# Boeing Alert Service Bulletin 737-53A1368: No revision named

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- Document: [Boeing Alert Service Bulletin 737-53A1368](https://openairdocs.org/service-documents/boeing/737-53a1368.md)
- Title as filed: SB-737-53A1368-00
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### Page 1

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1368
Original Issue: February 27, 2018
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Lower Bulkhead Chords at Body Station 540 - Inspection, Repair
and Preventive Modification
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 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Unpublished Work.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.
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Table of Contents
S u m m a r y  ...................................................... 9
1. PLANNING INFORMATION ........................................ 1 5
A . E f f e c t i v i t y  ............................................... 1 5
1. Airplanes ............................................ 1 5
2 . S p a r e s  A f f e c t e d  ........................................ 3 8
B. Concurrent Requirements ...................................... 3 8
C. Reason ................................................ 3 8
D. Description .............................................. 3 9
E. Compliance .............................................. 4 1
F . A p p r o v a l  ............................................... 5 3
G. Manpower .............................................. 5 4
H. Weight and Balance Changes .................................... 8 4
I. Electrical Load Data ......................................... 9 0
J . R e f e r e n c e s  .............................................. 9 0
1. Existing Data: ......................................... 9 0
2. Data Supplied with this Service Bulletin: ........................... 9 1
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 9 1
K. Publications Affected ........................................ 9 1
L. Interchangeability and Intermixability of Parts ........................... 9 2
M. Software Accomplishment Summary ................................ 9 2
2. MATERIAL INFORMATION ........................................ 9 3
A. Material - Price and Availability ................................... 9 3
B. Industry Support Information .................................... 9 6
C. Parts Necessary for Each Airplane ................................. 9 6
1 . K i t s / P a r t s  ............................................ 9 6
2. Parts and Materials Supplied by the Operator ....................... 1 0 5
3. Parts Modified and Reidentified ............................... 1 0 7
4. Parts Removed and Not Replaced .............................. 1 0 7
D. Parts Necessary to Change Spares ................................ 1 0 7
E. Special Tooling - Price and Availability .............................. 1 0 7
F. Special Tooling Necessary to do this Service Bulletin ...................... 1 0 7
3. ACCOMPLISHMENT INSTRUCTIONS ................................. 1 0 9
A. GENERAL INFORMATION .................................... 1 0 9
B. WORK INSTRUCTIONS ...................................... 1 1 1
FIGURE 1: LEFT SIDE - STA 540 - SKIN - ULTRASONIC INSPECTION [Group 1, Configuration 2, 4-5;
Group 2, Configuration 2, 4-5; Group 3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5;
Group 5-8] ........................................... 1 3 1
FIGURE 2: RIGHT SIDE - STA 540 - SKIN - ULTRASONIC INSPECTION [Group 1, Configuration 2-3, 5;
Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5;
Group 5-8] ........................................... 1 3 3
FIGURE 3: LEFT SIDE - STA 540 - REPAIR TRIPLER - ULTRASONIC INSPECTION [Group 1, Configuration
1-3, 5; Group 2, Configuration 1-3, 5; Group 3, Configuration 1-3, 5; Group 4, Configuration 1-3,
5; Group 5-8] ......................................... 1 3 5
FIGURE 4: RIGHT SIDE - STA 540 - REPAIR TRIPLER - ULTRASONIC INSPECTION [Group 1,
Configuration 1-2, 4-5; Group 2, Configuration 1-2, 4-5; Group 3, Configuration 1-2, 4-5; Group
4, Configuration 1-2, 4-5; Group 5-8] ............................. 1 3 8
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FIGURE 5: LEFT SIDE - STA 540 - SKIN AND BULKHEAD CHORD OPEN HOLE HFEC INSPECTION
[Group 1, Configuration 2, 4-5; Group 2, Configuration 2, 4-5; Group 3, Configuration 2, 4-5;
Group 4, Configuration 2, 4-5; Group 5-8] .......................... 1 4 1
FIGURE 6: RIGHT SIDE - STA 540 - SKIN AND BULKHEAD CHORD OPEN HOLE HFEC INSPECTION
[Group 1, Configuration 2-3, 5; Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5;
Group 4, Configuration 2-3, 5; Group 5-8] .......................... 1 4 3
FIGURE 7: LEFT SIDE - STA 540 - SKIN, TRIPLER, DOUBLER, AND BULKHEAD CHORD - OPEN HOLE
HFEC INSPECTION [Group 1, Configuration 1, 3; Group 2, Configuration 1, 3; Group 3,
Configuration 1, 3; Group 4, Configuration 1, 3] ....................... 1 4 5
FIGURE 8: RIGHT SIDE - STA 540 - SKIN, TRIPLER, DOUBLER, AND BULKHEAD CHORD - OPEN HOLE
HFEC INSPECTION [Group 1, Configuration 1, 4; Group 2, Configuration 1, 4; Group 3,
Configuration 1, 4; Group 4, Configuration 1, 4] ....................... 1 4 7
FIGURE 9: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY REMOVAL [Group 1, Configuration 2, 4-5;
Group 3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ........ 1 4 9
FIGURE 10: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY REMOVAL [Group 1, Configuration 2-3, 5;
Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ........ 1 5 3
FIGURE 11: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY REMOVAL [Group 2, Configuration 2, 4-5;
Group 6] ............................................ 1 5 7
FIGURE 12: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY REMOVAL [Group 2, Configuration 2-3, 5;
Group 6] ............................................ 1 6 1
FIGURE 13: LEFT SIDE - STA 540 - SKIN - SURFACE HFEC INSPECTION UNDER THE DRAG LINK
ASSEMBLY [Group 1, Configuration 2, 4-5; Group 2, Configuration 2, 4-5; Group 3, Configuration
2, 4-5; Group 4, Configuration 2, 4-5; Group 5-8] ...................... 1 6 5
FIGURE 14: RIGHT SIDE - STA 540 - SKIN - SURFACE HFEC INSPECTION UNDER THE DRAG LINK
ASSEMBLY [Group 1, Configuration 2-3, 5; Group 2, Configuration 2-3, 5; Group 3, Configuration
2-3, 5; Group 4, Configuration 2-3, 5; Group 5-8] ...................... 1 6 8
FIGURE 15: LEFT SIDE - STA 540 - SKIN - CRACK CUT OUT [Group 1-4, Configuration 5; Group 5-8] . 171
FIGURE 16: RIGHT SIDE - STA 540 - SKIN - CRACK CUT OUT [Group 1-4, Configuration 5; Group 5-8]
................................................. 1 7 4
FIGURE 17: LEFT SIDE - STA 540 - SKIN - CRACK CUT OUT [Group 1, Configuration 2, 4; Group 2,
Configuration 2, 4; Group 3, Configuration 2, 4; Group 4, Configuration 2, 4] ....... 1 7 7
FIGURE 18: RIGHT SIDE - STA 540 - SKIN - CRACK CUT OUT [Group 1, Configuration 2-3; Group 2,
Configuration 2-3; Group 3, Configuration 2-3; Group 4, Configuration 2-3] ........ 1 8 0
FIGURE 19: LEFT SIDE - STA 540 - STRINGER 22 - CUT [Group 1-4, Configuration 5] ........ 1 8 3
FIGURE 20: RIGHT SIDE - STA 540 - STRINGER 22 - CUT [Group 1-4, Configuration 5] ....... 1 8 5
FIGURE 21: LEFT SIDE - STA 540 BULKHEAD CHORD - OPEN HOLE HFEC INSPECTION [Group 1-4,
Configuration 5] ........................................ 1 8 7
FIGURE 22: RIGHT SIDE - STA 540 BULKHEAD CHORD - OPEN HOLE HFEC INSPECTION [Group 1-4,
Configuration 5] ........................................ 1 8 9
FIGURE 23: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 1-3, Configuration
5 ]  ................................................ 1 9 1
FIGURE 24: RIGHT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 1-4, Configuration
5 ]  ................................................ 1 9 3
FIGURE 25: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 4, Configuration
5 ]  ................................................ 1 9 5
FIGURE 26: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 1-3, Configuration
5 ]  ................................................ 1 9 7
FIGURE 27: RIGHT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 1-4, Configuration
5 ]  ................................................ 1 9 9
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FIGURE 28: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 4, Configuration
5 ]  ................................................ 2 0 1
FIGURE 29: LEFT SIDE - STA 540 - DOUBLER, TRIPLER AND FILLER FABRICATION [Group 1,
Configuration 2, 4-5; Group 3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8]
................................................. 2 0 3
FIGURE 30: RIGHT SIDE - STA 540 - DOUBLER, TRIPLER AND FILLER FABRICATION [Group 1,
Configuration 2-3, 5; Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8]
................................................. 2 1 0
FIGURE 31: LEFT SIDE - STA 540 - DOUBLER, TRIPLER AND FILLER FABRICATION [Group 2,
Configuration 2, 4-5; Group 6] ................................ 2 1 7
FIGURE 32: RIGHT SIDE - STA 540 - DOUBLER, TRIPLER AND FILLER FABRICATION [Group 2,
Configuration 2-3, 5; Group 6] ................................ 2 2 4
FIGURE 33: LEFT SIDE - STA 540 - SHIM AND REPAIR ANGLE FABRICATION [Group 1, Configuration
2, 4-5; Group 2, Configuration 2, 4-5; Group 3, Configuration 2, 4-5; Group 4, Configuration 2,
4-5; Group 5-8] ........................................ 2 3 1
FIGURE 34: RIGHT SIDE - STA 540 - SHIM AND REPAIR ANGLE FABRICATION [Group 1, Configuration
2-3, 5; Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3,
5; Group 5-8] ......................................... 2 3 4
FIGURE 35: LEFT SIDE - STA 540 - FASTENER REMOVAL [Group 1, Configuration 2, 4-5; Group 3,
Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ............. 2 3 7
FIGURE 36: RIGHT SIDE - STA 540 - FASTENER REMOVAL [Group 1, Configuration 2-3, 5; Group 3,
Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ............. 2 4 1
FIGURE 37: LEFT SIDE - STA 540 - FASTENER REMOVAL [Group 2, Configuration 2, 4-5; Group 6] . 245
FIGURE 38: RIGHT SIDE - STA 540 - FASTENER REMOVAL [Group 2, Configuration 2-3, 5; Group 6] . 249
FIGURE 39: LEFT SIDE - STA 540 - REPAIR INSTALLATION [Group 1, Configuration 2, 4-5; Group 3,
Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ............. 2 5 3
FIGURE 40: RIGHT SIDE - STA 540 - REPAIR INSTALLATION [Group 1, Configuration 2-3, 5; Group 3,
Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ............. 2 6 0
FIGURE 41: LEFT SIDE - STA 540 - REPAIR INSTALLATION [Group 2, Configuration 2, 4-5; Group 6] . 267
FIGURE 42: RIGHT SIDE - STA 540 - REPAIR INSTALLATION [Group 2, Configuration 2-3, 5; Group 6]
................................................. 2 7 4
FIGURE 43: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 1-3, Configuration
5 ]  ................................................ 2 8 1
FIGURE 44: RIGHT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 1-4, Configuration
5 ]  ................................................ 2 8 4
