# Boeing Alert Service Bulletin 737-57A1326: No revision named

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2015-4205; AD 2015-21-08 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Service Bulletin 737-57A1326](https://openairdocs.org/service-documents/boeing/737-57a1326.md)
- Title as filed: SB-737-57A1326-00 (1)
- Pages: 39
- PDF: https://openairdocs.org/files/sha256/73/6a/736a6d4913faab3fb9dbbd77c402002c03750cdadc6065f43118c62529e2940c
- Page: https://openairdocs.org/service-documents/boeing/737-57a1326/file/736a6d4913fa

## Text

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### Page 1

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-57A1326
Original Issue: September 22, 2015
ATA System: 5711
SUBJECT: WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line
157
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 © 2015 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Unpublished Work.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, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, 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.
Original Issue: September 22, 2015
737-57A1326
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### Page 3

Table of Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2. Data Supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . . 26
K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
M. Software Accomplishment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
C. Parts Necessary for Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 29
3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 29
3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157 [Group 1,
Configuration 2, 5] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR,
WBL 157 [Group 1, Configuration 3, 6] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR
TRIPLER AT REAR SPAR, WBL 157 [Group 1, Configuration 4, 7] . . . . . . . . . . . . . 38
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Commercial 
Airplanes
737
Service Bulletin
ALERT
SummaryNumber: 737-57A1326Original Issue: September 22, 2015
ATA System: 5711
SUBJECT: WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line
157
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
For airplanes that have not been inspected using the High Frequency Eddy Current (HFEC) open hole inspection
in accordance with Service Bulletin (SB) 737-57-1318, this SB gives instructions to do inspections for any crack
in the inspar upper skin area near the rear spar at Wing Buttock Line (WBL) 157 until SB 737-57-1318 is
accomplished. For an airplane that has not been inspected using the HFEC open hole inspection in accordance
with SB 737-57-1318, if the inspections in this service bulletin are not done, a crack in the upper chord and skin
can grow undetected and result in the inability of the structure to carry limit load or result in a fuel leak and could
prevent a continued safe flight and landing.
While doing SB 737-57-1318, an operator discovered a crack in the inspar upper skin at WBL 157 just forward
of the rear spar on the right wing. The crack measured 2.375 inches long. Two additional cracks were found in
the skin at two holes common to the rear spar in the same area. Subsequent inspections per SB 737-57-1318
revealed that the rear spar upper chord was almost completely severed. Further inspections per SB 737-57-1318
revealed that the left rear spar upper chord was completely severed. Web cracks were also discovered on both
wings.
The airplane was a 737-300 with 64,095 flight hours and 51,548 flight cycles. The airplane was within the 4,500
flight cycle grace period allowed by SB 737-57-1318. The inspections in this SB will ensure there is no undetected
crack in the inspar upper skin area near the rear spar at WBL 157 prior to the accomplishment of the inspections
required by SB 737-57-1318.
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### Page 6

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., 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 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
NoOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
Airplanes that have not been inspected using the HFEC open hole inspection in accordance with SB 737-57-1318,
do an eddy current inspection for any crack in the inspar upper skin area near the rear spar at WBL 157. If a
repair has been installed, do an eddy current inspection for any crack in the repair parts. If any crack is found,
do the HFEC open hole inspection in accordance with SB 737-57-1318 and contact Boeing for repair instructions
and do the repair.
EFFECTIVITY
All 737-100, 737-200, 737-200C, 737-300, 737-400, and 737-500 airplanes. Refer to Paragraph 1.A.1., Airplanes,
for the list of affected airplanes.
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent
revision or Information Notice will address the warranty remedies available, if any.
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MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
None.
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### Page 8 (OCR)

BOEING SERVICE BULLETIN 737-57A1326
ALERT  ALERT
LEFT WING SHOWN
RIGHT WING OPPOSITE
DO A HIGH FREQUENCY EDDY CURRENT  INSPECTION FOR ANY CRACK IN THE INSPAR  UPPER SKIN AT THE FASTENERS INDICATED  WBL  157  UPPER SKIN  INSPAR
- REAR
SPAR
INBD  TRAILING
EDGE SKIN
CONFIGURATION 2 SHOWN, OTHER CONFIGURATIONS SIMILIAR
2456646
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### Page 9

