Commercial

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2688

Original Issue: August 21, 2008

Revision 1: September 19, 2012

ATA System: 5321

SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord

Inspection and Repair at Floor Panel Attachment Fastener Holes

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 © 2008 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Unpublished Work.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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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT

BLANK PAGE
Table of Contents

Revision Transmittal Sheet ............................................ 5

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 29

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

1. Kits/Parts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2. Parts and Materials Supplied by the Operator: . . . . . . . . . . . . . . . . . . . . . . . . 31

3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4. Parts Removed and Not Replaced: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 35

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

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

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] . . . . . . . 50

FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 2] . . . . . . . 51

FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION . . . . . 55

FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION . . . . . . . . . . 59

FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL . . . . . . . . . . . 62

FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . 65

FIGURE 8: SECTION 41 - UPPER CHORD TRIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP . . . . . . . . . . . . . . . . . . . 72

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP . . . . . . . . . . . . . 76

FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8) . . 87

FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9) . . 92

FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11) . . . 97

FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12) . . 102

FIGURE 17: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 3] . . . . . . 107

FIGURE 18: SECTION 44 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] . . . . . . 108

FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION [Group 1] . 112

FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION [Group 1] . . . . 116

FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL [Group 1] . . . . . 119

FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION [Group 1] . . . . . . . . . . . . . . . . 122

FIGURE 24: SECTION 44 - UPPER CHORD TRIM [Group 1] . . . . . . . . . . . . . . . . . . . . . . 126

FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP [Group 1] . . . . . . . . . . . . 129

FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP [Group 1] . . . . . . 133

FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8) [Group

1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9) [Group

1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11) [Group 1]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12) [Group 1]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

[Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . 161

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
Commercial

Airplanes 747

Service Bulletin

ALERT

Revision Transmittal Sheet Number: 747-53A2688

Original Issue: August 21, 2008

Revision 1: September 19, 2012

ATA System: 5321

SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord

Inspection and Repair at Floor Panel Attachment Fastener Holes

This revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

Federal Aviation Administration (FAA) Airworthiness Directives AD 2009-10-06 and AD 2004-07-22 R1 are

related to this service bulletin.

Group 1: More work is necessary on airplane(s) inspected or changed in accordance with the original issue of

this service bulletin. Inspection of the Section 44 upper deck floor beam upper chords from Station (STA) 1000

to STA 1100 is necessary. Continue to do inspections of the Section 41 upper deck floor beam upper chords.

No more work is necessary to change any repairs installed in accordance with the original issue of this service

bulletin. Replace the upper deck floor beam upper chords at the compliance time given in paragraph 1.E.,

Compliance.

Group 2-3: No more work is necessary on airplane(s) inspected or changed in accordance with the original issue

of this service bulletin. Continue to do inspections of the Section 41 upper deck floor beam upper chords. No

more work is necessary to change any repairs installed in accordance with the original issue of this service

bulletin. Replace the upper deck floor beam upper chords at the compliance time given in paragraph 1.E.,

Compliance.

REASON FOR REVISION

This revision is sent to add inspections and repair of the Section 44 upper deck floor beam upper chords from

STA 1000 to STA 1100 and also to add replacement of the upper deck floor beam upper chords at the time

given in paragraph 1.E., Compliance.

These sections were changed:

1. In Summary: Updated Background, Action, Compliance, Manpower, and Summary illustration. Also,

added Planning Data table.

2. Paragraph 1.A., Effectivity: Airplanes RT021, RT031, RT032, RT033, RT061, RT161, RT164, RT461,

RT519, RT526, RT530, RT576, RT577, RT578, RT579, RT642, RT752 and RT837 are moved from

group 1 to group 2. Airplanes RT631, RT632, RT743 and RT876 are moved from group 1 to new group

3. Group 1 configurations are removed.

3. Paragraph 1.C., Reason: Revision information is added.

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4. Paragraph 1.D., Description: Section 44 access information is added and maintenance zone tables

are changed for group 1 airplanes.

5. Paragraph 1.E., Compliance: AD information is added. After-modification and after-repair inspection

requirements are clarified in compliance tables 1 and 2. Some after repair/modification inspection

compliance times are changed. Repairs are numbered. Compliance tables 3 and 4 are added for the

inspection, repair and after-repair inspection of Section 44 upper deck floor beam upper chords.

Compliance table 5 has been added for upper deck floor beam upper chord replacement.

6. Paragraph 1.F., Approval: New approval information is added.

7. Paragraph 1.G., Manpower: Manpower estimates are added for Section 44 inspections.

8. Paragraph 1.H., Weight and Balance Changes: Weight and balance information is added.

9. Paragraph 1.J., References: An AD is added to existing data.

10. Paragraph 1.K., Publications Affected: Damage Tolerance Inspection information is added.

11. Paragraph 2.C.2., Parts and Materials Supplied by the Operator: Part information is added for Section

44 repairs.

12. Paragraph 3.A., General Information: Notes are added.

13. Paragraph 3.B., Work Instructions: Modification and repair options are clarified. Repairs are added to

PART 2 table 2 for upper chords made from BAC1506-2441 extrusion. After repair/modification inspection

instructions are clarified. Existing repairs are numbered. Instruction is added for the inspection, repair

and after-repair inspection of Section 44 upper deck floor beam upper chords.

14. Figure 8: Instruction is added to measure the depth of the trim.

15. Figures 13 to 16: New figures are added for the repair of upper chords made from BAC1506-2441

extrusion.

16. Figure 17: New figure added to show the inspection area for Large Cargo Freighter (LCF) configuration

airplanes.

17. Figures 18 to 32: New figures are added for the inspection, repair and after-repair/modification inspection

of Section 44 upper deck floor beam upper chords.

Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location

of important changes.

Pages with no vertical lines have no important changes.

REVISION HISTORY

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Revision 1: September 19, 2012

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
Commercial

Airplanes 747

Service Bulletin

ALERT

Summary Number: 747-53A2688

Original Issue: August 21, 2008

Revision 1: September 19, 2012

ATA System: 5321

SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord

Inspection and Repair at Floor Panel Attachment Fastener Holes

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

CONCURRENT REQUIREMENTS

None

BACKGROUND

This service bulletin gives instructions to do inspections of the floor panel attachment fastener holes in the

Section 41 and Section 44 upper deck floor beam upper chords for fatigue cracks. Cracks in these chords that

are not found and repaired could become large and cause the floor beam to become severed. This can lead to

large deflection or deformation of the floor and of the body skin, frames, and stringers. This deflection or

deformation could result in damage to wire bundles and unintended inputs to the flight control cables which

could affect airplane controllability. Multiple adjacent severed floor beams could result in rapid decompression

of the airplane.

Flight critical wire bundles and control cables are routed through cutouts in the upper deck floor beams.

Cracks have been found at open floor panel attach fastener holes in the upper chord of two Section 41 upper

deck floor beam on three different 747-400D airplanes, which had flown 24,053, 24,783, and 25,631 flight-cycles.

Boeing believes that these 747-400D airplanes were operated at reduced cabin differential pressures. Similar

cracks were also found on the 747-400 Fatigue Test airplane.

Accomplishment of the inspections given in this service bulletin will ensure the structural integrity of the upper

chords of the Section 41 upper deck floor beams.

A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR) 25.571 as

amended in 1978, to ensure safe operation of 747 airplanes throughout their operational life. From this

requirement, the Section 41 upper deck floor beam upper chords were determined to be significant, in that they

are critical to airplane structural integrity. Therefore, a flight safety inspection program which will continue

throughout the operational life of the airplane is specified in this service bulletin.

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Between the original issue and Revision 1 of this service bulletin, Boeing has received two reports of cracking

in upper deck floor beam upper chords in Section 44. The cracks were at STA 1000 and STA 1100. Due to these

crack reports Boeing has determined that inspection of all upper deck floor beam upper chords in Section 44

(from STA 1000 to STA 1100) is required.

Boeing Service Related Problem (SRP) 747-SRP-53-0293 and 747-SRP-53-0353 are related to this service

bulletin.

The upper deck floor beam upper chords have been determined to be structure that is susceptible to Widespread

Fatigue Damage (WFD). For more information about WFD, refer to Boeing Service Letter 747-SL-53-088A.

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

information.

Planning Data Affected Reference

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

AD Related Yes Paragraph 1.E., Compliance

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

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

Publications Affected No Paragraph 1.K., Publications Affected

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

Operations Manual and/or FAA Approved Airplane Flight Manual)

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

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

by the Operator

Operator Supplied Material Yes

Paragraph 2.F., Special Tooling Necessary to

do this Service Bulletin

Special Tooling Required No

ACTION

Group 1:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from Station

(STA) 340 to STA 520 and to the upper chords of the Section 44 upper deck floor beams from STA 1000 to STA

1100.

Group 2:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340

to STA 440.

Group 3:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from STA 340

to STA 380.

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
NOTE: On Group 2 airplanes, upper deck floor beams from STA 460 to STA 520 do not require inspection as

given in this service bulletin because they were replaced with new floor beams during modification to

Boeing Converted Freighter (BCF). The new floor beams have floor panel attachment fastener holes

that have been cold-worked. Also, on Group 2 airplanes, inspection as given in this service bulletin are

not necessary in Section 44 because all floor beams in Section 44 were replaced with tension ties

during modification to BCF. On Group 3 airplanes, upper deck floor beams from STA 440 to STA 500

do not require inspection as given in this service bulletin because they were replaced with new floor

beams during modification to Large Cargo Freighter (LCF). The new floor beams have floor panel

attachment fastener holes that have been cold-worked.

If access was gained from above, do open hole HFEC inspections of the floor panel attachment fastener holes

in the upper chords for cracks. If access was gained from below, modify the clipnuts for the floor panel attachment

fasteners as given in this service bulletin. Do surface HFEC inspections of the forward and aft horizontal flanges

of the upper chord at floor panel attachment fastener holes.

If cracks are found, repair before any more flights. Repair as given in this service bulletin, or ask Boeing for

repair data. For areas repaired as given in this service bulletin, start to do repeat inspections at repaired locations

as given in this service bulletin at the times given in Paragraph 1.E., Compliance. For any locations that have

a repair that is different from those shown in this service bulletin, contact Boeing for an after-repair inspection

plan.

If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance.

EFFECTIVITY

All 747-400 and 747-400D airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes.

COMPLIANCE

Federal Aviation Administration (FAA) Airworthiness Directive AD 2009-10-06 is related to this service bulletin.

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

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

MANPOWER

Section 41 Inspections

Elapsed Time

(Hours)

Total ManHoursAirplanes

Passenger 259 77.25

Boeing Converted 241 72.25

Freighter

Large Cargo

Freighter

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
Section 44 Inspections

Elapsed Time

(Hours)

Total ManHoursAirplanes

Passenger 66.00 24.00

MATERIAL INFORMATION

None

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT

BLANK PAGE
Commercial

Airplanes 747

Service Bulletin

ALERT

Number: 747-53A2688

Original Issue: August 21, 2008

Revision 1: September 19, 2012

ATA System: 5321

SUBJECT: FUSELAGE - Floors - Section 41 and Section 44 Upper Deck Floor Beam Upper Chord

Inspection and Repair at Floor Panel Attachment Fastener Holes

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 Document D6-30300, Part 3 for Airplane Variable Number, Line

Number, and Serial Number data.

This service bulletin is for the airplanes shown below.

NOTE: This service bulletin is for the airplanes identified below. For Boeing Converted Freighter

(BCF) configuration airplanes, the effectivity list shown below is complete for airplanes

modified before November 01, 2011. For any Group 1 airplane that is modified to Boeing

Converted Freighter (BCF) configuration on or after November 01, 2011, do the work as

given for Group 2 airplanes in accordance with this service bulletin.

GROUP CONFIGURATION DESCRIPTION

All 747-400 and 747-400D airplanes, except those modified to the

Boeing Converted Freighter (BCF) and Large Cargo Freighter (LCF)

configurations.