FIGURE 45: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE PREPARATION [Group 4, Configuration
5 ]  ................................................ 2 8 7
FIGURE 46: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 1-3, Configuration
5 ]  ................................................ 2 9 0
FIGURE 47: RIGHT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 1-4, Configuration
5 ]  ................................................ 2 9 3
FIGURE 48: LEFT SIDE - STA 540 BULKHEAD CHORD - SPLICE INSTALLATION [Group 4, Configuration
5 ]  ................................................ 2 9 6
FIGURE 49: LEFT SIDE - STA 540 - RAM AIR INLET REPAIR [Group 1, Configuration 2, 4-5; Group 3,
Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ............. 2 9 9
FIGURE 50: RIGHT SIDE - STA 540 - RAM AIR INLET REPAIR [Group 1, Configuration 2-3, 5; Group 3,
Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ............. 3 0 5
FIGURE 51: LEFT SIDE - STA 540 - RAM AIR INLET REPAIR [Group 2, Configuration 2, 4-5; Group 6] . 311
FIGURE 52: RIGHT SIDE - STA 540 - RAM AIR INLET REPAIR [Group 2, Configuration 2-3, 5; Group 6]
................................................. 3 1 7
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FIGURE 53: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 1, Configuration 2,
4-5; Group 5] ......................................... 3 2 3
FIGURE 54: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 1, Configuration
2-3, 5; Group 5] ........................................ 3 3 2
FIGURE 55: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 3, Configuration 2,
4-5; Group 4, Configuration 2, 4-5; Group 7-8] ....................... 3 4 1
FIGURE 56: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 3, Configuration
2-3, 5; Group 4, Configuration 2-3, 5; Group 7-8] ...................... 3 4 9
FIGURE 57: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 2, Configuration 2,
4-5; Group 6] ......................................... 3 5 7
FIGURE 58: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 2, Configuration
2-3, 5; Group 6] ........................................ 3 6 5
FIGURE 59: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 1, Configuration 2,
4-5; Group 5] ......................................... 3 7 3
FIGURE 60: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 1, Configuration
2-3, 5; Group 5] ........................................ 3 8 2
FIGURE 61: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 3, Configuration 2,
4-5; Group 4, Configuration 2, 4-5; Group 7-8] ....................... 3 9 1
FIGURE 62: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 3, Configuration
2-3, 5; Group 4, Configuration 2-3, 5; Group 7-8] ...................... 4 0 0
FIGURE 63: LEFT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 2, Configuration 2,
4-5; Group 6] ......................................... 4 0 9
FIGURE 64: RIGHT SIDE - STA 540 - DRAG LINK ASSEMBLY INSTALLATION [Group 2, Configuration
2-3, 5; Group 6] ........................................ 4 1 7
FIGURE 65: LEFT SIDE - STA 540 - RADIUS FILLER INSTALLATION ................. 4 2 5
FIGURE 66: RIGHT SIDE - STA 540 - RADIUS FILLER INSTALLATION ................ 4 2 9
FIGURE 67: LEFT SIDE - STA 540 - TERMINATION FITTING SPACER FABRICATION ....... 4 3 3
FIGURE 68: RIGHT SIDE - STA 540 - TERMINATION FITTING SPACER FABRICATION ...... 4 3 6
FIGURE 69: LEFT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 1, 3, 5, 7-8] . 439
FIGURE 70: RIGHT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 1, 3-5, 7-8] . 444
FIGURE 71: LEFT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 2, 6] ..... 4 4 9
FIGURE 72: RIGHT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 2, 6] .... 4 5 4
FIGURE 73: LEFT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 1, Configuration 2,
4-5; Group 3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ..... 4 5 9
FIGURE 74: RIGHT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 1, Configuration
2-3, 5; Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] .... 4 6 4
FIGURE 75: LEFT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 2, Configuration 2,
4-5; Group 6] ......................................... 4 6 9
FIGURE 76: RIGHT SIDE - STA 540 - TERMINATION FITTING INSTALLATION [Group 2, Configuration
2-3, 5; Group 6] ........................................ 4 7 4
FIGURE 77: LEFT SIDE - STA 540 - SKIN DETAILED INSPECTION [Group 1, Configuration 2, 4-5; Group
3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ........... 4 7 9
FIGURE 78: RIGHT SIDE - STA 540 - SKIN DETAILED INSPECTION [Group 1, Configuration 2-3, 5; Group
3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ........... 4 8 3
FIGURE 79: LEFT SIDE - STA 540 - SKIN DETAILED INSPECTION [Group 2, Configuration 2, 4-5; Group
6 ]  ................................................ 4 8 7
FIGURE 80: RIGHT SIDE - STA 540 - SKIN DETAILED INSPECTION [Group 2, Configuration 2-3, 5; Group
6 ]  ................................................ 4 9 1
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FIGURE 81: LEFT SIDE - STA 540 - SKIN LFEC INSPECTION [Group 1, Configuration 2, 4-5; Group 3,
Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5, 7-8] ............. 4 9 5
FIGURE 82: RIGHT SIDE - STA 540 - SKIN LFEC INSPECTION [Group 1, Configuration 2-3, 5; Group 3,
Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5, 7-8] ............. 4 9 8
FIGURE 83: LEFT SIDE - STA 540 - SKIN LFEC INSPECTION [Group 2, Configuration 2, 4-5; Group 6]
................................................. 5 0 1
FIGURE 84: RIGHT SIDE - STA 540 - SKIN LFEC INSPECTION [Group 2, Configuration 2-3, 5; Group 6]
................................................. 5 0 4
FIGURE 85: LEFT SIDE - STA 540 - INTERNAL SKIN HFEC INSPECTION [Group 1, Configuration 2, 4-5;
Group 2, Configuration 2, 4-5; Group 3, Configuration 2, 4-5; Group 4, Configuration 2, 4-5;
Group 5-8] ........................................... 5 0 7
FIGURE 86: RIGHT SIDE - STA 540 - INTERNAL SKIN HFEC INSPECTION [Group 1, Configuration 2-3,
5; Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5; Group 4, Configuration 2-3, 5;
Group 5-8] ........................................... 5 1 0
FIGURE 87: LEFT SIDE - STA 540 - SPLICE STRAP AND BULKHEAD OUTER CHORD HFEC
INSPECTIONS [Group 1, Configuration 2, 4-5; Group 2, Configuration 2, 4-5; Group 3,
Configuration 2, 4-5; Group 4, Configuration 2, 4-5; Group 5-8] .............. 5 1 3
FIGURE 88: RIGHT SIDE - STA 540 - SPLICE STRAP AND BULKHEAD OUTER CHORD HFEC
INSPECTIONS [Group 1, Configuration 2-3, 5; Group 2, Configuration 2-3, 5; Group 3,
Configuration 2-3, 5; Group 4, Configuration 2-3, 5; Group 5-8] .............. 5 1 6
APPENDIX A: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 1: INSPECTION, REPAIR
AND MODIFICATION FOR AIRPLANES THAT DO NOT HAVE AN EXISTING REPAIR
INSTALLED  [Group 1, Configuration 2, 5; Group 2, Configuration 2, 5; Group 3, Configuration
2, 5; Group 4, Configuration 2, 5; Group 5-8] ........................ 5 1 9
APPENDIX B: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 2: INSPECTION, REPAIR
AND MODIFICATION FOR AIRPLANES THAT HAVE A REPAIR INSTALLED ON THE LEFT
SIDE AND A PREVENTIVE MODIFICATION INSTALLED ON THE RIGHT SIDE OF THE
AIRPLANE. [Group 1-4, Configuration 3] .......................... 5 2 2
APPENDIX C: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 3: INSPECTION, REPAIR
AND MODIFICATION FOR AIRPLANES THAT HAVE A REPAIR INSTALLED ON THE RIGHT
SIDE AND A PREVENTIVE MODIFICATION INSTALLED ON THE LEFT SIDE OF THE
AIRPLANE. [Group 1-4, Configuration 4] .......................... 5 2 7
APPENDIX D: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 4: INSPECTION, REPAIR
AND MODIFICATION FOR AIRPLANES THAT HAVE AN EXISTING REPAIR INSTALLED ON
BOTH THE LEFT AND RIGHT SIDE OF THE AIRPLANE.  [Group 1-4, Configuration 1] . 532
APPENDIX E: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 5: POST REPAIR
ULTRASONIC INSPECTIONS  [Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group
3, Configuration 2-5; Group 4, Configuration 2-5; Group 5-8] ................ 5 3 4
APPENDIX F: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 6: POST REPAIR EDDY
CURRENT INSPECTIONS  [Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3,
Configuration 2-5; Group 4, Configuration 2-5; Group 5-8] ................. 5 3 5
APPENDIX G: LOGIC DIAG RAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 7: POST REPAIR DETAILED
INSPECTIONS  [Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration
2-5; Group 4, Configuration 2-5; Group 5-8] ......................... 5 3 6
APPENDIX H: LOGIC DIAGRAM FOR PARAGRAPH 1.E., COMPLIANCE TABLE 8: POST PREVENTIVE
MODIFICATION INSPECTIONS .............................. 5 3 7
APPENDIX I: FORMING AND FITTING REQUIREMENTS FOR DETAIL METAL PARTS ....... 5 3 9
APPENDIX J: AIRPLANE JACKING REQUIREMENTS [Group 1, Configuration 2-5; Group 2, Configuration
2-5; Group 3, Configuration 2-5; Group 4, Configuration 2-5; Group 5-8] ......... 5 4 2
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APPENDIX K: SURFACE HIGH FREQUENCY EDDY CURRENT INSPECTION OF THE REPAIR ANGLE
[Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4,
Configuration 2-5; Group 5-8] ................................ 5 4 3
APPENDIX L: PART DEMAND INTENT .................................. 5 4 5
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Commercial 
Airplanes
737
Service Bulletin
ALERT
SummaryNumber: 737-53A1368Original Issue: February 27, 2018
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Lower Bulkhead Chords at Body Station 540 - Inspection, Repair
and Preventive Modification
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
Accomplishment of the inspection and preventive modification or repair given in this service bulletin will mitigate
cracking in the station (STA) 540 bulkhead chord and skin at stringer S-22, left and right side of the airplane.
Cracking in the STA 540 bulkhead chord or skin can potentially result in the inability of a primary structural
element to sustain limit load. If cracking is not detected and repaired, it can result in possible rapid decompression
and loss of structural integrity.
Multiple operators have reported cases of cracks in the skin and the STA 540 bulkhead chord at the three
fastener locations common to the drag link assembly at the STA 540 bulkhead chord. The cracks were found
during the accomplishment of Boeing Service Bulletin 737-53-1294. The crack findings indicate that fatigue
stresses in this area may be higher than predicted and current maintenance inspections do not provide adequate
opportunity for cracks to be detected.
History of Reported Skin Cracks Under the Drag Link
Hole 2
Crack
Length
Hole 1
Crack
Length
Side
(Left /
Right)
Flight
Cycles
Flight
Hours
Model
0.0660.130R33,32857,275737-700
0.012-L16,28647,791737-800
0.072-L24,71642,846737-700
0.058-L18,14643,811737-800
-0.030L24,92942,749737-700
0.0060.011L18,89753,630737-800
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### Page 10

