808 - RU809 1

RU831 1

RU833 - RU841 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

This service bulletin will reduce the possibility of water penetration into the main equipment center

(MEC). Disbonded aft MEC drip shield gutters have allowed water to drip past the MEC drip shield and

into the Wire Integration Units (WIU). Water penetration into the WIUs could result in loss of flight critical

systems.

An operator experienced water leaking from main deck cargo into the WIU. It flowed from the drip shield

through disbonded floor seams into the aft MEC drip shield gutter, then onto the WIU

Liquids can leak through the MEC drip shield due to disbonded aft MEC drip shield gutters resulting in

water intrusion into the WIU of the MEC. Disbonding can occur due to improper preparation of the drip

shield/gutter material, aging of materials, and/or poor workmanship.

This Service Bulletin does a general visual inspection of the aft MEC drip shield gutters for disbonded

seams, and repairs them if necessary. A reinforcing layer of fiberglass is applied over the seam in the

aft MEC drip shield gutter to ensure no future disbondments occur.

Boeing Service Related Problem (SRP) 747-SRP-25-0304 is related to this service bulletin

D. Description

- Do a general visual inspection of the aft MEC drip shield gutters for disbonded seam, and repair if

necessary.

- Add fiberglass reinforcement to aft MEC drip shield gutters.

The work in this service bulletin is done in the maintenance zone(s) given below.

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Affected Maintenance Zones

Model Zone

747-400, 747-400D, 747-400F 117, 118

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 inspection, change and/or repair 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.

Task Number of Persons Task Hours Elapsed Hours

Open Access 1 0.25 0.25

Figure 1 2 4.50 2.25

Figure 2 1 0.75 0.75

Figure 3 1 0.05 (a) 0.05 (a)

Figure 4 1 0.40 0.40

Figure 5 2 4.50 2.25

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Task Number of Persons Task Hours Elapsed Hours

Close Access 1 0.25 0.25

TOTAL FOR EACH AIRPLANE 10.65 6.15

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data:

a. Engineering Change Memo PRR 85901-117RS

b. Boeing Service Related Problem (SRP) 747-SRP-25-0304

c. Service Bulletin Index D6-30300

d. Standard Overhaul Practices Manual (SOPM) 20-30-03, 20-50-12

e. 747-400 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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ALERT ALERT
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 configuration changes, inspection, and/or 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

Part Number / QTY Name Notes

Specification

BMS 5-92, Any 1 Qt ADHESIVE (a)

Type

BMS 5-95, Type I, 1 Qt SEALANT (a)

Class B

BMS 9-3, Type H, 1 Roll FIBERGLASS CLOTH (a)

H-2, or H-3, Class

7

BMS 8-201, Type 1 Qt EPOXY RESIN (a)

III or Type IV

NAS1398D5-5 48 RIVET

(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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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
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

– Hole dimensions for standard solid rivets and fasteners are in Structural Repair

Manual (SRM) Chapter 51

– Torque limits to tighten nuts and bolts are in SRM Chapter 51

4. Use the approved fastener and process material substitutions in accordance with

SRM Chapter 51.

5. 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.

6. A General Visual Inspection is defined as: A visual examination of an interior or

exterior area, installation or assembly to detect obvious damage, failure or irregularity.

This level of inspection is made from within touching distance unless otherwise

specified. A mirror may be necessary to enhance visual access to all exposed surfaces

in the inspection area. This level of inspection is made under normally available

lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may

require removal or opening of access panels or doors. Stands, ladders or platforms

may be required to gain proximity to the area being checked.

7. 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.

8. 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.

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
9. 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.

10. Shaded areas in Figures are reference only. Shaded areas in Figures may look

different than your airplane.

B. WORK INSTRUCTIONS

1. Remove cargo liner support in accordance with Figure 1.

2. Clean the aft MEC drip shield gutter and do a general visual inspection for seam disbondment in

accordance with Figure 2.

a. If any seam disbondment is found, repair seam in accordance with Figure 3.

b. If no seam disbondment is found, proceed to step 3.

3. Install aft MEC drip shield gutter reinforcement in accordance with Figure 4.

4. Install cargo liner support in accordance with Figure 5.

5. Put the airplane back to a serviceable condition.

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
FIGURE 1: CARGO LINER SUPPORT REMOVAL

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 1: CARGO LINER SUPPORT REMOVAL

(SHEET 2 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
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 this figure.

FIGURE 1: CARGO LINER SUPPORT REMOVAL

(SHEET 3 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
Step Task Name Identification Qty More Data

1 Remove / Keep FASTENERS - 4

2 Remove / Keep SPLICE PLATE - 1

3 Remove / Keep FASTENERS - 4

4 Remove / Keep SPLICE PLATE - 1

5 Remove / Keep FASTENERS - 4

6 Remove / Keep SPLICE PLATE - 1

7 Remove / Keep FASTENERS - 15

LINER SUPPORT AS- - 1

SY

8 Remove / Keep

9 Remove / Keep FASTENERS - 15

LINER SUPPORT AS- - 1

SY

10 Remove / Keep

11 Remove / Keep FASTENERS - 4

12 Remove / Keep SPLICE PLATE - 1

13 Remove / Keep FASTENERS - 39

LINER SUPPORT AS- - 1

SY

14 Remove / Keep

15 Remove / Keep FASTENERS - 39

LINER SUPPORT AS- - 1

SY

16 Remove / Keep

FIGURE 1: CARGO LINER SUPPORT REMOVAL

(SHEET 4 OF 4)

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ALERT ALERT
FIGURE 2: AFT MEC DRIP SHIELD GUTTER CLEANING AND PREPARATION FOR GENERAL VISUAL

INSPECTION

(SHEET 1 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
FIGURE 2: AFT MEC DRIP SHIELD GUTTER CLEANING AND PREPARATION FOR GENERAL VISUAL

INSPECTION

(SHEET 2 OF 4)

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ALERT ALERT
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 this figure.