1 -

747-400 and 747-400D airplanes that have been modified to the

Boeing Converted Freighter (BCF) configuration.

2 -

All 747-400 airplanes that have been modified to the Large Cargo

Freighter (LCF) configuration.

3 -

Airplane Models:

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747-400, 747-400D

Variable Number Group

RF001 - RF006 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 - RM127 1

RM128 2

RM129 - RM132 1

RM136 - RM147 1

RM156 - RM158 1

RM166 - RM177 1

RM191 - RM192 1

RM231 - RM233 1

RM241 - RM246 1

RM261 - RM264 1

RM316 - RM318 1

RM331 - RM333 1

RM341 1

RM351 - RM355 1

RM366 - RM367 1

RM401 - RM403 1

RM426 1

RM431 1

RM441 - RM443 1

RM445 1

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
Variable Number Group

RM801 - RM803 1

RM811 - RM813 1

RT001 - RT014 1

RT021 - RT022 2

RT031 - RT033 2

RT034 - RT035 1

RT041 - RT047 1

RT061 2

RT071 - RT072 2

RT073 - RT074 1

RT075 2

RT101 - RT103 1

RT121 1

RT131 - RT137 1

RT151 - RT152 1

RT161 2

RT162 - RT163 1

RT164 2

RT165 - RT168 1

RT401 - RT412 1

RT431 - RT447 1

RT451 - RT455 1

RT456 2

RT457 - RT460 1

RT461 2

RT462 - RT469 1

RT471 - RT499 1

RT501 2

RT502 - RT505 1

RT506 - RT510 2

RT511 - RT512 1

RT513 2

RT514 - RT515 1

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ALERT ALERT
Variable Number Group

RT516 2

RT517 1

RT518 - RT520 2

RT521 - RT523 1

RT524 2

RT525 1

RT526 2

RT527 1

RT528 2

RT529 1

RT530 2

RT531 - RT535 1

RT551 - RT568 1

RT571 1

RT572 - RT579 2

RT580 - RT591 1

RT601 - RT630 1

RT631 - RT632 3

RT633 - RT641 1

RT642 2

RT643 - RT654 1

RT655 - RT657 2

RT671 - RT673 1

RT681 - RT682 1

RT691 - RT699 1

RT701 - RT704 1

RT711 - RT717 1

RT741 - RT742 1

RT743 3

RT744 - RT750 1

RT751 - RT752 2

RT753 - RT757 1

RT776 - RT777 1

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ALERT ALERT
Variable Number Group

RT781 - RT782 2

RT783 - RT784 1

RT801 - RT803 1

RT811 - RT814 1

RT831 - RT836 1

RT837 2

RT861 - RT864 1

RT876 3

RT877 - RT880 1

RT931 - RT932 1

RT945 - RT949 1

RT951 - RT955 1

RT966 1

RT967 2

RU001 - RU006 1

RU016 - RU017 1

RU031 - RU032 1

RU051 - RU052 1

RU059 - RU062 1

RU081 - RU083 1

RU101 - RU102 1

RU121 - RU132 1

RU801 - RU809 1

RU831 - RU841 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
C. Reason

This service bulletin gives instructions to do inspections of the Section 41 and Section 44 upper deck

floor beam upper chords for fatigue cracks. Cracks in these chords that are not found and repaired

could become large and cause the floor beam to become severed. This can lead to large deflection or

deformation of the floor and of the body skin, frames, and stringers. This deflection or deformation

could result in damage to wire bundles and unintended inputs to the flight control cables which could

affect airplane controllability. Multiple adjacent severed floor beams could result in rapid decompression

of the airplane.

Flight critical wire bundles and control cables are routed through cutouts in the upper deck floor beams.

Cracks have been found at open floor panel attach fastener holes in the upper chord of two Section

41 upper deck floor beam on three different 747-400D airplanes, which had flown 24,053, 24,783, and

25,631 flight-cycles. Boeing believes that these 747-400D airplanes were operated at reduced cabin

differential pressures. Similar cracks were also found on the 747-400 Fatigue Test airplane.

Accomplishment of the inspections given in this service bulletin will ensure the structural integrity of

the upper chords of the Section 41 upper deck floor beams.

A structural reassessment of the 747 airplane was conducted under the requirements of Federal Aviation

Administration (FAA) Advisory Circular 91-56, in accordance with Federal Aviation Regulation (FAR)

25.571 as amended in 1978, to ensure safe operation of 747 airplanes throughout their operational

life. From this requirement, the Section 41 upper deck floor beam upper chords were determined to be

significant, in that they are critical to airplane structural integrity. Therefore, a flight safety inspection

program which will continue throughout the operational life of the airplane is specified in this service

bulletin.

Between the original issue and Revision 1 of this service bulletin, the following cracks at upper deck

floor beam fastener hole locations have been reported:

Flight hours/cycles Crack location Crack length

37,561 / 29,013 STA 340,RBL 60 unknown

32,855 / 24,783 STA 440, BL 0 not reported

49,403 / 5,581 STA 440, RBL 58 1 inch (corrosion)

37,561 / 29,013 STA 1000, LBL 50 0.03 inch

37,283 / 29,425 STA 1100, RBL 53 0.4 inch

The cracks at STA 1000 and STA 1100 are at locations that are not common to the inspection area

given in the original issue of this service bulletin. Due to these crack reports Boeing has determined

that inspection of all upper deck floor beam upper chords in Section 44 (from STA 1000 to STA 1100)

is required.

Revision 1 is sent to add inspections and repair of the Section 44 upper deck floor beam upper chords

from STA 1000 to STA 1100.

NOTE: Inspections of Section 42 upper deck floor beam upper chords from STA 540 to STA 980 are

not added to this service bulletin because the floor panel attachment holes in this area were

cold worked in production.

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ALERT ALERT
Boeing Service Related Problem (SRP) 747-SRP-53-0293 and 747-SRP-53-0353 are related to this

service bulletin.

The upper deck floor beam upper chords have been determined to be structure that is susceptible to

Widespread Fatigue Damage (WFD). For more information about WFD, refer to Boeing Service Letter

747-SL-53-088A.

D. Description

Group 1:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from

STA 340 to STA 520 and to the upper chords of the Section 44 upper deck floor beams from STA 1000

to STA 1100.

Group 2:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from

STA 340 to STA 440.

Group 3:

Get access from above or below to the upper chords of the Section 41 upper deck floor beams from

STA 340 to STA 380.

NOTE: On Group 2 airplanes, upper deck floor beams from STA 460 to STA 520 do not require

inspection as given in this service bulletin because they were replaced with new floor beams

during modification to Boeing Converted Freighter (BCF). The new floor beams have floor

panel attachment fastener holes that have been cold-worked. Also, on Group 2 airplanes,

inspection as given in this service bulletin are not necessary in Section 44 because all floor

beams in Section 44 were replaced with tension ties during modification to BCF. On Group 3

airplanes, upper deck floor beams from STA 440 to STA 500 do not require inspection as

given in this service bulletin because they were replaced with new floor beams during

modification to Large Cargo Freighter (LCF). The new floor beams have floor panel attachment

fastener holes that have been cold-worked.

If access was gained from above, do open hole HFEC inspections of the floor panel attachment fastener

holes in the upper chords for cracks. If access was gained from below, modify the clipnuts for the floor

panel attachment fasteners as given in this service bulletin. Do surface HFEC inspections of the forward

and aft horizontal flanges of the upper chord at floor panel attachment fastener holes.

If cracks are found, repair before any more flights. Repair as given in this service bulletin, or ask Boeing

for repair data. For areas repaired as given in this service bulletin, start to do repeat inspections at

repaired locations as given in this service bulletin at the times given in Paragraph 1.E., Compliance.

For any locations that have a repair that is different from those shown in this service bulletin, contact

Boeing for an after-repair inspection plan.

If no cracks are found, do the inspection again at the time given in Paragraph 1.E., Compliance.

Group 1:

Revision 1 - More work is necessary on airplane(s) inspected or changed in accordance with the original

issue of this service bulletin. Inspection of the Section 44 upper deck floor beam upper chords from

Station (STA) 1000 to STA 1100 is necessary. Continue to do inspections of the Section 41 upper deck

floor beam upper chords. No more work is necessary to change any repairs installed in accordance

with the original issue of this service bulletin. Replace the upper deck floor beam upper chords at the

compliance time given in paragraph 1.E., Compliance.

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ALERT ALERT
Group 2-3:

Revision 1 - No more work is necessary on airplane(s) inspected or changed in accordance with the

original issue of this service bulletin. Continue to do inspections of the Section 41 upper deck floor

beam upper chords. No more work is necessary to change any repairs installed in accordance with

the original issue of this service bulletin. Replace the upper deck floor beam upper chords at the

compliance time given in paragraph 1.E., Compliance.

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

Group 1:

Affected Maintenance Zones

Model Zone

211, 212, 221, 222, 223, 224, 225, 226, 231,

232, 241, 242

747-400, 747-400D

Group 2-3:

Affected Maintenance Zones

Model Zone

747-400 211, 212, 221, 222, 223, 224, 231, 232

E. Compliance

Federal Aviation Administration (FAA) Airworthiness Directives AD 2009-10-06 and AD 2004-07-22

R1 are related to this service bulletin.

Table 1 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat Inspections

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time (Whichever Occurs Last)

Within 2,000 -

flight-cycles of

the last SSID inspection, if surface HFEC was

used in that inspection. Within

6,000 flight-cycles of the last

SSID inspection,

if open hole

HFEC was used

in that inspection. (a)

Within 1,000

flight-cycles

after June 17,

2009 (the effective date

of AD 2009-

10-06 ).

Before

20,000 total

flight-cycles.

Do open hole or surface HFEC inspection

of the floor panel attachment fastener holes in

the upper deck floor

beam upper chords for

cracks as given in

Paragraph 3.B., PART

1.

All affected airplanes.

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ALERT ALERT
Table 1 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat Inspections

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time (Whichever Occurs Last)

Do the applicable repair Before further flight. -

procedures as given in

Paragraph 3.B., PART

2, or contact Boeing for

repair data.

Any crack found in

the floor panel attachment fastener

holes.

2,000 flight-cycles

if surface HFEC

inspection was

used; 6,000 flightcycles if open

hole HFEC inspection was

used.

Within 2,000 flight-cycles if surface HFEC inspection was used, or within 6,000 flight-cycles

if open hole HFEC inspection was used.

Repeat open hole or

surface HFEC inspection of the floor panel

attachment fastener

holes in the upper deck

floor beam upper

chords for cracks as

given in Paragraph

3.B., PART 1.

No crack found in

the floor panel attachment fastener

holes.

As an option, do the Before further flight. -

hole modification procedure as given in FIGURE 5.

As an option, do one of Before further flight. -

the repair procedures

as a hole modification

as given in Paragraph

3.B., PART 2.

Refer to Table 2

in Paragraph

1.E., Compliance.

Refer to Table 2 in Paragraph 1.E., Compliance.Refer to Table 2 in

Paragraph 1.E., Compliance.

Location(s) modified or repaired as

given in FIGURE

5 or Paragraph

3.B., PART 2.

Do a repair. Contact Before further flight. -

Boeing for repair data.

Any crack found in

the repaired or

modified location(s).

(a) Applicable only to airplanes that have been previously inspected as given in SSID SSI's F-19B, F-19G,

or F-19K.

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ALERT ALERT
Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 15,000 flight-cycles after the modification

was accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 1.

Location(s) modified as given in

FIGURE 5 where edge margin

after modification is 2.0D or

more.

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 10,000 flight-cycles after the modification

was accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 1.

Location(s) modified as given in

FIGURE 5 where edge margin

after modification is 1.3D or

more and less than 2.0D.

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 15,000 flight-cycles after the repair was

accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 1.

Location(s) where repair #1 was

done as given in Paragraph

3.B., PART 2 of this service

bulletin. (a)

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 10,000 flight-cycles after the repair was

accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 1.

