Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2876

Original Issue: October 22, 2014

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Section 46 - Crown Skin Under Dorsal Fairing - Inspection, Repair,

and Modification

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 © 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Unpublished Work.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.

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BLANK PAGE
Table of Contents

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

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

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

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

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 31

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 34

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 36

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

FIGURE 1: DETAILED INSPECTION FOR WEAR OR CRACKS WITH THE DORSAL FAIRING REMOVED

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

FIGURE 2: APPLICATION OF TEFLON COATING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

FIGURE 3: RUB STRIP MODIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

FIGURE 4: GAP MEASUREMENT AND DETAILED INSPECTION FOR WEAR OR CRACKS WITH THE

DORSAL FAIRING INSTALLED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

FIGURE 5: EXTERNAL DOUBLER REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

FIGURE 6: SURFACE HFEC INSPECTION OF REPAIR DOUBLER . . . . . . . . . . . . . . . . . . 68

APPENDIX A: PART DEMAND INTENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

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ALERT ALERT

BLANK PAGE
Commercial 

Airplanes 747

Service Bulletin

ALERT

Summary Number: 747-53A2876

Original Issue: October 22, 2014

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Section 46 - Crown Skin Under Dorsal Fairing - Inspection, Repair,

and Modification

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

Accomplishment of this service bulletin will detect skin damage from the dorsal fairing forward of the vertical

stabilizer. The fuselage skin is subject to skin damage in the area of the dorsal fairing which can lead to cracking.

Undetected cracking in Section 46 could reach sufficient length to cause in-flight depressurization of the airplane.

During inspection for skin damage due to wear from the vertical stabilizer seals in accordance with Service

Bulletin 747-53A2478, two operators found significant skin damage from the dorsal fairing just forward of the

area inspected by Service Bulletin 747-53A2478 at Station (STA) 2280. The two airplanes with damage had

45,707 total flight hours and 71,702 total flight hours.

Boeing has determined that the skin damage occurred from inadequate clearance between crown skin and the

lower aft corners of the dorsal fairing. Affected airplanes are limited to line numbers that were delivered with or

retrofitted with 174U9000 series dorsal fairing assemblies. Airplanes with other dorsal fairing configurations are

not expected to develop skin wear.

This service bulletin gives instructions for operators of affected airplanes to inspect the skin for wear under the

dorsal fairing and repair any damage that may have already occurred. This service bulletin also gives instructions

to measure the clearance between the crown skin and lower edge of the dorsal fairing, and trim or adjust the

dorsal fairing to provide more clearance, as necessary. Accomplishment of these actions will ensure that skin

wear from the dorsal fairing does not lead to cracking and possible depressurization of the airplane.

Boeing Service Related Problem (SRP) 747-SRP-53-0442 is related to this service bulletin.

Boeing Fleet Team Digest (FTD) 747 FTD 53-13011 is related to this service bulletin.

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

information.

Export Controlled ECCN: 9E991 - BOEING

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Planning Data Affected Reference

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

Paragraph 1.E., Compliance and Paragraph

1.F., Approval

AD Related Yes.

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

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

Publications Affected Yes. 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 Yes. Paragraph 2.C.1., Kits/Parts

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

by the Operator

Operator Supplied Parts/Material Yes.

Paragraph 2.F., Special Tooling Necessary to

do this Service Bulletin

Special Tooling Required No.

ACTION (PRR 85901-130RS)

Get access and remove the dorsal fairing. Do a detailed inspection of the skin under the dorsal fairing for wear

or cracks.

If no skin crack or wear is found, apply teflon coating to the skin under the dorsal fairing and repeat the detailed

inspection for skin wear or cracks at the interval specified. As an option, install Corrosion Resistant Steel (CRES)

rub strips under the dorsal fairing as a preventive modification.

If any skin wear is found, do a blend repair or install a repair doubler depending on the depth of the skin wear.

If any skin crack is found, install a repair doubler or contact Boeing for repair instructions and do the repair.

If a blend repair is done, do initial and repetitive post-repair detailed and high frequency eddy current (HFEC)

inspections for cracks in the blended area of the skin, and do detailed inspection for wear or cracks in the

unrepaired areas of the skin under the dorsal fairing. If any crack or wear is found in a previously repaired area,

contact Boeing for repair instructions and do the repair.

If a repair doubler is installed, do initial and repetitive post-repair detailed and HFEC inspections for cracks in

the repair doubler, and do detailed inspection for wear or cracks in the unrepaired areas of the skin under the

dorsal fairing. If any crack is found in a previously repaired area, contact Boeing for repair instructions and do

the repair.

Upon re-installation of the fairing, make sure the clearance between the crown skin and the lower edge of the

dorsal fairing meets the gap requirements specified in the applicable Aircraft Maintenance Manual (AMM). If

necessary, trim the lower edge of the dorsal fairing or adjust the installation shims as specified in the AMM in

order to meet the gap requirements.

EFFECTIVITY

747-100, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, and 747-400F airplanes. Refer to

Paragraph 1.A.1., Airplanes, for the list of affected airplanes.

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
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.

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the inspection and/or repair procedures given in this service

bulletin.

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

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

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ALERT ALERT
Commercial 

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2876

Original Issue: October 22, 2014

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Section 46 - Crown Skin Under Dorsal Fairing - Inspection, Repair,

and Modification

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 applicable to 747-100, 747-200B, 747-200C, 747-200F, 747-300, 747-400,

747-400D, and 747-400F airplanes, line numbers 1017-1419, 27, 45, 75, 88, 135, 141, 163, 165,

470, 471, 437, 375, 465, 357, 374, 377, 378, 379, 412, 442, 594, 595, 642, 644, 651, 397, 474,

491, 271, 276, 336, 344, 369, 389, 539, 669, 712, 400, 878, 258, 261, 269, 308, 444, 680, 682,

968, 1002, 1008, 587, 600, 657, 735, 737, 763, 770, 783, 850, 854, 896, 938, 992, 1014, 743,

775, 792, 705, 728, 771, 788, 813, 834, 849, 873, 877, 887, 925, 930, 937, 949, 970, 993, 1007,

831, 852, 859, 860, 921, 923, 953, 955, 962, 981, 1010, 725, 732, 782, 888, 969, 769, 777, 833,

890, 945, 950, 1001, 827, 861, 926, 957 in 2(two) Group(s). The Variable Numbers and Group

Information for the applicable airplanes is given below. An equivalent change is on subsequent

production airplanes. Refer to PRR 85901-130RS for data about this change.

GROUP CONFIGURATION DESCRIPTION

747-400, 747-400D, and 747-400F airplanes, line numbers

1017-1419. These airplanes were delivered with a 174U9000 series

dorsal fairing assembly.

1 -

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GROUP CONFIGURATION DESCRIPTION

747-100, 747-200B, 747-200C, 747-200F, 747-300, 747-400, and

747-400F airplanes that have had a 174U9000 series dorsal fairing

installed in accordance with one of the following Boeing Master

Change service bulletins: 747-55-2037, 747-55-2038, 747-55-2040,

747-55-2041, 747-55-2044, 747-55-2047, 747-55-2049, or

747-55-2064.

2 -

Airplane Models:

747-100, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F

Variable Number Group

RA351 2

RA353 2

RA358 2

RA369 - RA373 2

RD056 - RD057 2

RD241 - RD243 2

RD251 - RD262 2

RD381 - RD383 2

RD601 - RD607 2

RF001 - RF006 1

RJ321 - RJ322 2

RL401 - RL403 1

RL411 - RL436 1

RL451 - RL456 1

RL461 - RL462 1

RL471 - RL481 1

RL491 - RL492 1

RL501 - RL502 1

RL511 - RL516 1

RL521 - RL522 1

RL531 - RL534 1

RL551 1

RL561 - RL568 1

RL571 - RL572 1

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Variable Number Group

RL576 - RL577 1

RL579 1

RL581 - RL586 1

RL651 - RL655 1

RL671 - RL675 1

RL681 - RL684 1

RL751 - RL752 1

RM001 - RM007 1

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 - 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

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Variable Number Group

RM431 1

RM441 - RM443 1

RM445 1

RM801 - RM803 1

RM811 - RM813 1

RM851 - RM859 1

RM861 - RM863 1

RM871 - RM899 1

RM901 - RM906 1

RM911 1

RR005 2

RR310 2

RR341 - RR345 2

RR431 - RR432 2

RR701 2

RR721 - RR722 2

RR723 - RR724 1

RR746 - RR748 1

RR851 - RR856 1

RR861 - RR862 1

RR951 - RR952 1

RS711 - RS713 2

RT001 - RT011 2

RT012 - RT014 1

RT031 - RT033 2

RT034 - RT035 1

RT135 - RT137 1

RT151 - RT152 1

RT165 - RT168 1

RT442 - RT447 1

RT451 - RT467 2

RT468 - RT469 1

RT497 - RT499 1

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Variable Number Group

RT508 2

RT510 - RT514 2

RT516 - RT519 2

RT522 2

RT524 - RT530 1

RT531 - RT535 2

RT583 - RT590 1

RT623 - RT630 1

RT636 - RT640 1

RT691 - RT697 2

RT698 - RT699 1

RT748 - RT750 1

RT756 - RT757 1

RT781 - RT782 2

RT801 - RT803 1

RT811 - RT814 1

RT831 - RT837 1

RT877 - RT878 2

RT879 - RT880 1

RT945 - RT949 1

RT955 1

RT966 - RT967 1

RU004 - RU006 1

RU016 - RU017 1

RU032 1

RU059 - RU060 1

RU062 1

RU081 - RU083 1

RU101 - RU102 1

RU121 - RU132 1

RU809 1

RU840 - RU841 1

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

Accomplishment of this service bulletin will detect skin damage from the dorsal fairing forward of the

vertical stabilizer. The fuselage skin is subject to wear damage in the area of the dorsal fairing which

can lead to cracking. Undetected cracking in Section 46 could reach sufficient length to cause in-flight

depressurization of the airplane.