History of Reported Skin Cracks Under the Drag Link
Hole 2
Crack
Length
Hole 1
Crack
Length
Side
(Left /
Right)
Flight
Cycles
Flight
Hours
Model
0.066-L22,28143,342737-800
0.012-L25,18242,954737-800
Accomplishment of this service bulletin will find and repair any crack and prevent any future cracking at the STA
bulkhead 540 chord.
Boeing Fleet Team Digest (FTD) 737NG FTD 53-16001 is related to this service bulletin.
Boeing Service Related Problem (SRP) 737NG-SRP-53-0496 is related to this service bulletin.
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 ChangesYesWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedNoPublications Affected
Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsYesKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
YesOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
YesSpecial Tooling Required
ACTION (PRR 38275-206S)
Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4,
Configuration 2-5; Group 5-8:
1. Do an ultrasonic inspection for any crack in the skin on the side or sides of the airplane with no repair
installed.
2. If any crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current (HFEC)
inspections and surface HFEC inspections for any crack.
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3. If no crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current (HFEC)
inspections and surface HFEC inspections for any crack or repeat the ultrasonic inspections at the time
given in Paragraph 1.E., Compliance.
4. If any crack is found in the skin at the first three fasteners forward of the wing during the open hole
HFEC and surface HFEC inspections, do the repair. If any crack is found at any other location contact
The Boeing Company for repair instructions and do the repair. If no crack is found do the preventive
modification.
5. Do post repair or post preventive modification inspections for any crack.
Group 1, Configuration 1, 3-4; Group 2, Configuration 1, 3-4; Group 3, Configuration 1, 3-4; Group
4, Configuration 1, 3-4:
1. Do an ultrasonic inspection for any crack in the repair tripler on the side or sides of the airplane with a
repair installed.
2. If any crack is found during the ultrasonic inspection contact The Boeing Company for repair instructions
and do the repair.
3. If no crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current (HFEC)
inspections for any crack or repeat the ultrasonic inspections at the time given in Paragraph 1.E.,
Compliance.
4. If any crack is found in the skin during the open hole HFEC inspections, contact The Boeing Company
for repair instructions and do the repair. If no crack is found do the preventive modification.
5. Do post preventive modification inspections for any crack.
EFFECTIVITY
737-600, -700, -700C, -800, -900, and -900ER Airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of
affected airplanes.
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the inspection, and/or repair procedures given in this service
bulletin.
MANPOWER
Refer to Paragraph 1.G., Manpower.
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MATERIAL INFORMATION
Boeing Supplied Kits/Parts.
Operator Supplied Parts/Materials.
Refer to Paragraph 2.A., Material - Price and Availability.
Operators are encouraged to complete the survey provided in APPENDIX L of this service bulletin to help Boeing
predict the quantity and timing of the Boeing Supplied Kits/Parts.
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### Page 13 (OCR)

BOEING SERVICE BULLETIN 737-53A1368
ALERT  ALERT
FWD
DO AN ULTRASONIC INSPECTION FOR ANY CRACK
UNDER THE DRAG ANGLE, IF ANY CRACK IS FOUND,
DO A SKIN REPAIR. IF NO CRACK IS FOUND, DO AN
OPTIONAL PREVENTIVE MODIFICATION OR REPEAT
ULTRASONIC INSPECTION.
LEFT WING SHOWN RIGHT WING OPPOSITE  2588751
(WING TO BODY FAIRING REMOVED)
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### Page 14

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BLANK PAGE

### Page 15

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-53A1368
Original Issue: February 27, 2018
ATA System: 5331
SUBJECT: FUSELAGE - Skin - Lower Bulkhead Chords at Body Station 540 - Inspection, Repair
and Preventive Modification
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
This service bulletin is applicable to 737-600, -700, -700C, -800, -900, and -900ER Airplanes, line
numbers 1-6472 in 8 Groups. The Variable Numbers and Group Information for the applicable
airplanes is given below. An equivalent change is on subsequent production airplanes. Refer to
PRR 38275-206S for data about this change.
Refer to Service Bulletin Index D6-19567 Part 3 for Airplane Variable Number, Line Number, and
Serial Number data.
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### Page 16