Location(s) where repair #2 was

done as given in Paragraph

3.B., PART 2 of this service

bulletin. (a)

Within 10,000 flight-cy- 3,000 flight-cycles.

cles after the repair was

accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 3.

Location(s) where repair #3 was

done as given in Paragraph

3.B., PART 2 of this service

bulletin. (a)

Within 5,000 flight-cycles 3,000 flight-cycles.

after the repair was accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 1.

Location(s) where repair #4 was

done as given in Paragraph

3.B., PART 2 of this service

bulletin. (a)

Within 5,000 flight-cycles 3,000 flight-cycles.

after the repair was accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 3.

Location(s) where repair #5 was

done as given in Paragraph

3.B., PART 2 of this service

bulletin. (a)

Within 10,000 flight-cy- 6,000 flight-cycles.

cles after the repair was

accomplished.

Do open hole and surface HFEC inspections

for cracks as given in

Paragraph 3.B., PART 3.

Location(s) where repair #6, #7,

#8, #9, #11 or #12 was done as

given in Paragraph 3.B., PART

2 of this service bulletin. (a)

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ALERT ALERT
Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

Contact Boeing for after-repair inspection instructions and do the inspections

at the compliance times specified by Boeing.

Location(s) where repair #10 or

#13 was done as given in Paragraph 3.B., PART 2 of this service bulletin. (a)

Do a repair. Contact Before further flight. -

Boeing for repair data.

Any crack found in the repaired

or modified location(s).

(a) Refer to Paragraph 3.B., Work Instructions, PART 2, Tables 1 and 2 for corresponding repair procedures.

Group 1:

Table 3 - Section 44 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat Inspections

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time (Whichever Occurs Last)

Within 2,000 -

flight-cycles of

the last SSID inspection, if surface HFEC was

used in that inspection. Within

6,000 flight-cycles of the last

SSID inspection,

if open hole

HFEC was used

in that inspection. (a)

Within 1,000

flight-cycles

after the Revision 1 date of

this service

bulletin.

Before

20,000 total

flight-cycles.

Do open hole or surface HFEC inspection

of the floor panel attachment fastener holes in

the upper deck floor

beam upper chords for

cracks as given in

Paragraph 3.B., PART

4.

All affected airplanes.

Do the applicable repair Before further flight. -

procedures as given in

Paragraph 3.B., PART

5, or contact Boeing for

repair data.

Any crack found in

the floor panel attachment fastener

holes.

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ALERT ALERT
Group 1:

Table 3 - Section 44 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat Inspections

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time (Whichever Occurs Last)

2,000 flight-cycles

if surface HFEC

inspection was

used; 6,000 flightcycles if open

hole HFEC inspection was

used.

Within 2,000 flight-cycles if surface HFEC inspection was used, or within 6,000 flight-cycles

if open hole HFEC inspection was used.

Repeat open hole or

surface HFEC inspection of the floor panel

attachment fastener

holes in the upper deck

floor beam upper

chords for cracks as

given in Paragraph

3.B., PART 4.

No crack found in

the floor panel attachment fastener

holes.

As an option, do the Before further flight. -

hole modification procedure as given in FIGURE 21.

As an option, do one of Before further flight. -

the repair procedures

as a hole modification

as given in Paragraph

3.B., PART 5.

Refer to Table 4

in Paragraph

1.E., Compliance.

Refer to Table 4 in Paragraph 1.E., Compliance.Refer to Table 4 in

Paragraph 1.E., Compliance.

Location(s) modified or repaired as

given in FIGURE

21 or Paragraph

3.B., PART 5.

Do a repair. Contact Before further flight. -

Boeing for repair data.

Any crack found in

the repaired or

modified location(s).

(a) Applicable only to airplanes that have been previously inspected as given in SSID SSI's F-19B, F-19G,

or F-19K.

Group 1:

Table 4 - Section 44 Compliance Times for Inspection of Location(s) Repaired or Modified

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 15,000 flight-cycles after the modification

was accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 4.

Location(s) modified as given in

FIGURE 21 where edge margin

after modification is 2.0D or

more.

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ALERT ALERT
Group 1:

Table 4 - Section 44 Compliance Times for Inspection of Location(s) Repaired or Modified

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 10,000 flight-cycles after the modification

was accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 4.

Location(s) modified as given in

FIGURE 21 where edge margin

after modification 1.3D or more

and less than 2.0D.

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 15,000 flight-cycles after the repair was

accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 4.

Location(s) where repair #1 was

done as given in Paragraph

3.B., PART 5 of this service

bulletin. (a)

2,000 flight-cycles if surface HFEC inspection

was used; 6,000 flightcycles if open hole

HFEC inspection was

used.

Within 10,000 flight-cycles after the repair was

accomplished.

Do open hole or surface

HFEC inspection for

cracks as given in Paragraph 3.B., PART 4.

Location(s) where repair #2 was

done as given in Paragraph

3.B., PART 5 of this service

bulletin. (a)

Within 10,000 flight-cy- 3,000 flight-cycles.

cles after the repair was

accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 6.

Location(s) where repair #3 was

done as given in Paragraph

3.B., PART 5 of this service

bulletin. (a)

Within 5,000 flight-cycles 3,000 flight-cycles.

after the repair was accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 4.

Location(s) where repair #4 was

done as given in Paragraph

3.B., PART 5 of this service

bulletin. (a)

Within 5,000 flight-cycles 3,000 flight-cycles.

after the repair was accomplished.

Do open hole HFEC inspection for cracks as

given in Paragraph 3.B.,

PART 6.

Location(s) where repair #5 was

done as given in Paragraph

3.B., PART 5 of this service

bulletin. (a)

Within 10,000 flight-cy- 6,000 flight-cycles.

cles after the repair was

accomplished.

Do open hole and surface HFEC inspections

for cracks as given in

Paragraph 3.B., PART 6.

Location(s) where repair #6, #7,

#8, #9, #11 or #12 was done as

given in Paragraph 3.B., PART

5 of this service bulletin. (a)

Contact Boeing for after-repair inspection instructions and do the inspections

at the compliance times specified by Boeing.

Location(s) where repair #10 or

#13 was done as given in Paragraph 3.B., PART 5 of this service bulletin. (a)

Do a repair. Contact Before further flight. -

Boeing for repair data.

Any crack found in the repaired

or modified location(s).

(a) Refer to Paragraph 3.B., Work Instructions, PART 5, Tables 3 and 4 for corresponding repair procedures.

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ALERT ALERT
Table 5 - Section 41 and 44 Upper Deck Floor Beam Upper Chord Replacement

Condition Action Compliance Time

After 15,000 total flight

cycles and before

35,000 total flight cycles.

(a)

Replace upper deck floor

beam upper chords in

accordance with Paragraph 3.B., PART 7.

All airplanes

(a) Due to the post-replacement requirements, and the possibility that it will be

necessary to replace the upper chords again, Boeing does not recommend

upper chord replacement prior to 15,000 total flight-cycles.

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.

This service bulletin has been approved by the Federal Aviation Administration (FAA). In addition, the

Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the accomplishment of the

inspection and repair actions with corresponding compliance times specified in Tables 1, 2, 3, and 4

under paragraph 1.E., "Compliance", of Service Bulletin 747-53A2688, Revision 1, as an alternative

method of compliance (AMOC) to the corresponding inspection and repair requirements of paragraphs

(h), (i), and (j) of AD 2004-07-22 R1, for the inspection of Structural Significant Items (SSI) F-19B,

F-19G, and F-19K of Supplemental Structural Inspection Document (SSID) D6-35022, Revision G,

dated December 2000 and Revision TR-08-001, dated June 2006. This AMOC only applies to the

areas where upper deck floor beam upper chords were inspected in accordance with this service

bulletin. When this service bulletin specifies contacting Boeing for repair instructions, the repair

instructions must be approved by the FAA in accordance with paragraph (l) of the AD. All provisions

of AD 2004-07-22 R1 that are not specifically referenced in this paragraph, including the initial inspection

threshold per paragraph (i) of AD 2004-07-22 R1, remain fully applicable and must be complied with.

In addition, the manager of the Seattle Aircraft Certification Office (ACO) approves the accomplishment

of the inspection and repair actions with corresponding compliance times specified in Tables 1 and 2

under paragraph 1.E., "Compliance," of Service Bulletin 747-53A2688, Revision 1, as an AMOC to the

inspection and repair actions with corresponding compliance times specified in Tables 1 and 2 under

paragraph 1.E.,"Compliance," of Service Bulletin 747-53A2688, original issue, dated August 21, 2008,

required by paragraphs (g) and (h) of AD 2009-10-06 . Tables 3, 4 and 5 of Service Bulletin

747-53A2688, Revision 1, are not mandated by AD 2009-10-06 . This AMOC is only for upper deck

floor beam upper chords that have been inspected and repaired in accordance with this service bulletin.

When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions

must be approved by the FAA in accordance with paragraph (j) of AD 2009-10-06 . All provisions of

AD 2009-10-06 that are not specifically referenced in this paragraph remain fully applicable and must

be complied with.

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G. Manpower

The table below shows an estimate of the man-hours necessary to do this inspection for each airplane.

This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator

man-hour data if necessary. The estimate does not include lost time. These are some examples of lost

time:

— Time to adjust to the workplace

— Time to schedule the work

— Time to examine the work

— Time to cure the materials

— Time to make the parts

— Time to find the tools.

Group 1:

Section 41 Inspections

Number of Task Hours Elapsed Hours

Persons

Task

Open Access 4 96 24

Inspect 2 50 25

Close Access 4 113 28.25

TOTAL FOR EACH AIRPLANE 259 77.25

Group 2:

Section 41 Inspections

Number of Task Hours Elapsed Hours

Persons

Task

Open Access 4 90 22.50

Inspect 2 48 24

Close Access 4 103 25.75

TOTAL FOR EACH AIRPLANE 241 72.25

Group 3:

Section 41 Inspections

Number of Task Hours Elapsed Hours

Persons

Task

Open Access 4 45 11.25

Inspect 2 24 12

Close Access 4 51.5 12.75

TOTAL FOR EACH AIRPLANE 120.5 36.0

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Group 1:

Section 44 Inspections

Number of Task Hours Elapsed Hours

Persons

Task

Open Access 4 16.00 4.00

Inspect 2 30.00 15.00

Close Access 4 20.00 5.00

TOTAL FOR EACH AIRPLANE 66.00 24.00

NOTE: More time will be necessary for repairs if cracks are found.

H. Weight and Balance Changes

The repairs in this service bulletin will affect the weight and balance of the airplane. However, because

of the variation in weight, location and quantity of repairs, it is not possible to specify weight and balance

changes in this service bulletin. It will be necessary for operators to calculate the weight and balance

changes for each airplane based on the repairs that are accomplished.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data:

a. Boeing Service Bulletin 747-53A2500

b. Boeing Service Letter 747-SL-53-088A

c. Boeing Service Related Problem (SRP) 747-SRP-53-0353

d. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2004-07-22 R1, 2009-10-06

e. 747 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00, Part 6, 53-10-53, Part 6, 53-10-54

f. 747-400 Aircraft Maintenance Manual (AMM) 25-11-01, 25-11-03, 25-16-00, 25-19-03,

25-21-04, 25-22-01, 25-23-00, 25-24-18, 25-25-01, 25-27-05, 25-28-01, 25-28-02, 25-32-01,

25-40-03, 25-59-01, 25-59-05, 53-21-02

g. 747-400 Structural Repair Manual (SRM) 51-40-05

h. Supplemental Structural Inspection Document (SSID) D6-35022, Revision G

2. Data Supplied with this Service Bulletin:

None.

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

None.

K. Publications Affected

1. Publications:

None.

