# Boeing Alert Service Bulletin 737-53A1361: No revision named

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- Document: [Boeing Alert Service Bulletin 737-53A1361](https://openairdocs.org/service-documents/boeing/737-53a1361.md)
- Title as filed: SB-737-53A1361-00
- Pages: 133
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## Text

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### Page 1

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1361
Original Issue: July 17, 2018
ATA System: 5311
SUBJECT: FUSELAGE - Frames and Bulkheads - Section 43 Lower Lobe Frames from STA 380
to STA 520, 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:
Copyright © 2018 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Unpublished Work.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: July 17, 2018
737-53A1361
1 of 133
3.0

### Page 2

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### Page 3

Table of Contents
S u m m a r y  ...................................................... 5
1. PLANNING INFORMATION ........................................ 9
A . E f f e c t i v i t y  ................................................ 9
1. Airplanes ............................................. 9
2 . S p a r e s  A f f e c t e d  ........................................ 1 9
B. Concurrent Requirements ...................................... 1 9
C. Reason ................................................ 1 9
D. Description .............................................. 2 0
E. Compliance .............................................. 2 1
F . A p p r o v a l  ............................................... 2 6
G. Manpower .............................................. 2 6
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 9
3. Installation Drawings Used in the Preparation of this Service  Bulletin: ........... 2 9
K. Publications Affected ........................................ 3 0
L. Interchangeability and Intermixability of Parts ........................... 3 0
M. Software Accomplishment Summary ................................ 3 0
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 1
4. Parts Removed and Not Replaced .............................. 3 1
D. Parts Necessary to Change Spares ................................. 3 1
E. Special Tooling - Price and Availability ............................... 3 1
F. Special Tooling Necessary to do this Service Bulletin ....................... 3 1
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 3
A. GENERAL INFORMATION ..................................... 3 3
B. WORK INSTRUCTIONS ....................................... 3 5
FIGURE 1: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION [Group 2]
.................................................. 4 8
FIGURE 2: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE -  INSPECTION [Group 2]
.................................................. 5 0
FIGURE 3: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION [Group 3]
.................................................. 5 2
FIGURE 4: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE -  INSPECTION [Group 3]
.................................................. 5 4
FIGURE 5: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION [Group 4]
.................................................. 5 6
FIGURE 6: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE -  INSPECTION [Group 4]
.................................................. 5 9
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FIGURE 7: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION [Group 5]
.................................................. 6 2
FIGURE 8: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE -  INSPECTION [Group 5]
.................................................. 6 5
FIGURE 9: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION [Group 6]
.................................................. 6 8
FIGURE 10: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 6]
.................................................. 7 0
FIGURE 11: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE -  INSPECTION [Group 2]
.................................................. 7 2
FIGURE 12: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 2]
.................................................. 7 6
FIGURE 13: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE -  INSPECTION [Group 3]
.................................................. 7 9
FIGURE 14: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 3]
.................................................. 8 5
FIGURE 15: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE -  INSPECTION [Group 4]
.................................................. 8 8
FIGURE 16: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 4]
.................................................. 9 2
FIGURE 17: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE -  INSPECTION [Group 5]
.................................................. 9 5
FIGURE 18: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 5]
.................................................. 9 9
FIGURE 19: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE -  INSPECTION [Group 6]
................................................. 1 0 2
FIGURE 20: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION [Group 6]
................................................. 1 0 6
FIGURE 21: LOWER LOBE FRAME AT STA 380 INTEGRAL INBOARD CHORD AN D WEB LEFT SIDE -
INSPECTION [Group 2, 4-5] ................................. 1 0 9
FIGURE 22: LOWER LOBE FRAME AT STA 380 INTEGRAL INBOARD CHORD AN D WEB RIGHT SIDE -
INSPECTION [Group 2, 4-5] ................................. 1 1 3
FIGURE 23: LOWER LOBE FRAME AT STA 380 INTEGRAL INBOARD CHORD AN D WEB LEFT SIDE -
INSPECTION [Group 6] .................................... 1 1 6
FIGURE 24: LOWER LOBE FRAME AT STA 380 INTEGRAL INBOARD CHORD AN D WEB RIGHT SIDE -
INSPECTION [Group 6] .................................... 1 2 0
APPENDIX A: LOGIC DIAGRAM TABLE 2: INSPECTIONS OF THE SECTION 43 LOWER LOBE FRAMES
FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE  [Group 2-6] ........... 1 2 3
APPENDIX B: LOGIC DIAGRAM TABLE 3: HIGH FREQUENCY EDDY CURRENT INSPECTIONS OF THE
SECTION 43 LOWER LOBE FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE
[Group 2-6] .......................................... 1 2 5
APPENDIX C: LOGIC DIAGRAM TABLE 4: HIGH FREQUENCY EDDY CURRENT INSPECTIONS OF THE
LOWER LOBE FRAME INTEGRAL INBOARD CHORD AND WEB AT STA 380, LEFT AND
RIGHT SIDE  [Group 2, 4-6] ................................. 1 2 9
APPENDIX D: TYPICAL FRAME CONSTRUCTION AND COMPONENT IDENTIFICATION [Group 2-6] . 132
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### Page 5

Commercial 
Airplanes
737
Service Bulletin
ALERT
SummaryNumber: 737-53A1361Original Issue: July 17, 2018
ATA System: 5311
SUBJECT: FUSELAGE - Frames and Bulkheads - Section 43 Lower Lobe Frames from STA 380
to STA 520, Inspection
THIS DOCUMENT 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 DOCUMENT
TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE
NEW OWNER.
CONCURRENT REQUIREMENTS
None.
BACKGROUND
This service bulletin provides instructions to inspect the Section 43 lower lobe (below the passenger floor)
fuselage frames from STA 380 to STA 520 for any crack. Frame cracking is the result of fatigue caused by cyclic
pressurization of the fuselage. If cracks are not detected and repaired, they can grow until the frames sever.
Continued operation of the airplane with multiple adjacent severed frames could result in uncontrolled
decompression of the airplane. Also, the combination of a severed frame and fuselage skin chem-mill cracks in
this area could result in an uncontrolled decompression of the airplane.
Fleet data demonstrates that frame web and frame integral inboard chord cracking is occurring on multiple
airplanes in multiple locations below the passenger floor in Section 43 from STA 380 to STA 520. At the frame
web stringer cutouts between stringers S-23 and S-28 left and right side, there have been five reports of cracking
at multiple frame locations occurring between 59,648 and 64,421 total flight cycles and between 72,998 and
82,393 total flight hours. The cracks were between 0.5 inches and 1.4 inches in length. At the STA 380 frame,
between S-20 and S-22 left side, there have been five reports of frame integral inboard chord cracking at multiple
bulkhead attachment holes occurring between 31,640 and 68,093 total flight cycles and between 34,337 and
76,555 total flight hours. The cracks were as long as 1 inch in length. There have also been three reports of
cracking in the frame integral inboard chords between STA 400 and STA 420 at the channel-cargo floor support
attachments, S-25 left side, occurring between 57,617 and 73,174 total flight cycles and between 66,575 and
80,536 total flight hours. The cracks were as long as 0.125 inches in length.
Refer to Boeing Service Bulletins 737-53A1160, 737-53A1279 and 737-53A1323 for other reports of frame
cracking and required inspections that are not addressed in this service bulletin.
Boeing Service Related Problem 737-SRP-53-0505 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) 737-FTD-53-10004 is related to this service bulletin.
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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
Group 1:
The Boeing Company endorses the new FAA rules related to Limit of Validity (LOV) and recommends immediate
and permanent removal from service of any airplanes upon reaching the LOV, whether or not it is operated
under FAA jurisdiction. As such, The Boeing Company no longer provides maintenance instructions for airplanes
that have accumulated flight cycles beyond the LOV. Airplanes in Group 1 (line number 1-291) have accumulated
flight cycles beyond the LOV of the maintenance program. 14 CFR 121.1115 and 129.115 prohibit operation of
an airplane beyond its LOV.
Group 2-6:
Do PART 2: Detailed and General Visual Inspection of the Section 43 lower lobe frames from STA 380 to STA
520, left and right side for any crack. If any crack is found, contact The Boeing Company for repair instructions
and do the repair and repeat PART 2 left and right side for any crack. If no crack is found, repeat PART 2 left
and right side for any crack.
Group 2-6:
Do a general visual inspection to determine if there are any repairs in the PART 3 eddy current inspection zones.
For any repairs found contact The Boeing Company for alternative inspections to this service bulletin and do
the inspection(s) and any corrective actions as applicable. Also do PART 3: High Frequency Eddy Current
(HFEC) Inspection at the unrepaired areas of the Section 43 lower lobe frames from STA 380 to STA 520, left
and right side for any crack. If no repairs are found do PART 3, left and right side for any crack. If any crack is
found, contact The Boeing Company for repair instructions and do the repair and repeat PART 3 left and right
side for any crack. If no crack is found, repeat PART 3 left and right side for any crack.
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### Page 7

