# Boeing Alert Service Bulletin 777-53A0078: No revision named

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- Document: [Boeing Alert Service Bulletin 777-53A0078](https://openairdocs.org/service-documents/boeing/777-53a0078.md)
- Title as filed: U.S. DOT/FAA - SB-777-53A0078-00
- Pages: 30
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### Page 1

Commercial 
Airplanes
777
Service Bulletin
ALERT
Number: 777-53A0078
Original Issue: December 05, 2014
ATA System: 5383
SUBJECT: FUSELAGE - Section 48 - Station 2150 - Aft Pressure Bulkhead Web Lap Splice
Inspection
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 2014 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
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Table of Contents
Summary ...................................................... 5
1. PLANNING INFORMATION ........................................ 9
A. Effectivity ................................................ 9
1. Airplanes ............................................. 9
2. Spares Affected ........................................ 1 5
B. Concurrent Requirements ...................................... 1 5
C. Reason ................................................ 1 5
D. Description .............................................. 1 5
E. Compliance .............................................. 1 6
F. Approval ............................................... 1 7
G. Manpower .............................................. 1 8
H. Weight and Balance Changes .................................... 1 8
I. Electrical Load Data ......................................... 1 8
J. References .............................................. 1 9
1. Existing Data: ......................................... 1 9
2. Data Supplied with this Service Bulletin: ........................... 1 9
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 1 9
K. Publications Affected ........................................ 1 9
L. Interchangeability and Intermixability of Parts ........................... 2 0
M. Software Accomplishment Summary ................................ 2 0
2. MATERIAL INFORMATION ........................................ 2 1
A. Material - Price and Availability ................................... 2 1
B. Industry Support Information .................................... 2 1
C. Parts Necessary for Each Airplane ................................. 2 1
1. Kits/Parts ............................................ 2 1
2. Parts and Materials Supplied by the Operator ........................ 2 1
3. Parts Modified and Reidentified ................................ 2 1
4. Parts Removed and Not Replaced .............................. 2 1
D. Parts Necessary to Change Spares ................................. 2 1
E. Special Tooling - Price and Availability ............................... 2 1
F. Special Tooling Necessary to do this Service Bulletin ....................... 2 1
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 2 3
A. GENERAL INFORMATION ..................................... 2 3
B. WORK INSTRUCTIONS ....................................... 2 4
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS ........ 2 6
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Commercial 
Airplanes
777
Service Bulletin
ALERT
SummaryNumber: 777-53A0078Original Issue: December 05, 2014
ATA System: 5383
SUBJECT: FUSELAGE - Section 48 - Station 2150 - Aft Pressure Bulkhead Web Lap Splice
Inspection
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 provide a through the thickness examination of the aft web of the radial
lap splices using Medium Frequency Eddy Current (MFEC) for fatigue cracks, and to install repairs if any crack
is found. If these inspections and repairs are not done, fatigue cracks can develop in the bulkhead webs. If this
Wide Spread Fatigue cracking is not found and repaired, the cracks can rapidly coalesce and can result in
possible rapid decompression and loss of structural integrity
Widespread Fatigue Damage (WFD) analysis of the 777, as required by 14 CFR 26.21(b), has resulted in the
conclusion that existing MPD Section 9, Airworthiness Limitation Instruction (ALI) inspection program is not
sufficient to preclude the occurrence of WFD in the aft webs of the aft pressure bulkhead lap splices as the
airplane ages. The pressure bulkhead lap splices have multiple adjacent identical details which have the potential
for Multi-Site Damage (MD) and the potential for WFD. 14 CFR 26.21 requires evaluation of such designs for
the potential for WFD and implementation of the appropriate Service Actions to ensure that WFD is precluded
before the Limit of Validity (LOV). The aft pressure bulkhead web lap splices affected by this service bulletin
have been determined to be structure that is susceptible to WFD. Boeing has not received any reports of cracks
in the pressure bulkhead lap splices. Fatigue cracking was found in the pressure bulkhead aft webs of the radial
lap splices common to the full scale fatigue test article.
Accomplishment of the inspections and repairs in this service bulletin will ensure that the aft web of the aft
pressure bulkhead web lap splices are free of detectable cracks and maintain the structural integrity of the aft
pressure bulkhead.
Boeing Service Related Problem (SRP) 777-SRP-53-0463 is related to this service bulletin.