2. Damage Tolerance Based Structural Inspections:

Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue

Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the

Maintenance Program. This service bulletin affects FCS. DTI requirements for the structure affected

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

L. Interchangeability and Intermixability of Parts

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

M. Software Accomplishment Summary

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BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

None

B. Industry Support Information

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

service bulletin.

C. Parts Necessary for Each Airplane

1. Kits/Parts:

None.

2. Parts and Materials Supplied by the Operator:

NOTE: The number in the QTY column in the tables that follow is the number of parts

necessary to accomplish one repair.

1.

2. More than one repair may be necessary if cracks are found.

3. Refer to 747 Structural Repair Manual Chapter 51 for alternative fasteners.

Table 1 - Section 41 or Section 44 Repair Strap Installation (Refer to Figure 7 or Figure 23)

QTY Part Number Name

1 A (a) Repair Strap

10 BACB30NW6K4 Bolt

10 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD4 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 7 or FIGURE 23 .

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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

supplier data.

Table 2 - Section 41 or Section 44 Upper Chord Strap Repair (Refer to Figure 9 or Figure 25)

QTY Part Number Name

1 A (a) Repair Strap

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Table 2 - Section 41 or Section 44 Upper Chord Strap Repair (Refer to Figure 9 or Figure 25)

QTY Part Number Name

1 B (a) Filler

10 BACB30NW6K4 Bolt

10 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD4 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 9 or FIGURE 25 .

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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

supplier data.

Table 3 - Section 41 or Section 44 Upper Chord Clip Repair (Refer to Figure 10 or Figure 26)

QTY Part Number Name

1 A (a) Repair Strap

1 B (a) Filler

1 C (a) Repair Clip

3 BACB30MY6K7X Bolt

10 BACB30NW6K4 Bolt

13 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD4 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 10 or FIGURE 26 .

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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

supplier data.

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Table 4 - Section 44 Upper Chord Clip Repair (Refer to Figure 13 or Figure 27 )

QTY Part Number Name

1 A (a) Repair Strap

1 B (a) Filler

1 C (a) Repair Strap

2 BACB30NW6K5 Bolt

12 BACB30NW6K7 Bolt

14 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD4 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 13 or FIGURE 27.

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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

supplier data.

Table 5 - Section 44 Upper Chord Clip Repair (Refer to Figure 14 or Figure 28)

QTY Part Number Name

1 A (a) Repair Angle

1 B (a) Filler

1 C (a) Repair Strap

14 BACB30MY6K7X Bolt

2 BACB30NW6K5 Bolt

12 BACB30NW6K7 Bolt

28 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD3 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 14 or FIGURE 28.

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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Table 5 - Section 44 Upper Chord Clip Repair (Refer to Figure 14 or Figure 28)

QTY Part Number Name

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

supplier data.

Table 6 - Section 44 Upper Chord Clip Repair (Refer to Figure 15 or Figure 29)

QTY Part Number Name

1 A (a) Repair Strap

1 B (a) Filler

12 BACB30NW6K3 Bolt

12 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD3 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 15 or FIGURE 29.

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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

supplier data.

Table 7 - Section 44 Upper Chord Clip Repair (Refer to Figure 16 or Figure 30)

QTY Part Number Name

1 A (a) Repair Angle

1 B (a) Filler

12 BACB30MY6K5 Bolt

12 BACB30NW6K4 Bolt

24 BACC30M6 Collar

(b) BACN10JR3F Nutplate

(b) BACR15CE3AD3 Rivet

Pressure and Environmental Sealant -

Chromate Type

2 oz. (c) BMS 5-95

2 oz. (c) BMS 10-11, Type I Chemical and Solvent Resistant Finish

(a) Make as given in FIGURE 16 or FIGURE 30.

(b) Dependent upon the number of floor panel attachment fastener holes affected by the repair.

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Table 7 - Section 44 Upper Chord Clip Repair (Refer to Figure 16 or Figure 30)

QTY Part Number Name

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

supplier data.

3. Parts Modified and Reidentified:

None.

4. Parts Removed and Not Replaced:

None.

D. Parts Necessary to Change Spares

None.

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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BLANK PAGE
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 limits to tighten nuts and bolts are in SRM Chapter 51

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

SRM Chapter 51.

5. If the length of any fastener specified in this service bulletin does not meet installation

standards given in SRM Chapter 51, then a fastener of the same specification, or

an approved substitute, with a length which meets the installation standards given

in SRM Chapter 51 may be used. In addition, washers may be installed for fastener

grip length in accordance with SRM Chapter 51.

6. A 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.

7. These work instructions refer to procedures included on 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 "as

given in" are included in the instruction, the procedure in the Boeing document must

be used.

8. For initial and repeat inspections of unrepaired and unmodified holes, either the open

hole HFEC inspection method or the surface HFEC inspection method can be used.

At hole locations where a repair or modification procedure has been done, do the

type of inspection specified in paragraph 1.E., Compliance, depending on which

repair was done.

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9. The affected areas are also visually inspected as given in Boeing Service Bulletin

747-53A2500, "FUSELAGE - Main Frame - Inspections Based on Fatigue Test

Results".

10. If affected floor beams or floor beam upper chords have been previously replaced

with new parts, the inspection threshold for the replaced part should be counted from

the time of the replacement.

11. Fasteners may be oversized 1/64 or 1/32 inch in diameter as needed. Maintain 1.7D

minimum edge margin on the upper chord and all adjacent parts. Edge margin is

defined as the distance from the edge of the part to the center of the hole, and "D"

is the hole diameter

12. 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.

13. 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.

14. 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.

15. 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.

16. Figures 9, 10, 25, and 26 are for upper chords that have forward and aft flanges of

the same thickness. Figures 13, 14, 15, 16, 27, 28, 29, and 30 are for upper chords

with forward and aft flanges with different thickness. All other figures are applicable

to either configuration.

17. In Figures 13, 14, 15, 16, 27, 28, 29, and 30, the typical illustrations show the thick

flange on the forward side of the floor beam. However, at STA 1000, the thick flange

is on the aft side of the floor beam.

B. WORK INSTRUCTIONS

PART 1 -SECTION 41 - INITIAL INSPECTION, REPEAT INSPECTION, and INSPECTION OF HOLES

THAT HAVE ONLY BEEN REPAIRED OR MODIFIED BY OVERSIZING

1. Group 1:

The area to be inspected is shown in FIGURE 1.

2. Group 2:

The area to be inspected is shown in FIGURE 2.

3. Group 3:

The area to be inspected is shown in FIGURE 17.

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NOTE: For airplane RT743, inspection is not required at STA 400 and STA 420. New floor beams

were installed at STA 400 and STA 420 during RT743 conversion to Large Cargo Freighter.

4. If the open hole High Frequency Eddy Current (HFEC) inspection method will be used at the floor

panel attach fastener holes:

a. Remove equipment from the upper deck as given in the table that follows for access to the

affected upper deck floor beams from above:

Refer to as an accepted

procedure

Equipment

Flight Compartment Floor Covering 747-400 AMM 25-16-00

Captain and First Officer Seat 747-400 AMM 25-11-01

Observer's Seat 747-400 AMM 25-11-03

Flight Deck Crew Rest Partitions 747-400 AMM 25-19-03

Upper Deck Passenger Seat 747-400 AMM 25-25-01

Upper Deck Floor Covering 747-400 AMM 25-27-05

Upper Deck Lavatories 747-400 AMM 25-40-03

Upper Deck Closets 747-400 AMM 25-24-18

Upper Deck Galleys 747-400 AMM 25-32-01

Upper Deck Floor Panels 747-400 AMM 53-21-02

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This

list is only intended to show equipment typically installed in the upper deck cabin on

a typical 747 airplane.

b. At all floor panel attach hole locations in the affected floor beam upper chords, do open hole

HFEC inspections for cracks as given in FIGURE 3.

c. Condition 1 - No crack indications found at floor panel attach hole locations:

(1) Option 1: Install the floor panels and equipment that were removed for access to the area.

Do inspections again, as given in Paragraph 1.E., Compliance.

(2) Option 2: A new inspection threshold can be obtained by doing one of the following:

(a) Do the fastener hole modification as given in FIGURE 5. After the modification, do

inspections again, as given in Paragraph 1.E., Compliance.

(b) Do one of the repair procedures as given in PART 2 to modify the hole. After the

modification, do inspections again, as given in Paragraph 1.E., Compliance.

d. Condition 2 - If crack indications are found at floor panel attach fastener holes, repair as given

in PART 2 or ask Boeing for repair data.

e. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph

1.E., Compliance.

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NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at

least five fasteners away from the end of the repair strap is not considered a repaired

hole.

5. If the surface HFEC inspection method will be used at the floor panel attach fastener holes:

a. Get access to the affected upper deck floor beams from below as follows:

Group 1:

Refer to as an accepted

procedure

Equipment

Ceiling Insulation 747-400 AMM 25-21-04

Ceiling Access Panels 747-400 AMM 25-22-01

Passenger Service Units 747-400 AMM 25-23-00

Passenger Seats 747-400 AMM 25-25-01

Center Overhead Stowage Compartments 747-400 AMM 25-28-02

Side Overhead Stowage Compartments 747-400 AMM 25-28-01

Group 1:

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This

list is only intended to show equipment typically installed in the main deck on a typical

747 Passenger airplane.

Group 2-3:

Refer to as an accepted

procedure

Equipment

Main Deck Cargo Compartment Ceiling Lining 747-400 AMM 25-59-01

Main Deck Ceiling Insulation 747-400 AMM 25-59-05

b. At all floor panel attach hole locations, modify the clipnuts and do surface HFEC inspections

for cracks as given in FIGURE 4.

c. If no crack indications are found, install the floor panels and equipment that were removed

for access to the area. Do inspections again, as given in Paragraph 1.E., Compliance.

d. If crack indications are found, repair as given in PART 2 or ask Boeing for repair data.

e. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph

1.E., Compliance.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at

least five fasteners away from the end of the repair strap is not considered a repaired

hole.

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PART 2 - SECTION 41 - REPAIR (Can also be accomplished as a modification)

1. If not already done, remove equipment and floor panels as necessary for access to the affected

fastener hole from above.

2. For hole locations where this repair procedure is being accomplished as a modification (no crack

has been found), make the fastener hole diameter 1/64 oversize, then go to step 4.

3. For hole locations where a crack indication was found during an inspection, do the following:

NOTE: It is acceptable to skip this step at any fastener where the chord will be trimmed as given

in FIGURE 8. For example, if the crack extends to the edge of the upper chord, or if you

think that oversizing the crack will result in less edge margin less than 1.3D, then you

can do a trim out as given in FIGURE 8 instead of doing this step.

a. Make the affected fastener hole diameter 1/64 inch oversize.

b. Do an open hole HFEC inspection of the hole as given in 747 NDT Part 6, 53-10-54 or 747

NDT Part 6, 51-00-00, Figure 1, 11, or 16 for cracks.

c. If crack indications are found, repeat the hole oversize and open hole HFEC inspection until

no crack indication is found.

d. If no crack indication is found, continue to the next step.

4. Prior to any insurance cut, measure the edge margin and hole diameter as given in FIGURE 6.

5. Repair the hole as given in Table 1 - Hole Repair Instructions.

NOTE: Before starting the repair, confirm that the damaged location meets all the repair

requirements.

Table 1 - Hole Repair Instructions

Crack-Free Hole Diam- Edge Margin Repair Procedure

eter

Repair #

Make hole 1/16 inch oversize (Insurance Cut)

(a)

2.5D or more (before

insurance cut)

0.281 inch or less (before insurance cut) 1

Make hole 1/16 inch oversize (Insurance Cut)

(a)

1.6D or more and less

than 2.5D (before insurance cut)

0.281 inch or less (be2 fore insurance cut)

Make hole 1/16 inch oversize (Insurance Cut)

and install strap as given in FIGURE 7. (a)

1.3D or more and less

than 1.6D (before insurance cut)

0.281 inch or less (be3 fore insurance cut)

Trim the chord as given in FIGURE 8. Install the

appropriate repair from Table 2 - Hole Trimout

Repairs.

