# Boeing Alert Service Bulletin 747-53A2688: Revision 1

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- Document: [Boeing Alert Service Bulletin 747-53A2688](https://openairdocs.org/service-documents/boeing/747-53a2688.md)
- Title as filed: U.S. DOT/FAA - SB-747-53A2688-01
- Pages: 163
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## Text

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### Page 1

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.
9E991ECCN:
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Unpublished Work.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.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner™,
BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and Boeing
liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in connection
with this document unless provided in writing by Boeing. BOEING is a trademark of Boeing Management
Company.
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1 of 163
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Table of Contents
Revision Transmittal Sheet ............................................ 5
S u m m a r y ...................................................... 7
1. PLANNING INFORMATION ........................................ 1 3
A . E f f e c t i v i t y  ............................................... 1 3
1. Airplanes ............................................ 1 3
2 . S p a r e s  A f f e c t e d  ........................................ 1 7
B. Concurrent Requirements ...................................... 1 7
C. Reason ................................................ 1 8
D. Description .............................................. 1 9
E. Compliance .............................................. 2 0
F . A p p r o v a l  ............................................... 2 6
G. Manpower .............................................. 2 7
H. Weight and Balance Changes .................................... 2 8
I. Electrical Load Data ......................................... 2 8
J . R e f e r e n c e s  .............................................. 2 8
1. Existing Data: ......................................... 2 8
2. Data Supplied with this Service Bulletin: ........................... 2 8
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 2 9
K. Publications Affected ........................................ 2 9
L. Interchangeability and Intermixability of Parts ........................... 2 9
M. Software Accomplishment Summary ................................ 2 9
2. MATERIAL INFORMATION ........................................ 3 1
A. Material - Price and Availability ................................... 3 1
B. Industry Support Information .................................... 3 1
C. Parts Necessary for Each Airplane ................................. 3 1
1 . K i t s / P a r t s :  ........................................... 3 1
2. Parts and Materials Supplied by the Operator: ........................ 3 1
3. Parts Modified and Reidentified: ............................... 3 5
4. Parts Removed and Not Replaced: .............................. 3 5
D. Parts Necessary to Change Spares ................................. 3 5
E. Special Tooling - Price and Availability ............................... 3 5
F. Special Tooling Necessary to do this Service Bulletin ....................... 3 5
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 7
A. GENERAL INFORMATION ..................................... 3 7
B. WORK INSTRUCTIONS ....................................... 3 8
FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] ....... 5 0
FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 2] ....... 5 1
FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER
LOCATIONS .......................................... 5 2
FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION ..... 5 5
FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION .......... 5 9
FIGURE 6: SECTION 41 - HOLE MEASUREMENTS AFTER CRACK REMOVAL ........... 6 2
FIGURE 7: SECTION 41 - REPAIR STRAP INSTALLATION ....................... 6 5
FIGURE 8: SECTION 41 - UPPER CHORD TRIM ............................ 6 9
FIGURE 9: SECTION 41 - UPPER CHORD REPAIR WITH STRAP ................... 7 2
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FIGURE 10: SECTION 41 - UPPER CHORD REPAIR WITH STRAP AND CLIP ............. 7 6
FIGURE 11: SECTION 41 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR
.................................................. 8 1
FIGURE 12: SECTION 41 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM
REPAIR WITH STRAP OR ANGLE .............................. 8 4
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] ...... 1 0 7
FIGURE 18: SECTION 44 - UPPER DECK FLOOR BEAM INSPECTION AREA [Group 1] ...... 1 0 8
FIGURE 19: SECTION 44 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER
LOCATIONS [Group 1] .................................... 1 0 9
FIGURE 20: SECTION 44 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION [Group 1] . 112
FIGURE 21: SECTION 44 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION [Group 1] .... 1 1 6
FIGURE 22: SECTION 44 - HOLE MEASUREMENTS AFTER CRACK REMOVAL [Group 1] ..... 1 1 9
FIGURE 23: SECTION 44 - REPAIR STRAP INSTALLATION [Group 1] ................ 1 2 2
FIGURE 24: SECTION 44 - UPPER CHORD TRIM [Group 1] ...................... 1 2 6
FIGURE 25: SECTION 44 - UPPER CHORD REPAIR WITH STRAP [Group 1] ............ 1 2 9
FIGURE 26: SECTION 44 - UPPER CHORD REPAIR WITH STRAP AND CLIP [Group 1] ...... 1 3 3
FIGURE 27: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH STRAP (REPAIR 8) [Group
1 ]  ................................................ 1 3 8
FIGURE 28: SECTION 44 - UPPER CHORD THICK FLANGE REPAIR WITH ANGLE (REPAIR 9) [Group
1 ]  ................................................ 1 4 3
FIGURE 29: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH STRAP (REPAIR 11) [Group 1]
................................................. 1 4 8
FIGURE 30: SECTION 44 - UPPER CHORD THIN FLANGE REPAIR WITH ANGLE (REPAIR 12) [Group 1]
................................................. 1 5 3
FIGURE 31: SECTION 44 - AFTER-REPAIR INSPECTION FOR LOCATIONS WITH THE STRAP REPAIR
[Group 1] ............................................ 1 5 8
FIGURE 32: SECTION 44 - AFTER-REPAIR INSPECTIONS FOR LOCATIONS WITH UPPER CHORD TRIM
REPAIR WITH STRAP OR ANGLE [Group 1] ........................ 1 6 1
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Commercial
Airplanes
747
Service Bulletin
ALERT
Revision Transmittal SheetNumber: 747-53A2688Original 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
August 21, 2008Original Issue:
September 19, 2012Revision 1:
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Commercial
Airplanes
747
Service Bulletin
ALERT
SummaryNumber: 747-53A2688Original 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.
ReferenceAffectedPlanning Data
Paragraph 1.A.2., Spares AffectedNoSpares Affected
Paragraph 1.E., ComplianceYesAD Related
Paragraph 1.H., Weight and Balance ChangesYesWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedNoPublications Affected
Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsNoKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
YesOperator Supplied Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
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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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 Man-
Hours
Airplanes
77.25259Passenger
72.25241Boeing Converted
Freighter
Large Cargo
Freighter
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Section 44 Inspections
Elapsed Time
(Hours)
Total Man-
Hours
Airplanes
24.0066.00Passenger
MATERIAL INFORMATION
None
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BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
STA
1100
STA  SECTION 44
1000  INSPECTION AREA
SECTION 41
INSPECTION AREA
STA
340
STA
360
STA
STA
STA  520  380
340  :==  _ STA
400
STA
420
SECTION 41 INSPECTION  STA
440
AREA SHOWN,
SECTION 44 INSPECTION  STA
460
AREA SIMILAR
STA
480
STA
500
FLOOR PANEL ATTACH  STA
FASTENER HOLE  520
A-A  FWD
UPPER CHORD
TYPICAL SECTION 41
INSPECTION AREA
WEB OR STRAP  FLOOR PANEL
DO OPEN-HOLE OR SURFACE HFEC INSPECTIONS AT ALL
FLOOR PANEL ATTACH FASTENER HOLES COMMON TO THE
UPPER DECK FLOOR BEAM UPPER CHORDS.
> FWD  B-B  1454601
(TYPICAL)
Original Issue: August 21, 2008
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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.
DESCRIPTIONCONFIGURATIONGROUP
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
GroupVariable Number
1RF001 - RF006
1RM001 - RM007
1RM010 - RM013
1RM021 - RM024
1RM026 - RM030
1RM036 - RM045
1RM051 - RM053
1RM071
1RM081 - RM084
1RM091
1RM096 - RM097
1RM116 - RM117
1RM126 - RM127
2RM128
1RM129 - RM132
1RM136 - RM147
1RM156 - RM158
1RM166 - RM177
1RM191 - RM192
1RM231 - RM233
1RM241 - RM246
1RM261 - RM264
1RM316 - RM318
1RM331 - RM333
1RM341
1RM351 - RM355
1RM366 - RM367
1RM401 - RM403
1RM426
1RM431
1RM441 - RM443
1RM445
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GroupVariable Number
1RM801 - RM803
1RM811 - RM813
1RT001 - RT014
2RT021 - RT022
2RT031 - RT033
1RT034 - RT035
1RT041 - RT047
2RT061
2RT071 - RT072
1RT073 - RT074
2RT075
1RT101 - RT103
1RT121
1RT131 - RT137
1RT151 - RT152
2RT161
1RT162 - RT163
2RT164
1RT165 - RT168
1RT401 - RT412
1RT431 - RT447
1RT451 - RT455
2RT456
1RT457 - RT460
2RT461
1RT462 - RT469
1RT471 - RT499
2RT501
1RT502 - RT505
2RT506 - RT510
1RT511 - RT512
2RT513
1RT514 - RT515
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GroupVariable Number
2RT516
1RT517
2RT518 - RT520
1RT521 - RT523
2RT524
1RT525
2RT526