This table is provided to operators for planning purposes only. Refer to the applicable sections for more
information.
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ReferenceAffectedPlanning Data
Paragraph 1.A.2., Spares AffectedNoSpares Affected
Paragraph 1.E., Compliance and Paragraph
1.F., Approval
YesAD Related
Paragraph 1.H., Weight and Balance ChangesNoWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedYesPublications 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
NoOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
Get access to the aft side of the aft pressure bulkhead.
Do the Medium Frequency Eddy Current (MFEC) inspections around fasteners in the aft webs at the aft pressure
bulkhead radial lap splices.
If cracks are found, repair in accordance with the 777 Structural Repair Manual (SRM) or contact Boeing for
repair instructions and do the repair.
EFFECTIVITY
All 777-200, 777-200LR, 777 -300, 777 -300ER and 777F Airplane(s), Refer to Paragraph 1.A.1., Airplanes, for
the list of affected airplane(s).
COMPLIANCE
Federal Aviation Administration (FAA) Airworthiness Directive AD 2012-07-06 is related to this service bulletin.
The effective date of AD 2012-07-06 is May 15, 2012.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the inspection(s) and/or repair procedures given in this service
bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
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MATERIAL INFORMATION
None.
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### Page 9

Commercial 
Airplanes
777
Service Bulletin
ALERT
Number: 777-53A0078
Original Issue: December 05, 2014
ATA System: 5383
SUBJECT: FUSELAGE - Section 48 - Station 2150 - Aft Pressure Bulkhead Web Lap Splice
Inspection
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 D624W001 Part 3 for Airplane Variable Number, Line Number, and
Serial Number data.
This service bulletin is applicable to all 777-200, 777-200LR, 777-300, 777- 300ER and 777F
airplanes in 1 Group. The Variable Numbers and Group Information for the applicable airplanes
is given below.
NOTE: The Variable Number table below includes all affected airplanes up to Line Number 1356.
Affected airplanes after Line Number 1356 will be added to the service bulletin's
MyBoeingFleet.com (MBF) "get effectivity" result when they are added to the MBF Fleet
Profile Page.
DESCRIPTIONCONFIGURATIONGROUP
All 777 airplanes-1
Airplane Models:
777-200, 777-200LR, 777-300, 777-300ER, 777F
GroupVariable Number
1WA001 - WA017
1WA076 - WA080
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GroupVariable Number
1WA086 - WA093
1WA101 - WA104
1WA116 - WA119
1WA131 - WA137
1WA171 - WA175
1WA196 - WA198
1WA206 - WA212
1WA221 - WA223
1WA231 - WA232
1WA241 - WA250
1WA261 - WA266
1WA281 - WA283
1WA301 - WA304
1WB001 - WB021
1WB031 - WB046
1WB051 - WB088
1WB101 - WB106
1WB121 - WB125
1WB131 - WB148
1WB151 - WB155
1WB161 - WB177
1WB181 - WB194
1WB201 - WB215
1WB231 - WB247
1WB271 - WB273
1WB276 - WB286
1WB291 - WB302
1WB306 - WB307
1WB311 - WB337
1WB341 - WB342
1WB366 - WB368
1WB371 - WB388
1WB406
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GroupVariable Number
1WB411 - WB413
1WB416 - WB439
1WB446 - WB453
1WB476
1WB481 - WB484
1WB501 - WB512
1WB531 - WB537
1WB551 - WB554
1WB591 - WB597
1WB601 - WB606
1WB611 - WB622
1WB631 - WB638
1WB646 - WB649
1WC051 - WC073
1WC101 - WC104
1WC111 - WC120
1WC221 - WC224
1WC241 - WC243
1WC281 - WC290
1WC301 - WC308
1WC361 - WC364
1WC371 - WC374
1WC381 - WC395
1WC441
1WC446 - WC449
1WC456 - WC459
1WC486 - WC493
1WC506 - WC508
1WC521 - WC522
1WC531 - WC536
1WC546 - WC548
1WC556
1WC566 - WC567
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GroupVariable Number
1WC571 - WC574
1WC581
1WC586 - WC587
1WC591 - WC595
1WD001 - WD002
1WD011 - WD018
1WD031 - WD036
1WD046 - WD055
1WD066 - WD075
1WD081 - WD089
1WD091
1WD096