0.281 inch or less Less than 1.3D (Refer to

Table 2)

4 0.282 - 0.343 inch 1.3D or more None (b)

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ALERT ALERT
Table 1 - Hole Repair Instructions

Crack-Free Hole Diam- Edge Margin Repair Procedure

eter

Repair #

1.1D or more and less Install strap as given in FIGURE 7. (b)

than 1.3D

0.282 - 0.343 inch 5

Trim the chord as given in FIGURE 8. Install the

appropriate repair from Table 2 - Hole Trimout

Repairs.

0.282 - 0.343 inch Less than 1.1D (Refer to

Table 2)

Trim the chord as given in FIGURE 8. Install the

appropriate repair from Table 2 - Hole Trimout

Repairs.

More than 0.343 inch Any (Refer to

Table 2)

(a) The hole diameter must not exceed 0.343 inch.

(b) As an alternative it is acceptable to trim the chord as given in FIGURE 8 and then install the appropriate

repair from Table 2 - Hole Trimout Repairs.

Table 2 - Hole Trimout Repairs

Repair # Body Station (STA) Condition Repair as given in

Affected hole location is common to FIGURE 10

the fasteners that support any upper

deck equipment support brackets.

Affected floor beam locations where

upper chord is not made from

BAC1506-2441 extrusion

6

Affected hole location is not com- FIGURE 9

mon to the fasteners that support

any upper deck equipment support

brackets.

7

'f' is less than or equal to 0.75 inch. FIGURE 13

(a)

Affected floor beam locations where

upper chord is made from BAC1506-

2441 extrusion and cracking is located on the thick flange of the upper

chord.

8

'f' is more than 0.75 inch and less FIGURE 14

than or equal to 0.90 inch. (a) 9

10 'f' is more than 0.90 inch. (a) Contact Boeing (c)

'a' is less than or equal to 0.60 inch. FIGURE 15

(b)

Affected floor beam locations where

upper chord is made from BAC1506-

2441 extrusion and cracking is located on the thin flange of the upper

chord.

11

'a' is more than 0.60 inch and less FIGURE 16

than or equal to 0.80 inch. (b) 12

13 'a' is more than 0.80 inch. (b) Contact Boeing (c)

(a) 'f' is the depth of the trim from the edge of the thick flange of the upper chord. Refer to FIGURE 8.

(b) 'a' is the depth of the trim from the edge of the thin flange of the upper chord. Refer to FIGURE 8.

(c) Contact Boeing for repair instructions and do the repair instructed by Boeing.

6. Install all equipment that was removed for access to the repair area.

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7. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

NOTE: 1. Any floor panel attachment fastener hole under a repair strap that is not repaired

or modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is

not at least five fasteners away from the end of the repair strap is not considered

a repaired hole.

2. For any locations that have a repair that is different from those shown in this

service bulletin, contact Boeing for an after-repair inspection plan.

PART 3 - SECTION 41 - INSPECTION OF HOLES REPAIRED OR MODIFIED WITH STRAP OR

ANGLE

1. Remove the equipment that follows from the upper deck for access to the upper chords of the

upper deck floor beams from above:

Refer to as an accepted

procedure

Equipment

Flight Compartment Floor Covering 747-400 AMM 25-16-00

Captain and First Officer Seat 747-400 AMM 25-11-01

Observer's Seat 747-400 AMM 25-11-03

Flight Deck Crew Rest Partitions 747-400 AMM 25-19-03

Upper Deck Passenger Seat 747-400 AMM 25-25-01

Upper Deck Floor Covering 747-400 AMM 25-27-05

Upper Deck Lavatories 747-400 AMM 25-40-03

Upper Deck Closets 747-400 AMM 25-24-18

Upper Deck Galleys 747-400 AMM 25-32-01

Upper Deck Floor Panels 747-400 AMM 53-21-02

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list

is only intended to show equipment typically installed in the upper deck cabin on a typical

747 airplane.

2. Do inspections of repaired locations as follows:

a. For locations where repair #3 or #5 was done, inspect as given in FIGURE 11.

b. For locations where repair #6, #7, #8, #9, #11 or #12 was done, inspect as given in FIGURE

12.

c. For locations where repair #10 or #13 was done, contact Boeing for inspection instructions

and do the inspections.

3. If no crack indications are found, install the equipment that were removed for access and put the

airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

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ALERT ALERT
NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least

five fasteners away from the end of the repair strap is not considered a repaired hole.

4. If crack indications are found, install a repair. Ask Boeing for repair data.

5. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least

five fasteners away from the end of the repair strap is not considered a repaired hole.

Group 1:

PART 4 - SECTION 44 - INITIAL INSPECTION, REPEAT INSPECTION, and INSPECTION OF HOLES

THAT HAVE ONLY BEEN REPAIRED OR MODIFIED BY OVERSIZING

1. The area to be inspected is shown in FIGURE 18.

2. If the open hole High Frequency Eddy Current (HFEC) inspection method will be used at the floor

panel attach fastener holes:

a. Remove equipment from the upper deck as given in the table that follows for access to the

affected upper deck floor beams from above:

Refer to as an accepted

procedure

Equipment

Upper Deck Floor Covering 747-400 AMM 25-27-05

Upper Deck Galleys 747-400 AMM 25-32-01

Upper Deck Floor Panels 747-400 AMM 53-21-02

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This

list is only intended to show equipment typically installed in the upper deck cabin on

a typical 747 airplane.

b. At all floor panel attach hole locations in the affected floor beam upper chords, do open hole

HFEC inspections for cracks as given in FIGURE 19.

c. Condition 1 - No crack indications found at floor panel attach hole locations:

(1) Option 1: Install the floor panels and equipment that were removed for access to the area.

Do inspections again, as given in Paragraph 1.E., Compliance.

(2) Option 2: A new inspection threshold can be obtained by doing one of the following:

(a) Do the fastener hole modification as given in FIGURE 21. After modification, do

inspections again, as given in Paragraph 1.E., Compliance.

(b) Do one of the repair procedures as given in PART 5. After repair, do inspections

again, as given in Paragraph 1.E., Compliance.

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ALERT ALERT
d. Condition 2 - If crack indications are found at floor panel attach fastener holes, repair as given

in PART 5 or ask Boeing for repair data.

e. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph

1.E., Compliance.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not

at least five fasteners away from the end of the repair strap is not considered a

repaired hole.

3. If the surface HFEC inspection method will be used at the floor panel attach fastener holes:

a. Get access to the affected upper deck floor beams from below as follows:

Refer to as an accepted

procedure

Equipment

Ceiling Insulation 747-400 AMM 25-21-04

Ceiling Access Panels 747-400 AMM 25-22-01

Passenger Service Units 747-400 AMM 25-23-00

Passenger Seats 747-400 AMM 25-25-01

Center Overhead Stowage Compartments 747-400 AMM 25-28-02

Side Overhead Stowage Compartments 747-400 AMM 25-28-01

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This

list is only intended to show equipment typically installed in the main deck on a typical

747 Passenger airplane.

b. At all floor panel attach hole locations, modify the clipnuts and do surface HFEC inspections

for cracks as given in FIGURE 20.

c. If no crack indications are found, install the floor panels and equipment that were removed

for access to the area. Do inspections again, as given in Paragraph 1.E., Compliance.

d. If crack indications are found, repair as given in PART 5 or ask Boeing for repair data.

e. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph

1.E., Compliance.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not

at least five fasteners away from the end of the repair strap is not considered a

repaired hole.

Group 1:

PART 5 - SECTION 44 - REPAIR (Can also be accomplished as a modification)

1. If not already done, remove equipment and floor panels as necessary for access to the affected

fastener hole from above.

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ALERT ALERT
2. For hole locations where this repair procedure is being accomplished as a modification (no crack

has been found), make the fastener hole diameter 1/64 oversize, then go to step 4.

3. For hole locations where a crack indication was found during an inspection, do the following:

NOTE: It is acceptable to skip this step at any fastener where the chord will be trimmed as given

in FIGURE 24. For example, if the crack extends to the edge of the upper chord, or if you

think that oversizing the crack will result in less edge margin less than 1.3D, then you

can do a trim out as given in FIGURE 24 instead of doing this step.

a. Make the affected fastener hole diameter 1/64 inch oversize.

b. Do an open hole HFEC inspection of the hole as given in 747 NDT Part 6, 53-10-54 or 747

NDT Part 6, 51-00-00, Figure 1, 11, or 16 for cracks.

c. If crack indications are found, repeat the hole oversize and open hole HFEC inspection until

no crack indication is found.

d. If no crack indication is found, continue to the next step.

4. Prior to any insurance cut, measure the edge margin and hole diameter as given in FIGURE 22.

5. Repair the hole as given in Table 3 - Hole Repair Instructions.

NOTE: Before starting the repair, confirm that the damaged location meets all the repair

requirements.

Table 3 - Hole Repair Instructions

Crack-Free Hole Diam- Edge Margin Repair Procedure

eter

Repair #

Make hole 1/16 inch oversize (Insurance Cut)

(a)

2.5D or more (before

insurance cut)

0.281 inch or less (before insurance cut) 1

Make hole 1/16 inch oversize (Insurance Cut)

(a)

1.6D or more and less

than 2.5D (before insurance cut)

0.281 inch or less (be2 fore insurance cut)

Make hole 1/16 inch oversize (Insurance Cut)

and install strap as given in FIGURE 23. (a)

1.3D or more and less

than 1.6D (before insurance cut)

0.281 inch or less (be3 fore insurance cut)

Trim the chord as given in FIGURE 24. Install

the appropriate repair from Table 4 - Hole Trimout Repairs.

0.281 inch or less Less than 1.3D (Refer to

Table 4)

4 0.282 - 0.343 inch 1.3D or more None (b)

1.1D or more and less Install strap as given in FIGURE 23. (b)

than 1.3D

0.282 - 0.343 inch 5

Trim the chord as given in FIGURE 24. Install

the appropriate repair from Table 4 - Hole Trimout Repairs.

0.282 - 0.343 inch Less than 1.1D (Refer to

Table 4)

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ALERT ALERT
Table 3 - Hole Repair Instructions

Crack-Free Hole Diam- Edge Margin Repair Procedure

eter

Repair #

Trim the chord as given in FIGURE 24. Install

the appropriate repair from Table 4 - Hole Trimout Repairs.

More than 0.343 inch Any (Refer to

Table 4)

(a) The hole diameter must not exceed 0.343 inch.

(b) As an alternative it is acceptable to trim the chord as given in FIGURE 24 and then install the appropriate

repair from Table 4 - Hole Trimout Repairs.

Table 4 - Hole Trimout Repairs

Repair # Location Condition Repair as given in

Affected hole location is common to FIGURE 26

the fasteners that support any upper

deck equipment support brackets.

Affected floor beam locations where

upper chord is not made from

BAC1506-2441 extrusion.

6

Affected hole location is not com- FIGURE 25

mon to the fasteners that support

any upper deck equipment support

brackets.

7

'f' is less than or equal to 0.75 inch. FIGURE 27

(a)

Affected floor beam locations where

upper chord is made from BAC1506-

2441 extrusion and cracking is located on the thick flange of the upper

chord.

8

'f' is more than 0.75 inch and less FIGURE 28

than or equal to 0.90 inch. (a) 9

10 'f' is more than 0.90 inch. (a) Contact Boeing (c)

'a' is less than or equal to 0.60 inch. FIGURE 29

(b)

Affected floor beam locations where

upper chord is made from BAC1506-

2441 extrusion and cracking is located on the thin flange of the upper

chord.

11

'a' is more than 0.60 inch and less FIGURE 30

than or equal to 0.80 inch. (b) 12

13 'a' is more than 0.80 inch. (b) Contact Boeing (c)

(a) 'f' is the depth of the trim from the forward edge of the thick flange of the upper chord. Refer to FIGURE

24.