Group 2, 4-6:
Do a general visual inspection to determine if there are any repairs in the PART 4 eddy current inspection zones.
For any repairs found contact The Boeing Company for alternative inspections to this service bulletin and do
the inspection(s) and any corrective actions as applicable. Also do PART 4: High Frequency Eddy Current
(HFEC) inspection at the unrepaired areas of the lower lobe frame integral inboard chord and web at STA 380,
left and right side for any crack. If no repairs are found do PART 4, left and right side for any crack. If any crack
is found, contact The Boeing Company for repair instructions and do the repair and repeat PART 4 left and right
side for any crack. If no crack is found, repeat PART 4 left and right side for any crack.
EFFECTIVITY
737-100, 737-200, 737-200C, 737-300, 737-400, 737-500 Airplanes. Refer to Paragraph 1.A., Effectivity, 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
Boeing warranty remedies are not available for the inspection given in this service bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
None.
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### Page 8 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
GROUPS 2, 4-6:
DO PART 4: HIGH FREQUENCY EDDY
CURRENT (HFEC) INSPECTION OF THE
LOWER LOBE FRAME INTEGRAL INBOARD
CHORD AND WEB AT STA 380 LEFT SIDE
STA
380
LEVO
GROUPS 2-6:
DO PART 3: HIGH FREQUENCY EDDY
CURRENT (HFEC) INSPECTIONS OF
THE SECTION 43 LOWER LOBE
FRAMES FROM STA 380 TO 520,
LEFT SIDE
DO PART 2: DETAILED AND GENERAL
VISUAL INSPECTIONS OF THE
SECTION 43 LOWER LOBE FRAMES
FROM STA 380 TO STA 520 RIGHT
SIDE
00  GROUPS 2-6:  DO PART 2: DETAILED AND GENERAL
VISUAL INSPECTIONS OF THE
SECTION 43 LOWER LOBE FRAMES
- FROM STA 380 TO STA 520 LEFT SIDE
~S-17L
GROUPS 2, 4-6:
DO PART 4: HIGH FREQUENCY EDDY
CURRENT (HFEC) INSPECTION OF
THE LOWER LOBE FRAME INTEGRAL
INBOARD CHORD AND WEB AT STA
BL-O  380 RIGHT SIDE
00000
S-17R
STA
380
GROUPS 2-6:
DO PART 3: HIGH FREQUENCY EDDY
737-200 / -300 / -400 / -500  (737-200C SAME AS 737-200  BL-O  STA  CURRENT (HFEC) INSPECTIONS OF  THE SECTION 43 LOWER LOBE
EXCEPT FOR CARGO DOOR  ABOVE S-17 ON LEFT HAND SIDE)  520  RIGHT SIDE  FRAMES FROM STA 380 TO STA 520,  2550177
Original Issue: July 17, 2018
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### Page 9