DESCRIPTIONCONFIGURATIONGROUP
737-600/700/800 airplanes, line numbers 1 through 2849.-1
Airplanes with a repair installed on the left and right side of the
airplane in accordance with SB 737-53-1294.
1
Airplanes with a preventive modification installed on the left and right
side of the airplane in accordance with SB 737-53-1294.
2
Airplanes with a repair installed on the left side and a preventive
modification installed on the right side of the airplane in accordance
with SB 737-53-1294.
3
Airplanes with a preventive modification installed on the left side and
a repair installed on the right side of the airplane in accordance with
SB 737-53-1294.
4
Airplanes without a repair or preventive modification installed on the
left and right side of the airplane in accordance with SB 737-53-1294.
5
All 737-900 airplanes.-2
Airplanes with a repair installed on the left and right side of the
airplane in accordance with SB 737-53-1294.
1
Airplanes with a preventive modification installed on the left and right
side of the airplane in accordance with SB 737-53-1294.
2
Airplanes with a repair installed on the left side and preventive
modification installed on the right side of the airplane in accordance
with SB 737-53-1294.
3
Airplanes with a preventive modification installed on the left side and
a repair installed on the right side of the airplane in accordance with
SB 737-53-1294.
4
Airplanes without a repair or preventive modification installed on the
left and right side of the airplane in accordance with SB 737-53-1294.
5
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DESCRIPTIONCONFIGURATIONGROUP
737-700 airplanes with increased gross weight, line numbers 101
through 2822.
-3
Airplanes with a repair installed on the left and right side of the
airplane in accordance with SB 737-53-1294.
1
Airplanes with a preventive modification installed on the left and right
side of the airplane in accordance with SB 737-53-1294.
2
Airplanes with a repair installed on the left side and a preventive
modification installed on the right side of the airplane in accordance
with SB 737-53-1294.
3
Airplanes with a preventive modification installed on the left side and
a repair installed on the right side of the airplane in accordance with
SB 737-53-1294.
4
Airplanes without a repair or preventive modification installed on the
left and right side of the airplane in accordance with SB 737-53-1294.
5
737-700C airplanes, line numbers 496 through 2531.-4
Airplanes with a repair installed on the left and right side of the
airplane in accordance with SB 737-53-1294.
1
Airplanes with a preventive modification installed on the left and right
side of the airplane in accordance with SB 737-53-1294.
2
Airplanes with a repair installed on the left side and a preventive
modification installed on the right side of the airplane in accordance
with SB 737-53-1294.
3
Airplanes with a preventive modification installed on the left side and
a repair installed on the right side of the airplane in accordance with
SB 737-53-1294.
4
Airplanes without a repair or preventive modification installed on the
left and right side of the airplane in accordance with SB 737-53-1294.
5
737-700/800 airplanes, line numbers 2850 through 6471.-5
737-900ER airplanes, line numbers 1981 through 6470.-6
737-700 airplanes with increased gross weight, line numbers 2869
through 5749.
-7
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DESCRIPTIONCONFIGURATIONGROUP
737-700C airplanes, line numbers 3346 through 6060.-8
Airplane Models:
737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER
GroupVariable Number
1YA001 - YA099
1YA101 - YA199
1YA201 - YA211
1YA221
1YA231 - YA242
1YA251 - YA256
1YA271 - YA272
1YA291
1YA301 - YA302
1YA311 - YA314
1YA321 - YA323
1YA336 - YA345
1YA351
1YA356 - YA357
1YA366 - YA367
1YA371 - YA377
1YA501 - YA536
1YA541 - YA552
1YA571 - YA578
1YA601 - YA615
1YA621 - YA622
1YA626 - YA631
1YA635 - YA636
1YA641 - YA642
1YA645 - YA650
1YA656 - YA659
1YA666 - YA667
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GroupVariable Number
1YA671 - YA672
1YA681 - YA691
1YA701 - YA710
1YA721 - YA722
1YA731 - YA734
1YA751 - YA756
1YA801 - YA803
1YA809
1YA811 - YA814
1YA831 - YA835
1YA841 - YA862
1YA881 - YA882
1YA891 - YA892
1YA961 - YA978
1YB001 - YB006
1YB101 - YB132
1YB151 - YB153
1YB156 - YB158
1YB161 - YB164
1YB171 - YB172
1YB181 - YB184
1YB201 - YB208
1YB271
1YB276
1YB301 - YB310
1YB371 - YB392
1YB501 - YB502
1YB521 - YB526
1YB541 - YB544
1YB551
1YB561 - YB598
1YB601 - YB632
5YB633 - YB636
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GroupVariable Number
1YB651
1YB656
1YB671 - YB672
1YB851 - YB863
1YB871 - YB874
1YB881 - YB893
1YB901 - YB903
1YB911
1YB961 - YB974
5YB975
5YB981
1YB986 - YB987
5YB988 - YB998
1YC001 - YC030
1YC051 - YC084
1YC091 - YC094
5YC095
1YC101 - YC104
1YC111 - YC113
1YC121
1YC126 - YC127
1YC136 - YC141
1YC146 - YC147
1YC151 - YC156
1YC166 - YC171
1YC176 - YC179
1YC186 - YC190
1YC201 - YC203
1YC206 - YC207
1YC301 - YC305
1YC321 - YC387
1YC391 - YC394
1YC396
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GroupVariable Number
1YC401 - YC417
1YC421 - YC422
1YC426 - YC428
1YC436 - YC439
1YC441 - YC448
1YC451 - YC455
1YC459
1YC461 - YC467
1YC471 - YC499
1YC501 - YC526
1YC571 - YC583
1YC587 - YC589
1YC591 - YC593
1YC601 - YC655
1YC681 - YC696
1YC701 - YC715
1YC720 - YC725
1YC727 - YC752
1YC761 - YC770
1YC781 - YC793
1YC801 - YC892
1YC901 - YC907
1YC921 - YC922
1YC931 - YC932
1YC941 - YC951
1YC971 - YC978
1YC981 - YC983
1YD001 - YD007
1YD021 - YD025
1YD041 - YD057
1YD081 - YD084
1YD101 - YD110
5YD111 - YD117
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GroupVariable Number
1YD121 - YD126
1YD151 - YD159
1YD171 - YD172
1YD201 - YD203
1YD206 - YD209
1YD216 - YD219
1YD251 - YD254
1YD256 - YD257
1YD261
1YD301 - YD334
1YD391
1YD401 - YD410
1YD412 - YD415
5YD416 - YD422
1YD481 - YD485
1YD491 - YD499
2YD501 - YD512
2YD531 - YD535
2YD541 - YD547
2YD561 - YD564
2YD571 - YD572
2YD591 - YD595
2YD601 - YD612
2YD651 - YD655
1YE001 - YE020
1YE051
1YE101 - YE109
1YE151 - YE157
1YE171 - YE172
1YE201 - YE206
1YE301 - YE305
1YE321 - YE326
1YE371 - YE383
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GroupVariable Number
1YF001 - YF002
5YF003 - YF011
1YF021 - YF029
5YF030 - YF049
1YF051 - YF054
5YF055 - YF080
1YF086
5YF087
1YF106 - YF107
1YF111
5YF112 - YF114
5YF116 - YF119
5YF121 - YF132
1YF176 - YF178
5YF191 - YF192
1YF201 - YF202
5YF203 - YF276
5YF401 - YF402
5YF431 - YF432
5YF436 - YF437
5YF441 - YF442
5YF451 - YF460
1YF501 - YF513
5YF514 - YF599
5YF601 - YF685
5YF691 - YF695
5YF701 - YF707
5YF801 - YF805
5YF831 - YF832
5YF836 - YF838
5YF871 - YF872
5YF901 - YF905
5YF921 - YF928
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GroupVariable Number
5YF951 - YF954
3YG001 - YG044
3YG061 - YG064
3YG066 - YG089
3YG091 - YG099
3YG101 - YG103
7YG104
3YG111 - YG114
3YG116 - YG121
7YG122 - YG146
3YG201 - YG205
3YG211 - YG214
3YG221
7YG222 - YG224
3YG251 - YG252
4YG501 - YG509
8YG510 - YG515
4YG601 - YG602
4YG701
4YG711
8YG721 - YG722
6YH001 - YH012
6YH031 - YH055
6YH071 - YH080
6YH101 - YH132
6YH201 - YH202
6YH206 - YH207
6YH301 - YH307
6YH321 - YH322
6YH501 - YH542
6YH551 - YH594
6YH601 - YH606
6YH611 - YH620
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GroupVariable Number
6YH631 - YH632
6YH636 - YH637
6YH641
6YH681 - YH685
6YH701 - YH755
6YH801 - YH880
6YH901 - YH908
6YH911 - YH915
6YH951 - YH952
1YJ001 - YJ013
1YJ021
1YJ471 - YJ480
1YJ501 - YJ517
1YJ531 - YJ570
5YJ571 - YJ579
1YJ591 - YJ598
5YJ599
1YJ631 - YJ632
1YJ671 - YJ694
1YJ801 - YJ867
1YJ871 - YJ876
5YJ877 - YJ880
1YJ901 - YJ904
1YJ908 - YJ929
1YJ931 - YJ937
1YJ941 - YJ956
5YJ961
1YJ976 - YJ977
1YK001 - YK007
1YK101 - YK104
1YK111 - YK112
1YK121 - YK122
1YK131 - YK133
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GroupVariable Number
1YK136 - YK139
1YK141 - YK142
1YK146 - YK148
1YK151 - YK154
1YK161 - YK167
1YK171
1YK176 - YK177
1YK186
1YK191
5YK196
5YK201 - YK202
1YK301 - YK310
5YK311 - YK314
1YK321 - YK339
5YK340
1YK361 - YK375
5YK376 - YK378
1YK401 - YK406
1YK426 - YK427
1YK431 - YK450
1YK456 - YK461
5YK462 - YK467
5YK471 - YK473
1YK476
5YK478
1YK480 - YK487
5YK491 - YK493
1YK495
5YK496 - YK499
1YK511 - YK516
1YK521 - YK524
5YK525 - YK530
1YK551 - YK571
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GroupVariable Number
1YK576 - YK577
1YK580 - YK585
1YK601 - YK602
1YK606 - YK607
1YK611 - YK616
1YK621 - YK634
1YK641 - YK644
1YK651 - YK661
5YK662 - YK665
1YK671 - YK672
1YK676 - YK677
1YK681 - YK684
5YK685 - YK686
5YK691
5YK695 - YK699
1YK701 - YK713
1YK716 - YK719
1YK721 - YK741
1YK751 - YK764
5YK765 - YK770
5YK776 - YK778
5YK781 - YK785
1YK791 - YK792
1YK796 - YK797
1YK801 - YK899
1YK901 - YK912
1YK918 - YK919
1YK921 - YK927
5YK928 - YK929
1YK941 - YK955
5YK956 - YK960
1YK961 - YK971
5YK972 - YK980
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GroupVariable Number
1YK981 - YK987
5YK988 - YK999
1YL001 - YL005
1YL011 - YL016
1YL021 - YL024
1YL051 - YL052
1YL056 - YL057
1YL061
1YL066 - YL069
1YL076 - YL077
1YL101 - YL125
5YL126 - YL137
1YL201 - YL211
5YL212 - YL237
5YL241 - YL242
1YL271 - YL272
1YL281 - YL284
1YL301 - YL303
1YL311 - YL312
5YL313 - YL314
1YL316 - YL320
5YL321
1YL351 - YL353
1YL371 - YL374
1YL401
1YL421 - YL427
5YL428 - YL429
1YL431 - YL437
5YL438 - YL444
1YL461 - YL474
5YL475 - YL478
1YL501 - YL507
5YL508 - YL509
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GroupVariable Number
1YL531 - YL534
1YL541
5YL542 - YL551
1YL561 - YL565
5YL566 - YL579
1YL591 - YL592
5YL593 - YL598
1YL601 - YL606
1YL611
5YL612
1YL616 - YL617
1YL621
5YL626
5YL631 - YL634
5YL636 - YL637
1YL661 - YL664
1YL676
5YL677 - YL691
5YL696 - YL697
5YL701 - YL707
5YL731
5YL751 - YL752
5YL756 - YL757
5YL761 - YL780
5YL796 - YL797
5YL801 - YL815
1YL901 - YL910
1YL921
5YL922 - YL930
1YL931 - YL934
5YL935 - YL940
1YL951 - YL954
5YL955 - YL968
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### Page 30