(b) 'a' is the depth of the trim from the aft edge of the thin flange of the upper chord. Refer to FIGURE 24.

(c) Contact Boeing for repair instructions and do the repair instructed by Boeing.

6. Install all equipment that was removed for access to the repair area.

7. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

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ALERT ALERT
NOTE: 1. Any floor panel attachment fastener hole under a repair strap that is not repaired

or modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and

is not at least five fasteners away from the end of the repair strap is not

considered a repaired hole.

2. For any locations that have a repair that is different from those shown in this

service bulletin, contact Boeing for an after-repair inspection plan.

Group 1:

PART 6 - SECTION 44 - INSPECTION OF HOLES REPAIRED OR MODIFIED WITH STRAP OR

ANGLE

1. Remove the equipment that follows from the upper deck for access to the upper chords of the

upper deck floor beams from above:

Refer to as an accepted

procedure

Equipment

Upper Deck Floor Covering 747-400 AMM 25-27-05

Upper Deck Galleys 747-400 AMM 25-32-01

Upper Deck Floor Panels 747-400 AMM 53-21-02

NOTE: All of the equipment listed above may not be installed on all affected airplanes. This list

is only intended to show equipment typically installed in the upper deck cabin on a typical

747 airplane.

2. Do inspections of repaired locations as follows:

a. For locations where repair #3 or #5 was done, inspect as given in FIGURE 31.

b. For locations where repair #6, #7, #8, #9, #11 or #12 was done, inspect as given in FIGURE

32.

c. For locations where repair #10 or #13 was done, contact Boeing for inspection instructions

and do the inspections.

3. If no crack indications are found, install the equipment that were removed for access and put the

airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least

five fasteners away from the end of the repair strap is not considered a repaired hole.

4. If crack indications are found, install a repair. Ask Boeing for repair data.

5. Put the airplane back to a serviceable condition. Do inspections again, as given in Paragraph 1.E.,

Compliance.

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ALERT ALERT
NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or

modified (as given in FIGURE 21 or as given in Paragraph 3.B., Part 5) and is not at least

five fasteners away from the end of the repair strap is not considered a repaired hole.

PART 7 - SECTION 41 AND SECTION 44 UPPER DECK FLOOR BEAM UPPER CHORD

REPLACEMENT

1. Group 1:

Replace all upper deck floor beam upper chords with identical parts and restore all structure to

original drawing requirements in the areas shown in FIGURE 1 and FIGURE 18 at the time given

in Paragraph 1.E., Compliance.

2. Group 2:

Replace all upper deck floor beam upper chords with identical parts and restore all structure to

original drawing requirements in the area shown in FIGURE 2 at the time given in Paragraph 1.E.,

Compliance.

3. Group 3:

Replace all upper deck floor beam upper chords with identical parts and restore all structure to

original drawing requirements in the area shown in FIGURE 17 at the time given in Paragraph

1.E., Compliance.

NOTE: For airplane RT743, replacement is not required at STA 400 and STA 420. New floor

beams were installed at STA 400 and STA 420 during RT743 conversion to Large Cargo

Freighter.

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This Figure applies only to: Group 1.

FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA

(SHEET 1 OF 1)

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This Figure applies only to: Group 2.

FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA

(SHEET 1 OF 1)

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FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 1 OF 3)

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FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 2 OF 3)

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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 affected floor panel attachment fastener

hole.

NOTE: 1. As shown in FIGURE 2, the STA 460 - 520 floor beams are not affected on Group 2 airplanes.

2. As shown in FIGURE 17 , the STA 440 - STA 520 floor beam is not affected on Group 3

airplanes.

3. Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward

and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right

body frame, are affected.

4. If clipnuts are installed, move or remove the clipnuts to accomplish this inspection. Reinstall

the clipnuts after the inspection is complete. Prior to clipnut reinstallation, touch up any areas

of damaged finish with chemical film treatment and one coat of BMS 10-11, Type 1 primer.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

Open hole HFEC for

cracks, as given in 747

NDT Part 6, 53-10-54 or

747 NDT Part 6, 51-00-00

Figure 1, 11, or 16. (a) (b)

1 Inspect Fastener Hole - -

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23. (a) (b)

2 Inspect Upper Chord - -

(a) Optional: As an alternative to open hole HFEC inspections, do surface HFEC inspections of the upper

and lower surfaces of the horizontal flange of the upper chord at each affected floor panel attachment

fastener hole. This option is NOT applicable if the floor panel attachment hole modification shown in

Figure 5 is to be done.

(b) On Group 2 airplanes, a portion of the STA 440 floor beam has a strap on the upper surface. However,

this should not affect the inspection procedure.

FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 3 OF 3)

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FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 1 OF 4)

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FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 2 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward

and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right

body frame, are affected.

1.

2. Modify clipnuts in the affected area for access to the floor beam upper chord. This clipnut

modification is only necessary the first time this inspection is done.

3. Steps 1 - 4 that follow give a suggested method for clipnut modification. Any clipnut modification

procedure that allows access to the horizontal flange of the upper chord can be used, as long

as the surface HFEC inspections in Steps 5 or 6, and in Step 7, can be accomplished.

4. Do the inspections in Steps 5, 6, and 7 in the area within 1 inch inboard and outboard of each

floor panel attachment hole.

CAUTION: WHEN CLIPNUTS ARE CUT, USE CAUTION TO AVOID DAMAGE TO THE FLOOR BEAM

UPPER CHORD OR ITS FINISH. MORE WORK WILL BE NECESSARY FOR REPAIRS IF THE

UPPER CHORD OR ITS FINISH IS DAMAGED.

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 affected fastener hole location..

STEP TASK NAME IDENTIFICATION QTY MORE DATA

as close as possible to

the top of the clipnut

1 Cut Clipnut - -

down to expose the edge

of the upper chord

2 Bend Clipnut - -

On the clipnut lower

flange

3 Cut Clipnut - -

4 Remove / Discard Clipnut Flange - - -

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23 (a) (c)

Vertical Edge of -

Upper Chord

5 Inspect

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23 (b) (c)

Horizontal Edge of -

Upper Chord

6 Inspect

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23 (c)

7 Inspect Upper Chord -

FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 3 OF 4)

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STEP TASK NAME IDENTIFICATION QTY MORE DATA

(a) As an alternative if adequate access to the vertical edge of the horizontal flange cannot be gained, do

the inspection of the horizontal edge of the horizontal flange as given in Step 6.

(b) This inspection is not necessary if the inspection of the vertical edge of the horizontal flange can be

done as given in Step 5.

(c) On Group 2 airplanes, a portion of the STA 440 floor beam has a strap on the upper surface. However,

this should not affect the inspection procedure.

FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 4 OF 4)

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FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 1 OF 3)

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FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: This modification can only be used if no cracks are detected using the open hole HFEC

inspection. (The surface HFEC inspection option shown in Figure 4 is not allowed.)

1.

2. This modification should not be used if the hole that exists is larger than 0.281 inch diameter.

3. This modification makes the diameter of the floor panel attachment fastener hole in the upper

chord 1/16 inch oversize. It is not necessary to make the floor panel attachment fastener

oversize.

4. After oversizing in step 1, if the edge margin at the fastener hole is less than 1.3D, repair as

given in Paragraph 3.B., Work Instructions, PART 2 - REPAIR, or contact Boeing for repair

instructions and do the repair.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Oversize Fastener Hole - - By 1/16 inch diameter

Edge margin must be greater than or

equal to 1.3D

2 Measure Edge Margin - -

FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

Distance from center of hole to

the edge of the upper chord

1 Measure Edge margin - -

2 Measure "D" - - Hole diameter

FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION

(SHEET 2 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the area to be covered by

the repair strap

1 Remove / Discard Clipnuts - -

2 Make Repair Strap A 1 (a) (b)

On repair strap A for each floor

panel attach fastener location

covered by the repair strap

3 Install Nutplate BACN10JR3F 1

4 Install Repair Strap A 1 -

(a) Length as necessary to install at least five bolts on either side of the affected fastener hole. Material,

thickness, and width to match the horizontal flange of the trimmed upper chord.

(b) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION

(SHEET 3 OF 4)

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size is given

for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make the

hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

B Bolt BACB30NW6K4

Collar BACC30M6

FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION

(SHEET 4 OF 4)

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ALERT ALERT
FIGURE 8: SECTION 41 - UPPER CHORD TRIM

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 8: SECTION 41 - UPPER CHORD TRIM

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the area to be covered by the

repair strap

1 Remove / Discard Clipnuts - -

Maintain a minimum trim radius of

0.5 inch (a)

2 Trim Upper Chord - 1

3 Measure Depth of trim - - (b)

(a) Do the steps that follow: 1. Trim to remove the crack. Do a surface HFEC inspection along the edge of

the trimmed surface as given in 747 NDT Manual D6-7170, Part 6, Subject 51-00-00, Figure 4 or 23 to

confirm that there is no crack. 2. Remove an additional 0.03 inch of material as an "insurance cut" to

ensure crack removal. Do not trim beyond any point within 0.25 inch of the vertical flange. Ask Boeing

for repair data if crack removal requires trimming beyond any point within 0.25 inch of the vertical flange.

(b) If the upper chord is made from BAC1506-2441 extrusion, measure the depth of the trim from the edge

of the thick flange ("f") or from the edge of the thin flange ("a") as shown.

FIGURE 8: SECTION 41 - UPPER CHORD TRIM

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP

(SHEET 2 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Make Filler B 1 From 2024-T3 aluminum (a)

2 Make Repair Strap A 1 (b) (c)

On repair strap A for each floor

panel attach fastener location

covered by the repair strap

3 Install Nutplate BACN10JR3F 1

4 Install Filler B 1 -

5 Install Repair Strap A 1 -

(a) Size to match the trimmed area, the same thickness as the upper chord.

(b) Length as necessary to install at least five bolts on either side of the trimmed area. Material, thickness,

and width to match the horizontal flange of the trimmed upper chord.

(c) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as

given in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from

the end of the repair strap is not considered a repaired hole.

FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP

(SHEET 3 OF 4)

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size is given

for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make the

hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

B Bolt BACB30NW6K4

Collar BACC30M6

FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP

(SHEET 4 OF 4)

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ALERT ALERT
FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 3 OF 5)

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the vertical flange of the

upper chord

1 Remove / Discard Fasteners - 3

2 Make Filler B 1 From 2024-T3 aluminum (a)

3 Make Repair Strap A 1 (b) (d)

4 Make Repair Clip C 1 (c)

On repair strap A or repair clip C,

as necessary, for each floor panel

attach fastener location covered

by the repair

5 Install Nutplate BACN10JR3F 1

6 Install Repair Strap A 1 -

7 Install Repair Clip C 1 -

8 Install Filler B 1 -

(a) Size to match the trimmed area, the same thickness as the upper chord.

(b) Length as necessary to install at least five bolts on either side of the trimmed area. Material, thickness,

and width to match the horizontal flange of the trimmed upper chord.

(c) Make from 2024-T3511 AND10134-1206, AND10134-1407, or AND10134-1602 aluminum extrusion

0.125 inch thick, length as necessary to install one bolt on either side of the trimmed area and three

bolts common to the vertical flange, width to match the flanges of the upper chord.

(d) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 4 OF 5)

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size may be

given for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make

the hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

C Bolt BACB30NW6K()

Collar BACC30M6

Use at existing 5/32 inch rivet locations (a)D Bolt BACB30MY6K7 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (a)Bolt BACB30MY6K7X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (a)Bolt BACB30MY6K7Y 0.216 - 0.219

Collar BACC30R6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 5 OF 5)

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ALERT ALERT
FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 2 OF 3)

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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 repair.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Remove / Discard Fastener - 2 -

2 Inspect Fastener Hole - 2 (a) for cracks

Floor Panel Attach - - (a) for cracks

Fastener Hole

3 Inspect

4 Oversize Fastener Hole - 2 1/64 inch diameter (b)

Install Fastener - 2 (c) if no cracks are found

(a) Do open hole HFEC inspections as given in 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00

Figure 1, 11, or 16.