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1361
Original Issue: July 17, 2018
ATA System: 5311
SUBJECT: FUSELAGE - Frames and Bulkheads - Section 43 Lower Lobe Frames from STA 380
to STA 520, Inspection
THIS DOCUMENT 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 DOCUMENT
TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE
NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index D6-19567 Part 3 for Airplane Variable Number, Line Number, and
Serial Number data.
This service bulletin is applicable to 737-100/-200/-200C/-300/-400/-500 Airplanes, line numbers
1-2565 in six groups. The Variable Numbers and Group Information for the applicable airplanes
is given below.
DESCRIPTIONCONFIGURATIONGROUP
737-100/-200/-200C Airplanes, Line Numbers 1-291.-1
737-200 Airplanes, Line Numbers 292 - 1585.-2
737-200C Airplanes, Line Numbers 294 - 1113.-3
737-300 Airplanes, Line Numbers 1001 - 2565.-4
737-400 Airplanes, Line Numbers 1487 - 2564.-5
737-500 Airplanes, Line Numbers 1718 - 2553.-6
Airplane Models:
737-100, 737-200, 737-200C, 737-300, 737-400, 737-500
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GroupVariable Number
1PA001 - PA022
1PA099
1PA231 - PA232
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 - PG583
2PG584 - PG586
1PG621 - PG630
1PG651 - PG652
1PG701 - PG705
2PH001
2PH011 - PH013
2PH021 - PH024
1PH701 - PH715
1PH731 - PH732
1PH741 - PH742
2PH743
1PJ001 - PJ002
2PJ003 - PJ009
1PJ031 - PJ032
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GroupVariable Number
1PJ071 - PJ072
1PJ101 - PJ104
2PJ105 - PJ119
2PJ201 - PJ219
5PJ301 - PJ302
5PJ551 - PJ552
2PK026 - PK029
2PK041 - PK053
2PK061 - PK070
2PK081 - PK082
2PK091 - PK099
2PK101 - PK103
2PK111 - PK120
2PK141 - PK146
2PK201 - PK204
2PK211 - PK223
2PK231 - PK241
2PK251 - PK258
2PK271 - PK274
2PK281 - PK289
2PK291
2PK301 - PK318
2PK341
2PK351 - PK361
2PK391
2PK431 - PK433
2PK451 - PK452
2PK461 - PK469
2PK495
2PK501 - PK504
2PK511 - PK515
2PK519
2PK521 - PK528
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GroupVariable Number
2PK541 - PK565
2PK581
2PK591 - PK599
2PK601 - PK617
2PK621 - PK637
2PK641 - PK642
2PK661 - PK666
2PK671 - PK681
2PK691 - PK697
2PK711 - PK716
2PK731 - PK765
2PK771 - PK779
2PK801 - PK804
2PK819 - PK827
2PK830
2PK861 - PK863
2PK871 - PK874
2PK881 - PK884
2PK901 - PK938
2PK971 - PK974
2PL001 - PL028
2PL061
2PL081
2PL101 - PL113
2PL151
2PL171 - PL172
2PL201 - PL203
2PL221
2PL401 - PL417
2PL421
2PL441
2PL451 - PL456
2PL471
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GroupVariable Number
2PL491
2PL501 - PL506
2PL551 - PL562
2PL581
2PL601 - PL603
2PL611
2PL621 - PL626
2PL631 - PL632
1PL711 - PL712
1PL716
2PL717 - PL747
2PL756
2PL758
2PL761 - PL770
2PL781 - PL788
2PL793
1PL801 - PL803
2PM001 - PM006
2PM016 - PM017
2PM021 - PM023
2PM051 - PM066
2PM101 - PM119
2PM141 - PM142
2PM171
2PM181
2PM251 - PM255
2PM281 - PM283
4PM381 - PM399
4PM401 - PM417
4PM541 - PM547
5PM551 - PM564
2PN001 - PN002
2PN021 - PN043
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GroupVariable Number
2PN081 - PN086
2PN101 - PN117
2PN131 - PN163
2PN401 - PN420
2PN431 - PN433
2PN451 - PN456
2PN471 - PN474
2PN481
2PN491 - PN493
2PN501 - PN502
2PN511 - PN512
2PN521
4PP001 - PP054
4PP101 - PP169
4PP181 - PP199
4PP201 - PP205
4PP221
4PP231 - PP243
4PP281 - PP286
4PP301 - PP305
4PP351 - PP353
4PP376 - PP384
4PP391 - PP393
4PP401 - PP440
4PP471 - PP475
4PP501 - PP517
4PP521 - PP522
4PP631 - PP634
4PP651 - PP652
4PP671 - PP699
4PP701 - PP733
4PP771 - PP779
4PP801 - PP808
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GroupVariable Number
4PP821 - PP827
4PP831 - PP848
4PP851 - PP852
4PP861 - PP875
4PP891 - PP899
4PP901 - PP936
4PP946 - PP948
4PP951 - PP952
4PP961 - PP967
4PP981 - PP991
4PP993
4PQ001 - PQ016
4PQ026 - PQ041
4PQ051 - PQ092
4PQ101 - PQ199
4PQ201 - PQ202
4PQ221 - PQ237
4PQ241 - PQ243
4PQ251 - PQ267
4PQ281 - PQ296
4PQ301 - PQ307
4PQ331 - PQ332
4PQ341 - PQ344
4PQ361 - PQ369
4PQ401 - PQ408
4PQ411 - PQ413
4PQ421
4PQ471 - PQ473
4PQ479 - PQ481
4PQ486 - PQ487
4PQ491 - PQ493
4PQ771
4PQ791 - PQ793
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GroupVariable Number
4PQ801 - PQ805
4PQ931 - PQ932
4PS601 - PS616
4PS631
4PS636 - PS638
4PS641 - PS644
4PS651 - PS657
4PS666 - PS669
4PS691 - PS692
4PS701 - PS703
4PS751 - PS762
6PT001 - PT011
6PT021 - PT028
6PT041 - PT064
6PT101 - PT105
6PT121 - PT125
6PT146 - PT148
6PT161 - PT170
6PT181 - PT187
6PT211 - PT220
6PT295
6PT301 - PT306
6PT331 - PT360
6PT381 - PT399
6PT401 - PT438
6PT501 - PT512
6PT561 - PT565
6PT581 - PT584
6PT611 - PT621
6PT641 - PT642
6PT651 - PT655
6PT671 - PT672
6PT701 - PT703
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GroupVariable Number
6PU001 - PU025
5PV001 - PV055
5PV201 - PV203
5PV231 - PV237
5PV271 - PV272
5PV281 - PV283
5PW001 - PW054
5PW061 - PW068
5PW072
5PW091 - PW094
5PW101 - PW102
5PW106
5PW111 - PW120
5PW156 - PW157
5PW161 - PW167
5PW201 - PW245
5PW261
5PW265 - PW268
5PW278
5PW281 - PW284
5PW293
5PW296
5PW301 - PW327
5PW461 - PW467
5PW501 - PW504
5PW511 - PW520
5PW526
5PW531 - PW546
5PW556 - PW557
5PW561 - PW564
5PW571 - PW576
5PW591 - PW596
5PW611 - PW620
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GroupVariable Number
5PW631 - PW634
5PW661 - PW662
5PW681 - PW683
5PW701 - PW702
5PW711 - PW717
5PW741 - PW742
5PW761
5PW771
1PX071
1PX701
1PY001 - PY008
1PY021
3PY022
1PY031
3PY036 - PY037
3PY046 - PY048
3PY051 - PY053
3PY056 - PY057
3PY101 - PY103
3PY111 - PY113
3PY131 - PY135
3PY141 - PY143
3PY151 - PY154
3PY156 - PY157
3PY161 - PY162
3PY166
3PY191
3PY201
3PY221 - PY222
3PY231
3PY241 - PY244
3PY270 - PY275
3PY281
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GroupVariable Number
3PY286
1PY301 - PY304
1PY321 - PY323
1PY341 - PY346
1PY361 - PY362
1PY381
3PY401
3PY409 - PY411
3PY421 - PY422
3PY441
3PY451
3PY461 - PY463
3PY591 - PY595
3PY611 - PY612
3PY621
3PY631
3PY651
3PY671 - PY672
3PY721
3PY741
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
This service bulletin provides instructions to inspect the Section 43 lower lobe (below the passenger
floor) fuselage frames from STA 380 to STA 520 for any crack. Frame cracking is the result of fatigue
caused by cyclic pressurization of the fuselage. If cracks are not detected and repaired, they can grow
until the frames sever. Continued operation of the airplane with multiple adjacent severed frames could
result in uncontrolled decompression of the airplane. Also, the combination of a severed frame and
fuselage skin chem-mill cracks in this area could result in an uncontrolled decompression of the airplane.
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Fleet data demonstrates that frame web and frame integral inboard chord cracking is occurring on
multiple airplanes in multiple locations below the passenger floor in Section 43 from STA 380 to STA
520. At the frame web stringer cutouts between stringers S-23 and S-28 left and right side, there have
been five reports of cracking at multiple frame locations occurring between 59,648 and 64,421 total
flight cycles and between 72,998 and 82,393 total flight hours. The cracks were between 0.5 inches
and 1.4 inches in length. At the STA 380 frame, between S-20 and S-22 left side, there have been five
reports of frame integral inboard chord cracking at multiple bulkhead attachment holes occurring
between 31,640 and 68,093 total flight cycles and between 34,337 and 76,555 total flight hours. The
cracks were as long as 1 inch in length. There have also been three reports of cracking in the frame
integral inboard chords between STA 400 and STA 420 at the channel-cargo floor support attachments,
S-25 left side, occurring between 57,617 and 73,174 total flight cycles and between 66,575 and 80,536
total flight hours. The cracks were as long as 0.125 inches in length.
Boeing Service Related Problem 737-SRP-53-0505 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) 737-FTD-53-10004 is related to this service bulletin.
D. Description
Group 1:
The Boeing Company endorses the new FAA rules related to Limit of Validity (LOV) and recommends
immediate and permanent removal from service of any airplanes upon reaching the LOV, whether or
not it is operated under FAA jurisdiction. As such, The Boeing Company no longer provides maintenance
instructions for airplanes that have accumulated flight cycles beyond the LOV. Airplanes in Group 1
(line number 1-291) have accumulated flight cycles beyond the LOV of the maintenance program. 14
CFR 121.1115 and 129.115 prohibit operation of an airplane beyond its LOV.
Group 2-6:
Do PART 2: Detailed and General Visual Inspection of the Section 43 lower lobe frames from STA 380
to STA 520, left and right side for any crack. If any crack is found, contact The Boeing Company for
repair instructions and do the repair and repeat PART 2 left and right side for any crack. If no crack is
found, repeat PART 2 left and right side for any crack.
Group 2-6:
Do a general visual inspection to determine if there are any repairs in the PART 3 eddy current inspection
zones. For any repairs found contact The Boeing Company for alternative inspections to this service
bulletin and do the inspection(s) and any corrective actions as applicable. Also do PART 3: High
Frequency Eddy Current (HFEC) Inspection at the unrepaired areas of the Section 43 lower lobe frames
from STA 380 to STA 520, left and right side for any crack. If no repairs are found do PART 3 left and
right side for any crack. If any crack is found, contact The Boeing Company for repair instructions and
do the repair and repeat PART 3 left and right side for any crack. If no crack is found, repeat PART 3
left and right side for any crack.
Group 2, 4-6:
Do a general visual inspection to determine if there are any repairs in the PART 4 eddy current inspection
zones. For any repairs found contact The Boeing Company for alternative inspections to this service
bulletin and do the inspection(s) and any corrective actions as applicable. Also do PART 4: High
Frequency Eddy Current (HFEC) inspection at the unrepaired areas of the lower lobe frame integral
inboard chord and web at STA 380, left and right side for any crack. If no repairs are found do PART
4 left and right side for any crack. If any crack is found, contact The Boeing Company for repair
instructions and do the repair and repeat PART 4 left and right side for any crack. If no crack is found,
repeat PART 4 left and right side for any crack.
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The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
2-8737-100, 737-200, 737-200C
Group 2:
Affected Maintenance Zones
ZoneModel
2-8737-200
Group 3:
Affected Maintenance Zones
ZoneModel
2-8737-200C
Group 4:
Affected Maintenance Zones
ZoneModel
208737-300
Group 5:
Affected Maintenance Zones
ZoneModel
208737-400
Group 6:
Affected Maintenance Zones
ZoneModel
208737-500
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.
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Do the required actions in accordance with Paragraph 3. Accomplishment Instructions.