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-57A1326
Original Issue: September 22, 2015
ATA System: 5711
SUBJECT: WING - Wing Spars - Inspection of Upper Wing Skin at Rear Spar, Wing Buttock Line
157
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
This service bulletin is applicable to line numbers 1 to 3132 in 1 Group. The Variable Numbers
and Group Information for the applicable airplanes is given below.
Refer to Service Bulletin Index D6-19567 Part 3 for Airplane Variable Number, Line Number, and
Serial Number data.
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DESCRIPTIONCONFIGURATIONGROUP
737-100, 737-200, 737-200C, 737-300, 737-400, and 737-500
airplanes Line Numbers 1 to 3132.
-1
Airplanes that have been inspected using the High Frequency Eddy
Current (HFEC) open hole inspection in accordance with Service
Bulletin 737-57-1318.
1
Airplanes that have been inspected using only the HFEC surface
inspection in accordance with Service Bulletin 737-57-1318 and do
not have a repair doubler or repair tripler in the inspection area.
2
Airplanes that have been inspected using only the HFEC surface
inspection in accordance with Service Bulletin 737-57-1318 and have
a repair doubler in the inspection area common to the rear spar chord
fasteners that extends to the aft edge of the inspar skin similar to
repair drawing 65C30105.
3
Airplanes that have been inspected using only the HFEC surface
inspection in accordance with Service Bulletin 737-57-1318 and have
a repair tripler and a repair doubler in the inspection area common
to the rear spar chord fasteners that extends forward to the adjacent
stringer similar to repair drawing 65C30113.
4
Airplanes that have not been inspected in accordance with Service
Bulletin 737-57-1318 and do not have a repair doubler or repair tripler
in the inspection area.
5
Airplanes that have not been inspected in accordance with Service
Bulletin 737-57-1318 and have a repair doubler in the inspection area
common to the rear spar chord fasteners that extends to the aft edge
of the inspar skin similar to repair drawing 65C30105.
6
Airplanes that have not been inspected in accordance with Service
Bulletin 737-57-1318 and have a repair tripler and a repair doubler
in the inspection area common to the rear spar chord fasteners that
extends forward to the adjacent stringer similar to repair drawing
65C30113.
7
Airplane Models:
737-100, 737-200, 737-200C, 737-300, 737-400, 737-500
GroupVariable Number
1PA001 - PA022
1PA099
1PA231 - PA232
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GroupVariable Number
1PC001 - PC005
1PG001 - PG075
1PG199
1PG201 - PG230
1PG251 - PG255
1PG271 - PG279
1PG301 - PG314
1PG331 - PG332
1PG351 - PG356
1PG375
1PG401 - PG403
1PG431 - PG442
1PG471 - PG475
1PG501 - PG505
1PG571 - PG586
1PG621 - PG630
1PG651 - PG652
1PG701 - PG705
1PH001
1PH011 - PH013
1PH021 - PH024
1PH701 - PH715
1PH731 - PH732
1PH741 - PH743
1PJ001 - PJ009
1PJ031 - PJ032
1PJ071 - PJ072
1PJ101 - PJ119
1PJ201 - PJ219
1PJ301 - PJ302
1PJ551 - PJ561
1PJ601 - PJ615
1PJ811
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GroupVariable Number
1PJ816 - PJ817
1PK026 - PK029
1PK041 - PK053
1PK061 - PK070
1PK081 - PK082
1PK091 - PK099
1PK101 - PK103
1PK111 - PK120
1PK141 - PK146
1PK201 - PK204
1PK211 - PK223
1PK231 - PK241
1PK251 - PK258
1PK271 - PK274
1PK281 - PK289
1PK291
1PK301 - PK318
1PK341
1PK351 - PK361
1PK391
1PK431 - PK433
1PK451 - PK452
1PK461 - PK469
1PK495
1PK501 - PK504
1PK511 - PK515
1PK519
1PK521 - PK528
1PK541 - PK565
1PK581
1PK591 - PK599
1PK601 - PK617
1PK621 - PK637
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GroupVariable Number
1PK641 - PK642
1PK661 - PK666
1PK671 - PK681
1PK691 - PK697
1PK711 - PK716
1PK731 - PK765
1PK771 - PK779
1PK801 - PK804
1PK819 - PK827
1PK830
1PK861 - PK863
1PK871 - PK874
1PK881 - PK884
1PK901 - PK938
1PK971 - PK974
1PL001 - PL028
1PL061
1PL081
1PL101 - PL113
1PL151
1PL171 - PL172
1PL201 - PL203
1PL221
1PL401 - PL417
1PL421
1PL441
1PL451 - PL456
1PL471
1PL491
1PL501 - PL506
1PL551 - PL562
1PL581
1PL601 - PL603