Step Task Name Identification Qty More Data

Solvent clean, refer

to SOPM 20-30-03

as an accepted procedure.(a)

1 Clean MEC DRIP SHIELD - -

Carefully remove

any loose old adhesive without causing

further damage to

MEC drip shield.(a)

2 Remove ADHESIVE BMS 5-92 -

FIGURE 2: AFT MEC DRIP SHIELD GUTTER CLEANING AND PREPARATION FOR GENERAL VISUAL

INSPECTION

(SHEET 3 OF 4)

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ALERT ALERT
Step Task Name Identification Qty More Data

Solvent clean, refer

to SOPM 20-30-03

as an accepted procedure.(a)

3 Clean MEC DRIP SHIELD - -

Abrasive clean, refer

to SOPM 20-30-03

as an accepted procedure.(a)

4 Clean MEC DRIP SHIELD - -

Solvent clean, refer

to SOPM 20-30-03

as an accepted procedure.(a)

5 Clean MEC DRIP SHIELD - -

Do a general visual

inspection of the aft

MEC drip shield gutters for disbonded

seams.

6 Inspect MEC DRIP SHIELD - -

(a) Cleaning and preparation of the aft MEC drip shield gutters should extend a minimum 2" on either side

of the seams.

FIGURE 2: AFT MEC DRIP SHIELD GUTTER CLEANING AND PREPARATION FOR GENERAL VISUAL

INSPECTION

(SHEET 4 OF 4)

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ALERT ALERT
FIGURE 3: AFT MEC DRIP SHIELD GUTTER REPAIR

(SHEET 1 OF 3)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
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 this figure.

FIGURE 3: AFT MEC DRIP SHIELD GUTTER REPAIR

(SHEET 2 OF 3)

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ALERT ALERT
Step Task Name Identification Qty More Data

Bond the aft MEC

drip shield gutter

seam using BMS 5-

92. Refer to SOPM

20-50-12, Type 70

as an accepted procedure.

1 Apply ADHESIVE BMS 5-92 -

FIGURE 3: AFT MEC DRIP SHIELD GUTTER REPAIR

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
FIGURE 4: AFT MEC DRIP SHIELD GUTTER REINFORCEMENT

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 4: AFT MEC DRIP SHIELD GUTTER REINFORCEMENT

(SHEET 2 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
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 this figure.

Step Task Name Identification Qty More Data

BMS 9-3, TYPE H, H-2, - (a)

OR H-3, CLASS 7

1 Cut FIBERGLASS CLOTH

2 Prepare EPOXY RESIN BMS 8-201 - (b)

FIGURE 4: AFT MEC DRIP SHIELD GUTTER REINFORCEMENT

(SHEET 3 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
Step Task Name Identification Qty More Data

BMS 9-3, TYPE H, H-2, - (c)

OR H-3, CLASS 7

3 Install (New) FIBERGLASS CLOTH

Bond using BMS 8-

201, Type III or Type

IV. Refer to 747-400

SRM 51-70-06 as an

accepted procedure.

Vacuum bagging is

not required.

Apply EPOXY RESIN BMS 8-201 -

(a) Cut fiberglass cloth to overlay the aft MEC drip shield gutter seam in sections as required. Two plies will

be required. All sections of fiberglass cloth shall overlap 2 inch minimum.

(b) Prepare epoxy resin in sufficient quantity. Work in small batches consistent with working life of resin.

Apply mixed epoxy resin and fiberglass cloth using squeegee or similar tool.

(c) Install the prepared BMS 9-3 fiberglass impregnated fabric to the underside of the bonded seams. Place

edge of impregnated fabric 0.40-0.60 inch forward from edge of re-bonded seam and extend upward and

aft over seam gutter.

FIGURE 4: AFT MEC DRIP SHIELD GUTTER REINFORCEMENT

(SHEET 4 OF 4)

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ALERT ALERT
FIGURE 5: CARGO LINER SUPPORT INSTALLATION

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 5: CARGO LINER SUPPORT INSTALLATION

(SHEET 2 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT
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 this figure.

FIGURE 5: CARGO LINER SUPPORT INSTALLATION

(SHEET 3 OF 4)

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ALERT ALERT
Step Task Name Identification Qty More Data

LINER SUPPORT AS- - 1

SY

1 Install (Kept)

2 Install (Kept) FASTENERS - 15

LINER SUPPORT AS- - 1

SY

3 Install (Kept)

4 Install (Kept) FASTENERS - 15

5 Install (Kept) SPLICE PLATE - 1

6 Install (Kept) FASTENERS - 4

7 Install (Kept) SPLICE PLATE - 1

8 Install (Kept) FASTENERS - 4

9 Install (Kept) SPLICE PLATE - 1

10 Install (Kept) FASTENERS - 4

LINER SUPPORT AS- - 1

SY

11 Install (Kept)

12 Install (Kept) FASTENERS - 15

LINER SUPPORT AS- - 1

SY

13 Install (Kept)

14 Install (Kept) FASTENERS - 15

15 Install (New) RIVET NAS1398D5-5 24

16 Install (New) RIVET NAS1398D5-5 24

17 Install (Kept) SPLICE PLATE - 1

18 Install (Kept) FASTENERS - 4

FIGURE 5: CARGO LINER SUPPORT INSTALLATION

(SHEET 4 OF 4)

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BOEING SERVICE BULLETIN 747-25A3613

ALERT ALERT