During inspection for skin damage due to wear from the vertical stabilizer seals in accordance with

Service Bulletin 747-53A2478, two operators found significant skin damage from the dorsal fairing just

forward of the area inspected by Service Bulletin 747-53A2478 at Station (STA) 2280. The two airplanes

with damage had 45,707 total flight hours and 71,702 total flight hours.

Boeing has determined that the skin damage occurred from inadequate clearance between crown skin

and the lower aft corners of the dorsal fairing. Affected airplanes are limited to line numbers that were

delivered with or retrofitted with 174U9000 series dorsal fairing assemblies. Airplanes with other dorsal

fairing configurations are not expected to develop skin wear.

This service bulletin gives instructions for operators of affected airplanes to inspect the skin for wear

under the dorsal fairing and repair any damage that may have already occurred. This service bulletin

also gives instructions to measure the clearance between the crown skin and lower edge of the dorsal

fairing, and trim or adjust the dorsal fairing to provide more clearance, as necessary. Accomplishment

of these actions will ensure that skin wear from the dorsal fairing does not lead to cracking and possible

depressurization of the airplane.

Boeing Service Related Problem (SRP) 747-SRP-53-0442 is related to this service bulletin.

Boeing Fleet Team Digest (FTD) 747 FTD 53-13011 is related to this service bulletin.

D. Description

Get access and remove the dorsal fairing. Do a detailed inspection of the skin under the dorsal fairing

for wear or cracks.

If no skin crack or wear is found, apply teflon coating to the skin under the dorsal fairing and repeat

the detailed inspection for skin wear or cracks at the interval specified. As an option, install Corrosion

Resistant Steel (CRES) rub strips under the dorsal fairing as a preventive modification.

If any skin wear is found, do a blend repair or install a repair doubler depending on the depth of the

skin wear. If any skin crack is found, install a repair doubler or contact Boeing for repair instructions

and do the repair.

If a blend repair is done, do initial and repetitive post-repair detailed and HFEC inspections for cracks

in the blended area of the skin, and do detailed inspection for wear or cracks in the unrepaired areas

of the skin under the dorsal fairing. If any crack or wear is found in a previously repaired area, contact

Boeing for repair instructions and do the repair.

Export Controlled ECCN: 9E991 - BOEING

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
If a repair doubler is installed, do initial and repetitive post-repair detailed and HFEC inspections for

cracks in the repair doubler, and do detailed inspection for wear or cracks in the unrepaired areas of

the skin under the dorsal fairing. If any crack is found in a previously repaired area, contact Boeing for

repair instructions and do the repair.

Upon re-installation of the fairing, make sure the clearance between the crown skin and the lower edge

of the dorsal fairing meets the gap requirements specified in the applicable Aircraft Maintenance Manual

(AMM). If necessary, trim the lower edge of the dorsal fairing or adjust the installation shims as specified

in the AMM in order to meet the gap requirements.

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

Group 1:

Affected Maintenance Zones

Model Zone

747-400, 747-400D, 747-400F 273, 274

Group 2:

Affected Maintenance Zones

Model Zone

747-100, 747-200B, 747-200C, 273, 274

747-200F, 747-300, 747-400,

747-400F

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.

Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.

When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When

more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION

numbers for that CONDITION number or OPTION number.

The Conditions, Actions and Compliance times shown apply on each side of the dorsal fairing

independently.

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Table 1: Initial Inspection, Repair, and Rub Strip Modification

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 6,000 -

flight hours after

the Original Issue date of this

service bulletin.

Before 20,000

total flight hours.

Do PART 1: Detailed Inspection for Wear or

Cracks with the Dorsal

Fairing Removed.

All Group 1 airplanes.

Within 6,000 -

flight hours after

the Original Issue date of this

service bulletin.

Within 20,000

flight hours after

a 174U9000 series dorsal fairing was installed

in accordance

with Boeing

Master Change.

Do PART 1: Detailed Inspection for Wear or

Cracks with the Dorsal

Fairing Removed.

All Group 2 airplanes.

(a)

OPTION 1 (ACTION 1): Before further flight. -

Do PART 2: Application

of Teflon Coating.

CONDITION 1: NO SKIN

CRACK OR WEAR

FOUND.

At the times given in compliance -

Table 2.

OPTION 1 (ACTION 2):

Do Repetitive Inspection,

Repair, or Rub Strip

Modification - Locations

with No Skin Wear or

Cracks.

OPTION 2 (ACTION 1): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 3.

OPTION 2 (ACTION 2):

Do Post-Modification Inspection - Locations with

a Rub Strip Installed, but

Not Repaired (no blend,

no doubler).

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Table 1: Initial Inspection, Repair, and Rub Strip Modification

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

OPTION 1 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

CONDITION 2: SKIN

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS LESS THAN OR

EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH.

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 4.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair, but No Rub

Strip.

(b)

OPTION 2 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 5.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair and a Rub

Strip Installed.

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Table 1: Initial Inspection, Repair, and Rub Strip Modification

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

OPTION 1 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

CONDITION 3: SKIN

CRACK FOUND, OR

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS MORE THAN

THE MAXIMUM ALLOWABLE REWORK DEPTH.

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 6.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair, but No

Rub Strip.

(b)

OPTION 2 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 7.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair and a

Rub Strip Installed.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 4: ANY

CRACK OR WEAR

FOUND FORWARD OF

STA 2260.

(a) One of the following Master Change service bulletins for dorsal fairing replacement is applicable to each

of the airplanes in Group 2: Service Bulletin 747-55-2037, 747-55-2038, 747-55-2040, 747-55-2041, 747-

55-2044, 747-55-2047, 747-55-2049, or 747-55-2064.

(b) The maximum allowable rework depth is 0.015 inch if the damage is less than 10 inches in length and

all of the damage is within an area that is less than 20 inches x 20 inches square. Otherwise, the maximum

allowable rework depth is 0.012 inch. Refer to 747-100/200/300 SRM 53-30-01 or 747-400 SRM 53-00-

01 or 747-400F SRM 53-00-01 or 747-400SF SRM 53-00-01, as applicable.

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Table 2: Repetitive Inspection, Repair, or Rub Strip Modification - Locations with No Skin Wear or Cracks

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

Within 6,000 flight hours after the -

initial inspection.

Do PART 6: Gap Measurement and Detailed

Inspection for Wear or

Cracks with the Dorsal

Fairing Installed.

No crack or wear found

during initial inspection in

accordance with PART 1.

Repeat PART 6: Gap - 6,000 flight hours.

Measurement and Detailed Inspection for Wear

or Cracks with the Dorsal

Fairing Installed.

CONDITION 5: GAP IS

0.10 INCH OR MORE,

AND NO SKIN CRACK OR

WEAR FOUND.

ACTION 1: Do PART 7: Before further flight. -

Dorsal Fairing Trim or

Adjustment.

CONDITION 6: GAP IS

LESS THAN 0.10 INCH,

AND NO SKIN CRACK OR

WEAR FOUND. ACTION 2: Repeat PART - 6,000 flight hours.

6: Gap Measurement and

Detailed Inspection for

Wear or Cracks with the

Dorsal Fairing Installed.

Do PART 1: Detailed In- Before further flight. -

spection for Wear or

Cracks with the Dorsal

Fairing Removed.

CONDITION 7: SKIN

CRACK FOUND OR

WEAR FOUND DURING

PART 6 INSPECTION.

(a)

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ALERT ALERT
Table 2: Repetitive Inspection, Repair, or Rub Strip Modification - Locations with No Skin Wear or Cracks

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

OPTION 1 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

CONDITION 8: SKIN

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS LESS THAN OR

EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH.

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 4.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair, but No Rub

Strip.

(b)

OPTION 2 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 5.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair and a Rub

Strip Installed.

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ALERT ALERT
Table 2: Repetitive Inspection, Repair, or Rub Strip Modification - Locations with No Skin Wear or Cracks

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

OPTION 1 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

CONDITION 9: SKIN

CRACK FOUND, OR

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS MORE THAN

THE MAXIMUM ALLOWABLE REWORK DEPTH.

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 6.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair, but No

Rub Strip.

(b)

OPTION 2 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 7.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair and a

Rub Strip Installed.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 10: ANY

CRACK OR WEAR

FOUND FORWARD OF

STA 2260.

(a) Do this inspection to find the extent and severity of the damage.

(b) The maximum allowable rework depth is 0.015 inch if the damage is less than 10 inches in length and

all of the damage is within an area that is less than 20 inches x 20 inches square. Otherwise, the maximum

allowable rework depth is 0.012 inch. Refer to 747-100/200/300 SRM 53-30-01 or 747-400 SRM 53-00-

01 or 747-400F SRM 53-00-01 or 747-400SF SRM 53-00-01, as applicable.

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ALERT ALERT
Table 3: Post-Modification Inspection - Locations with Rub Strip Installed, but Not Repaired (No Blend,

No Doubler)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 36,000 -

flight hours after

the rub strip was

installed.

Within 10,000

flight cycles after the rub strip

was installed.

Do PART 6: Gap Measurement and Detailed

Inspection for Wear or

Cracks with the Dorsal

Fairing Installed.