1RT527
2RT528
1RT529
2RT530
1RT531 - RT535
1RT551 - RT568
1RT571
2RT572 - RT579
1RT580 - RT591
1RT601 - RT630
3RT631 - RT632
1RT633 - RT641
2RT642
1RT643 - RT654
2RT655 - RT657
1RT671 - RT673
1RT681 - RT682
1RT691 - RT699
1RT701 - RT704
1RT711 - RT717
1RT741 - RT742
3RT743
1RT744 - RT750
2RT751 - RT752
1RT753 - RT757
1RT776 - RT777
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GroupVariable Number
2RT781 - RT782
1RT783 - RT784
1RT801 - RT803
1RT811 - RT814
1RT831 - RT836
2RT837
1RT861 - RT864
3RT876
1RT877 - RT880
1RT931 - RT932
1RT945 - RT949
1RT951 - RT955
1RT966
2RT967
1RU001 - RU006
1RU016 - RU017
1RU031 - RU032
1RU051 - RU052
1RU059 - RU062
1RU081 - RU083
1RU101 - RU102
1RU121 - RU132
1RU801 - RU809
1RU831 - RU841
2. Spares Affected
None.
B. Concurrent Requirements
None.
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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:
Crack lengthCrack locationFlight hours/cycles
unknownSTA 340,RBL 6037,561 / 29,013
not reportedSTA 440, BL 032,855 / 24,783
1 inch (corrosion)STA 440, RBL 5849,403 / 5,581
0.03 inchSTA 1000, LBL 5037,561 / 29,013
0.4 inchSTA 1100, RBL 5337,283 / 29,425
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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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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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
ZoneModel
211, 212, 221, 222, 223, 224, 225, 226, 231,
232, 241, 242
747-400, 747-400D
Group 2-3:
Affected Maintenance Zones
ZoneModel
211, 212, 221, 222, 223, 224, 231, 232747-400
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 In-
spections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs Last)ActionCondition
-Within 2,000
flight-cycles of
the last SSID in-
spection, if sur-
face HFEC was
used in that in-
spection. Within
6,000 flight-cy-
cles of the last
SSID inspection,
if open hole
HFEC was used
in that inspec-
tion. (a)
Within 1,000
flight-cycles
after June 17,
2009 (the ef-
fective date
of AD 2009-
10-06 ).
Before
20,000 total
flight-cycles.
Do open hole or sur-
face HFEC inspection
of the floor panel attach-
ment fastener holes in
the upper deck floor
beam upper chords for
cracks as given in
Paragraph 3.B., PART
1.
All affected air-
planes.
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Table 1 - Section 41 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In-
spections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs Last)ActionCondition
-Before further flight.Do the applicable repair
procedures as given in
Paragraph 3.B., PART
2, or contact Boeing for
repair data.
Any crack found in
the floor panel at-
tachment fastener
holes.
2,000 flight-cycles
if surface HFEC
inspection was
used; 6,000 flight-
cycles if open
hole HFEC in-
spection was
used.
Within 2,000 flight-cycles if surface HFEC in-
spection was used, or within 6,000 flight-cycles
if open hole HFEC inspection was used.
Repeat open hole or
surface HFEC inspec-
tion 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 at-
tachment fastener
holes.
-Before further flight.As an option, do the
hole modification proce-
dure as given in FIG-
URE 5.
-Before further flight.As an option, do one of
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., Compli-
ance.
Refer to Table 2 in
Paragraph 1.E., Compli-
ance.
Location(s) modi-
fied or repaired as
given in FIGURE
5 or Paragraph
3.B., PART 2.
-Before further flight.Do a repair. Contact
Boeing for repair data.
Any crack found in
the repaired or
modified loca-
tion(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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Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
2,000 flight-cycles if sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 15,000 flight-cy-
cles after the modification
was accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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 sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 10,000 flight-cy-
cles after the modification
was accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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 sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 15,000 flight-cy-
cles after the repair was
accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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 sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 3.B., PART 1.
Location(s) where repair #2 was
done as given in Paragraph
3.B., PART 2 of this service
bulletin. (a)
3,000 flight-cycles.Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole HFEC in-
spection 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)
3,000 flight-cycles.Within 5,000 flight-cycles
after the repair was ac-
complished.
Do open hole HFEC in-
spection 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)