A logic diagram showing compliance tasks and compliance times is included as an aid in APPENDIX
A thru APPENDIX C.
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:
The Boeing Company endorses the new FAA rules related to Limit of Validity (LOV) and recommends
immediate and permanent removal from service of any airplanes upon reaching the LOV, whether or
not it is operated under FAA jurisdiction. As such, The Boeing Company no longer provides maintenance
instructions for airplanes that have accumulated flight cycles beyond the LOV. Airplanes in Group 1
(line number 1-291) have accumulated flight cycles beyond the LOV of the maintenance program. 14
CFR 121.1115 and 129.115 prohibit operation of an airplane beyond its LOV.
Table 1: Part - Title Index
DescriptionPART
DETAILED AND GENERAL VISUAL INSPECTION OF THE SECTION 43 LOWER LOBE
FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
PART 2
HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE SECTION 43 LOWER
LOBE FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
PART 3
HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE LOWER LOBE FRAME
INTEGRAL INBOARD CHORD AND WEB AT STA 380, LEFT AND RIGHT SIDE.
PART 4
Group 2-6:
Table 2: Inspections of the Section 43 Lower Lobe Frames from STA 380 to STA 520, Left and Right Side
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
this service
bulletin.
Before 30,000
total flight cy-
cles.
Do PART 2 for any crack.All Airplanes.
-Before further flight.CONDITION 1 (ACTION 1):CONDITION 1:
Contact The Boeing Company
for repair instructions and do the
repair.
ANY CRACK
FOUND.
9,000 flight cycles.-CONDITION 1 (ACTION 2):
Repeat PART 2 for any crack.
9,000 flight cycles.-Repeat PART 2 for any crack.CONDITION 2:
NO CRACK FOUND.
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Group 2-6:
Table 3: High Frequency Eddy Current Inspection of the Section 43 Lower Lobe Frames from STA 380
to STA 520, Left and Right Side
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
this service
bulletin.
Before 30,000
total flight cy-
cles.
Do a general visual inspection
to determine if there are any re-
pairs in the PART 3 eddy cur-
rent inspection zones.
All airplanes.
-Before further flight.CONDITION 3 (ACTION 1):CONDITION 3:
Contact The Boeing Company
for alternative inspection(s) to
this service bulletin and do the
inspection(s) and any corrective
actions as applicable.
ANY REPAIR
FOUND.
(a)(b)
-Before further flight.CONDITION 3 (ACTION 2):
Do PART 3 at the unrepaired
areas for any crack.
-Before further flight.CONDITION 3.1 (ACTION 1):CONDITION 3.1:
Contact The Boeing Company
for repair instructions and do the
repair.
ANY CRACK
FOUND.
9,000 flight cycles.-CONDITION 3.1 (ACTION 2):
Repeat PART 3 for any crack.
(a)(b)(c)
9,000 flight cycles.-Repeat PART 3 for any crack.CONDITION 3.2:
(a)(b)(c)NO CRACK FOUND.
-Before further flight.Do PART 3 for any crack.CONDITION 4:
NO REPAIR FOUND
-Before further flight.CONDITION 4.1 (ACTION 1):CONDITION 4.1:
Contact The Boeing Company
for repair instructions and do the
repair.
ANY CRACK
FOUND.
9,000 flight cycles.-CONDITION 4.1 (ACTION 2):
Repeat PART 3 for any crack.
(a)(b)(c)
9,000 flight cycles.-Repeat PART 3 for any crack.CONDITION 4.2:
(a)(b)(c)NO CRACK FOUND.
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Group 2-6:
Table 3: High Frequency Eddy Current Inspection of the Section 43 Lower Lobe Frames from STA 380
to STA 520, Left and Right Side
Repeat Interval
(Not to Exceed)
Compliance Time
(Whichever Occurs Later)
ActionCondition
(a) It is not required to contact Boeing or do PART 3 inspections of the frame web at the stringer cutouts at
locations where one of the following repairs has been installed:
1. For 737-200 airplanes repaired in accordance with 737-100/200  SRM 53-10-4, Figure 7, Figure
8, Figure 9 or Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300 SRM  53-00-07, Repair 4, Repair 5,
Repair 6 or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400 SRM  53-00-07, Repair 4, Repair 5,
Repair 6 or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500 SRM  53-00-07, Repair 4, Repair 5,
Repair 6 or Repair 8.
5. A frame repair where the stringer cutout radius has been elim inated by trimming off the shear
tie and is approved by the Boeing Organization Designation Authorization (ODA) via a FAA
Form 8100-9.
(b) It is not required to contact Boeing or do the PART 3 inspections at the frame integral inboard chord
common to the channel-cargo floor support fasteners at locations where one of the following repairs has
been installed:
1. For 737-300 airplanes repaired in accordance with 737-300 SRM  53-00-07, Repair 14, Detail
II, Detail III or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400 SRM  53-00-07, Repair 14, Detail
II, Detail III or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500 SRM  53-00-07, Repair 14, Detail
II, Detail III or Detail IV.
4. A frame repair that is the corrective action to the crack con dition identified in this service bulletin
and installed after the original issue date of this service bulletin and approved by the Boeing
ODA via a FAA Form 8100-9.
(c) It is not required to do PART 3 inspections in areas where a repair covers the affected inspection zone
provided:
1. The repair is the corrective action to the crack condition id entified in this service bulletin and in-
stalled after the original issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a FAA  Form 8100-9.
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Group 2, 4-6:
Table 4: High Frequency Eddy Current Inspection of the Lower Lobe Frame Integral Inboard Chord and
Web at STA 380, Left and Right Side
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
this service
bulletin.
Before 30,000
total flight cy-
cles.
Do a general visual inspection
to determine if there are any re-
pairs in the PART 4 eddy cur-
rent inspection zones.
All airplanes.
-Before further flight.CONDITION 5 (ACTION 1):CONDITION 5:
Contact The Boeing Company
for alternative inspection(s) to
this service bulletin and do the
inspection(s) and any corrective
actions as applicable.
ANY REPAIR
FOUND.
-Before further flight.CONDITION 5 (ACTION 2):
Do PART 4 at the unrepaired
areas for any crack.
(a)(b)
-Before further flight.CONDITION 5.1 (ACTION 1):CONDITION 5.1:
Contact The Boeing Company
for repair instructions and do the
repair.
ANY CRACK
FOUND.
4,500 flight cycles.-CONDITION 5.1 (ACTION 2):
Repeat PART 4 for any crack.
(a)(b)(c)
4,500 flight cycles.-Repeat PART 4 for any crack.CONDITION 5.2:
(a)(b)(c)NO CRACK FOUND.
-Before further flight.Do PART 4 for any crack.CONDITION 6:
(a)(b)NO REPAIR FOUND
-Before further flight.CONDITION 6.1 (ACTION 1):CONDITION 6.1:
Contact The Boeing Company
for repair instructions and do the
repair.
ANY CRACK
FOUND.
4,500 flight cycles.-CONDITION 6.1 (ACTION 2):
Repeat PART 4 for any crack.
(a)(b)(c)
4,500 flight cycles.-Repeat PART 4 for any crack.CONDITION 6.2:
(a)(b)(c)NO CRACK FOUND.
(a) It is not required to do the open hole HFEC inspections of the open holes (tooling holes and insulation
blanket holes) in accordance with PART 4 at locations where a rivet was installed to fill the open hole
during production.
(b) If an insulation blanket stud is installed in the tooling hole, the tooling hole is considered open.
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Group 2, 4-6:
Table 4: High Frequency Eddy Current Inspection of the Lower Lobe Frame Integral Inboard Chord and
Web at STA 380, Left and Right Side
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
(c) It is not required to do PART 4 inspections in areas where a repair covers the affected inspection zone
provided:
1. The repair is the corrective action to the crack condition id entified in this service bulletin and in-
stalled after the original issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a FAA  Form 8100-9.
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 inspection 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 2:
Elapsed HoursTask HoursNumber of PersonsTask
6.0012.002Open Access
10.0020.002FIGURE 1
7.0014.002FIGURE 2
0.751.502FIGURE 11
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Group 2:
Elapsed HoursTask HoursNumber of PersonsTask
0.200.402FIGURE 12
2.002.001FIGURE 21
2.002.001FIGURE 22
6.0012.002Close Access
33.9563.90TOTAL FOR EACH AIRPLANE
Group 3:
Elapsed HoursTask HoursNumber of PersonsTask
6.0012.002Open Access
10.0020.002FIGURE 3
7.0014.002FIGURE 4
0.651.302FIGURE 13
0.200.402FIGURE 14
6.0012.002Close Access
29.8559.70TOTAL FOR EACH AIRPLANE
Group 4:
Elapsed HoursTask HoursNumber of PersonsTask
6.0012.002Open Access
12.0024.002FIGURE 5
9.0018.002FIGURE 6
0.551.102FIGURE 15
0.200.402FIGURE 16
2.002.001FIGURE 21
2.002.001FIGURE 22
6.0012.002Close Access
37.7571.50TOTAL FOR EACH AIRPLANE
Group 5:
Elapsed HoursTask HoursNumber of PersonsTask
6.0012.002Open Access
15.0030.002FIGURE 7
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Group 5:
Elapsed HoursTask HoursNumber of PersonsTask
12.0024.002FIGURE 8
0.551.102FIGURE 17
0.200.402FIGURE 18
2.002.001FIGURE 21
2.002.001FIGURE 22
6.0012.002Close Access
43.7583.50TOTAL FOR EACH AIRPLANE
Group 6:
Elapsed HoursTask HoursNumber of PersonsTask
6.0012.002Open Access
9.0018.002FIGURE 9
6.0012.002FIGURE 10
0.501.002FIGURE 19
0.100.202FIGURE 20
2.002.001FIGURE 23
6.006.001FIGURE 24
6.0012.002Close Access
35.6063.20TOTAL FOR EACH AIRPLANE
H. Weight and Balance Changes
Weight and Balance changes affected by incorporation of this service bulletin are dependent on the
type, number and location of repairs done on each particular airplane. Weight and Balance are to be
calculated by the operator by weighing parts installed or removed. Operators should make necessary
revisions to the appropriate weight and balance report.
I. Electrical Load Data
Not applicable.
J. References
1. Existing Data:
a. Boeing Service Bulletin 737-53A1160, 737-53A1279, 737-53A1323
b. Boeing Service Letter 737-SL-51-042
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c. Boeing Service Related Problem (SRP) 737-SRP-53-0505
d. 737 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00
e. 737-100/200 Aircraft Maintenance Manual (AMM) 25-52-121, 25-5 2-141, 52-31-00
f. 737-100/200 Structural Repair Manual (SRM) 53-10-4
g. 737-300/400/500 Aircraft Maintenance Manual (AMM) 25-52-73, 2 5-52-91, 52-31-00
h. 737-300 Structural Repair Manual (SRM) 53-00-07
i. 737-400 Structural Repair Manual (SRM) 53-00-07
j. 737-500 Structural Repair Manual (SRM) 53-00-07
k. Boeing Fleet Team Digest (FTD) 737-FTD-53-10004
2. Data Supplied with this Service Bulletin:
None.
3. Installation Drawings Used in the Preparation of this Service  Bulletin:
TitleDrawing Number
FRAME INSTL - BODY STA 38065-46525
FRAME INSTL - BODY STA 40065-46526
FRAME INSTL - BODY STA 40065C33509
FRAME INSTL - BODY STA 42065C33510
FRAME INSTL - BODY STA 42065-46527
FRAME INSTL - BODY STA 44065-46529
FRAME INSTL - BODY STA 44065C33511
FRAME INSTL - BODY STA 46065-46530
FRAME INSTL - BODY STA 46065C33512
FRAME INSTL - BODY STA 48065-46532
FRAME INSTL - BODY STA 48265C34355
FRAME INSTL - BODY STA 482A65C34356