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GroupVariable Number
1PL611
1PL621 - PL626
1PL631 - PL632
1PL711 - PL712
1PL716 - PL747
1PL756
1PL758
1PL761 - PL770
1PL781 - PL788
1PL793
1PL801 - PL803
1PM001 - PM006
1PM016 - PM017
1PM021 - PM023
1PM051 - PM066
1PM101 - PM119
1PM141 - PM142
1PM171
1PM181
1PM251 - PM255
1PM281 - PM283
1PM381 - PM399
1PM401 - PM417
1PM541 - PM564
1PN001 - PN002
1PN021 - PN043
1PN081 - PN086
1PN101 - PN117
1PN131 - PN163
1PN401 - PN420
1PN431 - PN433
1PN451 - PN456
1PN471 - PN474
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GroupVariable Number
1PN481
1PN491 - PN493
1PN501 - PN502
1PN511 - PN512
1PN521
1PP001 - PP054
1PP101 - PP169
1PP181 - PP199
1PP201 - PP205
1PP221
1PP231 - PP243
1PP281 - PP286
1PP301 - PP305
1PP351 - PP353
1PP376 - PP384
1PP391 - PP393
1PP401 - PP440
1PP471 - PP475
1PP501 - PP522
1PP631 - PP634
1PP651 - PP652
1PP671 - PP699
1PP701 - PP733
1PP771 - PP779
1PP801 - PP808
1PP821 - PP827
1PP831 - PP848
1PP851 - PP852
1PP861 - PP877
1PP891 - PP899
1PP901 - PP936
1PP946 - PP948
1PP951 - PP952
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GroupVariable Number
1PP961 - PP967
1PP981 - PP991
1PP993
1PQ001 - PQ016
1PQ026 - PQ041
1PQ051 - PQ092
1PQ101 - PQ199
1PQ201 - PQ202
1PQ221 - PQ237
1PQ241 - PQ243
1PQ251 - PQ267
1PQ281 - PQ299
1PQ301 - PQ307
1PQ331 - PQ332
1PQ341 - PQ348
1PQ361 - PQ373
1PQ391 - PQ395
1PQ401 - PQ418
1PQ421
1PQ431 - PQ438
1PQ447 - PQ448
1PQ451
1PQ454
1PQ471 - PQ475
1PQ479 - PQ481
1PQ486 - PQ487
1PQ491 - PQ493
1PQ771 - PQ772
1PQ791 - PQ793
1PQ801 - PQ805
1PQ931 - PQ935
1PQ951
1PQ971 - PQ997
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GroupVariable Number
1PR001 - PR017
1PR021 - PR034
1PR041 - PR045
1PR061 - PR072
1PR077 - PR082
1PR091 - PR092
1PR096
1PR101
1PR121 - PR122
1PR131 - PR132
1PR141 - PR143
1PR161 - PR172
1PR181
1PS601 - PS631
1PS636 - PS638
1PS641 - PS644
1PS651 - PS657
1PS666 - PS669
1PS691 - PS692
1PS701 - PS706
1PS751 - PS799
1PS811
1PS836 - PS837
1PS841 - PS846
1PS851 - PS852
1PS856
1PS861 - PS863
1PS866 - PS868
1PS871 - PS874
1PS896 - PS897
1PS901 - PS941
1PS956 - PS957
1PS961 - PS963
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GroupVariable Number
1PS971 - PS978
1PT001 - PT015
1PT021 - PT031
1PT041 - PT064
1PT101 - PT105
1PT121 - PT138
1PT146 - PT148
1PT161 - PT170
1PT181 - PT188
1PT211 - PT220
1PT295
1PT301 - PT309
1PT331 - PT360
1PT381 - PT399
1PT401 - PT438
1PT501 - PT517
1PT561 - PT565
1PT581 - PT586
1PT611 - PT621
1PT641 - PT644
1PT651 - PT656
1PT671 - PT672
1PT681 - PT685
1PT701 - PT703
1PT716 - PT717
1PT721 - PT725
1PT801 - PT834
1PT851 - PT854
1PT871 - PT886
1PT901 - PT930
1PT971 - PT973
1PT981 - PT985
1PT996
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GroupVariable Number
1PU001 - PU025
1PU301
1PU311 - PU313
1PV001 - PV055
1PV201 - PV209
1PV226 - PV229
1PV231 - PV237
1PV271 - PV272
1PV281 - PV287
1PV296
1PV301 - PV302
1PV351
1PV356 - PV357
1PW001 - PW054
1PW061 - PW068
1PW072
1PW086 - PW088
1PW091 - PW094
1PW101 - PW102
1PW106
1PW111 - PW120
1PW156 - PW157
1PW161 - PW171
1PW201 - PW252
1PW261 - PW268
1PW271 - PW276
1PW278
1PW281 - PW293
1PW296
1PW301 - PW327
1PW401 - PW408
1PW411 - PW418
1PW421 - PW424
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GroupVariable Number
1PW431 - PW435
1PW441 - PW450
1PW461 - PW467
1PW501 - PW504
1PW511 - PW522
1PW524 - PW550
1PW556 - PW557
1PW561 - PW564
1PW571 - PW576
1PW591 - PW596
1PW611 - PW622
1PW631 - PW637
1PW661 - PW662
1PW681 - PW683
1PW701 - PW702
1PW711 - PW717
1PW741 - PW742
1PW761
1PW771
1PW831
1PW851 - PW856
1PX071
1PX701
1PY001 - PY008
1PY021 - PY022
1PY031
1PY036 - PY037
1PY046 - PY048
1PY051 - PY053
1PY056 - PY057
1PY101 - PY103
1PY111 - PY113
1PY131 - PY135
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GroupVariable Number
1PY141 - PY143
1PY151 - PY154
1PY156 - PY157
1PY161 - PY162
1PY166
1PY191
1PY201
1PY221 - PY222
1PY231
1PY241 - PY244
1PY270 - PY275
1PY281
1PY286
1PY301 - PY304
1PY321 - PY323
1PY341 - PY346
1PY361 - PY362
1PY381
1PY401
1PY409 - PY411
1PY421 - PY422
1PY441
1PY451
1PY461 - PY463
1PY591 - PY595