1WD101 - WD106
1WD111 - WD112
1WD116 - WD117
1WD121 - WD122
1WD501 - WD513
1WD521 - WD541
1WD546 - WD554
1WD561 - WD573
1WD581 - WD599
1WD606 - WD609
1WD621 - WD632
1WD651 - WD665
1WD671 - WD677
1WD691 - WD709
1WD741 - WD752
1WD761 - WD771
1WD786 - WD788
1WD796 - WD837
1WD846 - WD867
1WD871 - WD899
1WD911 - WD918
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GroupVariable Number
1WD921 - WD933
1WD936 - WD957
1WD966 - WD970
1WD981 - WD982
1WD986 - WD987
1WD991 - WD994
1WD996
1WE001 - WE007
1WE011 - WE012
1WE021 - WE026
1WE031 - WE037
1WE051 - WE057
1WE071 - WE078
1WE081 - WE084
1WE091 - WE095
1WE126 - WE148
1WE151 - WE170
1WE176 - WE178
1WE186 - WE219
1WE226 - WE231
1WE236 - WE253
1WE261 - WE267
1WE271 - WE278
1WE291 - WE297
1WE301 - WE317
1WE331 - WE343
1WE351 - WE356
1WE376 - WE377
1WE381
1WE386 - WE387
1WE391 - WE392
1WE396 - WE401
1WE416 - WE420
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GroupVariable Number
1WE426 - WE428
1WE436 - WE439
1WE441 - WE445
1WE451 - WE458
1WE471 - WE474
1WE486 - WE491
1WE501 - WE504
1WE511 - WE513
1WE526 - WE528
1WE536 - WE540
1WE556 - WE563
1WE566 - WE567
1WE591
1WE601 - WE605
1WE626
1WE631
1WF001 - WF004
1WF016 - WF027
1WF031 - WF043
1WF046 - WF067
1WF075 - WF077
1WF081 - WF088
1WF096 - WF101
1WF106 - WF109
1WF111 - WF118
1WF121 - WF124
1WF131 - WF133
1WF136 - WF140
1WF146 - WF147
1WF151 - WF152
1WF156 - WF160
1WF166 - WF173
1WF176 - WF178
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GroupVariable Number
1WF181 - WF182
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
This service bulletin gives instructions to provide a through the thickness examination of the aft web
of the radial lap splices using Medium Frequency Eddy Current (MFEC) for fatigue cracks, and to install
repairs if any crack is found. If these inspections and repairs are not done, fatigue cracks can develop
in the bulkhead webs. If this Wide Spread Fatigue cracking is not found and repaired, the cracks can
rapidly coalesce and can result in possible rapid decompression and loss of structural integrity
Widespread Fatigue Damage (WFD) analysis of the 777, as required by 14 CFR 26.21(b), has resulted
in the conclusion that existing MPD Section 9, Airworthiness Limitation Instruction (ALI) inspection
program is not sufficient to preclude the occurrence of WFD in the aft webs of the aft pressure bulkhead
lap splices as the airplane ages. The pressure bulkhead lap splices have multiple adjacent identical
details which have the potential for Multi-Site Damage (MSD) and the potential for WFD. 14 CFR 26.21
requires evaluation of such designs for the potential for WFD and implementation of the appropriate
Service Actions to ensure that WFD is precluded before the Limit of Validity (LOV). The aft pressure
bulkhead web lap splices affected by this service bulletin have been determined to be structure that is
susceptible to WFD. Boeing has not received any reports of cracks in the pressure bulkhead lap splices.
Fatigue cracking was found in the pressure bulkhead aft webs of the radial lap splices common to the
full scale fatigue test article.
Accomplishment of the inspections and repairs in this service bulletin will ensure that the aft web of
the aft pressure bulkhead web lap splices are free of detectable cracks and maintain the structural
integrity of the aft pressure bulkhead.
Boeing Service Related Problem (SRP) 777-SRP-53-0463 is related to this service bulletin.
D. Description
Get access to the aft side of the aft pressure bulkhead.
Do the Medium Frequency Eddy Current (MFEC) inspections around fasteners in the aft webs at the
aft pressure bulkhead radial lap splices.
If cracks are found, repair in accordance with the 777 Structural Repair Manual (SRM) or contact Boeing
for repair instructions and do the repair.
The work in this service bulletin is done in the maintenance zone(s) given below.