GroupVariable Number
1YM101 - YM103
1YM201 - YM240
5YM241 - YM244
1YM251 - YM299
1YM301 - YM378
5YM379 - YM399
5YM401 - YM415
1YM471
1YM481 - YM484
1YM501 - YM515
1YM521 - YM522
1YM541
1YM551 - YM553
1YM571 - YM572
1YM581 - YM582
1YM591 - YM593
5YM594 - YM599
1YM631 - YM634
1YM641 - YM652
1YM671 - YM672
5YM673 - YM674
1YM691 - YM694
5YM695 - YM699
1YM701 - YM707
5YM708 - YM710
5YM761 - YM765
5YM771 - YM779
1YN001 - YN016
1YN021 - YN024
1YN061
1YN071 - YN079
5YN080 - YN082
1YN091 - YN092
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GroupVariable Number
1YN101 - YN112
1YN121
5YN126
1YN201 - YN202
1YN211 - YN216
5YN217 - YN219
1YN231 - YN235
5YN236
5YN261
5YN501
5YN531 - YN534
5YN551 - YN566
5YN581 - YN585
5YN591 - YN593
5YN601 - YN606
5YN651 - YN653
5YN661 - YN663
5YN671
5YN701 - YN702
5YN741 - YN746
5YN756 - YN758
5YQ001 - YQ003
5YQ011 - YQ021
5YQ026 - YQ029
5YQ036 - YQ045
5YQ201 - YQ207
5YQ231
5YQ241 - YQ251
5YQ281 - YQ284
5YQ291 - YQ296
5YQ301 - YQ302
5YQ321 - YQ324
5YQ331 - YQ334
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GroupVariable Number
5YQ346 - YQ347
5YQ351 - YQ365
5YQ371
5YQ401 - YQ403
5YQ451 - YQ454
5YQ456
5YQ461
5YQ471
5YQ501 - YQ520
5YR001 - YR098
5YR101 - YR105
5YR111 - YR124
5YR126 - YR144
5YR166 - YR182
5YR186 - YR198
5YR201 - YR211
5YR231 - YR294
5YR296 - YR297
5YR301 - YR334
5YR338 - YR341
5YR361 - YR366
5YR371 - YR373
5YR376 - YR377
5YR381 - YR382
5YR386 - YR388
5YR391
5YR396 - YR399
5YR401 - YR405
5YR411 - YR413
5YR416 - YR418
5YR421 - YR424
5YR426 - YR455
5YR457 - YR499
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GroupVariable Number
5YR501 - YR506
5YR511 - YR520
5YR526 - YR544
5YR546 - YR551
5YR556 - YR562
5YR571 - YR582
5YR591 - YR592
5YR601 - YR605
5YR616 - YR658
5YR661 - YR663
5YR671 - YR673
5YR676 - YR678
5YR681 - YR682
5YR701 - YR769
5YR771 - YR799
5YR801 - YR822
5YR831 - YR838
5YR841 - YR899
5YR901 - YR903
5YR931 - YR934
5YR938 - YR944
5YR951 - YR998
5YS001 - YS002
5YS006 - YS009
5YS031 - YS032
5YS051 - YS073
5YS101 - YS120
5YS126 - YS142
5YS146 - YS160
5YS166 - YS194
5YS196 - YS197
5YS201 - YS209
5YS221 - YS225
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GroupVariable Number
5YS231 - YS236
5YS271 - YS288
5YS301 - YS348
5YS351 - YS378
5YS381 - YS383
5YS401
5YS451
5YS456 - YS457
5YS462 - YS465
5YS467
5YS501 - YS502
5YS506
5YS511 - YS518
5YS531
5YS536 - YS538
5YS541 - YS542
5YS546
5YS551 - YS556
5YS561 - YS578
5YS581 - YS595
5YS601 - YS690
5YS701 - YS711
5YS721 - YS762
5YS771 - YS780
5YS806 - YS810
5YS816 - YS818
5YS823 - YS825
5YS851 - YS861
5YS876
5YS881 - YS883
5YS896 - YS897
5YS901 - YS909
5YS911 - YS949
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GroupVariable Number
5YS951 - YS957
5YS961 - YS974
5YS976 - YS977
5YS981 - YS987
5YS991 - YS998
5YT001 - YT004
5YT006
5YT026 - YT027
5YT031 - YT032
5YT036 - YT038
5YT061 - YT068
5YT101 - YT121
5YT126 - YT138
5YT176 - YT185
5YT191
5YT196 - YT199
5YT201
5YT206 - YT207
5YT211 - YT213
5YT251 - YT299
5YT301 - YT307
5YT311 - YT312
5YT321 - YT354
5YT371 - YT372
5YT381
5YT391 - YT396
5YT401 - YT403
5YT411 - YT417
5YT427
5YT461 - YT477
5YT491 - YT492
5YT501 - YT521
5YT551 - YT552
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GroupVariable Number
5YT556 - YT563
5YT565
5YT571 - YT576
5YT601 - YT606
5YT701 - YT708
5YT761 - YT781
5YT791 - YT793
5YT796 - YT797
5YT801 - YT804
5YT811 - YT813
5YT826 - YT827
5YT831 - YT832
5YT841 - YT845
5YT851 - YT852
5YT856 - YT863
5YT885 - YT887
5YT891 - YT895
5YT901 - YT974
6YU001 - YU060
6YU201 - YU216
6YU301 - YU309
5YV001 - YV004
5YV006 - YV012
5YV021 - YV023
5YV030 - YV033
5YV041 - YV042
5YV045 - YV047
5YV051 - YV052
5YV081
5YV083 - YV084
5YV097 - YV099
5YV101 - YV144
5YV251 - YV252
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GroupVariable Number
5YV256 - YV257
5YV301 - YV312
5YV351 - YV368
5YV381 - YV388
5YV391 - YV394
5YV401
5YV411
5YV431 - YV433
5YV441 - YV450
5YV461 - YV462
5YV501 - YV504
5YV521
5YV571 - YV581
5YV601 - YV605
5YV651 - YV664
5YV695 - YV696
5YV711
5YV722 - YV731
5YV741 - YV758
5YV781 - YV786
5YV801 - YV810
5YV881 - YV883
5YV901 - YV909
5YV971 - YV980
5YW001
5YW011 - YW098
5YW226 - YW240
5YW245 - YW247
5YW261
5YW263
5YW267 - YW278
5YW283 - YW285
5YW292 - YW294
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GroupVariable Number
5YW356 - YW358
5YW361 - YW362
5YW371 - YW386
5YW401 - YW402
5YW451 - YW452
5YW471 - YW472
5YW491
5YW551
5YW881
5YW891 - YW893
5YW906 - YW907
5YW916 - YW918
5YW971 - YW973
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
Accomplishment of the inspection and preventive modification or repair given in this service bulletin
will mitigate cracking in the station (STA) 540 bulkhead chord and skin at stringer S-22, left and right
side of the airplane. Cracking in the STA 540 bulkhead chord or skin can potentially result in the inability
of a primary structural element to sustain limit load. If cracking is not detected and repaired, it can result
in possible rapid decompression and loss of structural integrity.
Multiple operators have reported cases of cracks in the skin and the STA 540 bulkhead chord at the
three fastener locations common to the drag link assembly at the STA 540 bulkhead chord. The cracks
were found during the accomplishment of Boeing Service Bulletin 737-53-1294. The crack findings
indicate that fatigue stresses in this area may be higher than predicted and current maintenance
inspections do not provide adequate opportunity for cracks to be detected.
History of Reported Skin Cracks Under the Drag Link
Hole 2
Crack
Length
Hole 1
Crack
Length
Side
(Left /
Right)
Flight
Cycles
Flight
Hours
Model
0.0660.130R33,32857,275737-700
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History of Reported Skin Cracks Under the Drag Link
Hole 2
Crack
Length
Hole 1
Crack
Length
Side
(Left /
Right)
Flight
Cycles
Flight
Hours
Model
0.012-L16,28647,791737-800
0.072-L24,71642,846737-700
0.058-L18,14643,811737-800
-0.030L24,92942,749737-700
0.0060.011L18,89753,630737-800
0.066-L22,28143,342737-800
0.012-L25,18242,954737-800
Accomplishment of this service bulletin will find and repair any crack and prevent any future cracking
at the STA 540 bulkhead chord.
Boeing Fleet Team Digest (FTD) 737NG FTD 53-16001 is related to this service bulletin.
Boeing Service Related Problem (SRP) 737NG-SRP-53-0496 is related to this service bulletin.
D. Description
Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4,
Configuration 2-5; Group 5-8:
1. Do an ultrasonic inspection for any crack in the skin on each side of the airplane with no repair
installed.
2. If any crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current
(HFEC) inspections and surface HFEC inspections for any crack.
3. If no crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current
(HFEC) inspections and surface HFEC inspections for any crack or repeat the ultrasonic inspections
at the time given in Paragraph 1.E., Compliance.
4. If any crack is found in the skin at the first three fasteners forward of the wing during the open hole
HFEC and surface HFEC inspections, do the repair. If any crack is found at any other location
contact The Boeing Company for repair instructions and do the repair. If no crack is found do the
preventive modification.
5. Do post repair or post preventive modification inspections for any crack.
Group 1, Configuration 1, 3-4; Group 2, Configuration 1, 3-4; Group 3, Configuration 1, 3-4;
Group 4, Configuration 1, 3-4:
1. Do an ultrasonic inspection for any crack in the repair tripler on each side of the airplane with a
repair installed.
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### Page 40