FRAME INSTL - BODY STA 482B65C34357
FRAME INSTL - BODY STA 50065-46533
FRAME INSTL - BODY STA 50065-54956
FRAME INSTL - BODY STA 500A65-46593
FRAME INSTL - BODY STA 500A65-54957
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TitleDrawing Number
FRAME INSTL - BODY STA 500B65C22908
FRAME INSTL - BODY STA 500B65-54958
FRAME INSTL - BODY STA 500B65-46594
FRAME INSTL - BODY STA 500C65C22909
FRAME INSTL - BODY STA 500D65C22910
FRAME INSTL - BODY STA 500E65C32351
FRAME INSTL - BODY STA 500F65C32352
FRAME INSTL - BODY STA 500G65C32353
FRAME INSTL - BODY STA 52065-46534
FRAME INSTL - BODY STA 52065-62173
The table above lists applicable drawings used to prepare this service bulletin. The drawings are
not necessary to make the specified changes, and are not supplied with this service bulletin. The
drawings may not be applicable to all airplane configurations or operators.
K. Publications Affected
1. Publications:
None.
2. Damage Tolerance Based Structural Inspections:
This service bulletin affects Fatigue Critical Structure (FCS) but does not contain repairs or changes.
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 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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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
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.
CAUTION
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).
— 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 737
Aircraft Maintenance Manual (AMM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
4. 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.
5. A General Visual Inspection is defined as: A visual examinati on of an interior or
exterior area, installation or assembly to detect obvious damage, failure or irregularity.
This level of inspection is made from within touching distance unless otherwise
specified. A mirror may be necessary to enhance visual access to all exposed surfaces
in the inspection area. This level of inspection is made under normally available
lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may
require removal or opening of access panels or doors. Stands, ladders or platforms
may be required to gain proximity to the area being checked.
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6. 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.
7. Boeing Service Letter 737-SL-51-042, Damage Reporting and Rep air 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.
8. Refer to APPENDIX A, APPENDIX B and APPENDIX C for logic diag rams. Logic
diagrams are provided as an aid only. Information contained in Paragraph 1.E.,
Compliance is the primary source for compliance times. Information in Paragraph
3.B., Work Instructions is the primary source for tasks required for compliance.
9. Refer to APPENDIX D for typical frame construction and compon ent identification.
10. The instructions in Paragraph 3.B., Work Instructions and th e 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.
11. 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.
12. Use of colors in Figures is based on guidance from the ATA e -Business Program
(ATA) iSpec 2200.
13. 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.
14. The compliance times for the actions in Paragraph 3.B., WORK  INSTRUCTIONS
are in Paragraph 1.E., Compliance.
15. 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. If a step or sub-step is labeled
"RC Exempt," then the RC requirement is removed from that step or sub-step. 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.
16. Use the table below for the description of each PART.
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Part - Title Index
DescriptionPART
GET ACCESS TO THE SECTION 43 LOWER LOBE FRAMES FROM STA 380 TO STA 520,
LEFT AND RIGHT SIDE
PART 1
DETAILED AND GENERAL VISUAL INSPECTION OF THE SECTION 43 LOWER LOBE
FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
PART 2
HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE SECTION 43 LOWER
LOBE FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
PART 3
HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE LOWER LOBE FRAME
INTEGRAL INBOARD CHORD AND WEB AT STA 380, LEFT AND RIGHT SIDE.
PART 4
CLOSE ACCESS TO THE SECTION 43 LOWER LOBE FRAMES FROM STA 380 TO STA 520,
LEFT AND RIGHT SIDE.
PART 5
B. WORK INSTRUCTIONS
Group 1:
1. The Boeing Company endorses the new FAA rules related to Limi t of Validity (LOV) and
recommends immediate and permanent removal from service of any airplanes upon reaching the
LOV, whether or not it is operated under FAA jurisdiction. As such, The Boeing Company no longer
provides maintenance instructions for airplanes that have accumulated flight cycles beyond the
LOV. Airplanes in Group 1 (line number 1-291) have accumulated flight cycles beyond the LOV
of the maintenance program. 14 CFR 121.1115 and 129.115 prohibit operation of an airplane
beyond its LOV.
Group 2-6:
1. Do PART 1.
2. RC - Do PART 2 for any crack.
a. CONDITION 1: ANY CRACK FOUND
(1) CONDITION 1 (ACTION 1): Contact The Boeing Company for repair instructions and do
the repair.
(2) CONDITION 1 (ACTION 2): Repeat PART 2 for any crack at the repeat interval specified
in Paragraph 1.E., Compliance.
b. CONDITION 2: NO CRACK FOUND.
(1) Repeat PART 2 for any crack at the repeat interval specified in Paragraph 1.E.,
Compliance.
3. RC - Do a general visual inspection to determine if there are any repairs in the PART 3 eddy current
inspection zones.
a. CONDITION 3: ANY REPAIR FOUND.
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(1) CONDITION 3 (ACTION 1): Contact The Boeing Company for alternative inspection(s)
to this service bulletin and do the inspection(s) and any corrective actions as applicable.
NOTE: It is not required to contact Boeing or do the PART 3 inspections of the frame
web at the stringer cutouts at locations where one of the following repairs has
been installed:
1. For 737-200 airplanes repaired in accordance with 737-100/200  SRM
53-10-4, Figure 7, Figure 8, Figure 9 or Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300 SRM
53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400 SRM
53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500 SRM
53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
5. A frame repair where the stringer cutout radius has been elim inated
by trimming off the shear tie and is approved by the Boeing Organization
Designation Authorization (ODA) via a FAA Form 8100-9.
NOTE: It is not required to contact Boeing or do the PART 3 inspections at the frame
integral inboard chord common to the channel-cargo floor support fasteners at
locations where one of the following repairs has been installed:
1. For 737-300 airplanes repaired in accordance with 737-300 SRM
53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400 SRM
53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500 SRM
53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
4. A frame repair that is the corrective action to the crack con dition
identified in this service bulletin and installed after the original issue
date of this service bulletin and approved by the Boeing ODA via a
FAA Form 8100-9.
(2) CONDITION 3 (ACTION 2): Do PART 3 at the unrepaired areas for any crack.
(a) CONDITION 3.1: ANY CRACK FOUND
1) CONDITION 3.1 (ACTION 1): Contact The Boeing Company for repair
instructions and do the repair.
2) CONDITION 3.1 (ACTION 2): Repeat PART 3 for any crack at the repeat interval
specified in Paragraph 1.E., Compliance.
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NOTE: It is not required to contact Boeing or do the PART 3 inspections of the
frame web at the stringer cutouts at locations where one of the following
repairs has been installed:
1. For 737-200 airplanes repaired in accordance with
737-100/200 SRM 53-10-4, Figure 7, Figure 8, Figure 9 or
Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
5. A frame repair where the stringer cutout radius has been
eliminated by trimming off the shear tie and is approved by
the Boeing Organization Designation Authorization (ODA) via
a FAA Form 8100-9.
NOTE: It is not required to contact Boeing or do the PART 3 inspections at the
frame integral inboard chord common to the channel-cargo floor support
fasteners at locations where one of the following repairs has been
installed:
1. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
4. A frame repair that is the corrective action to the crack
condition identified in this service bulletin and installed after
the original issue date of this service bulletin and approved
by the Boeing ODA via a FAA Form 8100-9.
NOTE: It is not required to do PART 3 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
(b) CONDITION 3.2: NO CRACK FOUND
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1) Repeat PART 3 for any crack at the repeat interval specified in Paragraph 1.E.,
Compliance.
NOTE: It is not required to contact Boeing or do the PART 3 inspections of the
frame web at the stringer cutouts at locations where one of the following
repairs has been installed:
1. For 737-200 airplanes repaired in accordance with
737-100/200 SRM 53-10-4, Figure 7, Figure 8, Figure 9 or
Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
5. A frame repair where the stringer cutout radius has been
eliminated by trimming off the shear tie and is approved by
the Boeing Organization Designation Authorization (ODA) via
a FAA Form 8100-9.
NOTE: It is not required to contact Boeing or do the PART 3 inspections at the
frame integral inboard chord common to the channel-cargo floor support
fasteners at locations where one of the following repairs has been
installed:
1. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
4. A frame repair that is the corrective action to the crack
condition identified in this service bulletin and installed after
the original issue date of this service bulletin and approved
by the Boeing ODA via a FAA Form 8100-9.
NOTE: It is not required to do PART 3 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
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b. CONDITION 4: NO REPAIR FOUND.
(1) Do PART 3 for any crack.
(a) CONDITION 4.1: ANY CRACK FOUND
1) CONDITION 4.1 (ACTION 1): Contact The Boeing Company for repair
instructions and do the repair.
2) CONDITION 4.1 (ACTION 2): Repeat PART 3 for any crack at the repeat interval
specified in Paragraph 1.E., Compliance.
NOTE: It is not required to contact Boeing or do the PART 3 inspections of the
frame web at the stringer cutouts at locations where one of the following
repairs has been installed:
1. For 737-200 airplanes repaired in accordance with
737-100/200 SRM 53-10-4, Figure 7, Figure 8, Figure 9 or
Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
5. A frame repair where the stringer cutout radius has been
eliminated by trimming off the shear tie and is approved by
the Boeing Organization Designation Authorization (ODA) via
a FAA Form 8100-9.
NOTE: It is not required to contact Boeing or do the PART 3 inspections at the
frame integral inboard chord common to the channel-cargo floor support