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Affected Maintenance Zones
ZoneModel
311, 312777-200, 777-200LR, 777-300,
777-300ER, 777F
E. Compliance
Federal Aviation Administration (FAA) Airworthiness Directive AD 2012-07-06 is related to this service
bulletin. The effective date of AD 2012-07-06 is May 15, 2012.
Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.
When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When
more than one ACTION is given for a CONDITION number or an OPTION number, do all of the ACTION
numbers for that CONDITION number or OPTION number.
Table 1 - Aft Pressure Bulkhead Web Lap Splice MFEC Inspections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later )
ActionCondition
-Within 4,000
flight cycle or
750 days after
the original is-
sue date of this
service bulletin.
whichever oc-
curs first.
Before 38,000
total flight cy-
cles.
Do PART 1: AFT PRES-
SURE BULKHEAD RADI-
AL LAP SPLICE MEDI-
UM FREQUENCY EDDY
CURRENT INSPECTION
for any crack.
(a)
All airplanes
8,400 flight cyclesWithin 8,400 flight cycles of the
previous inspection.
Repeat PART 1: AFT
PRESSURE BULKHEAD
RADIAL LAP SPLICE
MEDIUM FREQUENCY
EDDY CURRENT IN-
SPECTION for any crack.
CONDITION 1: NO
CRACK FOUND
(a)
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Table 1 - Aft Pressure Bulkhead Web Lap Splice MFEC Inspections
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later )
ActionCondition
-Before further flightOPTION 1 (ACTION 1):
Repair in accordance with
the Structural Repair
Manual (SRM).
CONDITION 2: ANY
CRACK FOUND
8,400 flight cyclesWithin 8,400 flight cycles of the
previous inspection.
OPTION 1 (ACTION 2):
Repeat PART 1: AFT
PRESSURE BULKHEAD
RADIAL LAP SPLICE
MEDIUM FREQUENCY
EDDY CURRENT IN-
SPECTION for any crack
in unrepaired areas.
(a)
-Before further flightOPTION 2 (ACTION 1):
Contact Boeing for repair
instructions and do the
repair.
8,400 flight cyclesWithin 8,400 flight cycles of the
previous inspection.
OPTION 2 (ACTION 2):
Repeat PART 1: AFT
PRESSURE BULKHEAD
RADIAL LAP SPLICE
MEDIUM FREQUENCY
EDDY CURRENT IN-
SPECTION for any crack
in unrepaired areas.
(a)
(a) It is not necessary to do inspections in accordance with this service bulletin in areas where existing repairs
approved by the Boeing ODA via FAA form 8100-9 cover the affected aft web inspection areas. Continue
to do inspections of these repairs in accordance with existing Damage Tolerance Inspection instructions,
including those provided in the 777 Structural Repair Manual Section 53-80 and in Boeing Service Bulletin
777-53A0039.
NOTE: Once initiated, the Service Bulletin inspections will satisfy the High Frequency Eddy Current
(HFEC) inspections of the aft webs currently required by Structural Significant Item in 777
MPD 53-80-I13A Section 9. The aft web detail identified as HFEC direction 1, from the aft
side in the DTR check form.
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.
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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.
The Manager of the FAA Seattle Aircraft Certification Office approves incorporation of the inspections
per this service bulletin (SB) along with the corresponding compliance times specified in Paragraph
1.E. "Compliance" of SB 777-53A0078, Original Issue, as an Alternative Method of Compliance (AMOC)
to the inspections defined in the Damage Tolerance Rating Check Form Document D622W001-DTR
for the corresponding locations of Structural Significant Item 53-80-I13A and in Subsection B,
Airworthiness Limitations-Structural Inspections of Section 9 of the Maintenance Planning Document
D622W001-9, required by paragraphs (g) and (h) of AD 2012-07-06. When this SB specifies contacting
Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with
paragraph (j) of AD 2012-07-06. This AMOC only applies to the areas inspected in accordance with
this SB. All provisions of AD 2012-07-06 that are not specifically referenced in this paragraph remain
fully applicable and must be complied with accordingly.
G. Manpower
The table below shows an estimate of the task hours necessary to do this inspection for each aft
pressure bulkhead. This estimate is for direct labor only, done by an experienced crew. Adjust the
estimate with operator task hour data if necessary. The estimate does not include lost time. These are
some examples of lost time:
 Time to adjust to the workplace
 Time to schedule the work
 Time to inspect the work
 Time to cure the materials
 Time to make the parts
 Time to find the tools.