2. If any crack is found during the ultrasonic inspection contact The Boeing Company for repair
instructions and do the repair.
3. If no crack is found during the ultrasonic inspection do open hole High Frequency Eddy Current
(HFEC) inspections for any crack or repeat the ultrasonic inspections at the time given in Paragraph
1.E., Compliance.
4. If any crack is found in the skin during the open hole HFEC inspections, contact The Boeing
Company for repair instructions and do the repair. If no crack is found do the preventive modification.
5. Do post preventive modification inspections for any crack.
The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-600, 737-700, 737-800
Group 2:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-900
Group 3, 7:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-700
Group 4, 8:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-700C
Group 5:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-700, 737-800
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Group 6:
Affected Maintenance Zones
ZoneModel
131, 132, 192737-900ER
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.
Federal Aviation Administration (FAA) Airworthiness Directive AD 2017-02-10 is related to this service
bulletin. The effective date of AD 2017-02-10 is March 17, 2017.
For airplanes which have incorporated Boeing Business Jet (BBJ) Lower Cabin Altitude Supplemental
Type Certificate (STC) ST01697SE (6500 feet maximum cabin altitude in lieu of 8000 feet) as referenced
in Boeing SB 737-21-1149, the flight cycle related compliance times are different from those specified
in this service bulletin. All initial compliance times (thresholds) specified in flight cycles must be reduced
to half of those specified in this service bulletin. All repeat interval compliance times specified in flight
cycles must be reduced to one-quarter of those specified in this service bulletin.
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.
Accomplish the required actions, based on the applicable conditions in Tables 1 through 8, in accordance
with Paragraph 3. Accomplishment Instructions.
Logic diagrams showing compliance tasks and compliance times are included as an aid in APPENDIX
A, APPENDIX B, APPENDIX C, APPENDIX D, APPENDIX E, APPENDIX F, APPENDIX G and
APPENDIX H.
Group 1, Configuration 2, 5; Group 2, Configuration 2, 5; Group 3, Configuration 2, 5; Group 4, Config-
uration 2, 5; Group 5-8:
Table 1: Inspection, Repair and Modification for Airplanes That Do Not Have an Existing Repair Installed.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 25,000
total flight cy-
cles.
Do PART 2: ULTRASON-
IC INSPECTION OF THE
SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack.
All airplanes.
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### Page 42

Group 1, Configuration 2, 5; Group 2, Configuration 2, 5; Group 3, Configuration 2, 5; Group 4, Config-
uration 2, 5; Group 5-8:
Table 1: Inspection, Repair and Modification for Airplanes That Do Not Have an Existing Repair Installed.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on each side of
the airplane on which the
crack was found.
CONDITION 1:
ANY CRACK FOUND.
-Before further flight.Do PART 4: REPAIR on
each side of the airplane
on which the crack was
found. (a)
CONDITION 1.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on each side of the
airplane on which the
crack was found.
CONDITION 1.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
6,000 flight cycles.
(a)(b)
-OPTION 1:
Repeat PART 2: ULTRA-
SONIC INSPECTION OF
THE SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack on each
side of the airplane on
which no crack was
found.
CONDITION 2:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on each side of
the airplane on which no
crack was found.
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### Page 43

Group 1, Configuration 2, 5; Group 2, Configuration 2, 5; Group 3, Configuration 2, 5; Group 4, Config-
uration 2, 5; Group 5-8:
Table 1: Inspection, Repair and Modification for Airplanes That Do Not Have an Existing Repair Installed.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Do PART 4: REPAIR on
each side of the airplane
on which the crack was
found. (a)
CONDITION 2.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on each side of the
airplane on which the
crack was found.
CONDITION 2.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
each side of the airplane
on which no crack was
found. (b)
CONDITION 2.3:
NO CRACK FOUND DUR-
ING THE PART 3 INSPEC-
TIONS.
(a) Accomplishment of PART 4: REPAIR terminates the PART 2 repeat inspection requirement on the side
of the airplane on which the repair was done. Refer to Table 5, Table 6 and Table 7 for post repair inspec-
tion requirements.
(b) Accomplishment of PART 5: PREVENTIVE MODIFICATION terminates the PART 2 repeat inspection
requirement on the side of the airplane on which the preventive modification was done. Refer to Table
8 for post preventive modification inspection requirements.
Group 1-4, Configuration 3:
Table 2: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Left Side
and a Preventive Modification Installed on the Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 25,000
total flight cy-
cles.
Do PART 2: ULTRASON-
IC INSPECTION OF THE
SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack on the right
side of the airplane.
All airplanes.
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### Page 44

Group 1-4, Configuration 3:
Table 2: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Left Side
and a Preventive Modification Installed on the Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on the right
side of the airplane.
CONDITION 1:
ANY CRACK FOUND.
-Before further flight.Do PART 4: REPAIR on
the right side of the air-
plane. (a)
CONDITION 1.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the right side of
the airplane.
CONDITION 1.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
6,000 flight cycles.
(a)(b)
-OPTION 1:
Repeat PART 2: ULTRA-
SONIC INSPECTION OF
THE SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack on the right
side of the airplane.
CONDITION 2:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on the right
side of the airplane.
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### Page 45

Group 1-4, Configuration 3:
Table 2: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Left Side
and a Preventive Modification Installed on the Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Do PART 4: REPAIR on
the right side of the air-
plane. (a)
CONDITION 2.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the right side of
the airplane.
CONDITION 2.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
the right side of the air-
plane. (b)
CONDITION 2.3:
NO CRACK FOUND DUR-
ING THE PART 3 INSPEC-
TIONS.
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 36,000
total flight cy-
cles.
Do PART 6: ULTRASON-
IC INSPECTION OF THE
REPAIR TRIPLER UN-
DER THE DRAG LINK
ASSEMBLY for any crack
on the left side of the air-
plane.
All airplanes.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the left side of the
airplane.
CONDITION 3:
ANY CRACK FOUND.
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### Page 46

Group 1-4, Configuration 3:
Table 2: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Left Side
and a Preventive Modification Installed on the Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
6,000 flight cycles.
(c)
-OPTION 1:
Repeat PART 6: ULTRA-
SONIC INSPECTION OF
THE REPAIR TRIPLER
UNDER THE DRAG LINK
ASSEMBLY for any crack
on the left side of the air-
plane.
CONDITION 4:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 7: OPEN HOLE
HFEC INSPECTION AT
THE HOLES COMMON
TO THE DRAG LINK AS-
SEMBLY for any crack on
the left side of the air-
plane.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the left side of the
airplane.
CONDITION 4.1:
ANY CRACK FOUND
DURING THE PART 7 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
the left side of the air-
plane. (c)
CONDITION 4.2:
NO CRACK FOUND DUR-
ING THE PART 7 INSPEC-
TIONS.
(a) Accomplishment of PART 4: REPAIR terminates the PART 2 repeat inspection requirement on the right
side of the airplane. Refer to Table 5, Table 6 and Table 7 for post repair inspection requirements.
(b) Accomplishment of PART 5: PREVENTIVE MODIFICATION on the right side of the airplane terminates
the PART 2 repeat inspection requirement on the right side of the airplane. Refer to Table 8 for post
preventive modification inspection requirements.
(c) Accomplishment of PART 5: PREVENTIVE MODIFICATION on the left side of the airplane terminates
the PART 6 repeat inspection requirement on the left side of the airplane. Refer to Table 8 for post pre-
ventive modification inspection requirements.
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### Page 47

Group 1-4, Configuration 4:
Table 3: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Right
Side and a Preventive Modification Installed on the Left Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 25,000
total flight cy-
cles.
Do PART 2: ULTRASON-
IC INSPECTION OF THE
SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack on the left
side of the airplane.
All airplanes.
-Before further flight.Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on the left side
of the airplane.
CONDITION 1:
ANY CRACK FOUND.
-Before further flight.Do PART 4: REPAIR on
the left side of the air-
plane. (a)
CONDITION 1.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the left side of the
airplane.
CONDITION 1.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
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### Page 48