fasteners at locations where one of the following repairs has been
installed:
1. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
4. A frame repair that is the corrective action to the crack
condition identified in this service bulletin and installed after
the original issue date of this service bulletin and approved
by the Boeing ODA via a FAA Form 8100-9.
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NOTE: It is not required to do PART 3 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
(b) CONDITION 4.2: NO CRACK FOUND
1) Repeat PART 3 for any crack at the repeat interval specified in Paragraph 1.E.,
Compliance.
NOTE: It is not required to contact Boeing or do the PART 3 inspections of the
frame web at the stringer cutouts at locations where one of the following
repairs has been installed:
1. For 737-200 airplanes repaired in accordance with
737-100/200 SRM 53-10-4, Figure 7, Figure 8, Figure 9 or
Figure 11.
2. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
3. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
4. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 4, Repair 5, Repair 6, or Repair 8.
5. A frame repair where the stringer cutout radius has been
eliminated by trimming off the shear tie and is approved by
the Boeing Organization Designation Authorization (ODA) via
a FAA Form 8100-9.
NOTE: It is not required to contact Boeing or do the PART 3 inspections at the
frame integral inboard chord common to the channel-cargo floor support
fasteners at locations where one of the following repairs has been
installed:
1. For 737-300 airplanes repaired in accordance with 737-300
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
2. For 737-400 airplanes repaired in accordance with 737-400
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
3. For 737-500 airplanes repaired in accordance with 737-500
SRM 53-00-07, Repair 14, Detail II, Detail III, or Detail IV.
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4. A frame repair that is the corrective action to the crack
condition identified in this service bulletin and installed after
the original issue date of this service bulletin and approved
by the Boeing ODA via a FAA Form 8100-9.
NOTE: It is not required to do PART 3 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
4. Group 2, 4-6:
RC - Do a general visual inspection to determine if there are any repairs in the PART 4 eddy current
inspection zones.
a. CONDITION 5: ANY REPAIR FOUND.
(1) CONDITION 5 (ACTION 1): Contact The Boeing Company for alternative inspection(s)
to this service bulletin and do the inspection(s) and any corrective actions as applicable.
(2) CONDITION 5 (ACTION 2): Do PART 4 at the unrepaired areas for any crack.
NOTE: It is not required to do the open hole HFEC inspections of the open holes (tooling
holes and insulation blanket holes) in accordance with PART 4 at locations
where a rivet was installed to fill the open hole during production.
NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling hole is
considered open.
(a) CONDITION 5.1: ANY CRACK FOUND
1) CONDITION 5.1 (ACTION 1): Contact The Boeing Company for repair
instructions and do the repair.
2) CONDITION 5.1 (ACTION 2): Repeat PART 4 for any crack at the repeat interval
specified in Paragraph 1.E., Compliance.
NOTE: It is not required to do the open hole HFEC inspections of the open
holes (tooling holes and insulation blanket holes) in accordance with
PART 4 at locations where a rivet was installed to fill the open hole
during production.
NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling
hole is considered open.
NOTE: It is not required to do the PART 4 inspections in areas where a repair
covers the affected inspection zone provided:
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1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
(b) CONDITION 5.2: NO CRACK FOUND
1) Repeat PART 4 for any crack at the repeat interval specified in Paragraph 1.E.,
Compliance.
NOTE: It is not required to do the open hole HFEC inspections of the open
holes (tooling holes and insulation blanket holes) in accordance with
PART 4 at locations where a rivet was installed to fill the open hole
during production.
NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling
hole is considered open.
NOTE: It is not required to do the PART 4 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
b. CONDITION 6: NO REPAIR FOUND.
(1) Do PART 4 for any crack.
NOTE: It is not required to do the open hole HFEC inspections of the open holes (tooling
holes and insulation blanket holes) in accordance with PART 4 at locations
where a rivet was installed to fill the open hole during production.
NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling hole is
considered open.
(a) CONDITION 6.1: ANY CRACK FOUND
1) CONDITION 6.1 (ACTION 1): Contact The Boeing Company for repair
instructions and do the repair.
2) CONDITION 6.1 (ACTION 2): Repeat PART 4 for any crack at the repeat interval
specified in Paragraph 1.E., Compliance.
NOTE: It is not required to do the open hole HFEC inspections of the open
holes (tooling holes and insulation blanket holes) in accordance with
PART 4 at locations where a rivet was installed to fill the open hole
during production.
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NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling
hole is considered open.
NOTE: It is not required to do the PART 4 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
(b) CONDITION 6.2: NO CRACK FOUND
1) Repeat PART 4 for any crack at the repeat interval specified in Paragraph 1.E.,
Compliance.
NOTE: It is not required to do the open hole HFEC inspections of the open
holes (tooling holes and insulation blanket holes) in accordance with
PART 4 at locations where a rivet was installed to fill the open hole
during production.
NOTE: If an insulation blanket stud is installed in the tooling hole, the tooling
hole is considered open.
NOTE: It is not required to do the PART 4 inspections in areas where a repair
covers the affected inspection zone provided:
1. The repair is the corrective action to the crack condition
identified in this service bulletin and installed after the original
issue date of this service bulletin, AND
2. The installed repair was approved by the Boeing ODA via a
FAA Form 8100-9.
5. Group 2-6:
Do PART 5.
6. Put the airplane back to a serviceable condition.
Group 2-6:
PART 1: GET ACCESS TO THE SECTION 43 LOWER LOBE FRAMES FROM STA 380 TO STA
520, LEFT AND RIGHT SIDE.
1. Group 2-3:
a. Open the forward cargo door to get access to the forward carg o compartment. Refer to
737-100/200 AMM 52-31-00 as an accepted procedure.
b. Remove and keep forward cargo compartment sidewall linings. R efer to 737-100/200 AMM
25-52-121 as an accepted procedure.
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c. Remove and keep forward cargo compartment insulation. Refer to 737-100/200 AMM 25-52-141
as an accepted procedure.
2. Group 4-6:
a. Open the forward cargo door to get access to the forward carg o compartment. Refer to
737-300/400/500 AMM 52-31-00 as an accepted procedure.
b. Remove and keep forward cargo compartment sidewall linings. R efer to 737-300/400/500
AMM 25-52-73 as an accepted procedure.
c. Remove and keep forward cargo compartment insulation. Refer t o 737-300/400/500 AMM
25-52-91 as an accepted procedure.
Group 2-6:
PART 2: DETAILED AND GENERAL VISUAL INSPECTION OF THE SECTION 43 LOWER LOBE
FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
1. Group 2:
a. Do a detailed and general visual inspection of the Section 43  lower lobe frames, left side for
any crack in accordance with FIGURE 1.
b. Do a detailed and general visual inspection of the Section 43 lower lobe frames, right side for
any crack in accordance with FIGURE 2.
2. Group 3:
a. Do a detailed and general visual inspection of the Section 43  lower lobe frames, left side for
any crack in accordance with FIGURE 3.
b. Do a detailed and general visual inspection of the Section 43 lower lobe frames, right side for
any crack in accordance with FIGURE 4.
3. Group 4:
a. Do a detailed and general visual inspection of the Section 43  lower lobe frames, left side for
any crack in accordance with FIGURE 5.
b. Do a detailed and general visual inspection of the Section 43 lower lobe frames, right side for
any crack in accordance with FIGURE 6.
4. Group 5:
a. Do a detailed and general visual inspection of the Section 43  lower lobe frames, left side for
any crack in accordance with FIGURE 7.
b. Do a detailed and general visual inspection of the Section 43 lower lobe frames, right side for
any crack in accordance with FIGURE 8.
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5. Group 6:
a. Do a detailed and general visual inspection of the Section 43  lower lobe frames, left side for
any crack in accordance with FIGURE 9.
b. Do a detailed and general visual inspection of the Section 43 lower lobe frames, right side for
any crack in accordance with FIGURE 10.
Group 2-6:
PART 3: HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE SECTION 43 LOWER
LOBE FRAMES FROM STA 380 TO STA 520, LEFT AND RIGHT SIDE.
1. Group 2:
a. Do a High Frequency Eddy Current (HFEC) surface inspection of  the frame integral inboard
chord at the channel-cargo floor support attachment, left side for any crack and do a HFEC
surface inspection of the frame web Section 43 lower lobe frames at the stringer cutout radius,
left side for any crack in accordance with FIGURE 11.
b. Do a HFEC surface inspection of the frame web at the stringer  cutout radius, right side for
any crack in accordance with FIGURE 12.
2. Group 3:
a. Do a HFEC surface inspection of the frame integral inboard ch ord at the channel-cargo floor
support attachment, left side for any crack and do a HFEC surface inspection of the frame
web Section 43 lower lobe frames at the stringer cutout radius, left side for any crack in
accordance with FIGURE 13.
b. Do a HFEC surface inspection of the frame web at the stringer  cutout radius, right side for
any crack in accordance with FIGURE 14.
3. Group 4:
a. Do a HFEC surface inspection of the frame integral inboard ch ord at the channel-cargo floor
support attachment, left side for any crack and do a HFEC surface inspection of the frame
web Section 43 lower lobe frames at the stringer cutout radius, left side for any crack in
accordance with FIGURE 15.
b. Do a HFEC surface inspection of the frame web at the stringer  cutout radius, right side for
any crack in accordance with FIGURE 16.
4. Group 5:
a. Do a HFEC surface inspection of the frame integral inboard ch ord at the channel-cargo floor
support attachment, left side for any crack and do a HFEC surface inspection of the frame
web Section 43 lower lobe frames at the stringer cutout radius, left side for any crack in
accordance with FIGURE 17.
b. Do a HFEC surface inspection of the frame web at the stringer  cutout radius, right side for
any crack in accordance with FIGURE 18.
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
45 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 46