No wear or cracks found

during initial inspection in

accordance with PART 1,

and a rub strip was installed in accordance with

PART 3.

10,000 flight cycles

or 36,000 flight

hours, whichever is

later.

Repeat PART 6: Gap -

Measurement and Detailed Inspection for Wear

or Cracks with the Dorsal

Fairing Installed.

CONDITION 11: GAP IS

0.10 INCH OR MORE,

AND NO CRACK OR

WEAR FOUND.

ACTION 1: Do PART 7: Before further flight. -

Dorsal Fairing Trim or

Adjustment.

CONDITION 12: GAP IS

LESS THAN 0.10 INCH,

AND NO CRACK OR

WEAR FOUND. 10,000 flight cycles

or 36,000 flight

hours, whichever is

later.

ACTION 2: Repeat PART -

6: Gap Measurement and

Detailed Inspection for

Wear or Cracks with the

Dorsal Fairing Installed.

Do PART 1: Detailed In- Before further flight. -

spection for Wear or

Cracks with the Dorsal

Fairing Removed.

CONDITION 13: ANY

CRACK, SKIN WEAR, OR

RUB STRIP WEAR

FOUND DURING PART 6

INSPECTION. (a)

10,000 flight cycles

or 36,000 flight

hours, whichever is

later.

Repeat PART 6: Gap -

Measurement and Detailed Inspection for Wear

or Cracks with the Dorsal

Fairing Installed.

CONDITION 14: NO

CRACK OR SKIN WEAR

FOUND DURING PART 1

INSPECTION, AND RUB

STRIP WEAR IS LESS

THAN 0.008 INCH.

ACTION 1: Replace the Before further flight. -

rub strip in accordance

with PART 3: Rub Strip

Modification.

CONDITION 15: NO

CRACK OR SKIN WEAR

FOUND DURING PART 1

INSPECTION, AND RUB

STRIP WEAR IS 0.008

INCH OR MORE. 10,000 flight cycles

or 36,000 flight

hours, whichever is

later.

ACTION 2: Repeat PART -

6: Gap Measurement and

Detailed Inspection for

Wear or Cracks with the

Dorsal Fairing Installed.

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ALERT ALERT
Table 3: Post-Modification Inspection - Locations with Rub Strip Installed, but Not Repaired (No Blend,

No Doubler)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

OPTION 1 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

CONDITION 16: SKIN

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS LESS THAN OR

EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 4.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair, but No Rub

Strip.

OPTION 2 (ACTION 1): Before further flight. -

Do PART 4: Blend Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 5.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Blend Repair and a Rub

Strip Installed.

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ALERT ALERT
Table 3: Post-Modification Inspection - Locations with Rub Strip Installed, but Not Repaired (No Blend,

No Doubler)

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

OPTION 1 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

CONDITION 17: SKIN

CRACK FOUND, OR

WEAR FOUND BETWEEN

STA 2260 AND STA 2280

THAT IS MORE THAN

THE MAXIMUM ALLOWABLE REWORK DEPTH

OPTION 1 (ACTION 2): Before further flight. -

Do PART 2: Application

of Teflon Coating.

At the times given in compliance -

Table 6.

OPTION 1 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair, but No

Rub Strip.

OPTION 2 (ACTION 1): Before further flight. -

Do PART 5: Doubler Repair.

OPTION 2 (ACTION 2): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 7.

OPTION 2 (ACTION 3):

Do Post-Repair Inspection - Locations with a

Doubler Repair and a

Rub Strip Installed.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 18: ANY

CRACK OR WEAR

FOUND FORWARD OF

STA 2260.

(a) Do this inspection to find the extent and severity of the damage.

(b) The maximum allowable rework depth is 0.015 inch if the damage is less than 10 inches in length and

all of the damage is within an area that is less than 20 inches x 20 inches square. Otherwise, the maximum

allowable rework depth is 0.012 inch. Refer to 747-100/200/300 SRM 53-30-01 or 747-400 SRM 53-00-

01 or 747-400F SRM 53-00-01 or 747-400SF SRM 53-00-01, as applicable.

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ALERT ALERT
Table 4: Post-Repair Inspection - Locations with a Blend Repair, No Rub Strip Installed

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 6,000 -

flight hours after

the blend repair

was done.

Before 20,000

total flight cycles, or within

6,000 flight cycles after the

blend repair was

done, whichever

is later.

Do PART 8: Detailed and

HFEC or LFEC Inspection of the Blended Area

and Detailed Inspection

of Unrepaired Areas.

A blend repair was done

between STA 2260 and

STA 2280 in accordance

with PART 4, and no rub

strip is installed.

OPTION 1 (ACTION 1): Before further flight.

Do PART 2: Application

of Teflon Coating.

CONDITION 19: NO SKIN

CRACK OR WEAR

FOUND.

Within 6,000 flight hours after ini- 6,000 flight hours.

tial PART 8 inspection.

OPTION 1 (ACTION 2):

Do Initial and Repeat Inspections in accordance

with PART 6: Gap Measurement and Detailed

Inspection for Wear or

Cracks with the Dorsal

Fairing Installed.

OPTION 1 (ACTION 3): - 6,000 flight cycles.

Repeat PART 8: Detailed

and HFEC or LFEC Inspection of the Blended

Area and Detailed Inspection of Unrepaired Areas.

OPTION 2 (ACTION 1): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 5.

OPTION 2 (ACTION 2):

Do Post-Repair Inspection - Locations with a

Blend Repair and a Rub

Strip Installed.

Do PART 7: Dorsal Fair- Before further flight. -

ing Trim or Adjustment.

CONDITION 20: GAP IS

LESS THAN 0.10 INCH,

AND NO SKIN CRACK OR

WEAR FOUND.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 21: ANY SKIN

CRACK OR WEAR

FOUND.

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ALERT ALERT
Table 5: Post-Repair Inspection - Locations with a Blend Repair and a Rub Strip Installed

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 6,000 -

flight hours after

the blend repair

was done.

Before 20,000

total flight cycles, or within

6,000 flight cycles after the

blend repair was

done, whichever

is later.

Do PART 8: Detailed and

HFEC or LFEC Inspection of the Blended Area,

and Detailed Inspection

of Unrepaired Areas.

A blend repair was done

between STA 2260 and

STA 2280 in accordance

with PART 4, and a rub

strip was installed in accordance with PART 3.

Repeat PART 8: Detailed - 6,000 flight cycles.

and HFEC or LFEC Inspection of the Blended

Area and Detailed Inspection of Unrepaired Areas.

CONDITION 22: NO SKIN

CRACK OR WEAR

FOUND, AND RUB STRIP

WEAR IS LESS THAN

0.008 INCH.

ACTION 1: Replace the Before further flight. -

Rub Strip in accordance

with PART 3: Rub Strip

Modification.

CONDITION 23: NO SKIN

CRACK OR WEAR

FOUND, AND RUB STRIP

WEAR IS 0.008 INCH OR

MORE. ACTION 2: Repeat PART - 6,000 flight cycles.

8: Detailed and HFEC or

LFEC Inspection of the

Blended Area and Detailed Inspection of Unrepaired Areas.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 24: ANY SKIN

CRACK OR WEAR

FOUND.

Table 6: Post-Repair Inspection - Locations with a Doubler Repair but No Rub Strip

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 20,000 -

flight hours after

the repair was

done.

Within 10,000

flight cycles after the doubler

repair was

done.

Do PART 9: Detailed and

HFEC or LFEC Inspection of the Doubler Repair, and Detailed Inspection of Unrepaired Areas.

A doubler repair was done

between STA 2260 and

STA 2280 in accordance

PART 5.

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ALERT ALERT
Table 6: Post-Repair Inspection - Locations with a Doubler Repair but No Rub Strip

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

OPTION 1 (ACTION 1): Before further flight. -

Do PART 2: Application

of Teflon Coating.

CONDITION 25: NO

CRACK OR WEAR

FOUND IN THE SKIN OR

DOUBLER. 6,000 flight cycles

(HFEC) or 1,500

flight cycles

(LFEC).

OPTION 1 (ACTION 2): -

Repeat PART 9: Detailed

and HFEC or LFEC Inspection of the Doubler

Repair, and Detailed Inspection of Unrepaired

Areas.

OPTION 2 (ACTION 1): Before further flight. -

Do PART 3: Rub Strip

Modification.

At the times given in compliance -

Table 7.

OPTION 2 (ACTION 2):

Do Post-Repair Inspection - Locations with a

Doubler Repair and a

Rub Strip Installed.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 26: ANY

CRACK OR WEAR

FOUND IN THE SKIN OR

DOUBLER.

Table 7: Post-Repair Inspection - Locations with a Doubler Repair and a Rub Strip Installed

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

Within 20,000 -

flight hours after

the repair was

done.

Within 10,000

flight cycles after the doubler

repair was

done.

Do PART 9: Detailed and

HFEC or LFEC Inspection of the Doubler Repair, and Detailed Inspection of Unrepaired Areas.

A doubler repair was done

between STA 2260 and

STA 2280 in accordance

with PART 5, and rub strip

was installed in accordance

with PART 3.

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ALERT ALERT
Table 7: Post-Repair Inspection - Locations with a Doubler Repair and a Rub Strip Installed

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later)

Condition Action

ACTION 1: Re-install ex- Before further flight. -

isting rub strip or install

an new rub strip in accordance with PART 3: Rub

Strip Modification.

CONDITION 27: NO

CRACK OR WEAR

FOUND IN THE SKIN OR

DOUBLER, AND RUB

STRIP WEAR IS LESS

THAN 0.008 INCH. 6,000 flight cycles

(HFEC) or 1,500

flight cycles

(LFEC).