3,000 flight-cycles.Within 5,000 flight-cycles
after the repair was ac-
complished.
Do open hole HFEC in-
spection 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)
6,000 flight-cycles.Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole and sur-
face 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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Table 2 - Section 41 Compliance Times for Inspection of Location(s) Repaired or Modified
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
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 Para-
graph 3.B., PART 2 of this ser-
vice bulletin. (a)
-Before further flight.Do a repair. Contact
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 In-
spections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs Last)ActionCondition
-Within 2,000
flight-cycles of
the last SSID in-
spection, if sur-
face HFEC was
used in that in-
spection. Within
6,000 flight-cy-
cles of the last
SSID inspection,
if open hole
HFEC was used
in that inspec-
tion. (a)
Within 1,000
flight-cycles
after the Revi-
sion 1 date of
this service
bulletin.
Before
20,000 total
flight-cycles.
Do open hole or sur-
face HFEC inspection
of the floor panel attach-
ment fastener holes in
the upper deck floor
beam upper chords for
cracks as given in
Paragraph 3.B., PART
4.
All affected air-
planes.
-Before further flight.Do the applicable repair
procedures as given in
Paragraph 3.B., PART
5, or contact Boeing for
repair data.
Any crack found in
the floor panel at-
tachment fastener
holes.
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Group 1:
Table 3 - Section 44 Compliance Times for Upper Deck Floor Beam Upper Chord Initial and Repeat In-
spections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs Last)ActionCondition
2,000 flight-cycles
if surface HFEC
inspection was
used; 6,000 flight-
cycles if open
hole HFEC in-
spection was
used.
Within 2,000 flight-cycles if surface HFEC in-
spection was used, or within 6,000 flight-cycles
if open hole HFEC inspection was used.
Repeat open hole or
surface HFEC inspec-
tion 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 at-
tachment fastener
holes.
-Before further flight.As an option, do the
hole modification proce-
dure as given in FIG-
URE 21.
-Before further flight.As an option, do one of
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., Compli-
ance.
Refer to Table 4 in
Paragraph 1.E., Compli-
ance.
Location(s) modi-
fied or repaired as
given in FIGURE
21 or Paragraph
3.B., PART 5.
-Before further flight.Do a repair. Contact
Boeing for repair data.
Any crack found in
the repaired or
modified loca-
tion(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)
Compliance TimeActionCondition
2,000 flight-cycles if sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 15,000 flight-cy-
cles after the modification
was accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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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Group 1:
Table 4 - Section 44 Compliance Times for Inspection of Location(s) Repaired or Modified
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
2,000 flight-cycles if sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 10,000 flight-cy-
cles after the modification
was accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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 sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 15,000 flight-cy-
cles after the repair was
accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 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 sur-
face HFEC inspection
was used; 6,000 flight-
cycles if open hole
HFEC inspection was
used.
Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole or surface
HFEC inspection for
cracks as given in Para-
graph 3.B., PART 4.
Location(s) where repair #2 was
done as given in Paragraph
3.B., PART 5 of this service
bulletin. (a)
3,000 flight-cycles.Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole HFEC in-
spection 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)
3,000 flight-cycles.Within 5,000 flight-cycles
after the repair was ac-
complished.
Do open hole HFEC in-
spection 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)
3,000 flight-cycles.Within 5,000 flight-cycles
after the repair was ac-
complished.
Do open hole HFEC in-
spection 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)
6,000 flight-cycles.Within 10,000 flight-cy-
cles after the repair was
accomplished.
Do open hole and sur-
face 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 Para-
graph 3.B., PART 5 of this ser-
vice bulletin. (a)
-Before further flight.Do a repair. Contact
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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### Page 26