1PY611 - PY612
1PY621
1PY631
1PY651
1PY671 - PY672
1PY721
1PY741
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2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
For airplanes that have not been inspected using the High Frequency Eddy Current (HFEC) open hole
inspection in accordance with Service Bulletin (SB) 737-57-1318, this SB gives instructions to do
inspections for any crack in the inspar upper skin area near the rear spar at Wing Buttock Line (WBL)
157 until SB 737-57-1318 is accomplished. For an airplane that has not been inspected using the HFEC
open hole inspection in accordance with SB 737-57-1318, if the inspections in this service bulletin are
not done, a crack in the upper chord and skin can grow undetected and result in the inability of the
structure to carry limit load or result in a fuel leak and could prevent a continued safe flight and landing.
While doing SB 737-57-1318, an operator discovered a crack in the inspar upper skin at WBL 157 just
forward of the rear spar on the right wing. The crack measured 2.375 inches long. Two additional cracks
were found in the skin at two holes common to the rear spar in the same area. Subsequent inspections
per SB 737-57-1318 revealed that the rear spar upper chord was almost completely severed. Further
inspections per SB 737-57-1318 revealed that the left rear spar upper chord was completely severed.
Web cracks were also discovered on both wings.
The airplane was a 737-300 with 64,095 flight hours and 51,548 flight cycles. The airplane was within
the 4,500 flight cycle grace period allowed by SB 737-57-1318. The inspections in this SB will ensure
there is no undetected crack in the inspar upper skin area near the rear spar at WBL 157 prior to the
accomplishment of the inspections required by SB 737-57-1318.
D. Description
Airplanes that have not been inspected using the HFEC open hole inspection in accordance with SB
737-57-1318, do an eddy current inspection for any crack in the inspar upper skin area near the rear
spar at WBL 157. If a repair has been installed, do an eddy current inspection for any crack in the repair
parts. If any crack is found, do the HFEC open hole inspection in accordance with SB 737-57-1318
and contact Boeing for repair instructions and do the repair.
The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
3-5, 4-5737-100, 737-200, 737-200C
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Group 1:
Affected Maintenance Zones
ZoneModel
305, 405737-300, 737-400, 737-500
E. Compliance
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this
service bulletin mandatory.
Group 1, Configuration 1:
No action required.
Group 1, Configuration 2-7:
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.
Group 1, Configuration 2-7:
Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.
NOTE: "Repair Parts" are defined as any combination of a repair doubler and repair tripler.
NOTE: Boeing endorses the new FAA rules related to Limit of Validity (LOV) and recommends
immediate and permanent removal from service of any airplane upon reaching the LOV,
whether or not it is operated under FAA jurisdiction. As such, Boeing no longer provides
maintenance instructions for airplanes that have accumulated flight cycles beyond the LOV.
Line numbers 1-291 have accumulated flight cycles beyond the LOV of the airplane. 14 Code
of Federal Regulations (CFR) Part 121.1115 and 129.115 prohibit operation of an airplane
beyond its LOV.
Group 1, Configuration 2-4:
Table 1: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 500 flight
cycles after the
Original Issue
date of this ser-
vice bulletin.
Before 30,000
total flight cy-
cles.
Do PART 1: EDDY CUR-
RENT INSPECTION for
any crack in the inspar
upper skin and, if in-
stalled, the repair parts.
All Airplanes.
---No further action re-
quired.
CONDITION 1: NO
CRACK FOUND
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Group 1, Configuration 2-4:
Table 1: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further
flight.
ACTION 1: Do the HFEC
open hole inspection in