ACTION 2: Repeat PART -

9: Detailed and HFEC or

LFEC Inspection of the

Doubler Repair, and Detailed Inspection of Unrepaired Areas.

ACTION 1: Install a new Before further flight. -

Rub Strip in accordance

with PART 3: Rub Strip

Modification.

CONDITION 28: NO

CRACK OR WEAR

FOUND IN THE SKIN OR

DOUBLER, AND RUB

STRIP WEAR IS 0.008

INCH OR MORE. 6,000 flight cycles

(HFEC) or 1,500

flight cycles

(LFEC).

ACTION 2: Repeat PART -

9: Detailed and HFEC or

LFEC Inspection of the

Doubler Repair, and Detailed Inspection of Unrepaired Areas.

Contact Boeing for repair Before further flight. -

instructions and do the

repair.

CONDITION 29: ANY

CRACK OR WEAR

FOUND IN THE SKIN OR

DOUBLER.

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 service bulletin 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:

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ALERT ALERT
• 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.

Initial Inspection, Application of Teflon Coating, and Optional Rub Strip Modification

Task Number of Persons Task Hours Elapsed Hours

Access and Dorsal 1 2.15 2.15

Fairing Removal

FIGURE 1 - Detailed 1 1.50 1.50

Inspection for Wear

or Cracks

FIGURE 2 - Applica- 1 4.00 4.00

tion of Teflon Coating

FIGURE 3 - Rub 2 8.00 4.00

Strip Modification (a)

Install Dorsal Fairing 1 1.40 1.40

and Close Access

TOTAL FOR EACH AIRPLANE 9.05 9.05

(b) (b)

(a) Optional to Application of Teflon Coating. Not included in total.

(b) More time will be needed if repairs are necessary.

Repetitive Inspection

Task Number of Persons Task Hours Elapsed Hours

Access 1 0.25 0.25

FIGURE 4 - Gap 1 1.00 1.00

Measurement and

Detailed Inspection

for Wear or Cracks

with the Dorsal Fairing Installed (a)

Close Access 1 0.25 0.25

TOTAL FOR EACH AIRPLANE 1.50 1.50

(b) (b)

(a) Different inspections will be required in previously repaired areas.

(b) More time will be needed if repairs are necessary.

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ALERT ALERT
External Doubler Repair

Task Number of Persons Task Hours Elapsed Hours

FIGURE 5 - External 2 16.00 8.00

Doubler Repair

TOTAL FOR EACH REPAIR 16.00 8.00

Post-Repair Inspection - External Doubler Repair

Task Number of Persons Task Hours Elapsed Hours

Access and Dorsal 1 1.15 1.15

Fairing Removal

FIGURE 6 - Surface 1 1.50 1.50

HFEC or LFEC Inspection of Repair

Doubler

Close Access and 1 1.40 1.40

Install Dorsal Fairing

TOTAL FOR EACH AIRPLANE 4.05 4.05

H. Weight and Balance Changes

Change in Moment (PoundInches)Change in Weight (Pounds)

Airplane

All Groups +1.0 +2220.0

(a) This change is only applicable if rub strips are installed in accordance with this service

bulletin. If other parts are installed, such as a repair doubler, weight and moment

changes should be determined by the operator based on the size and configuration

of the repair parts that are installed.

I. Electrical Load Data

Not applicable.

J. References

1. Existing Data:

a. Engineering Change Memo PRR 85901-130RS

b. Boeing Service Bulletin 747-53-2721, 747-53A2478

c. Boeing Service Letter 747-SL-51-048

d. Boeing Service Related Problem (SRP) 747-SRP-53-0442

e. Service Bulletin Index D6-30300

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ALERT ALERT
f. Standard Overhaul Practices Manual (SOPM) 20-30-02, 20-41-02, 20-43-03, 20-44-01,

20-44-04, 20-50-01, 20-50-19

g. 747 Fleet Team Digest (FTD) 53-13011

h. 747 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00, Part 6, 51-00-11

i. 747-100/200/300 Aircraft Maintenance Manual (AMM) 51-21, 55-30-03

j. 747-100/200/300 Structural Repair Manual (SRM) 51-30-08, 53-30-01

k. 747-400 Aircraft Maintenance Manual (AMM) 51-21, 51-24-04, 55-30-03

l. 747-400 Structural Repair Manual (SRM) 51-40-08, 53-00-01

m. 747-400F Structural Repair Manual (SRM) 51-40-08, 53-00-01

n. 747-400SF Structural Repair Manual (SRM) 51-40-08, 53-00-01

2. Data Supplied with this Service Bulletin:

None.

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

Drawing Number Title

KIT - RUB STRIP INSTL, VERTICAL FIN TO FUSELAGE, SECT

46

675U0008

174U9000 INSTL - DORSAL FIN

The table above lists applicable drawings used to prepare this service bulletin. The drawings are

not necessary to make the specified changes, and are not supplied with this service bulletin. The

drawings may not be applicable to all airplane configurations or operators.

K. Publications Affected

1. Publications:

Publication Chapter-Section

747 Aircraft Maintenance Manual 55-30

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 affects FCS. DTI requirements for the structure affected

are contained in Paragraph 1.E., Compliance of this service bulletin.

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ALERT ALERT
L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

M. Software Accomplishment Summary

Not affected.

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ALERT ALERT
2. MATERIAL INFORMATION

A. Material - Price and Availability

Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary for Each Airplane . Operators

are encouraged to share schedule requirements with Boeing for incorporation of the service bulletin.

The parts are subject to the terms and conditions of the Boeing standard purchase order

acknowledgment. Prices are in United States Dollars. Terms: Net 30 days.

Reference this service bulletin and submit your purchase order by one of these methods:

1. Order on-line via ATA Spec 2000 or The Boeing PART Page

2. Fax to (206) 662-7145

REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST RESPONDER

AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE INFORMATION

Unit Price as of

the original issue

date of this Service Bulletin (US

Dollars)

ROLT as of the

original issue

date of this Service Bulletin (Calendar Days)

Kit Number Name Date QTY

Kit - Rub Strip Instl, Sept 26, 2014 50 139 $2,842.00

Vertical Fin to Fuselage

Sect 46

675U0008-3

Nov 7, 2014 45

Operators are encouraged to complete the survey provided in APPENDIX A of this service bulletin to

help Boeing predict the quantity and timing of the Boeing Supplied Kits/Parts.

B. Industry Support Information

Boeing warranty remedies are not available for the inspection and/or repair procedures given in this

service bulletin.

C. Parts Necessary for Each Airplane

1. Kits/Parts

To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability.

NOTE: One top kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied by

the Operator, are necessary for each airplane.

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ALERT ALERT
ALL

Kit 675U0008

Existing Part Notes

Number

New Part Number Qty Name

-3

KIT - RUB STRIP (a)

INSTL, VERTICAL

FIN TO FUSELAGE SECT 46

675U0008-3 -

675U0008-1 1 RUB STRIP (b)

675U0008-2 1 RUB STRIP (b)

BOLT, PROTRUD- (c)

ING HD

BACB30NX6K2 8

BOLT, PROTRUD- (c)

ING HD

BACB30NX6K3Y 2

BOLT, PROTRUD- (c)

ING HD

BACB30NX6K4Y 2

BACC30AC6 4 COLLAR -

BACC30BH6 8 COLLAR -

(a) This kit is only required if the operator chooses to install optional rub

strips in the dorsal fairing wear areas.

(b) This part is not used in production.

(c) If grip length shown is not available at Boeing, fasteners supplied in kits

may be one grip length longer than indicated. Also, if any fasteners part

numbers listed are not available or have been superseded, substitute

fasteners may be supplied in kits.

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.

Part Number / QTY Name Notes

Specification

4 Primer (a)

ounces

BMS 10-11, Type

1

4 Primer (a) (b)

ounces

BMS 10-79, Type

3

2 Chemical Conversion Coating (b) (c)

ounces

Alodine: Type 2,

Class A

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Part Number / QTY Name Notes

Specification

as re- Repair Washers (d)

quired

66-2955-( )

4 Sealant (a) (b)

ounces

BMS 5-95

as re- Stock (Repair Doubler) (f)

quired

2024-T3 Clad

Sheet (0.071)

as re- Stock (Repair Filler) (g)

quired

2024-T3 Clad

Sheet (0.063)

BACB30NX6K3 8 BOLT, PROTRUDING HD (e) (j)

as re- Rivet (h) (e)

quired

BACR15BB6D( )

as re- Rivet (h) (e)

quired

BACR15CE6D( )

BACS40R014B016F 2 Shim (i)

BACS40R014C016F 2 Shim (i)

BACS40R016C019F 4 Shim (i)

BACS40R016D016F 2 Shim (i)

BACS40R014E016F 2 Shim (i)

(a) Refer to the Qualified Products List at the end of the Boeing Material Specification (BMS)

for supplier data.

(b) Required only for FIGURE 3 - Rub Strip Modification or FIGURE 5 - External Doubler

Repair.

(c) Refer to SOPM 20-43-03 or 747 SRM Chapter 51 for material alternatives.

(d) No specific part number required. Make repair washers as required for FIGURE 3 - Rub

Strip Modification or FIGURE 5 - External Doubler Repair. Refer to 747-100/200/300

SRM 51-30-08, or 747-400 SRM 51-40-08, or 747-400F SRM 51-40-08, or 747-400SF

SRM 51-40-08 for accepted procedures.

(e) Refer to 747 Structural Repair Manual Chapter 51 for alternate fasteners.