5. Group 6:
a. Do a HFEC surface inspection of the frame integral inboard ch ord at the channel-cargo floor
support attachment, left side for any crack and do a HFEC surface inspection of the frame
web Section 43 lower lobe frames at the stringer cutout radius, left side for any crack in
accordance with FIGURE 19.
b. Do a HFEC surface inspection of the frame web at the stringer  cutout radius, right side for
any crack in accordance with FIGURE 20.
Group 2, 4-6:
PART 4: HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTIONS OF THE LOWER LOBE
FRAME INTEGRAL INBOARD CHORD AND WEB AT STA 380, LEFT AND RIGHT SIDE.
1. Group 2, 4-5:
a. Do an open hole HFEC inspection at the open insulation attach ment holes and the tooling
holes of the lower lobe frame web at STA 380 and do a HFEC surface inspection of the frame
integral inboard chord, left side for any crack in accordance with FIGURE 21.
b. Do an open hole HFEC inspection at the open insulation attach ment holes and the tooling
holes of the lower lobe frame web at STA 380 and do a HFEC surface inspection of the frame
integral inboard chord, right side for any crack in accordance with FIGURE 22.
2. Group 6:
a. Do an open hole HFEC inspection at the open insulation attach ment holes and the tooling
holes of the lower lobe frame web at STA 380 and do a HFEC surface inspection of the frame
integral inboard chord, left side for any crack in accordance with FIGURE 23.
b. Do an open hole HFEC inspection at the open insulation attach ment holes and the tooling
holes of the lower lobe frame web at STA 380 and do a HFEC surface inspection of the frame
integral inboard chord, right side for any crack in accordance with FIGURE 24.
Group 2-6:
PART 5: CLOSE ACCESS TO THE SECTION 43 LOWER LOBE FRAMES FROM STA 380 TO STA
520, LEFT AND RIGHT SIDE.
1. Group 2-3:
a. Install the forward cargo compartment insulation. Refer to 73 7-100/200 AMM 25-52-141 as
an accepted procedure.
b. Install the forward cargo compartment sidewall linings. Refer to 737-100/200 AMM 25-52-121
as an accepted procedure.
c. Close the forward cargo door. Refer to 737-100/200 AMM 52-31-00 as an accepted procedure.
2. Group 4-6:
a. Install the forward cargo compartment insulation. Refer to 73 7-300/400/500 AMM 25-52-91
as an accepted procedure.
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
46 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 47