Table 5 - Section 41 and 44 Upper Deck Floor Beam Upper Chord Replacement
Compliance TimeActionCondition
After 15,000 total flight
cycles and before
35,000 total flight cycles.
(a)
Replace upper deck floor
beam upper chords in
accordance with Para-
graph 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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### Page 27

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
Elapsed HoursTask HoursNumber of
Persons
Task
24964Open Access
25502Inspect
28.251134Close Access
77.25259TOTAL FOR EACH AIRPLANE
Group 2:
Section 41 Inspections
Elapsed HoursTask HoursNumber of
Persons
Task
22.50904Open Access
24482Inspect
25.751034Close Access
72.25241TOTAL FOR EACH AIRPLANE
Group 3:
Section 41 Inspections
Elapsed HoursTask HoursNumber of
Persons
Task
11.25454Open Access
12242Inspect
12.7551.54Close Access
36.0120.5TOTAL FOR EACH AIRPLANE
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Group 1:
Section 44 Inspections
Elapsed HoursTask HoursNumber of
Persons
Task
4.0016.004Open Access
15.0030.002Inspect
5.0020.004Close Access
24.0066.00TOTAL FOR EACH AIRPLANE
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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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)
NamePart NumberQTY
Repair StrapA (a)1
BoltBACB30NW6K410
CollarBACC30M610
NutplateBACN10JR3F(b)
RivetBACR15CE3AD4(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
Repair StrapA (a)1
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Table 2 - Section 41 or Section 44 Upper Chord Strap Repair (Refer to Figure 9 or Figure 25)
NamePart NumberQTY
FillerB (a)1
BoltBACB30NW6K410
CollarBACC30M610
NutplateBACN10JR3F(b)
RivetBACR15CE3AD4(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
Repair StrapA (a)1
FillerB (a)1
Repair ClipC (a)1
BoltBACB30MY6K7X3
BoltBACB30NW6K410
CollarBACC30M613
NutplateBACN10JR3F(b)
RivetBACR15CE3AD4(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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 )
NamePart NumberQTY
Repair StrapA (a)1
FillerB (a)1
Repair StrapC (a)1
BoltBACB30NW6K52
BoltBACB30NW6K712
CollarBACC30M614
NutplateBACN10JR3F(b)
RivetBACR15CE3AD4(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
Repair AngleA (a)1
FillerB (a)1
Repair StrapC (a)1
BoltBACB30MY6K7X14
BoltBACB30NW6K52
BoltBACB30NW6K712
CollarBACC30M628
NutplateBACN10JR3F(b)
RivetBACR15CE3AD3(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
(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)
NamePart NumberQTY
Repair StrapA (a)1
FillerB (a)1
BoltBACB30NW6K312
CollarBACC30M612
NutplateBACN10JR3F(b)
RivetBACR15CE3AD3(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
Repair AngleA (a)1
FillerB (a)1
BoltBACB30MY6K512
BoltBACB30NW6K412
CollarBACC30M624
NutplateBACN10JR3F(b)
RivetBACR15CE3AD3(b)
Pressure and Environmental Sealant -
Chromate Type
BMS 5-952 oz. (c)
Chemical and Solvent Resistant FinishBMS 10-11, Type I2 oz. (c)
(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)
NamePart NumberQTY
(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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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
747-400 AMM 25-16-00Flight Compartment Floor Covering
747-400 AMM 25-11-01Captain and First Officer Seat
747-400 AMM 25-11-03Observer's Seat
747-400 AMM 25-19-03Flight Deck Crew Rest Partitions
747-400 AMM 25-25-01Upper Deck Passenger Seat
747-400 AMM 25-27-05Upper Deck Floor Covering
747-400 AMM 25-40-03Upper Deck Lavatories
747-400 AMM 25-24-18Upper Deck Closets
747-400 AMM 25-32-01Upper Deck Galleys
747-400 AMM 53-21-02Upper Deck Floor Panels
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
747-400 AMM 25-21-04Ceiling Insulation
747-400 AMM 25-22-01Ceiling Access Panels
747-400 AMM 25-23-00Passenger Service Units
747-400 AMM 25-25-01Passenger Seats
747-400 AMM 25-28-02Center Overhead Stowage Compartments
747-400 AMM 25-28-01Side Overhead Stowage Compartments
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
747-400 AMM 25-59-01Main Deck Cargo Compartment Ceiling Lining
747-400 AMM 25-59-05Main Deck Ceiling Insulation
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
Repair ProcedureEdge MarginCrack-Free Hole Diam-
eter
Repair #
Make hole 1/16 inch oversize (Insurance Cut)
(a)
2.5D or more (before
insurance cut)
0.281 inch or less (be-
fore insurance cut)1
Make hole 1/16 inch oversize (Insurance Cut)
(a)
1.6D or more and less
than 2.5D (before insur-
ance cut)
0.281 inch or less (be-
fore insurance cut)2
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 insur-
ance cut)
0.281 inch or less (be-
fore insurance cut)3
Trim the chord as given in FIGURE 8. Install the
appropriate repair from Table 2 - Hole Trimout
Repairs.
Less than 1.3D0.281 inch or less(Refer to
Table 2)
None (b)1.3D or more0.282 - 0.343 inch4
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Table 1 - Hole Repair Instructions
Repair ProcedureEdge MarginCrack-Free Hole Diam-
eter
Repair #
Install strap as given in FIGURE 7. (b)1.1D or more and less
than 1.3D
0.282 - 0.343 inch5
Trim the chord as given in FIGURE 8. Install the
appropriate repair from Table 2 - Hole Trimout
Repairs.
Less than 1.1D0.282 - 0.343 inch(Refer to
Table 2)
Trim the chord as given in FIGURE 8. Install the
appropriate repair from Table 2 - Hole Trimout
Repairs.
AnyMore than 0.343 inch(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 as given inConditionBody Station (STA)Repair #
FIGURE 10Affected hole location is common to
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
FIGURE 9Affected hole location is not com-
mon to the fasteners that support
any upper deck equipment support
brackets.
7
FIGURE 13'f' is less than or equal to 0.75 inch.
(a)
Affected floor beam locations where
upper chord is made from BAC1506-
2441 extrusion and cracking is locat-
ed on the thick flange of the upper
chord.
8
FIGURE 14'f' is more than 0.75 inch and less
than or equal to 0.90 inch. (a)9
Contact Boeing (c)'f' is more than 0.90 inch. (a)10
FIGURE 15'a' is less than or equal to 0.60 inch.
(b)
Affected floor beam locations where
upper chord is made from BAC1506-
2441 extrusion and cracking is locat-
ed on the thin flange of the upper
chord.
11
FIGURE 16'a' is more than 0.60 inch and less
than or equal to 0.80 inch. (b)12
Contact Boeing (c)'a' is more than 0.80 inch. (b)13
(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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 43