accordance with SB 737-
57-1318.
CONDITION 2: ANY
CRACK FOUND
--Before further
flight.
ACTION 2: Contact Boe-
ing for repair instructions
and do the repair.
Group 1, Configuration 5-7:
Table 2: Eddy Current Inspection of Inspar Upper Skin Common to the Rear Spar at WBL 157
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 500 flight
cycles after the
Original Issue
date of this ser-
vice bulletin.
Before 30,000
total flight cy-
cles.
Do PART 1: EDDY CUR-
RENT INSPECTION for
any crack in the inspar
upper skin and, if in-
stalled, the repair parts.
All Airplanes with 40,000
total flight cycles or less as
of the Original Issue date
of this service bulletin.
-Within 30 days
after the Origi-
nal Issue date of
this service bul-
letin.
-Do PART 1: EDDY CUR-
RENT INSPECTION, for
any crack in the inspar
upper skin and, if in-
stalled, the repair parts.
All Airplanes with more
than 40,000 total flight cy-
cles as of the Original Is-
sue date of this service
bulletin.
500 flight cycles.
(a)
--Repeat PART 1: EDDY
CURRENT INSPEC-
TION, for any crack in the
inspar upper skin and, if
installed, the repair parts.
CONDITION 1: NO
CRACK FOUND
-Before further
flight.
ACTION 1: Do the HFEC
open hole inspection in
accordance with SB 737-
57-1318. (b)
CONDITION 2: ANY
CRACK FOUND
--Before further
flight.
ACTION 2: Contact Boe-
ing for repair instructions
and do the repair.
(a) Accomplishment of any inspection in accordance with SB 737-57-1318 terminates the repeat inspections
in this SB.
(b) Accomplishment of the HFEC open hole inspection in accordance with SB 737-57-1318 terminates the
repeat inspections in this SB.
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F. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified
in this service bulletin comply with the applicable regulations and are FAA approved, as well as European
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on
the airplane in its original Boeing delivery configuration or as modified by other approved Boeing
changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
G. Manpower
The table below shows an estimate of the task hours necessary to do this work for each airplane. This
estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator task
hour data if necessary. The estimate does not include lost time. These are some examples of lost time:
• Time to adjust to the workplace
• Time to schedule the work
• Time to inspect the work
• Time to cure the materials
• Time to make the parts
• Time to find the tools.
Group 1, Configuration 2, 5:
Elapsed HoursTask HoursNumber of PersonsTask
1.01.01Figure 1
1.01.0TOTAL FOR EACH AIRPLANE
Group 1, Configuration 3, 6:
Elapsed HoursTask HoursNumber of PersonsTask
1.01.01Figure 2
1.01.0TOTAL FOR EACH AIRPLANE
Group 1, Configuration 4, 7:
Elapsed HoursTask HoursNumber of PersonsTask
1.01.01Figure 3
1.01.0TOTAL FOR EACH AIRPLANE
H. Weight and Balance Changes
None.
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I. Electrical Load Data
Not changed.
J. References
1. Existing Data:
a. Boeing Service Bulletin 737-57-1318
b. Boeing Service Letter 737-SL-51-042
c. Service Bulletin Index D6-19567
d. 737 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00 Procedure 4 or Procedure 23,
Part 6, 51-00-26
2. Data Supplied with this Service Bulletin:
a. Drawings:
ADCNDCN/REVSheetTitleDrawing No
--DWGUPPER REAR SPAR CHORD REINFORCE-
MENT - RSS 224
65C30105
--DWGSKIN REPAIR INSTL - UPPER, WBL 157.0,
REAR SPAR TO S-4
65C30113
3. Installation Drawings Used in the Preparation of this Service Bulletin:
TitleDrawing Number
WING SKIN65C25204
REAR SPAR INSTALLATION - WING65-45321
UPPER REAR SPAR CHORD REINFORCEMENT - RSS 22465C30105
SKIN REPAIR INSTL - UPPER, WBL 157.0, REAR SPAR TO S-465C30113
The table above lists applicable drawings used to prepare this service bulletin. The drawings are
not necessary to make the specified changes, and are not supplied with this service bulletin. The
drawings may not be applicable to all airplane configurations or operators.
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### Page 27