(f) 0.071 inch thick stock required only if FIGURE 5 - External Doubler Repair is necessary.

(g) 0.063 inch thick stock required only if a filler is necessary during FIGURE 5 - External

Doubler Repair.

(h) If necessary for FIGURE 5 - External Doubler Repair.

(i) These shims could be required during dorsal fairing installation to adjust the fairing to

skin gap. The fairing can also be trimmed to adjust the gap. As an option, equivalent

shims can be made by the operator.

(j) Required only if rub strip is installed over a repair doubler.

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ALERT ALERT
3. Parts Modified and Reidentified

None.

4. Parts Removed and Not Replaced

None.

D. Parts Necessary to Change Spares

None.

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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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

– 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 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. 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.

6. A Detailed Inspection is defined as: An intensive examination of a specific item,

installation, or assembly to detect damage, failure, or irregularity. Available lighting

is normally supplemented with a direct source of good lighting at an intensity deemed

appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be

necessary. Surface cleaning and elaborate procedures may be required.

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ALERT ALERT
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. Boeing Service Letter 747-SL-51-048, Damage Reporting and Repair Plan/Design

Guidelines, is an acceptable procedure to request information from Boeing for

additional structural repair instructions. The Service Letter describes what information

must be provided to Boeing before a structural repair can be provided.

9. The instructions in Paragraph 3.B., Work Instructions and the figures can include

operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated

Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing

Index contain data on versions of the tools or test equipment that you can use. It is

permitted to use replaced tools. It is not permitted to use superseded tools.

10. 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.

11. 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.

12. If shading is used, shaded areas in Figures are to separate the non-critical and

non-authoritative information from the critical and authoritative information.

13. Use of colors in Figures is based on guidance from the ATA e-Business Program

(ATA) iSpec 2200.

14. When more than one OPTION is given for a CONDITION, do only one of the OPTION

numbers. When more than one ACTION is given for a CONDITION number or an

OPTION number, do all of the ACTION numbers for that CONDITION number or

OPTION number.

15. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS

are in Paragraph 1.E., Compliance.

16. The initial inspection should be done on both the left side and right side of the airplane.

However, depending on inspection findings and subsequent repairs, follow-on

inspections and compliance times could be different on each side of the airplane.

Therefore, the CONDITIONS, ACTIONS and OPTIONS shown can apply to the skin

(including any repair doublers) on each side of the dorsal fairing independently. The

term "location" as used in the Work Instructions below means the skin (including any

repair doubler) on the left side or the right side of the dorsal fairing.

17. 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.

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ALERT ALERT
18. The maximum allowable rework depth given in the SRM is 0.015 inch if the damage

is less than 10 inches in length and all of the damage is within an area that is less

than 20 inches x 20 inches square. Otherwise, the maximum allowable rework depth

is 0.012 inch. Refer to 747-100/200/300 SRM 53-30-01 or 747-400 SRM 53-00-01

or 747-400F SRM 53-00-01 or 747-400SF SRM 53-00-01, as applicable.

B. WORK INSTRUCTIONS

Initial Inspection, Repair, and Rub Strip Modification (see Compliance Table 1)

1. Get access to dorsal fairing forward of Station (STA) 2280, and remove the dorsal fairing. Refer

to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 as an accepted procedure.

2. Do PART 1: Detailed Inspection for Wear or Cracks with the Dorsal Fairing Removed.

CONDITION 1: NO SKIN CRACK OR WEAR FOUND

a. Do one of the following:

(1) OPTION 1:

(a) OPTION 1 (ACTION 1): Do PART 2: Application of Teflon Coating.

(b) OPTION 1 (ACTION 2): Do Repetitive Inspection, Repair, or Rub Strip Modification

- Locations with No Skin Wear or Cracks.

(2) OPTION 2:

(a) OPTION 2 (ACTION 1): Do PART 3: Rub Strip Modification.

(b) OPTION 2 (ACTION 2): Do Post-Modification Inspection - Locations with Rub Strip

Installed, but Not Repaired.

CONDITION 2: SKIN WEAR FOUND BETWEEN STA 2260 AND STA 2280 THAT IS LESS

THAN OR EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH

a. Do one of the following:

(1) OPTION 1:

(a) OPTION 1 (ACTION 1): Do PART 4: Blend Repair.

(b) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

(c) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend Repair,

but No Rub Strip.

(2) OPTION 2:

(a) OPTION 2 (ACTION 1): Do PART 4: Blend Repair.

(b) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

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(c) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend Repair

and a Rub Strip Installed.

CONDITION 3: SKIN CRACK FOUND, OR WEAR FOUND BETWEEN STA 2260 AND STA 2280

THAT IS MORE THAN THE MAXIMUM ALLOWABLE REWORK DEPTH

a. Do one of the following:

(1) OPTION 1:

(a) OPTION 1 (ACTION 1): Do PART 5: Doubler Repair.

(b) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

(c) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler Repair,

but No Rub Strip.

(2) OPTION 2:

(a) OPTION 2 (ACTION 1): Do PART 5: Doubler Repair.

(b) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

(c) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler Repair

and a Rub Strip Installed.

CONDITION 4: ANY CRACK OR WEAR FOUND FORWARD OF STA 2260

a. Contact Boeing for repair instructions and do the repair.

3. Put the airplane back to a serviceable condition.

Repetitive Inspection, Repair, and Rub Strip Modification - Locations with No Skin Wear or

Cracks (see Compliance Table 2)

1. Do PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the Dorsal Fairing

Installed.

CONDITION 5: GAP IS 0.10 INCH OR MORE, AND NO SKIN CRACK OR WEAR FOUND

a. Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the

Dorsal Fairing Installed.

CONDITION 6: GAP IS LESS THAN 0.10 INCH, AND NO SKIN CRACK OR WEAR FOUND

a. ACTION 1: Do PART 7: Dorsal Fairing Trim or Adjustment.

b. ACTION 2: Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks

with the Dorsal Fairing Installed.

CONDITION 7: SKIN CRACK FOUND, OR WEAR FOUND DURING PART 6 INSPECTION

a. Do PART 1: Detailed Inspection for Wear or Cracks with the Dorsal Fairing Removed.

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ALERT ALERT
CONDITION 8: SKIN WEAR FOUND BETWEEN STA 2260 AND STA 2280 THAT IS LESS

THAN OR EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH

(1) Do one of the following:

(a) OPTION 1:

1) OPTION 1 (ACTION 1): Do PART 4: Blend Repair.

2) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

3) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend

Repair, but No Rub Strip.

(b) OPTION 2:

1) OPTION 2 (ACTION 1): Do PART 4: Blend Repair.

2) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

3) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend

Repair and a Rub Strip Installed.

CONDITION 9: SKIN CRACK FOUND, OR WEAR FOUND BETWEEN STA 2260 AND STA

2280 THAT IS MORE THAN THE MAXIMUM ALLOWABLE REWORK DEPTH

(1) Do one of the following:

(a) OPTION 1:

1) OPTION 1 (ACTION 1): Do PART 5: Doubler Repair.

2) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

3) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler

Repair, but No Rub Strip.

(b) OPTION 2:

1) OPTION 2 (ACTION 1): Do PART 5: Doubler Repair.

2) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

3) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler

Repair and a Rub Strip Installed.

CONDITION 10: ANY CRACK OR WEAR FOUND FORWARD OF STA 2260

(1) Contact Boeing for repair instructions and do the repair.

2. Put the airplane back to a serviceable condition.

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ALERT ALERT
Post-Modification Inspection - Locations with Rub Strip Installed, but No Skin Repair (No Skin

Blend, No Skin Doubler. See Compliance Table 3)

1. Do PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the Dorsal Fairing

Installed.

CONDITION 11: GAP IS 0.10 INCH OR MORE, AND NO CRACK OR WEAR FOUND

a. Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the

Dorsal Fairing Installed.

CONDITION 12: GAP IS LESS THAN 0.10 INCH, AND NO CRACK OR WEAR FOUND

a. ACTION 1: Do PART 7: Dorsal Fairing Trim or Adjustment.

b. ACTION 2: Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks

with the Dorsal Fairing Installed.

CONDITION 13: CRACK, SKIN WEAR, OR RUB STRIP WEAR FOUND DURING PART 6

INSPECTION

a. Do PART 1: Detailed Inspection for Wear or Cracks with the Dorsal Fairing Removed.

CONDITION 14: NO CRACK OR SKIN WEAR FOUND DURING PART 1 INSPECTION,

AND RUB STRIP WEAR IS LESS THAN 0.008 INCH.

(1) Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the

Dorsal Fairing Installed.

CONDITION 15: NO CRACK OR SKIN WEAR FOUND DURING PART 1 INSPECTION,

AND RUB STRIP WEAR IS 0.008 INCH OR MORE.

(1) ACTION 1: Remove the existing rub strip and install a new rub strip in accordance with

PART 3: Rub Strip Modification.

(2) ACTION 2: Repeat PART 6: Gap Measurement and Detailed Inspection for Wear or

Cracks with the Dorsal Fairing Installed.

CONDITION 16: SKIN WEAR FOUND BETWEEN STA 2260 AND STA 2280 THAT IS LESS

THAN OR EQUAL TO THE MAXIMUM ALLOWABLE REWORK DEPTH

(1) Do one of the following:

(a) OPTION 1:

1) OPTION 1 (ACTION 1): Do PART 4: Blend Repair.

2) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

3) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend

Repair, but No Rub Strip.

(b) OPTION 2:

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1) OPTION 2 (ACTION 1): Do PART 4: Blend Repair.

2) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

3) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Blend

Repair and a Rub Strip Installed.