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
747-400 AMM 25-16-00Flight Compartment Floor Covering
747-400 AMM 25-11-01Captain and First Officer Seat
747-400 AMM 25-11-03Observer's Seat
747-400 AMM 25-19-03Flight Deck Crew Rest Partitions
747-400 AMM 25-25-01Upper Deck Passenger Seat
747-400 AMM 25-27-05Upper Deck Floor Covering
747-400 AMM 25-40-03Upper Deck Lavatories
747-400 AMM 25-24-18Upper Deck Closets
747-400 AMM 25-32-01Upper Deck Galleys
747-400 AMM 53-21-02Upper Deck Floor Panels
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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: August 21, 2008
747-53A2688Revision 1: September 19, 2012
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 44

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
747-400 AMM 25-27-05Upper Deck Floor Covering
747-400 AMM 25-32-01Upper Deck Galleys
747-400 AMM 53-21-02Upper Deck Floor Panels
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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 45

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
747-400 AMM 25-21-04Ceiling Insulation
747-400 AMM 25-22-01Ceiling Access Panels
747-400 AMM 25-23-00Passenger Service Units
747-400 AMM 25-25-01Passenger Seats
747-400 AMM 25-28-02Center Overhead Stowage Compartments
747-400 AMM 25-28-01Side Overhead Stowage Compartments
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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 46