(b) If necessary to meet the hole size and quality criteria shown in 747-400 SRM 51-40-05.

(c) Install fasteners of the same type and size as was removed, or 1/64 inch oversize as necessary.

FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 2 OF 3)

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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 repair.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Remove / Keep Filler B 1 -

2 Inspect Upper Chord - - (a) for cracks

Floor Panel Attach - - (b) for cracks

Fastener Hole

3 Inspect

4 Remove / Discard Fastener - 2 -

5 Inspect Fastener Hole - 2 (b) for cracks

If no cracks are found, wet

with BMS 5-95 sealant

6 Install Filler (Kept) - 1

7 Oversize Fastener Hole - 2 1/64 inch diameter (c)

Install Fastener - 2 (d) if no cracks are found

(a) Do a surface HFEC inspections along the edge of the trimmed surface as given in 747 NDT Part 6, 53-

10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23.

(b) Do open hole HFEC inspections as shown in 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00

Figure 1, 11, or 16.

(c) If necessary to meet the hole size and quality criteria shown in 747-400 SRM 51-40-05.

(d) Install fasteners of the same type and size as was removed, or 1/64 inch oversize as necessary.

FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 3 OF 3)

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ALERT ALERT
FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 3 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 repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Make Filler B 1 From 2024-T3 aluminum (a)

2 Make Repair Strap A 1 From 2024-T3 aluminum (b)

From 2024-T3 aluminum (c)

(d)

3 Make Repair Strap C 1

On repair strap A or C, as

necessary, for each floor

panel attach fastener location

covered by the repair

4 Install Nutplate BACN10JR3F 1

5 Install Repair Strap A 1 -

6 Install Repair Strap C 1 -

7 Install Filler B 1 -

(a) Size to match the trimmed area, 0.180 inch thick to match the flange of the upper chord.

(b) 0.100 inch thick, 1.125 inch wide, length as necessary to install at least 7 bolts on either side of the

trimmed area. Radius strap corner (0.15R) as necessary to nest into the radius of the upper chord.

(c) 0.125 inch thick, 1.125 inch wide, length as necessary to install at least 6 bolts on either side of the

trimmed area.

(d) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

FIGURE 13: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 5 OF 5)

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BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 1 OF 5)

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FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 3 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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Remove / Discard Fasteners - (a) -

2 Make Filler B 1 From 2024-T3 aluminum (b)

3 Make Repair Angle A 1 From 2024-T3 aluminum (c)

From 2024-T3 aluminum (d)

(e)

4 Make Repair Strap C 1

On repair angle A or repair

strap C, as necessary, for

each floor panel attach fastener location covered by the repair

5 Install Nutplate BACN10JR3F 1

6 Install Repair Angle A 1 -

7 Install Repair Strap C 1 -

8 Install Filler B 1 -

(a) At approximately 14 locations, as necessary to properly size repair angle A.

(b) Size to match the trimmed area, 0.180 inch thick to match the flange of the upper chord.

(c) 0.080 inch thick sheet, width as necessary to match the upper flange and the vertical flange of the upper

chord. Length as necessary to install at least 7 bolts in the horizontal flange and 7 bolts in the vertical

flange on either side of the trimmed area.

(d) 0.160 inch thick, width as necessary to match the upper flange, length as necessary to install at least 6

bolts on either side of the trimmed area.

FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 4 OF 5)

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ALERT ALERT
STEP TASK NAME PART NUMBER QTY NOTES

(e) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD() - (a)

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

Use at existing 5/32 inch rivet locations (b)D Bolt BACB30MY6K7 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (b)Bolt BACB30MY6K7X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (b)Bolt BACB30MY6K7Y 0.216 - 0.219

Collar BACC30R6

(a) For nutplates in repair strap C use BACR15CE3AD5 rivets. For nutplates in repair angle A use

BACR15CE3AD3 rivets.

(b) Typical. Longer bolts may be necessary in some locations.

FIGURE 14: SECTION 41 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 5 OF 5)

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ALERT ALERT
FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 3 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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Make Filler B 1 From 2024-T3 aluminum (a)

From 2024-T3 aluminum (b)

(c)

2 Make Repair Strap A 1

On repair strap A for each floor

panel attach fastener location

covered by the repair

3 Install Nutplate BACN10JR3F 1

4 Install Repair Strap A 1 -

5 Install Filler B 1 -

(a) Size to match the trimmed area, 0.063 inch thick to match the flange of the upper chord.

(b) 0.071 inch thick, 1.0 inch wide, length as necessary to install at least 6 bolts on either side of the trimmed

area.

(c) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD3 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 15: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 5 OF 5)

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ALERT ALERT
FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 3 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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Remove / Discard Fasteners - (a) -

2 Make Filler B 1 From 2024-T3 aluminum (b)

From 2024-T3 aluminum (c)

(d)

3 Make Repair Angle A 1

On repair angle A for each

floor panel attach fastener location covered by the repair

4 Install Nutplate BACN10JR3F 1

5 Install Repair Angle A 1 -

6 Install Filler B 1 -

(a) Approximately 12 locations, as necessary to properly size repair angle A.

(b) Size to match the trimmed area, 0.063 inch thick to match the flange of the upper chord.

(c) 0.071 inch thick sheet, width as necessary to match the upper flange and the vertical flange of the upper

chord. Length as necessary to install at least 6 bolts in the horizontal flange and 6 bolts in the vertical

flange on either side of the trimmed area.

(d) Any floor panel attachment fastener hole under the repair angle that is not repaired or modified (as given

in FIGURE 5 or as given in Paragraph 3.B., Part 2) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD3 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

Use at existing 5/32 inch rivet locations (a)D Bolt BACB30MY6K() 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (a)Bolt BACB30MY6K()X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (a)Bolt BACB30MY6K()Y 0.216 - 0.219

Collar BACC30R6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 16: SECTION 41 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 5 OF 5)

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ALERT ALERT
This Figure applies only to: Group 3.

FIGURE 17: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA

(SHEET 1 OF 1)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 18: SECTION 44 - UPPER DECK FLOOR BEAM INSPECTION AREA

(SHEET 1 OF 1)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 2 OF 3)

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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 affected floor panel attachment fastener

hole.

NOTE: Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward

and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right

body frame, are affected.

1.

2. If clipnuts are installed, move or remove the clipnuts to accomplish this inspection. Reinstall

the clipnuts after the inspection is complete. Prior to clipnut reinstallation, touch up any areas

of damaged finish with chemical film treatment and one coat of BMS 10-11, Type 1 primer.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

open hole HFEC for

cracks, as given in 747

NDT Part 6, 53-10-54 or

747 NDT Part 6, 51-00-00

Figure 1, 11, or 16.

1 Inspect Fastener Hole - -

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23. (a)

2 Inspect Upper Chord - -

(a) Optional: As an alternative to open hole HFEC inspections, do surface HFEC inspections of the upper

and lower surfaces of the horizontal flange of the upper chord at each affected floor panel attachment

fastener hole. This option is NOT applicable if the floor panel attachment hole modification shown in

FIGURE 21 is to be done.

FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER

LOCATIONS

(SHEET 3 OF 3)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 1 OF 4)

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FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 2 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: Inspect all floor panel attachment fastener holes in each affected floor beam. Both the forward

and aft horizontal flanges of each floor beam upper chord, from the left body frame to the right

body frame, are affected.

1.

2. Modify clipnuts in the affected area for access to the floor beam upper chord. This clipnut

modification is only necessary the first time this inspection is done.

3. Steps 1 - 4 that follow give a suggested method for clipnut modification. Any clipnut modification

procedure that allows access to the horizontal flange of the upper chord can be used, as long

as the surface HFEC inspections in Steps 5 or 6, and in Step 7, can be accomplished.

4. Do the inspections in Steps 5, 6, and 7 in the area within 1 inch inboard and outboard of each

floor panel attachment hole.

CAUTION: WHEN CLIPNUTS ARE CUT, USE CAUTION TO AVOID DAMAGE TO THE FLOOR BEAM

UPPER CHORD OR ITS FINISH. MORE WORK WILL BE NECESSARY FOR REPAIRS IF THE

UPPER CHORD OR ITS FINISH IS DAMAGED.

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 affected fastener hole location.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

as close as possible to

the top of the clipnut

1 Cut Clipnut - -

down to expose the edge

of the upper chord

2 Bend Clipnut - -

On the clipnut lower

flange

3 Cut Clipnut - -

4 Remove / Discard Clipnut Flange - - -

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23 (a)

Vertical Edge of -

Upper Chord

5 Inspect

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23 (b)

Horizontal Edge of -

Upper Chord

6 Inspect

Surface HFEC for cracks,

as given in 747 NDT Part

6, 53-10-53 or 747 NDT

Part 6, 51-00-00 Figure 4

or 23

7 Inspect Upper Chord -

FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 3 OF 4)

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ALERT ALERT
STEP TASK NAME IDENTIFICATION QTY MORE DATA

(a) As an alternative if adequate access to the vertical edge of the horizontal flange cannot be gained, do

the inspection of the horizontal edge of the horizontal flange as given in Step 6.

(b) This inspection is not necessary if the inspection of the vertical edge of the horizontal flange can be

done as given in Step 5.

FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION

(SHEET 4 OF 4)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 1 OF 3)

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FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: This modification can only be used if no cracks are detected using the open hole HFEC

inspection. (The surface HFEC inspection option shown in FIGURE 20 is not allowed.)

1.

2. This modification should not be used if the hole that exists is larger than 0.281 inch diameter.

3. This modification makes the diameter of the floor panel attachment fastener hole in the upper

chord 1/16 inch oversize. It is not necessary to make the floor panel attachment fastener

oversize.

4. After oversizing in step 1, if the edge margin at the fastener hole is less than 1.3D, repair as

given in Paragraph 3.B., Work Instructions, PART 5 - REPAIR, or contact Boeing for repair

instructions and do the repair.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Oversize Fastener Hole - - By 1/16 inch diameter

Edge margin must be greater than or

equal to 1.3D.

2 Measure Edge Margin - -

FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION

(SHEET 3 OF 3)

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This Figure applies only to: Group 1.

FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 1 OF 3)

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FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

Distance from center of hole to

the edge of the upper chord

1 Measure Edge margin - -

2 Measure "D" - - Hole diameter

FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL

(SHEET 3 OF 3)

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This Figure applies only to: Group 1.

FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION

(SHEET 1 OF 4)

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FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION

(SHEET 2 OF 4)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the area to be covered by

the repair strap

1 Remove / Discard Clipnuts - -

2 Make Repair Strap A 1 (a) (b)

On repair strap A for each floor

panel attach fastener location

covered by the repair strap

3 Install Nutplate BACN10JR3F 1

4 Install Repair Strap A 1 -

(a) Length as necessary to install at least five bolts on either side of the affected fastener hole. Material,

thickness, and width to match the horizontal flange of the trimmed upper chord.

(b) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION

(SHEET 3 OF 4)

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size is given

for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make the

hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

B Bolt BACB30NW6K4

Collar BACC30M6

FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION

(SHEET 4 OF 4)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 24: SECTION 44 - UPPER CHORD TRIM

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 24: SECTION 44 - UPPER CHORD TRIM

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the area to be covered by the

repair strap

1 Remove / Discard Clipnuts - -

Maintain a minimum trim radius of

0.5 inch (a)

2 Trim Upper Chord - 1

3 Measure Depth of trim - - (b)

(a) Do the steps that follow: 1. Trim to remove the crack. Do a surface HFEC inspection along the edge of

the trimmed surface as given in 747 NDT Manual D6-7170, Part 6, Subject 51-00-00, Figure 4 or 23 to

confirm that there is no crack. 2. Remove an additional 0.03 inch of material as an "insurance cut" to

ensure crack removal. Do not trim beyond any point within 0.25 inch of the vertical flange. Ask Boeing

for repair data if crack removal requires trimming beyond any point within 0.25 inch of the vertical flange.