NOTE: Rub strip would need to be removed to inspect the skin.

CONDITION 17: SKIN CRACK FOUND, OR WEAR FOUND BETWEEN STA 2260 AND

STA 2280 THAT IS MORE THAN THE MAXIMUM ALLOWABLE REWORK DEPTH

(1) Do one of the following:

(a) OPTION 1:

1) OPTION 1 (ACTION 1): Do PART 5: Doubler Repair.

2) OPTION 1 (ACTION 2): Do PART 2: Application of Teflon Coating.

3) OPTION 1 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler

Repair, but No Rub Strip.

(b) OPTION 2:

1) OPTION 2 (ACTION 1): Do PART 5: Doubler Repair.

2) OPTION 2 (ACTION 2): Do PART 3: Rub Strip Modification.

3) OPTION 2 (ACTION 3): Do Post-Repair Inspection - Locations with a Doubler

Repair and a Rub Strip Installed.

CONDITION 18: ANY CRACK OR WEAR FOUND FORWARD OF STA 2260

(1) Contact Boeing for repair instructions and do the repair.

Post-Repair Inspection - Locations with a Blend Repair, but No Rub Strip (see Compliance Table

4)

1. Do PART 8: Detailed and Internal Surface High Frequency Eddy Current (HFEC) or External

Surface Low Frequency Eddy Current (LFEC) Inspection of the Blended Area and Detailed

Inspection of Unrepaired Areas.

CONDITION 19: NO SKIN CRACK OR WEAR FOUND

a. Do one of the following:

(1) OPTION 1:

(a) OPTION 1 (ACTION 1): Re-apply teflon coating in accordance with PART 2:

Application of Teflon Coating.

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(b) OPTION 1 (ACTION 2): Do initial and repeat inspections in accordance with PART

6: Gap Measurement and Detailed Inspection for Wear or Cracks with the Dorsal

Fairing Installed.

CONDITION 20: GAP LESS THAN 0.10 INCH, AND NO SKIN CRACK OR WEAR

FOUND

1) Do PART 7: Dorsal Fairing Trim or Adjustment.

(c) OPTION 1 (ACTION 3): Repeat PART 8: Detailed and HFEC or LFEC Inspection of

the Blended Area and Detailed Inspection of Unrepaired Areas.

(2) OPTION 2:

(a) OPTION 2 (ACTION 1): Do PART 3: Rub Strip Modification.

(b) OPTION 2 (ACTION 2): Do Post-Repair Inspection - Locations with a Blend Repair

and a Rub Strip Installed.

CONDITION 21: ANY SKIN CRACK OR WEAR FOUND

a. Contact Boeing for repair instructions and do the repair.

2. Put the airplane back to a serviceable condition.

Post-Repair Inspection - Locations with a Blend Repair and a Rub Strip Installed (see Compliance

Table 5)

1. Do PART 8: Detailed and HFEC or LFEC Inspection of the Blended Area and Detailed Inspection

of Unrepaired Areas, after removal of rub strip.

CONDITION 22: NO SKIN CRACK OR WEAR FOUND, AND RUB STRIP WEAR IS LESS THAN

0.008 INCH.

a. Repeat PART 8: Detailed and HFEC or LFEC Inspection of the Blended Area and Detailed

Inspection of Unrepaired Areas, after removal of rub strip.

CONDITION 23: NO SKIN CRACK OR WEAR FOUND, AND RUB STRIP WEAR IS 0.008 INCH

OR MORE.

a. ACTION 1: Remove the existing rub strip and install a new rub strip in accordance with PART

3: Rub Strip Modification.

b. ACTION 2: Repeat PART 8: Detailed and HFEC or LFEC Inspection of the Blended Area and

Detailed Inspection of Unrepaired Areas, while rub strip is removed.

CONDITION 24: ANY SKIN CRACK OR WEAR FOUND

a. Contact Boeing for repair instructions and do the repair.

2. Put the airplane back to a serviceable condition.

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ALERT ALERT
Post-Repair Inspection - Locations with a Doubler Repair, but No Rub Strip (see Compliance

Table 6)

1. Do PART 9: Detailed and HFEC or LFEC Inspection of Doubler Repair, and Detailed Inspection

of Unrepaired Areas

CONDITION 25: NO CRACK OR WEAR FOUND IN THE SKIN OR DOUBLER

a. Do one of the following:

(1) OPTION 1:

(a) OPTION 1 (ACTION 1): Re-apply teflon coating in accordance with PART 2:

Application of Teflon Coating.

(b) OPTION 1 (ACTION 2): Repeat PART 9: Detailed and HFEC or LFEC Inspection of

Doubler Repair, and Detailed Inspection of Unrepaired Areas

(2) OPTION 2:

(a) OPTION 2 (ACTION 1): Do PART 3: Rub Strip Modification.

(b) OPTION 2 (ACTION 2): Do Post-Repair Inspection - Locations with a Doubler Repair

and a Rub Strip Installed.

CONDITION 26: ANY CRACK OR WEAR FOUND IN THE SKIN OR DOUBLER

a. Contact Boeing for repair instructions and do the repair.

2. Put the airplane back to a serviceable condition.

Post-Repair Inspection - Locations with a Doubler Repair and a Rub Strip Installed (see

Compliance Table 7)

1. Do PART 9: Detailed and HFEC or LFEC Inspection of Doubler Repair, and Detailed Inspection

of Unrepaired Areas

CONDITION 27: NO CRACK OR WEAR FOUND IN THE SKIN OR DOUBLER, AND RUB STRIP

WEAR IS LESS THAN 0.008 INCH.

a. ACTION 1: Re-install the existing rub strip or install a new rub strip in accordance with PART

3: Rub Strip Modification.

b. ACTION 2: Repeat PART 9: Detailed and HFEC or LFEC Inspection of Doubler Repair, and

Detailed Inspection of Unrepaired Areas

CONDITION 28: NO CRACK OR WEAR FOUND IN THE SKIN OR DOUBLER, AND RUB STRIP

WEAR IS 0.008 INCH OR MORE.

a. ACTION 1: Install a new rub strip in accordance with PART 3: Rub Strip Modification.

b. ACTION 2: Repeat PART 9: Detailed and HFEC or LFEC Inspection of Doubler Repair, and

Detailed Inspection of Unrepaired Areas

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ALERT ALERT
CONDITION 29: ANY CRACK OR WEAR FOUND IN THE SKIN OR DOUBLER

a. Contact Boeing for repair instructions and do the repair.

2. Put the airplane back to a serviceable condition.

PART 1: Detailed Inspection for Wear or Cracks with the Dorsal Fairing Removed

1. Before removing the dorsal fairing, trace a line on the skin around the entire lower edge of the

dorsal fairing. This will help to identify where to inspect, and where to apply teflon coating (if used)

after the dorsal fairing is removed. do not use any object that could damage the skin.

2. Remove the dorsal fairing from the airplane. Refer to 747-100/200/300 AMM 55-30-03 or 747-400

AMM 55-30-03 as an accepted procedure.

3. RC - Do a detailed inspection for wear or cracks in the skin in accordance with FIGURE 1.

NOTE: This detailed inspection of the skin includes detailed inspection of any existing doubler

or rub strip that has been installed over the skin within the inspection area.

4. After the necessary actions have been completed, do the following:

a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

PART 2: Application of Teflon Coating

1. RC - Apply teflon coating to the skin in accordance with FIGURE 2.

NOTE: Application of teflon coating to the skin should include application of teflon coating to any

existing doubler in the application area.

2. After the necessary actions have been completed, do the following:

a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

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ALERT ALERT
PART 3: Rub Strip Modification

1. RC - Install rub strips in accordance with FIGURE 3.

2. After the necessary actions have been completed, do the following:

a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

PART 4: Blend Repair

1. RC - Do a blend repair in accordance with 747-100/200/300 SRM 53-30-01 or 747-400 SRM

53-00-01 or 747-400F SRM 53-00-01 or 747-400SF SRM 53-00-01, as applicable.

PART 5: Doubler Repair

1. RC - Install an external repair doubler in accordance with FIGURE 5.

PART 6: Gap Measurement and Detailed Inspection for Wear or Cracks with the Dorsal Fairing

Installed

1. RC - Measure the gap between the edge of the dorsal fairing and the skin, and do a detailed

inspection for wear or cracks in the skin and rub strip, if installed, in accordance with FIGURE 4.

2. After the necessary actions have been completed, do the following:

a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

PART 7: Dorsal Fairing Trim and/or Shim Adjustment

1. RC - Trim the dorsal fairing and/or adjust the thickness of the installation shims to obtain a gap of

0.10-0.17 inch. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 as an accepted

procedure.

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
NOTE: Trimming of the dorsal fairing is likely to be required after the initial gap measurement,

or when a new dorsal fairing is installed. However, adjustment of the installation shims

to change the gap is optional as long as bulb seal compression is maintained. If the fairing

will be trimmed, do the following steps.

2. If no more work is required, install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or

747-400 AMM 55-30-03 as an accepted procedure.

PART 8: Detailed and HFEC or LFEC Inspection of The Blended Area and Detailed Inspection

of Unrepaired Areas

1. Remove the dorsal fairing from the airplane. Refer to 747-100/200/300 AMM 55-30-03 or 747-400

AMM 55-30-03 as an accepted procedure.

2. RC - Do an Eddy Current inspection for cracks (remove rub strip if installed) in the skin in any area

where a blend repair was previously done. Do the Internal Surface HFEC inspection in accordance

with 747 NDT Manual Part 6, 51-00-11, procedure 4 or 23. Do the External Surface LFEC inspection

in accordance with 747 NDT Manual 6, 53-30-00, procedure 5. Do the inspection in both the vertical

and horizontal directions.