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 but no new DTIs are necessary.
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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### Page 29

2.    MATERIAL INFORMATION
A. Material - Price and Availability
None.
B. Industry Support Information
At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent
revision or Information Notice will address the warranty remedies available, if any.
C. Parts Necessary for Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
No special parts or materials are necessary to do the change in this service bulletin. But, parts
and materials in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator part and material supply to make sure all necessary parts and materials are available.
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 31

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 737 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 737
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 737-SL-51-042, 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. 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.
7. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
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8. 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.
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 labeled as Required for Compliance (RC).
If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps
labeled as RC, including sub-steps under an RC step and any figures identified in
an RC step, must be done to comply with the AD. An Alternative Method of
Compliance (AMOC) is required for any deviations to RC steps, including sub-steps
and identified figures. Steps not labeled as RC may be deviated from using accepted
methods in accordance with the operator's maintenance or inspection program without
obtaining approval of an AMOC. This is provided that the RC steps, including
sub-steps and identified figures, can still be done as specified, and the airplane can
be put back in an airworthy condition.
11. "Repair Parts" are defined as any combination of a repair doubler and repair tripler.
B. WORK INSTRUCTIONS
Group 1, Configuration 2-7:
1. RC - Do PART 1: EDDY CURRENT INSPECTION for any crack in the inspar upper skin, and if
installed, the repair parts.
a. CONDITION 1: NO CRACK FOUND.
(1) Group 1, Configuration 2-4:
No further action required.
(2) Group 1, Configuration 5-7:
Repeat PART 1: EDDY CURRENT INSPECTION for any crack in the inspar upper skin,
and if installed, the repair parts.
Group 1, Configuration 5-7:
NOTE: Accomplishment of any inspection in accordance with SB 737-57-1318 terminates
the repeat inspections in this SB.
b. CONDITION 2: ANY CRACK FOUND.
(1) ACTION 1: Do the High Frequency Eddy Current (HFEC) open hole inspection in
accordance with Service Bulletin (SB) 737-57-1318.
(2) ACTION 2: Contact Boeing for repair instructions and do the repair.
Group 1, Configuration 5-7:
NOTE: Accomplishment of the HFEC open hole inspection in accordance with SB
737-57-1318 terminates the repeat inspections in this SB.
2. Put the airplane back to a serviceable condition.
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### Page 33