(b) If the upper chord is made from BAC1506-2441 extrusion, measure the depth of the trim from the edge

of the thick flange ("f") or from the edge of the thin flange ("a") as shown.

FIGURE 24: SECTION 44 - UPPER CHORD TRIM

(SHEET 3 OF 3)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP

(SHEET 2 OF 4)

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130 of 163

BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Make Filler B 1 From 2024-T3 aluminum (a)

2 Make Repair Strap A 1 (b) (c)

On repair strap A for each floor

panel attach fastener location

covered by the repair strap

3 Install Nutplate BACN10JR3F 1

4 Install Filler B 1 -

5 Install Repair Strap A 1 -

(a) Size to match the trimmed area, the same thickness as the upper chord.

(b) Length as necessary to install at least five bolts on either side of the trimmed area. Material, thickness,

and width to match the horizontal flange of the trimmed upper chord.

(c) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as

given in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away

from the end of the repair strap is not considered a repaired hole.

FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP

(SHEET 3 OF 4)

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size is given

for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make the

hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

B Bolt BACB30NW6K4

Collar BACC30M6

FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP

(SHEET 4 OF 4)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 3 OF 5)

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135 of 163

BOEING SERVICE BULLETIN 747-53A2688

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

From the vertical flange of the

upper chord

1 Remove / Discard Fasteners - 3

2 Make Filler B 1 From 2024-T3 aluminum (a)

3 Make Repair Strap A 1 (b) (d)

4 Make Repair Clip C 1 (c)

On repair strap A or repair clip C,

as necessary, for each floor panel

attach fastener location covered

by the repair

5 Install Nutplate BACN10JR3F 1

6 Install Repair Strap A 1 -

7 Install Repair Clip C 1 -

8 Install Filler B 1 -

(a) Size to match the trimmed area, the same thickness as the upper chord.

(b) Length as necessary to install at least five bolts on either side of the trimmed area. Material, thickness,

and width to match the horizontal flange of the trimmed upper chord.

(c) Make from 2024-T3511 AND10134-1206, AND10134-1407, or AND10134-1602 aluminum extrusion

0.125 inch thick, length as necessary to install one bolt on either side of the trimmed area and three

bolts common to the vertical flange, width to match the flanges of the upper chord.

(d) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 4 OF 5)

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BOEING SERVICE BULLETIN 747-53A2688

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

NOTE: In the table that follows, for bolt locations, a transition-fit hole size and a close-ream hole size may be

given for each affected fastener code. If the transition-fit hole size is used, it may be necessary to make

the hole oversize and install oversize fasteners after each repeated open hole HFEC inspection. If the

close-ream hole size is used, it should not be necessary to make the fastener hole oversize.

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

0.187 - 0.190 or -

0.1895 - 0.1905

C Bolt BACB30NW6K()

Collar BACC30M6

Use at existing 5/32 inch rivet locations (a)D Bolt BACB30MY6K7 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (a)Bolt BACB30MY6K7X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (a)Bolt BACB30MY6K7Y 0.216 - 0.219

Collar BACC30R6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP

(SHEET 5 OF 5)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 3 OF 5)

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140 of 163

BOEING SERVICE BULLETIN 747-53A2688

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 repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Make Filler B 1 From 2024-T3 aluminum (a)

2 Make Repair Strap A 1 From 2024-T3 aluminum (b)

From 2024-T3 aluminum (c)

(d)

3 Make Repair Strap C 1

On repair strap A or C, as

necessary, for each floor

panel attach fastener location

covered by the repair

4 Install Nutplate BACN10JR3F 1

5 Install Repair Strap A 1 -

6 Install Repair Strap C 1 -

7 Install Filler B 1 -

(a) Size to match the trimmed area, 0.180 inch thick to match the flange of the upper chord.

(b) 0.100 inch thick, 1.125 inch wide, length as necessary to install at least 7 bolts on either side of the

trimmed area. Radius strap corner (0.15R) as necessary to nest into the radius of the upper chord.

(c) 0.125 inch thick, 1.125 inch wide, length as necessary to install at least 6 bolts on either side of the

trimmed area.

(d) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD4 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8)

(SHEET 5 OF 5)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 3 OF 5)

Export Controlled ECCN: 9E991 - BOEING

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145 of 163

BOEING SERVICE BULLETIN 747-53A2688

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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Remove / Discard Fasteners - (a) -

2 Make Filler B 1 From 2024-T3 aluminum (b)

3 Make Repair Angle A 1 From 2024-T3 aluminum (c)

From 2024-T3 aluminum (d)

(e)

4 Make Repair Strap C 1

On repair angle A or repair

strap C, as necessary, for

each floor panel attach fastener location covered by the repair

5 Install Nutplate BACN10JR3F 1

6 Install Repair Angle A 1 -

7 Install Repair Strap C 1 -

8 Install Filler B 1 -

(a) At approximately 14 locations, as necessary to properly size repair angle A.

(b) Size to match the trimmed area, 0.180 inch thick to match the flange of the upper chord.

(c) 0.080 inch thick sheet, width as necessary to match the upper flange and the vertical flange of the upper

chord. Length as necessary to install at least 7 bolts in the horizontal flange and 7 bolts in the vertical

flange on either side of the trimmed area.

(d) 0.160 inch thick, width as necessary to match the upper flange, length as necessary to install at least 6

bolts on either side of the trimmed area.

FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 4 OF 5)

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ALERT ALERT
STEP TASK NAME PART NUMBER QTY NOTES

(e) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD() - (a)

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

Use at existing 5/32 inch rivet locations (b)D Bolt BACB30MY6K7 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (b)Bolt BACB30MY6K7X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (b)Bolt BACB30MY6K7Y 0.216 - 0.219

Collar BACC30R6

(a) For nutplates in repair strap C use BACR15CE3AD5 rivets. For nutplates in repair angle A use

BACR15CE3AD3 rivets.

(b) Typical. Longer bolts may be necessary in some locations.

FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9)

(SHEET 5 OF 5)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 1 OF 5)

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ALERT ALERT
FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 2 OF 5)

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ALERT ALERT
FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 3 OF 5)

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BOEING SERVICE BULLETIN 747-53A2688

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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Make Filler B 1 From 2024-T3 aluminum (a)

From 2024-T3 aluminum (b)

(c)

2 Make Repair Strap A 1

On repair strap A for each floor

panel attach fastener location

covered by the repair

3 Install Nutplate BACN10JR3F 1

4 Install Repair Strap A 1 -

5 Install Filler B 1 -

(a) Size to match the trimmed area, 0.063 inch thick to match the flange of the upper chord.

(b) 0.071 inch thick, 1.0 inch wide, length as necessary to install at least 6 bolts on either side of the trimmed

area.

(c) Any floor panel attachment fastener hole under the repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD3 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11)

(SHEET 5 OF 5)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 1 OF 5)

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FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 2 OF 5)

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FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 3 OF 5)

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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 one repair.

NOTE: 1. The number in the QTY column is the number of parts necessary for one repair.

2. Break all sharp edges 0.015 - 0.030 inch.

3. Maintain a 125 microinch finish on all cut or trimmed surfaces.

4. The maximum gap allowed without installation of a shim is 0.010 inch.

5. Install all parts wet with BMS 5-95 faying surface sealant.

6. Finish all bare aluminum with chemical film treatment and one coat of BMS 10-11, Type I

primer.

7. At new fastener locations, maintain 0.75 - 1.125 inch between fasteners and a minimum edge

margin of 0.33 inch.

NOTE: The typical illustrations show the thick flange on the forward side of the floor beam. However, at STA

1000, the thick flange is on the aft side of the floor beam.

STEP TASK NAME PART NUMBER QTY NOTES

1 Remove / Discard Fasteners - (a) -

2 Make Filler B 1 From 2024-T3 aluminum (b)

From 2024-T3 aluminum (c)

(d)

3 Make Repair Angle A 1

On repair angle A for each

floor panel attach fastener location covered by the repair

4 Install Nutplate BACN10JR3F 1

5 Install Repair Angle A 1 -

6 Install Filler B 1 -

(a) Approximately 12 locations, as necessary to properly size repair angle A.

(b) Size to match the trimmed area, 0.063 inch thick to match the flange of the upper chord.

(c) 0.071 inch thick sheet, width as necessary to match the upper flange and the vertical flange of the upper

chord. Length as necessary to install at least 6 bolts in the horizontal flange and 6 bolts in the vertical

flange on either side of the trimmed area.

(d) Any floor panel attachment fastener hole under the repair angle that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the end

of the repair strap is not considered a repaired hole.

FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 4 OF 5)

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

CODE NAME PART NUMBER HOLE DIA NOTES

A Rivet BACR15CE3AD3 - -

C Bolt BACB30NW6K() 0.187 - 0.190 -

Collar BACC30M6

Use at existing 5/32 inch rivet locations (a)D Bolt BACB30MY6K() 0.187 - 0.190

Collar BACC30M6

Use at existing 3/16 inch bolt locations (a)Bolt BACB30MY6K()X 0.200 - 0.203

Collar BACC30M6

Use at existing 3/16 inch rivet locations (a)Bolt BACB30MY6K()Y 0.216 - 0.219

Collar BACC30R6

(a) Typical. Longer bolts may be necessary in some locations.

FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12)

(SHEET 5 OF 5)

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This Figure applies only to: Group 1.

FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 1 OF 3)

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FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 747-53A2688

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 repair.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the

end of the repair strap is not considered a repaired hole.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Remove / Discard Fastener - 2 -

2 Inspect Fastener Hole - 2 (a) for cracks

Floor Panel Attach - - (a) for cracks

Fastener Hole

3 Inspect

4 Oversize Fastener Hole - 2 1/64 inch diameter (b)

Install Fastener - 2 (c) if no cracks are found

(a) Do open hole HFEC inspections as given in 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00

Figure 1, 11, or 16.

(b) If necessary to meet the hole size and quality criteria shown in 747-400 SRM 51-40-05.

(c) Install fasteners of the same type and size as was removed, or 1/64 inch oversize as necessary.

FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR

(SHEET 3 OF 3)

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This Figure applies only to: Group 1.

FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 1 OF 3)

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FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 2 OF 3)

Export Controlled ECCN: 9E991 - BOEING

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BOEING SERVICE BULLETIN 747-53A2688

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 repair.

NOTE: Any floor panel attachment fastener hole under a repair strap that is not repaired or modified (as given

in FIGURE 21 or as given in paragraph 3.B., Part 5) and is not at least five fasteners away from the

end of the repair strap is not considered a repaired hole.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Remove / Keep Filler B 1 -

2 Inspect Upper Chord - - (a) for cracks

Floor Panel Attach - - (b) for cracks

Fastener Hole

3 Inspect

4 Remove / Discard Fastener - 2 -

5 Inspect Fastener Hole - 2 (b) for cracks

If no cracks are found, wet

with BMS 5-95 sealant

6 Install Filler (Kept) - 1

7 Oversize Fastener Hole - 2 1/64 inch diameter (c)

Install Fastener - 2 (d) if no cracks are found

(a) Do a surface HFEC inspections along the edge of the trimmed surface as given in 747 NDT Part 6, 53-

10-53 or 747 NDT Part 6, 51-00-00 Figure 4 or 23.

(b) Do open hole HFEC inspections as shown in 747 NDT Part 6, 53-10-54 or 747 NDT Part 6, 51-00-00

Figure 1, 11, or 16.

(c) If necessary to meet the hole size and quality criteria shown in 747-400 SRM 51-40-05.

(d) Install fasteners of the same type and size as was removed, or 1/64 inch oversize as necessary.

FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM

REPAIR WITH STRAP OR ANGLE

(SHEET 3 OF 3)

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ALERT ALERT