3. RC - Do a detailed inspection for wear or cracks in the skin in accordance with FIGURE 1.

4. After the necessary actions have been completed, do the following:

a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

PART 9: Detailed and HFEC or LFEC Inspection of Doubler Repair, and Detailed Inspection of

Unrepaired Areas

1. Remove the dorsal fairing from the airplane. Refer to 747-100/200/300 AMM 55-30-03 or 747-400

AMM 55-30-03 as an accepted procedure.

2. Remove any existing teflon coating from the HFEC inspection area.

3. If an existing rub strip is installed over the doubler repair, remove the rub strip.

4. RC - Do a detailed inspection for wear on the rub strip.

5. RC - Do Internal Surface HFEC or External Surface LFEC inspections for cracks in the external

doubler in accordance with FIGURE 6.

6. RC - Do a detailed inspection for wear or cracks in the skin in accordance with FIGURE 1.

7. After the necessary actions have been completed, do the following:

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ALERT ALERT
a. Install the dorsal fairing. Refer to 747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03

as an accepted procedure.

b. RC - Make sure the gap between the edge of the dorsal fairing and the skin is 0.10-0.17 inch.

NOTE: Adjust the fairing as required. No more than 0.10 - 0,17 trim is allowed per side.

c. If the gap is not within limits, trim the edge of the dorsal fairing or change the shim thicknesses

at the dorsal fairing attach points in order to meet the gap requirements. Refer to

747-100/200/300 AMM 55-30-03 or 747-400 AMM 55-30-03 for accepted procedures.

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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 each airplane.

Step Task Name Identification Qty More Data

146U3214-( ) OR 1 (a) (b) (c)

65B04155-( )

1 Inspect Skin

(a) Do a detailed inspection for wear or cracks in the skin in the area shown. Inspect a minimum of 3.0 inches

on both sides of where the dorsal fairing edge is located when the dorsal fairing is installed.

(b) If a doubler is installed in the inspection area, also do a detailed inspection for wear or cracks in the

doubler.

(c) If a rub strip is installed in the inspection area, also do a detailed inspection for wear or cracks in the rub

strip.

FIGURE 1: DETAILED INSPECTION FOR WEAR OR CRACKS WITH THE DORSAL FAIRING REMOVED

(SHEET 1 OF 1)

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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 each airplane.

Step Task Name Identification Qty More Data

1 Apply Primer BMS 10-11, TYPE 1 4 Oz (a)

BMS 10-86, TYPE 1 8 Oz (b)

OR TYPE 2

2 Apply Teflon Coating

(a) Refer to SOPM 20-41-02 for accepted procedures. If a doubler repair has been done between STA 2260

and STA 2280, apply the primer over the doubler instead of the skin.

FIGURE 2: APPLICATION OF TEFLON COATING

(SHEET 1 OF 2)

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ALERT ALERT
Step Task Name Identification Qty More Data

(b) Refer to SOPM 20-44-01 and/or 747-400 AMM 51-24-04 for accepted procedures. Apply the teflon coating

in the area shown. Make sure the teflon coating extends a minimum of 2.0 inches on both sides of where

the dorsal fairing edge is located when the dorsal fairing is installed. Apply the teflon coating with a minimum

thickness of 0.005 inch. If a doubler repair has been done between STA 2260 and STA 2280, apply the

teflon coating over the doubler instead of the skin.

FIGURE 2: APPLICATION OF TEFLON COATING

(SHEET 2 OF 2)

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ALERT ALERT
FIGURE 3: RUB STRIP MODIFICATION

(SHEET 1 OF 8)

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ALERT ALERT
FIGURE 3: RUB STRIP MODIFICATION

(SHEET 2 OF 8)

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ALERT ALERT
FIGURE 3: RUB STRIP MODIFICATION

(SHEET 3 OF 8)

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ALERT ALERT
FIGURE 3: RUB STRIP MODIFICATION

(SHEET 4 OF 8)

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ALERT ALERT
FIGURE 3: RUB STRIP MODIFICATION

(SHEET 5 OF 8)

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BOEING SERVICE BULLETIN 747-53A2876

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 each airplane.

NOTE: The following procedure gives instructions for installation of a rub strip on both the left side and right

side of the dorsal fairing. It is acceptable to install a rub strip on only the left side or the right side.

However, inspection requirements and compliance times will be different for areas with a rub strip vs.

areas without a rub strip.

Step Task Name Identification Qty More Data

BMS 10-86, TYPE 1 - (a)

OR TYPE 2

1 Remove Teflon Coating

2 Remove Existing Fasteners - 4 (b)

3 Remove Existing Finish - - (c)

Chemical Conversion TYPE 2, CLASS A 2 Oz (d)

Coating

4 Apply

5 Apply Primer BMS 10-79, TYPE 3 2 Oz (e)

6 Locate RUB STRIP 675U0008-1 1 (f)

Locate RUB STRIP 675U0008-2 1 (f)

Locate Tapered Fillers - 2 (g)

7 Drill / Ream Existing Holes - 4 (h)

Drill / Ream New Holes - 8 (h)

8 Drill / Ream RUB STRIP 675U0008-1 1 (i)

Drill / Ream RUB STRIP 675U0008-2 1 (i)

Drill / Ream Tapered Fillers - -

9 Install (New) Repair Washers - 4 (j)

10 Apply Faying Surface Sealant BMS 5-95 4 Oz (k)

11 Install (New) RUB STRIP 675U0008-1 1 Left side.

Install (New) RUB STRIP 675U0008-2 1 Right side.

Install (New) Tapered Fillers - -

(a) Remove any existing teflon coating that was previously applied to the skin or doubler. Refer to SOPM 20-

30-02 for accepted procedures. If there is no existing teflon coating, this step is not necessary.

(b) Remove existing fasteners at the locations shown that will be used to attach the forward ends of the rub

strips.

(c) Remove any loose or damaged finish (primer and/or enamel) in the area that the rub strips will be installed.

Blend the edges of the remaining finish to make a smooth surface. Refer to SOPM 20-30-02 for accepted

procedures.

(d) Apply Type 2, Class A chemical conversion coating (F-17.10) to bare aluminum. Refer to SOPM 20-43-

03 for accepted procedures.

FIGURE 3: RUB STRIP MODIFICATION

(SHEET 6 OF 8)

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Step Task Name Identification Qty More Data

(e) Apply BMS 10-79, Type 3 primer (F-19.47) to the reworked area plus a minimum of 0.25 inch beyond the

edge of where the rub strips will be installed. Refer to SOPM 20-44-04 for accepted procedures.

(f) Locate the rub strip as shown along the intersection of the skin and the dorsal fairing edge. If existing rub

strips have been installed aft of STA 2280 in accordance with Service Bulletin 747-53-2721, locate the

aft ends of the new rub strips with a maximum gap of 0.10 inch from the Service Bulletin 747-53-2721

rub strips. Maintain 1.7D minimum edge margin at new and existing fastener locations common to the

rub strip.

(g) Make and install tapered fillers for area adjacent to repair doubler as shown. Taper the fillers down to a

minimum thickness of 0.020 inch, with a taper ratio of at least 100 to 1. Install the tapered fillers with BMS

5-95 sealant. Limit pull-up to all parts to 0.010 maximum. Refer to SOPM 20-50-19 as an accepted procedures.

(h) Drill holes through the entire stack up to the size specified in the fastener table.

(i) Remove the rub strips and drill holes through the rub strips only to 0.247-0.258 inch diameter at existing

fastener locations, and 0.218-0.229 inch diameter at new fastener location.

(j) Make and install repair washers in the countersinks of the existing holes where fasteners were removed.

Refer to 747-100/200/300 SRM 51-30-08, or 747-400 SRM 51-40-08, or 747-400F SRM 51-40-08, for

accepted procedures. After the repair washers are firmly bonded in place, shave the washers flush within

+0.005 inch of the skin surface.

(k) Apply BMS 5-95 faying surface sealant to the mating surfaces of the rub strips and skin. Refer to SOPM

20-50-19 for accepted procedures. After rub strip installation, form the squeeze out into a small fillet

around the edge of the rub strips.

The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure.

A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the

number of fasteners necessary for this figure.

Code Name Identification Qty Hole Dia More Data

Drill 0.247-0.258 inch diameter through rub strips

only.

BOLT, PROTRUDING BACB30NX6K3Y 2 0.216-0.219

HD

A

(a) (b)

COLLAR BACC30AC6 2 - -

Drill 0.247-0.258 inch diameter through rub strips

only.

BOLT, PROTRUDING BACB30NX6K4Y 2 0.216-0.219

HD

B

(a) (b)

COLLAR BACC30AC6 2 - -

0.218-0.229 inch diameter

through rub strips only.

BOLT, PROTRUDING BACB30NX6K2 8 0.187-0.190

HD

C

(a) (b)

COLLAR BACC30BH6 8 - -

FIGURE 3: RUB STRIP MODIFICATION

(SHEET 7 OF 8)

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BOEING SERVICE BULLETIN 747-53A2876

ALERT ALERT
Code Name Identification Qty Hole Dia More Data

0.218-0.229 inch diameter

through rub strips only.

BOLT, PROTRUDING BACB30NX6K3 8 0.187-0.190

HD

D

(a) (b) (c)

COLLAR BACC30BH6 8 - -

(a) Maintain 2D minimum edge margin.

(b) Install fasteners wet with BMS 5-95 sealant. Refer to SOPM 20-50-19, fastener sealing Method 2 as an

accepted procedure.