Elapsed HoursTask HoursNumber of PersonsTask
0.500.501Open Access
3.757.502Figure 1
0.500.501Close Access
4.758.50TOTAL FOR EACH AIRPLANE
NOTE: Additional time will be required for repair if any crack is found.
H. Weight and Balance Changes
None.
I. Electrical Load Data
Not changed.
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J. References
1. Existing Data:
a. Boeing Service Bulletin 777-53A0039
b. Boeing Service Letter 777-SL-51-013
c. Boeing Service Related Problem (SRP) 777-SRP-53-0463
d. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2012-07-06
e. Service Bulletin Index D624W001
f. 777 Illustrated Tool and Equipment Manual (ITEM) 53-80-03
g. 777 Maintenance Planning Data (MPD), D622W001-9, Section 9, Subsection B, and
D622W001-DTR
h. 777 Non-Destructive Testing (NDT) Manual Part 6, 53-80-06
i. 777-200 Structural Repair Manual (SRM) 53-80-08
j. 777-300 Structural Repair Manual (SRM) 53-80-08
k. 777F Structural Repair Manual (SRM) 53-80-08
2. Data Supplied with this Service Bulletin:
None.
3. Installation Drawings Used in the Preparation of this Service Bulletin:
None.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
53-80-08 Repair 2777 Structural Repair Manual
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin affects FCS. DTI requirements for the structure affected
are contained in Paragraph 1.E., Compliance of this service bulletin.
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L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
M. Software Accomplishment Summary
Not affected.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
None.
B. Industry Support Information
Boeing warranty remedies are not available for the inspection(s) and/or repair procedures given in this
service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
None.
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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### Page 23

3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL
PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,
METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE
DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
2. Obey all of the warnings and cautions given in the specified manual sections.
3. Unless shown differently, these dimensions and tolerances are used:
– Linear dimensions are in inches
– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus
or minus 0.03 inch
– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
– Angular tolerance is plus or minus 2 degrees
– Hole dimensions for standard solid rivets and fasteners are in Structural Repair
Manual (SRM) Chapter 51
– Torque Values:
— Values for structural fasteners are given in 777 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 777
Aircraft Maintenance Manual (AMM).
— Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
— Values for engine maintenance tasks are included in Chapter 70 of 777
Aircraft Maintenance Manual (AMM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
4. These work instructions refer to procedures included in other Boeing documents.
When the words "refer to" are used and the operator has an accepted alternative
procedure, the accepted alternative procedure can be used. When the words "in
accordance with" are included in the instruction, the procedure in the Boeing document
must be used.
5. Boeing Service Letter 777-SL-51-013, 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.
6. 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.
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### Page 24

7. 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.
8. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
9. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS
are in Paragraph 1.E., Compliance.
10. Some steps in the Work Instructions are identified as Required for Compliance (RC).
If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps
identified as RC must be done to comply with the AD. Alternative procedures for
steps not identified with RC can be used if the RC steps can still be done as specified,
and the airplane can be put back in a serviceable condition. An Alternative Method
of Compliance (AMOC) is not necessary for deviations to steps that are not identified
as RC.
B. WORK INSTRUCTIONS
1. Open Service Access Door 311BL for access to the aft side of the aft pressure bulkhead.
NOTE: Boeing recommends that an appropriate maintenance platform be installed for safe access
to the aft surface of the pressure bulkhead. Refer to Platform Assembly J53003-() in 777
ITEM 53-80-03 as an accepted platform.
2. RC - Do PART 1: AFT PRESSURE BULKHEAD RADIAL LAP SPLICE MEDIUM FREQUENCY
EDDY CURRENT INSPECTION for any crack.
3. RC - CONDITION 1: NO CRACK FOUND
a. Repeat PART 1: AFT PRESSURE BULKHEAD RADIAL LAP SPLICE MEDIUM FREQUENCY
EDDY CURRENT INSPECTION for any crack.
4. RC - CONDITION 2: ANY CRACK FOUND
a. OPTION 1:
(1) OPTION 1 (ACTION 1): Repair in accordance with 777-200 SRM 53-80-08 Repair 2,
777-300 SRM 53-80-08 Repair 2, or 777F SRM 53-80-08 Repair 2.