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
Repair ProcedureEdge MarginCrack-Free Hole Diam-
eter
Repair #
Make hole 1/16 inch oversize (Insurance Cut)
(a)
2.5D or more (before
insurance cut)
0.281 inch or less (be-
fore insurance cut)1
Make hole 1/16 inch oversize (Insurance Cut)
(a)
1.6D or more and less
than 2.5D (before insur-
ance cut)
0.281 inch or less (be-
fore insurance cut)2
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 insur-
ance cut)
0.281 inch or less (be-
fore insurance cut)3
Trim the chord as given in FIGURE 24. Install
the appropriate repair from Table 4 - Hole Tri-
mout Repairs.
Less than 1.3D0.281 inch or less(Refer to
Table 4)
None (b)1.3D or more0.282 - 0.343 inch4
Install strap as given in FIGURE 23. (b)1.1D or more and less
than 1.3D
0.282 - 0.343 inch5
Trim the chord as given in FIGURE 24. Install
the appropriate repair from Table 4 - Hole Tri-
mout Repairs.
Less than 1.1D0.282 - 0.343 inch(Refer to
Table 4)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 47

Table 3 - Hole Repair Instructions
Repair ProcedureEdge MarginCrack-Free Hole Diam-
eter
Repair #
Trim the chord as given in FIGURE 24. Install
the appropriate repair from Table 4 - Hole Tri-
mout Repairs.
AnyMore than 0.343 inch(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 as given inConditionLocationRepair #
FIGURE 26Affected hole location is common to
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
FIGURE 25Affected hole location is not com-
mon to the fasteners that support
any upper deck equipment support
brackets.
7
FIGURE 27'f' is less than or equal to 0.75 inch.
(a)
Affected floor beam locations where
upper chord is made from BAC1506-
2441 extrusion and cracking is locat-
ed on the thick flange of the upper
chord.
8
FIGURE 28'f' is more than 0.75 inch and less
than or equal to 0.90 inch. (a)9
Contact Boeing (c)'f' is more than 0.90 inch. (a)10
FIGURE 29'a' is less than or equal to 0.60 inch.
(b)
Affected floor beam locations where
upper chord is made from BAC1506-
2441 extrusion and cracking is locat-
ed on the thin flange of the upper
chord.
11
FIGURE 30'a' is more than 0.60 inch and less
than or equal to 0.80 inch. (b)12
Contact Boeing (c)'a' is more than 0.80 inch. (b)13
(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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: August 21, 2008
747-53A2688Revision 1: September 19, 2012
47 of 163
BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 48

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
747-400 AMM 25-27-05Upper Deck Floor Covering
747-400 AMM 25-32-01Upper Deck Galleys
747-400 AMM 53-21-02Upper Deck Floor Panels
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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: August 21, 2008
747-53A2688Revision 1: September 19, 2012
48 of 163
BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 49

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.
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
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Original Issue: August 21, 2008
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49 of 163
BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 50 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
This Figure applies only to: Group 1.
loga
0000 0000000  STA
520
STA
340
STA  STA  STA STA  STA  STA  STA  STA
360  380  440  460  480  500  520
STA
340
FWD A-A
UPPER DECK FLOOR BEAM  1452156
INSPECTION LOCATIONS
FIGURE 1: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA
(SHEET 1 OF 1)
Original Issue: August 21, 2008
Revision 1 September 19, 2012  Export Controlled ECCN: 9E991 - BOEING  747-53A2688
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  50 of 163

### Page 51 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
This Figure applies only to: Group 2.
- A
0000 0000000j00  STA
520
STA
340
STA  STA  STA  STA  STA
360  380  400  420  440
STA
340
FWD A-A
UPPER DECK FLOOR BEAM  1452158
INSPECTION LOCATIONS
FIGURE 2: SECTION 41 - UPPER DECK FLOOR BEAM INSPECTION AREA
(SHEET 1 OF 1)
Original Issue: August 21, 2008
Revision 1 September 19, 2012  PROPRIETARY - Copyright © Unpublished  Export Controlled ECCN: 9E991 - BOEING  Work - See page 1 for details.  747-53A2688  51 of 163