Group 1-4, Configuration 4:
Table 3: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Right
Side and a Preventive Modification Installed on the Left Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
6,000 flight cycles.
(a)(b)
-OPTION 1:
Repeat PART 2: ULTRA-
SONIC INSPECTION OF
THE SKIN UNDER THE
DRAG LINK ASSEMBLY
for any crack on the left
side of the airplane.
CONDITION 2:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 3: HFEC IN-
SPECTION OF THE
SKIN AND STA 540
BULKHEAD CHORD for
any crack on the left side
of the airplane.
-Before further flight.Do PART 4: REPAIR on
the left side of the air-
plane. (a)
CONDITION 2.1:
ANY CRACK FOUND IN
THE SKIN AT ANY OF
THE FIRST THREE FAS-
TENERS FORWARD OF
THE WING DURING THE
PART 3 INSPECTIONS.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the left side of the
airplane.
CONDITION 2.2:
ANY CRACK FOUND IN
THE SKIN AT ANY LOCA-
TION OTHER THAN THE
FIRST THREE FASTEN-
ERS FORWARD OF THE
WING OR ANY CRACK IS
FOUND IN THE STA 540
BULKHEAD CHORD
DURING THE PART 3 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
the left side of the air-
plane. (b)
CONDITION 2.3:
NO CRACK FOUND DUR-
ING THE PART 3 INSPEC-
TIONS.
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 36,000
total flight cy-
cles.
Do PART 6: ULTRASON-
IC INSPECTION OF THE
REPAIR TRIPLER UN-
DER THE DRAG LINK
ASSEMBLY for any crack
on the right side of the
airplane.
All airplanes.
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### Page 49

Group 1-4, Configuration 4:
Table 3: Inspection, Repair and Modification for Airplanes That Have a Repair Installed on the Right
Side and a Preventive Modification Installed on the Left Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the right side of
the airplane.
CONDITION 3:
ANY CRACK FOUND.
6,000 flight cycles.
(c)
-OPTION 1:
Repeat PART 6: ULTRA-
SONIC INSPECTION OF
THE REPAIR TRIPLER
UNDER THE DRAG LINK
ASSEMBLY for any crack
on the right side of the
airplane.
CONDITION 4:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 7: OPEN HOLE
HFEC INSPECTION AT
THE HOLES COMMON
TO THE DRAG LINK AS-
SEMBLY for any crack on
the right side of the air-
plane.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on the right side of
the airplane.
CONDITION 4.1:
ANY CRACK FOUND
DURING THE PART 7 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
the right side of the air-
plane. (c)
CONDITION 4.2:
NO CRACK FOUND DUR-
ING THE PART 7 INSPEC-
TIONS.
(a) Accomplishment of PART 4: REPAIR terminates the PART 2 repeat inspection requirement on the left
side of the airplane. Refer to Table 5, Table 6 and Table 7 for post repair inspection requirements.
(b) Accomplishment of PART 5: PREVENTIVE MODIFICATION on the left side of the airplane terminates
the PART 2 repeat inspection requirement on the left side of the airplane. Refer to Table 8 for post pre-
ventive modification inspection requirements.
(c) Accomplishment of PART 5: PREVENTIVE MODIFICATION on the right side of the airplane terminates
the PART 6 repeat inspection requirement on the right side of the airplane. Refer to Table 8 for post
preventive modification inspection requirements.
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### Page 50

Group 1-4, Configuration 1:
Table 4: Inspection, Repair and Modification for Airplanes That Have an Existing Repair Installed on
Both the Left and Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 5,000
flight cycles af-
ter the original
issue date of
this service bul-
letin.
Before 36,000
total flight cy-
cles.
Do PART 6: ULTRASON-
IC INSPECTION OF THE
REPAIR TRIPLER UN-
DER THE DRAG LINK
ASSEMBLY for any
crack.
All airplanes.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on each side of the
airplane on which the
crack was found.
CONDITION 3:
ANY CRACK FOUND.
6,000 flight cycles.
(a)
-OPTION 1:
Repeat PART 6: ULTRA-
SONIC INSPECTION OF
THE REPAIR TRIPLER
UNDER THE DRAG LINK
ASSEMBLY for any crack
on each side of the air-
plane on which no crack
was found.
CONDITION 4:
NO CRACK FOUND.
-Before further flight.OPTION 2:
Do PART 7: OPEN HOLE
HFEC INSPECTION AT
THE HOLES COMMON
TO THE DRAG LINK AS-
SEMBLY for any crack on
each side of the airplane
on which no crack was
found.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair on each side of the
airplane on which the
crack was found.
CONDITION 4.1:
ANY CRACK FOUND
DURING THE PART 7 IN-
SPECTIONS.
-Before further flight.Do PART 5: PREVEN-
TIVE MODIFICATION on
each side of the airplane
on which the crack was
found. (a)
CONDITION 4.2:
NO CRACK FOUND DUR-
ING THE PART 7 INSPEC-
TIONS.
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### Page 51

Group 1-4, Configuration 1:
Table 4: Inspection, Repair and Modification for Airplanes That Have an Existing Repair Installed on
Both the Left and Right Side of the Airplane.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
(a) Accomplishment of PART 5: PREVENTIVE MODIFICATION terminates the PART 6 repeat inspection
requirement on the side of the airplane on which the preventive modification was done. Refer to Table
8 for post preventive modification inspection requirements.
Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4, Configu-
ration 2-5; Group 5-8:
Table 5: Post Repair Ultrasonic Inspections.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 10,000
flight cycles af-
ter the installa-
tion of the repair
in accordance
with this service
bulletin.
Before 50,000
total flight cy-
cles.
Do PART 8: POST RE-
PAIR ULTRASONIC IN-
SPECTIONS for any
crack on each side of the
airplane on which the re-
pair was installed.
Airplanes with a repair in-
stalled in accordance with
this service bulletin.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 5:
ANY CRACK FOUND.
10,000 flight cy-
cles.
-Repeat PART 8: POST
REPAIR ULTRASONIC
INSPECTIONS for any
crack on each side of the
airplane on which no
crack was found.
CONDITION 6:
NO CRACK FOUND.
Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4, Configu-
ration 2-5; Group 5-8:
Table 6: Post Repair Eddy Current Inspections.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 10,000
flight cycles af-
ter the installa-
tion of the repair
in accordance
with this service
bulletin.
Before 36,000
total flight cy-
cles.
Do PART 9: POST RE-
PAIR EDDY CURRENT
INSPECTIONS for any
crack on each side of the
airplane on which the re-
pair was installed.
Airplanes with a repair in-
stalled in accordance with
this service bulletin.
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### Page 52

Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4, Configu-
ration 2-5; Group 5-8:
Table 6: Post Repair Eddy Current Inspections.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 7:
ANY CRACK FOUND.
10,000 flight cy-
cles.
-Repeat PART 9: POST
REPAIR EDDY CUR-
RENT INSPECTIONS for
any crack on each side of
the airplane on which no
crack was found.
CONDITION 8:
NO CRACK FOUND.
Group 1, Configuration 2-5; Group 2, Configuration 2-5; Group 3, Configuration 2-5; Group 4, Configu-
ration 2-5; Group 5-8:
Table 7: Post Repair Detailed Inspections.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 5,000
flight cycles af-
ter the installa-
tion of the repair
in accordance
with this service
bulletin.
Before 36,000
total flight cy-
cles.
Do PART 10: POST RE-
PAIR DETAILED INSPEC-
TIONS for any crack on
each side of the airplane
on which the repair was
installed.
Airplanes with a repair in-
stalled in accordance with
this service bulletin.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 9:
ANY CRACK FOUND.
5,000 flight cycles.-Repeat PART 10: POST
REPAIR DETAILED IN-
SPECTIONS for any
crack on each side of the
airplane on which no
crack was found.
CONDITION 10:
NO CRACK FOUND.
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### Page 53