PART 1: EDDY CURRENT INSPECTION
1.
Group 1, Configuration 2, 5:
Do the inspections in accordance with FIGURE 1.
Group 1, Configuration 3, 6:
Do the inspections in accordance with FIGURE 2.
Group 1, Configuration 4, 7:
Do the inspections in accordance with FIGURE 3.
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### Page 34 (OCR)

BOEING SERVICE BULLETIN 737-57A1326
ALERT  ALERT
This Figure applies only to: Group 1, Configuration 2, 5.
INSPAR
WBL  UPPER SKIN
157
- S-4
- S-3
— REAR
SPAR
LEFT WING SHOWN  TRAILING
RIGHT WING OPPOSITE  EDGE SKIN
INBD
2456474
FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157
(SHEET 1 OF 2)
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### Page 35

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
Do an HFEC inspec-
tion in accordance
with 737 NDT Manu-
al Part 6, 51-00-00
Procedure 4 or Pro-
cedure 23 around
the fasteners indicat-
ed.
--Inspar Upper SkinInspect1
FIGURE 1: HFEC INSPECTION OF INSPAR UPPER SKIN AT REAR SPAR, WBL 157
(SHEET 2 OF 2)
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### Page 36 (OCR)

BOEING SERVICE BULLETIN 737-57A1326
ALERT  ALERT
This Figure applies only to: Group 1, Configuration 3, 6.
INSPAR
UPPER SKIN
WBL
157
- S-4
-S-3
• REPAIR
DOUBLER
— REAR
SPAR
RIGHT WING OPPOSITE  LEFT WING SHOWN  TRAILING  EDGE SKIN
INBD  2456518
FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR, WBL
(SHEET 1 OF 2)
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### Page 37

More DataQtyIdentificationNameTaskStep
Do an HFEC inspec-
tion in accordance
with 737 NDT Manu-
al Part 6, 51-00-00
Procedure 4 or Pro-
cedure 23 around
the fasteners indicat-
ed. (a)
--Inspar Upper Skin and
Repair Doubler
Inspect1
Do an HFEC inspec-
tion in accordance
with 737 NDT Manu-
al Part 6, 51-00-00
Procedure 4 or Pro-
cedure 23 along the
forward edge of the
repair doubler.
--Inspar Upper SkinInspect2
(a) It is a requirement that the repair doubler is the same material, thickness, and profile as repair drawing
65C30105.
FIGURE 2: HFEC INSPECTION OF INSPAR UPPER SKIN AND REPAIR DOUBLER AT REAR SPAR, WBL
157
(SHEET 2 OF 2)
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### Page 38 (OCR)

BOEING SERVICE BULLETIN 737-57A1326
ALERT  ALERT
This Figure applies only to: Group 1, Configuration 4, 7.
INSPAR
UPPER SKIN
WBL
157
S-4
REPAIR
TRIPLER
S-3
• REPAIR
DOUBLER
- REAR
SPAR
TRAILING
LEFT WING SHOWN  EDGE SKIN
INBD  RIGHT WING OPPOSITE
2456512
FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR
TRIPLER AT REAR SPAR, WBL 157
(SHEET 1 OF 2)
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### Page 39

More DataQtyIdentificationNameTaskStep
Do an HFEC inspec-
tion in accordance
with 737 NDT Manu-
al Part 6, 51-00-00
Procedure 4 or Pro-
cedure 23 around
the fasteners indicat-
ed. (a)
--Repair TriplerInspect1
Do a Low Frequency
Eddy Current
(LFEC) inspection in
accordance with 737
NDT Manual Part 6,
51-00-26 around the
fasteners indicated.
(a)
--Repair DoublerInspect2
Do an HFEC inspec-
tion in accordance
with 737 NDT Manu-
al Part 6, 51-00-00
Procedure 4 or Pro-
cedure 23 along the
aft edge of the repair
doubler.
--Inspar Upper SkinInspect3
(a) It is a requirement that the repair doubler and the repair tripler are the same material, thickness, and
profile as repair drawing 65C30113.
FIGURE 3: HFEC AND LFEC INSPECTION OF INSPAR UPPER SKIN, REPAIR DOUBLER, AND REPAIR
TRIPLER AT REAR SPAR, WBL 157
(SHEET 2 OF 2)
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Original Issue: September 22, 2015
737-57A1326
39 of 39
BOEING SERVICE BULLETIN 737-57A1326
ALERTALERT

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