### Page 52 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
00000000000/000  STA
520
STA
340
STA  STA  STA  STA  STA  STA  STA  STA  STA
360  380  400  420  440  460  480  500  520
STA
340
FWD A-A
TYPICAL INSPECTION  1452164
AREA
FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER
LOCATIONS
(SHEET 1 OF 3)
Original Issue: August 21, 2008
Revision 1 September 19, 2012  Export Controlled ECCN: 9E991 - BOEING  PROPRIETARY - Copyright © Unpublished  747-53A2688
Work - See page 1 for details.  52 of 163

### Page 53 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
1)  • FLOOR PANEL
ATTACH HOLE
UPPER CHORD
UP
FWD  B-B
TYPICAL AFFECTED FLOOR
BEAM UPPER CHORD
1 FLOOR PANEL  ATTACH HOLE
UPPER CHORD
RADIUS FILLER
UP
FWD
B-B
TYPICAL AFFECTED FLOOR BEAM UPPER
CHORD WITH RADIUS FILLER  1452181
(ANGLE SIMILAR)
FIGURE 3: SECTION 41 - OPEN HOLE HFEC INSPECTION AT FLOOR PANEL ATTACHMENT FASTENER
LOCATIONS
(SHEET 2 OF 3)
Original Issue: August 21, 2008
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Work - See page 1 for details.  53 of 163

### Page 54

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: As shown in FIGURE 2, the STA 460 - 520 floor beams are not affected on Group 2 airplanes.1.
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.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
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)
--Fastener HoleInspect1
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)
--Upper ChordInspect2
(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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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 55 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
009
00000000000/000  STA
520
STA
340
STA  STA  STA  STA  STA  STA  STA  STA
360  380  400  420  440  460 480 50  520
STA
340
SEE A
FWDO A-A
TYPICAL INSPECTION  1452244
AREA
FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION
(SHEET 1 OF 4)
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PROPRIETARY - Copyright © Unpublished
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### Page 56 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
CLIPNUT
(TYPICAL)
FLOOR PANEL
UPPER CHORD
• B
UP
WEB
A-A
TYPICAL CLIPNUT INSTALLATION
0.10
CUT LINE  CUT LINE 3
- 0.10
0.12 -
-0.10
B-B  1452247
TYPICAL CLIPNUT INSTALLATION
FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION
(SHEET 2 OF 4)
Original Issue: August 21, 2008
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PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  56 of 163

### Page 57

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..
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
as close as possible to
the top of the clipnut
--ClipnutCut1
down to expose the edge
of the upper chord
--ClipnutBend2
On the clipnut lower
flange
--ClipnutCut3
---Clipnut FlangeRemove / Discard4
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
Inspect5
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
Inspect6
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)
-Upper ChordInspect7
FIGURE 4: SECTION 41 - CLIPNUT MODIFICATION AND SURFACE HFEC INSPECTION
(SHEET 3 OF 4)
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BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 58

MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
(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)
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: August 21, 2008
747-53A2688Revision 1 September 19, 2012
58 of 163
BOEING SERVICE BULLETIN 747-53A2688
ALERTALERT

### Page 59 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
009
00000000000/000  STA
520
STA
340
STA  STA  STA  STA  STA  STA  STA  STA
360  380  400  420  440  460 480 50  520
STA
340
SEE A
FWDO A-A
TYPICAL INSPECTION  1452249
AREA
FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION
(SHEET 1 OF 3)
Original Issue: August 21, 2008
Revision 1 September 19, 2012  Export Controlled ECCN: 9E991 - BOEING  747-53A2688
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  59 of 163

### Page 60 (OCR)

BOEING SERVICE BULLETIN 747-53A2688
ALERT  ALERT
UPPER CHORD
WEB ~
1 FLOOR PANEL
ATTACH HOLES
UP
• INBD
LOWER CHORD
TYPICAL - UPPER DECK FLOOR BEAMS
UPPER
CHORD
EDGE *
MARGIN Y
TYPICAL FLOOR PANEL
ATTACHMENT FASTENER
LOCATION
A-A  1452253
FIGURE 5: SECTION 41 - FLOOR PANEL ATTACHMENT HOLE MODIFICATION
(SHEET 2 OF 3)
Original Issue: August 21, 2008
Revision 1 September 19, 2012  Export Controlled ECCN: 9E991 - BOEING  747-53A2688
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.  60 of 163

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