Table 8: Post Preventive Modification Inspections.
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 10,000
flight cycles af-
ter the installa-
tion of the repair
in accordance
with this service
bulletin.
Before 50,000
total flight cy-
cles.
Do PART 11: POST
PREVENTIVE MODIFICA-
TION INSPECTIONS for
any crack on each side of
the airplane on which the
preventive modification
was installed. (a)
Airplanes with a preventive
modification installed in ac-
cordance with this service
bulletin.
-Before further flight.Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 11:
ANY CRACK FOUND.
10,000 flight cy-
cles.
-Repeat PART 11: POST
PREVENTIVE MODIFICA-
TION INSPECTIONS for
any crack on each side of
the airplane on which no
crack was found.
CONDITION 12:
NO CRACK FOUND.
(a) For airplanes in Group 1; Configurations 1,3 & 4, Group 2; Configurations 1, 3 & 4, Group 3; Configurations
1,3 & 4 and Group 4; Configurations 1,3 & 4, all existing post repair inspections in service bulletin 737-
53-1294 must continue.
F. Approval
NOTE: The approval statement that follows is valid for 737-700C airplanes.
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 for the 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.
In addition, the Manager of the FAA Seattle ACO Branch approves accomplishment of the preventive
modification or skin repair defined in this service bulletin as an alternative method of compliance, only
for the repaired or modified side, to the requirements of paragraphs (g) and (h) of FAA AD 2017-02-10.
All provisions of AD 2017-02-10 that are not specifically referenced in the above statement remain fully
applicable and must be complied with accordingly.
This service bulletin is also approved for airplanes having FAA Aviation Partners Boeing (APB)
Supplemental Type Certificate (STC) number ST00830SE installed (not including any areas affected
by the split scimitar winglet configuration).
For 737-700C models that have APB winglets installed by STC number ST00830SE, the operator is
responsible for obtaining appropriate regulatory agency approval before incorporating this service
bulletin if the bulletin is in the area affected by blended winglets.
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If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
The instructions given in this Service Bulletin are in compliance with the Airworthiness Limitation number
28-AWL-12 as mandated by AD 2008-10-10 R1. These data have been reviewed by the Boeing ODA
for fuel tank ignition prevention requirements, and no further approval from the FAA Oversight Office
is required to satisfy the requirements of CDCCL 28-AWL-12 provided the repair or alteration is
accomplished in accordance with these instructions. The SRM 51-80-01 and Certification Maintenance
Requirements (CMR) document, D626A001-CMR are related to this service bulletin.
NOTE: The approval statement that follows is valid for all affected airplanes, except 737-700C
airplanes.
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.
In addition, the Manager of the FAA Seattle ACO Branch approves accomplishment of the preventive
modification or skin repair defined in this service bulletin as an alternative method of compliance, only
for the repaired or modified side, to the requirements of paragraphs (g) and (h) of FAA AD 2017-02-10.
All provisions of AD 2017-02-10 that are not specifically referenced in the above statement remain fully
applicable and must be complied with accordingly.
This service bulletin is also approved for airplanes having FAA Aviation Partners Boeing (APB)
Supplemental Type Certificate (STC) number ST00830SE installed (not including any areas affected
by the split scimitar winglet configuration).
For BBJ models that have APB winglets installed by STC number ST00830SE, the operator is
responsible for obtaining appropriate regulatory agency approval before incorporating this service
bulletin if the bulletin is in the area affected by blended winglets.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
The instructions given in this Service Bulletin are in compliance with the Airworthiness Limitation number
28-AWL-12 as mandated by AD 2008-10-10 R1. These data have been reviewed by the Boeing ODA
for fuel tank ignition prevention requirements, and no further approval from the FAA Oversight Office
is required to satisfy the requirements of CDCCL 28-AWL-12 provided the repair or alteration is
accomplished in accordance with these instructions. The SRM 51-80-01 and Certification Maintenance
Requirements (CMR) document, D626A001-CMR are related to this service bulletin.
G. Manpower
The tables below show an estimate of the task hours necessary to do this service bulletin 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:
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• Time to adjust to the workplace
• Time to schedule the work
• Time to inspect the work
• Time to cure the materials
• Time to make the parts
• Time to find the tools
Group 1, Configuration 1, 3; Group 2, Configuration 1, 3; Group 3, Configuration 1, 3; Group
4, Configuration 1, 3:
INSPECTIONS - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
1.751.751Open Access
2.12.11FIGURE 3: Ultrason-
ic inspection of the
tripler in the area un-
der the drag link as-
sembly at the three
critical fasteners (left
side)
1.81.81FIGURE 7: Open
hole HFEC inspec-
tion of skin and STA
540 Chord (left side)
1.751.751Close Access
7.47.40TOTAL FOR EACH AIRPLANE
Group 1, Configuration 1, 4; Group 2, Configuration 1, 4; Group 3, Configuration 1, 4; Group
4, Configuration 1, 4:
INSPECTIONS - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
1.751.751Open Access
2.12.11FIGURE 4: Ultrason-
ic inspection of the
tripler in the area un-
der the drag link as-
sembly at the three
critical fasteners
(right side)
1.81.81FIGURE 8: Open
hole HFEC inspec-
tion of skin and STA
540 Chord (right
side)
1.751.752Close Access
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### Page 56

Group 1, Configuration 1, 4; Group 2, Configuration 1, 4; Group 3, Configuration 1, 4; Group
4, Configuration 1, 4:
INSPECTIONS - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
7.47.4TOTAL FOR EACH AIRPLANE
Group 1, Configuration 2, 4-5; Group 2, Configuration 2, 4-5; Group 3, Configuration 2, 4-5;
Group 4, Configuration 2, 4-5; Group 5-8:
INSPECTIONS - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
1.751.751Open Access
2.12.11FIGURE 1: Ultrason-
ic inspection of the
skin in the area un-
der the drag link as-
sembly at the three
critical fasteners (left
side)
1.51.51FIGURE 5: Open
hole HFEC inspec-
tion of skin and STA
540 Chord (left side)
1.81.81FIGURE 9: Remove
drag link assembly
(left side) (a)
1.81.81FIGURE 11: Remove
drag link assembly
(left side) (b)
3.33.31FIGURE 13: Surface
HFEC inspection of
skin under drag link
assembly (left side)
1.751.751Close Access
14.014.0TOTAL FOR EACH AIRPLANE
(a) 737-600, 737-700, 737-700C, 737-700IGW and 737-800 airplanes.
(b) 737-900 and 737-900ER airplanes.
Group 1, Configuration 2-3, 5; Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5;
Group 4, Configuration 2-3, 5; Group 5-8:
INSPECTIONS - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
1.751.751Open Access
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### Page 57

Group 1, Configuration 2-3, 5; Group 2, Configuration 2-3, 5; Group 3, Configuration 2-3, 5;
Group 4, Configuration 2-3, 5; Group 5-8:
INSPECTIONS - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
2.12.11FIGURE 2: Ultrason-
ic inspection of the
skin in the area un-
der the drag link as-
sembly at the three
critical fasteners
(right side)
1.51.51FIGURE 6: Open
hole HFEC inspec-
tion of skin and STA
540 Chord (right
side)
1.81.81FIGURE 10: Remove
drag link assembly
(right side) (a)
1.81.81FIGURE 12: Remove
drag link assembly
(right side) (b)
3.33.31FIGURE 14: Surface
HFEC inspection of
skin under drag link
assembly (right side)
1.751.751Close Access
14.014.0TOTAL FOR EACH AIRPLANE
(a) 737-600, 737-700, 737-700C, 737-700IGW and 737-800 airplanes.
(b) 737-900 and 737-900ER airplanes.
Group 1, Configuration 5:
PREVENTIVE MODIFICATION - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
4.016.04Open Access
0.50.51FIGURE 19 : Cut
Stringer 22 at STA
540
1.051.051FIGURE 21: Open
hole HFEC inspec-
tion
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### Page 58

Group 1, Configuration 5:
PREVENTIVE MODIFICATION - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
0.50.51FIGURE 23: STA
540 chord splice
preparation
0.60.61FIGURE 26: Install
STA 540 chord splice
0.30.31FIGURE 67: Make
spacer for termina-
tion fitting
3.13.11FIGURE 53: Install
drag link assembly
0.30.31FIGURE 69: Install
termination fitting
and inner drag link
0.40.41FIGURE 65: Install
radius filler
5.05.01Close Access
15.7527.75TOTAL FOR EACH AIRPLANE
Group 1, Configuration 5:
PREVENTIVE MODIFICATION - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
4.016.04Open Access
0.50.51FIGURE 20: Cut
Stringer 22 at STA
540
1.051.051FIGURE 22: Open
hole HFEC inspec-
tion
0.50.51FIGURE 24: STA
540 chord splice
preparation
0.60.61FIGURE 27: Install
STA 540 chord splice
0.30.31FIGURE 68: Make
spacer for termina-
tion fitting
3.13.11FIGURE 54: Install
drag link assembly
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: February 27, 2018
737-53A1368
58 of 545
BOEING SERVICE BULLETIN 737-53A1368
ALERTALERT

### Page 59

Group 1, Configuration 5:
PREVENTIVE MODIFICATION - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
0.30.31FIGURE 70: Install
termination fitting
and inner drag link
0.40.41FIGURE 66: Install
radius filler
5.05.01Close Access
15.7527.75TOTAL FOR EACH AIRPLANE
Group 3, Configuration 5:
PREVENTIVE MODIFICATION - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
4.016.04Open Access
0.50.51FIGURE 19: Cut
Stringer 22 at STA
540
1.051.051FIGURE 21: Open
hole HFEC inspec-
tion
0.50.51FIGURE 23: STA
540 chord splice
preparation
0.60.61FIGURE 26: Install
STA 540 chord splice
0.30.31FIGURE 67: Make
spacer for termina-
tion fitting
3.13.11FIGURE 55: Install
drag link assembly
0.30.31FIGURE 69: Install
termination fitting
and inner drag link
0.40.41FIGURE 65: Install
radius filler
5.05.01Close Access
15.7527.75TOTAL FOR EACH AIRPLANE
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: February 27, 2018
737-53A1368
59 of 545
BOEING SERVICE BULLETIN 737-53A1368
ALERTALERT

### Page 60

Group 3, Configuration 5:
PREVENTIVE MODIFICATION - RIGHT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
4.016.04Open Access
0.50.51FIGURE 20: Cut
Stringer 22 at STA
540
1.051.051FIGURE 22: Open
hole HFEC inspec-
tion
0.50.51FIGURE 24: STA
540 chord splice
preparation
0.60.61FIGURE 27: Install
STA 540 chord splice
0.30.31FIGURE 68: Make
spacer for termina-
tion fitting
3.13.11FIGURE 56: Install
drag link assembly
0.30.31FIGURE 70: Install
termination fitting
and inner drag link
0.40.41FIGURE 66: Install
radius filler
5.05.01Close Access
15.7527.75TOTAL FOR EACH AIRPLANE
Group 4, Configuration 5:
PREVENTIVE MODIFICATION - LEFT SIDE
Elapsed HoursTask HoursNumber of PersonsTask
4.016.04Open Access
0.50.51FIGURE 19: Cut
Stringer 22 at STA
540
1.051.051FIGURE 21: Open
hole HFEC inspec-
tion
0.50.51FIGURE 25: STA
540 chord splice
preparation
Export Controlled ECCN: 9E991 - BOEING
PROPRIETARY - Copyright © Unpublished
Work - See page 1 for details.
Original Issue: February 27, 2018
737-53A1368
60 of 545
BOEING SERVICE BULLETIN 737-53A1368
ALERTALERT

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