(c) Install this fastener as required at locations where a doubler repair has been accomplished.

FIGURE 3: RUB STRIP MODIFICATION

(SHEET 8 OF 8)

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ALERT ALERT
FIGURE 4: GAP MEASUREMENT AND DETAILED INSPECTION FOR WEAR OR CRACKS WITH THE

DORSAL FAIRING INSTALLED

(SHEET 1 OF 2)

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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 each airplane.

Step Task Name Identification Qty More Data

Skin and Rub Strip (if - 1 (a)

installed)

1 Inspect

2 Measure Gap - 1 (b) (c)

(a) Do a detailed inspection for wear or cracks in the skin and rub strip, if installed, in the area shown. Inspect

a minimum of 3.0 inches around the outside perimeter of the dorsal fairing. The left side is shown, but do

the inspection of the skin on both sides of the fairing.

(b) Measure the gap between the edge of the dorsal fairing and the skin. Do the measurement along the

entire edge of the dorsal fairing on both sides of the fairing. The gap should be 0.10-0.17 inch.

(c) Adjustment of fairing may be required such that continuous trimming of fairing does not occur.

FIGURE 4: GAP MEASUREMENT AND DETAILED INSPECTION FOR WEAR OR CRACKS WITH THE

DORSAL FAIRING INSTALLED

(SHEET 2 OF 2)

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ALERT ALERT
FIGURE 5: EXTERNAL DOUBLER REPAIR

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 5: EXTERNAL DOUBLER REPAIR

(SHEET 2 OF 5)

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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 each airplane.

CAUTION: COMPLETE DAMAGE REMOVAL IS NECESSARY TO ESTABLISH APPROPRIATE REPAIR

ACTIONS AND TO AVOID DEVELOPMENT OF FATIGUE CRACKING. DAMAGE THAT IS NOT

COMPLETELY REMOVED CAN REDUCE THE FATIGUE STRENGTH OF THE PART, WHICH

CAN RESULT IN CRACKING. IN EXTREME CASES, UNDETECTED FATIGUE CRACKING CAN

COMPROMISE STRUCTURAL INTEGRITY.

Step Task Name Identification Qty More Data

1 Remove Existing Fasteners - - (a)

146U3214-( ) OR 1 (c)

65B04155-( )

2 Repair Skin

3 Inspect Existing Fastener Holes - 1 (g)

146U3214-( ) OR 1 (h)

65B04155-( )

4 Inspect Skin

146U3214-( ) OR 1 (b)

65B04155-( )

5 Cut Skin

146U3214-( ) OR 1 (i)

65B04155-( )

6 Inspect Skin

7 Make Repair Doubler - 1 (d)

Make Repair Filler - 1 (e)

Make Repair Washers - - (f)

8 Assemble Repair Doubler - 1 (j)

Assemble Repair Filler - 1 (j)

9 Drill / Ream Repair Doubler - 1 (j)

Drill / Ream Repair Filler - 1 (j)

10 Clean/Deburr Repair Doubler - 1 (k)

Clean/Deburr Repair Filler - 1 (k)

Chemical Conversion TYPE 2, CLASS A 4 Oz (l)

Coating

11 Apply

Apply Primer BMS 10-79, TYPE 3 4 Oz (m)

12 Apply Faying Surface Sealant BMS 5-95 4 (n)

13 Install (New) Repair Doubler - 1 (o)

Install (New) Repair Filler - 1 (o)

14 Apply Finish - - (p)

(a) Remove existing skin fasteners as necessary.

FIGURE 5: EXTERNAL DOUBLER REPAIR

(SHEET 3 OF 5)

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(b) Trim out and remove any damaged skin that is less than 0.050 inch thick after blending. Be careful not

to damage underlying support structure including tear straps. Keep a 0.50 inch minimum radius at the

corners of the skin cutout. If a rectangular cutout is made, align the edges to be parallel and perpendicular

to nearby tear straps and stringers. Maintain 3D minimum edge margin from cutout to any adjacent fastener holes. Maintain 2D minimum edges of parts. Maintain 63 microinches Ra or better surface finish on

the trimmed edges.

(c) Return all dented skin to the initial contour. Blend the damaged area to remove any nicks, scratches,

gouges, burrs, and sharp edges.

(d) Make a repair doubler from the same material as the initial skin, but one gage thicker than the initial skin.

The repair doubler need to be finished per F-17.10 + F-19.47. The repair shown is an example. Adjust

the repair and the size of the doubler as necessary to remove all of the skin damage.

(e) Make a repair filler (apply F-17.10 + F-20.02 to filler) of the same material and thickness as the initial skin.

A filler is required only if the repair is between tear straps, and between stringers.

(f) Make and install repair washers, as necessary, at existing fastener locations. Refer to 747-100/200/300

SRM 51-30-08, or 747-400 SRM 51-40-08, or 747-400F SRM 51-40-08, for accepted procedures.

(g) Do an open hole high frequency eddy current (HFEC) inspection at hole locations where fasteners were

removed to ensure a crack free condition. Do the inspection in accordance with 747 NDT Manual Part 6,

51-00-00, Procedure 1, 11, or 16. If any crack indication is found, contact Boeing for repair instructions

and do the repair.

(h) Do a surface HFEC inspection of the blended area of the skin to ensure a crack free condition. Do the

inspection in accordance with 747 NDT Manual Part 6, 51-00-00, Procedure 4 or 23. If any crack indication

is found, contact Boeing for repair instructions and do the repair, or do additional blending in the area as

necessary to remove the crack indication, but do not exceed the limits given in the 747 SRM.

(i) Do a surface HFEC inspection of trimmed edges of the cutout to ensure a crack free condition. Do the

inspection in accordance with 747 NDT Manual Part 6, 51-00-00, Procedure 4 or 23. If any crack indication

is found, make the trimmed area larger as necessary to remove the crack indication.

(j) Assemble the repair parts and drill the fastener holes with fastener spacing of 1.30 - 1.35 inch, except

spacing can be reduced to 4D minimum if limited by existing fastener row, the repair cutout, or if necessary

to maintain minimum 2D edge margin on adjacent structure. Use a drill stop to restrict penetration through

the skin to 0.06 inch maximum.

(k) Disassemble the repair parts and remove any nicks, scratches, gouges, burrs, or sharp edges from the

repair parts and initial parts.

(l) Apply Type 2, Class A chemical conversion coating (F-17.10) to the repair parts and to bare aluminum

surfaces of the initial parts and trimmed skin. Refer to SOPM 20-43-03 as an accepted procedures.

(m) Apply BMS 10-79, Type 3 primer (F-19.47) to the repair parts and to bare aluminum surfaces of the initial

parts. Refer to SOPM 20-44-04 as an accepted procedures.

(n) Apply BMS 5-95 faying surface sealant to the mating surfaces of the repair parts and initial parts. Make

sure all voids are filled with sealant. Refer to SOPM 20-50-19 as an accepted procedures.

FIGURE 5: EXTERNAL DOUBLER REPAIR

(SHEET 4 OF 5)

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(o) Install the repair parts with fasteners as specified in the illustration. If a rub strip will be installed, do not

install the fasteners identified as "rub strip attach location". Fasteners that are not made of aluminum

must be installed wet with BMS 5-95 sealant. After installation, form the squeeze out into fillet around the

doubler. Apply more sealant as necessary to make a continuous fillet seal around the doubler. Refer to

SOPM 20-50-19 as an accepted procedures. For aerodynamic seal refer to SOPM 20-50-11 as an accepted

procedures.

(p) Apply finish to the repair area. Refer to 747-100/200/300 AMM 51-21 or 747-400 AMM 51-21 for accepted

procedures.

The codes shown below agree with the letter shown in the upper left corner of the fastener symbols in the figure.

A number in the lower right corner gives the grip length of the fastener. The QTY numbers shown below are the

number of fasteners necessary for this figure.

Code Name Identification Qty Hole Dia More Data

A Rivet BACR15BB6D( ) - 0.191-0.202 (a)

B Rivet BACR15CE6D( ) - 0.191-0.202 (a)

(a) Quantity and grip lengths as required depending on the repair.

FIGURE 5: EXTERNAL DOUBLER REPAIR

(SHEET 5 OF 5)

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FIGURE 6: SURFACE HFEC INSPECTION OF REPAIR DOUBLER

(SHEET 1 OF 3)

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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.

Step Task Name Identification Qty More Data

1 Inspect Skin - - (a) (b)

FIGURE 6: SURFACE HFEC INSPECTION OF REPAIR DOUBLER

(SHEET 2 OF 3)

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(a) Do an internal surface HFEC inspection for cracks in the skin under the repair doubler. Inspect around

each fastener in the inspection area. Do the inspection in accordance with 747 NDT Manual Part 6, 51-

00-00, Procedure 4 or 23.

As an alternative, do an external surface LFEC inspection for cracks in the skin under the repair doubler.

Inspect around each fastener in the inspection area. Do the inspection in accordance with 747 NDT

Manual Part 6, 53-30-00, Procedure 6. If an existing rub strip is installed over any part of the inspection

area, remove the rub strip to do the inspection. After inspection, re-install the existing rub strip or install

a new rub strip in accordance with FIGURE 3.

(b) It is not necessary to do the internal HFEC (High Frequency Eddy Current) inspection at locations where

the skin is covered by internal structure.

FIGURE 6: SURFACE HFEC INSPECTION OF REPAIR DOUBLER

(SHEET 3 OF 3)

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APPENDIX A: PART DEMAND INTENT

(SHEET 1 OF 1)

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