b. Install the forward cargo compartment sidewall linings. Refer to 737-300/400/500 AMM 25-52-73
as an accepted procedure.
c. Close the forward cargo door. Refer to 737-300/400/500 AMM 52 -31-00 as an accepted
procedure.
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
47 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 48 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 2.
000000
0000
* S-17L
STA
360
STA
360
STA  380  S-17L
- S-18L
420  STA  _S-19L
-S-21L
STA  —S￾22L
48¢  _S-23L
STA
500
STA  _ S-25L
500A
STA
500B
STA
520
STA
540
BL-O*
INSPECTION ZONE  2802345
FIGURE 1: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 1 OF 2)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991  737-53A1361
Copyright © Unpublished
Work - See page 1 for details.  48 of 133

### Page 49

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(c)(d)1STA 380, S-17L TO BL-
0
FRAMEInspect1
(a)(b)(c)(d)1STA 400, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 420, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 440, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 460, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 480, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500A, S-17L TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 500B, S-17L TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 520, S-17L TO BL-
0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties, and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and frame integral
inboard chord at the attachment common to the channel-cargo floor support for any crack.
(c) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(d) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 1: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 2 OF 2)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
49 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 50 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 2.
00000000000
S-17R
STA
360
STA
STA  540
360  STA
380
STA
492.4
STA
STA
500
STA
500A
STA
500B
STA
520
STA
540
*S-17R
S-18F
S-19R
Ho-S
S-21R
S-22R
* S-23R
S-24R
S-25R
INSPECTION ZONE  2802346
FIGURE 2: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 1 OF 2)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.  EEL O OG

### Page 51

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(d)(e)1STA 380, S-17R TO S-
18R
FRAMEInspect1
(a)(c)(d)(e)1STA 380, S-22R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 400, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 420, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500A, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500B, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 520, S-17R TO
BL-0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack.
(c) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and the frame
integral inboard chord at the attachment common to the channel-cargo floor support for any crack.
(d) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(e) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 2: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 2 OF 2)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
51 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 52 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 3.
00
* S-17L
STA  STA
360  367.1
STA
360
TBL-O  STA  380  1S-17L  Fa S-18L
. S-19L
- S-20L
S-21L
→ S-221
STA
480
, S-25L
S-26L
S-27L
S-28L
BL-O
INSPECTION ZONE  2802347
FIGURE 3: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 1 OF 2)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991  737-53A1361
Copyright © Unpublished
Work - See page 1 for details.  52 of 133

### Page 53

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(c)(d)1STA 380, S-18L TO BL-
0
FRAMEInspect1
(a)(b)(c)(d)1STA 400, S-18L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 420, S-18L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 440, S-18L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 460, S-18L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 480, S-18L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500A, S-17L TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 500B, S-17L TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 520, S-17L TO BL-
0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties, and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and the frame
integral inboard chord at the attachment common to the channel-cargo floor support for any crack.
(c) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(d) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 3: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 2 OF 2)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
53 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 54 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 3.
00000000000
S-17R
STA
360
STA
STA  540
360
STA
492.4
STA
STA
500
STA
500A
STA
500B
STA
520
STA
540
*S-17R
S-18F
- S-19R
Ho-S
* S-21R
S-22R
* S-23R
S-24R
INSPECTION ZONE  2802348
FIGURE 4: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 1 OF 2)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.  ELO US

### Page 55

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(c)(d)1STA 380, S-17R TO
BL-0
FRAMEInspect1
(a)(b)(c)(d)1STA 400, S-17R TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 420, S-17R TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 500, S-17R TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 500A, S-17R TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 500B, S-17R TO
BL-0
FRAMEInspect
(a)(b)(c)(d)1STA 520, S-17R TO
BL-0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and the frame
integral inboard chord at the attachment common to the channel-cargo floor support for any crack.
(c) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(d) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 4: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 2 OF 2)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
55 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 56 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 4.
00000000000
STA  S-17L
360
STA
360
STA  380  —S-17L
STA  420  13S-18L  S-19L
STA  S-20L
440
_ S-21L
. S-22L
TEZ-S
, S-24L
, S-25L
_ S-26L
- S-27L
_S-28L
BL-O
INSPECTION ZONE
FIGURE 5: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 1 OF 3)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.  56 of 133

### Page 57

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(c)(d)1STA 380, S-17L TO BL-
0
FRAMEInspect1
(a)(b)(c)(d)1STA 400, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 420, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 440, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 460, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 480, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500, S-17L TO BL-
0
FRAMEInspect
(a)(b)(c)(d)1STA 500A, S-17L TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500B, S-17L TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500C, S-17L TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500D, S-17L TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 520, S-17L TO BL-
0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties, and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and the frame
integral inboard chord at the attachment common to the channel-cargo floor support for any crack.
(c) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(d) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 5: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 2 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
57 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 58

More DataQtyIdentificationNameTaskStep
(e) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack, except fastener attachments of the frame web to the inner chord
reinforcement from S-19R to S-22R. Do a detailed inspection of the S-25 frame splice and the frame integral
inboard chord at the attachment common to the channel-cargo floor support for any crack.
FIGURE 5: LOWER LOBE FRAMES FROM STA 380 TO STA 520 LEFT SIDE - INSPECTION
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
58 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

### Page 59 (OCR)

BOEING SERVICE BULLETIN 737-53A1361
ALERT  ALERT
This Figure applies only to: Group 4.
00000000000
S-17R  STA
360
STA
360
STA
380
STA  400  5 S 50
STA
492.4
500
500B STA
500G STA
500D STA  520
STA
540
*S-17R
S-18R
*S-19R
-S-20R
*S-21R
-S-22F
* S-23R
S-24R
*S-25R
S-26R
S-27R
S-28R
BL-O
INSPECTION ZONE  2802351
FIGURE 6: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 1 OF 3)
Original Issue: July 17, 2018
Export Controlled ECCN: 9E991  Copyright © Unpublished  737-53A1361
Work - See page 1 for details.  59 of 133

### Page 60

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.
More DataQtyIdentificationNameTaskStep
(a)(b)(d)(e)1STA 380, S-17R TO S-
18R
FRAMEInspect1
(a)(c)(d)(e)1STA 380, S-22R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 400, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 420, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500, S-17R TO
BL-0
FRAMEInspect
(a)(c)(d)(e)1STA 500A, S-17R TO
BL-0
FRAMEInspect
(a)(d)(e)(f)1STA 500B, S-17R TO
BL-0
FRAMEInspect
(a)(d)(e)(f)1STA 500C, S-17R TO
BL-0
FRAMEInspect
(a)(d)(e)(f)1STA 500D, S-17R TO
BL-0
FRAMEInspect
(a)(d)(e)(f)1STA 520, S-17R TO
BL-0
FRAMEInspect
(a) Do a general visual inspection of the frame shear ties and integral shear ties for any crack. Inspect the
bend radius and all fastener attachment locations.
(b) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack.
(c) Do a detailed inspection of the frame web from the forward and aft side for any crack. Inspect around all
open hole locations, at all stringer cutout locations, and all fastener attachments including at the fail-safe
chord, shear ties and stringer clips for any crack. Do a detailed inspection of the frame integral inboard
chord and fail-safe chord for any crack. Do a detailed inspection of the S-25 frame splice and the frame
integral inboard chord at the attachment common to the channel-cargo floor support for any crack.
(d) If structure, existing repairs, or systems hardware attached to the frame covers a structural detail that is
to be inspected, then it is only necessary to inspect the area of the structural detail that is visible. It is not
necessary to remove structure, existing repairs, or systems hardware attached to the frame to do the in-
spection.
(e) Refer to APPENDIX D for typical frame construction and component identification.
FIGURE 6: LOWER LOBE FRAMES FROM STA 380 TO STA 520 RIGHT SIDE - INSPECTION
(SHEET 2 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 17, 2018
737-53A1361
60 of 133
BOEING SERVICE BULLETIN 737-53A1361
ALERTALERT

The text continues at https://openairdocs.org/service-documents/boeing/737-53a1361/file/74dc19c1d1e6.md?from=61

---
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