(2) OPTION 1 (ACTION 2): Repeat PART 1: AFT PRESSURE BULKHEAD RADIAL LAP
SPLICE MEDIUM FREQUENCY EDDY CURRENT INSPECTION for any crack in
unrepaired areas.
b. OPTION 2:
(1) OPTION 2 (ACTION 1): Contact Boeing for repair instructions if the repair exceeds the
applicability of 777-200 SRM 53-80-08 Repair 2, 777-300 SRM 53-80-08 Repair 2, or
777F SRM 53-80-08 Repair 2, and do the repair in accordance with the instructions from
Boeing.
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(2) OPTION 2 (ACTION 2): Repeat PART 1: AFT PRESSURE BULKHEAD RADIAL LAP
SPLICE MEDIUM FREQUENCY EDDY CURRENT INSPECTION for any crack in
unrepaired areas.
5. Put the airplane back into a serviceable condition. Do the inspection again at the time given in
Paragraph 1.E., Compliance.
PART 1: AFT PRESSURE BULKHEAD RADIAL LAP SPLICE MEDIUM FREQUENCY EDDY
CURRENT INSPECTION
1. Do Medium Frequency Eddy Current (MFEC) inspections of the aft webs in the aft pressure
bulkhead radial lap splices for any crack in accordance with Figure 1.
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### Page 26 (OCR)

BOEING SERVICE BULLETIN 777-53A0078
ALERT  ALERT
AFT COVER PAN
RS-18L
RS-16L  RS-16R  RADIAL WEB  / LAP SPLICE
(12 LOCATIONS)
2150  STA  (TYPICAL  TEAR STRAPS  4 LOCATIONS)
RS-13L  1 RS-13R
RS-10L  DON RS-10R
RS-7L  7RS-7R
FAIL SAFE
STRAPS
(2 LOCATIONS)
RS-4L  RS-4R
RS-1
INSPECTION
AFT PRESSURE BULKHEAD  AREA
(VIEW LOOKING FWD)
2361258
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS
(SHEET 1 OF 5)
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### Page 27 (OCR)

BOEING SERVICE BULLETIN 777-53A0078
ALERT  ALERT
INSPECTION  AFT COVER PAN
ROW OF
RIVETS  AFT WEB
CRACKS
* *  * *  ********  *****
TEAR
LAP SPLICE EDGE  ON THE AFT WEB OF  STRAP
THE LAP SPLICE
AFT COVER PAN  INSPECTION
TEAR STRAP  INBD  TYPICAL  AREA
PRESSURE
BULKHEAD
AFT WEB
RADIAL
STIFFENER
1 INSPECTION
LOCATION
PRESSURE
BULKHEAD
FWD  FWD WEB
A-A  2353568
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS
(SHEET 2 OF 5)
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### Page 28 (OCR)

BOEING SERVICE BULLETIN 777-53A0078
ALERT  ALERT
* *
***
****
***+  ****  ******
********  *******  INSPECTION
TERE  AREA
INBD
RS-4L
TYPICAL AT RS-4L AND RS-7L
2365191
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS
(SHEET 3 OF 5)
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### Page 29 (OCR)

BOEING SERVICE BULLETIN 777-53A0078
ALERT  ALERT
INSPECTION
AREA
INSPECTION 1
LOCATION
PRESSURE BULKHEAD  PRESSURE BULKHEAD
AFT WEB  FORWARD WEB
B-B  2372669
The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for this figure.
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS
(SHEET 4 OF 5)
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### Page 30

More DataQtyIdentificationNameTaskStep
(a) (b) (c) (d)12-RADIAL WEB LAP
SPLICES
Inspect1
(a) It is not necessary to do the inspection at locations covered by tear straps, failsafe straps, doublers, aft
cover pan or the Y-ring pressure chord/failsafe chord.
(b) Do Medium Frequency Eddy Current (MFEC) for any crack in accordance with 777 NDT Manual Part 6,
53-80-06.
(c) It is not necessary to do inspections in accordance with this service bulletin in area where existing repairs
cover the affected aft web inspection areas. Continue to do inspections of these repairs in accordance
with existing Damage Tolerance Inspection instructions, including those provided in the 777 Structural
Repair Manual and in Boeing Service Bulletin 777-53A0039.
(d) On airplanes line number 423 and on, two bays common to Radial Web Lap Splice RS-16R contain Hi-
Locs, not rivets. Refer to View A-A.
FIGURE 1: AFT PRESSURE BULKHEAD RADIAL WEB LAP SPLICES INSPECTIONS
(SHEET 5 OF 5)
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