# Boeing Alert Service Bulletin 737-57A1301: U.S. DOT/FAA - Service Bulletin

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- Document: [Boeing Alert Service Bulletin 737-57A1301](https://openairdocs.org/service-documents/boeing/737-57a1301.md)
- Title as filed: U.S. DOT/FAA - Service Bulletin
- Pages: 94
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## Text

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### Page 1

Commercial 
Airplanes
737
Service Bulletin
Number: 737-57A1301
Original Issue: February 05, 2008
Revision 3: August 11, 2011
ATA System: 5754
SUBJECT: WINGS - Flight Surfaces - Leading Edge Slats - Main Track Downstop Assembly
Inspection and Modification
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 730-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET
Copyright © 2008 The Boeing Company
Unpublished Work - All Rights Reserved
Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable
subject matter. Boeing also claims copyright in this document as a compilation and/or collective work.
This document includes proprietary information owned by The Boeing Company and/or one or more third parties.
Treatment of the document and the information it contains is governed by contract with Boeing. For more
information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
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connection with this document unless provided in writing by Boeing.
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Table of Contents
Revision Transmittal Sheet ............................................ 5
Summary ...................................................... 7
1. PLANNING INFORMATION ........................................ 1 1
A. Effectivity ............................................... 1 1
1. Airplanes ............................................ 1 1
2. Spares Affected ........................................ 1 8
B. Concurrent Requirements ...................................... 1 8
C. Reason ................................................ 1 8
D. Description .............................................. 1 9
E. Compliance .............................................. 2 0
F. Approval ............................................... 2 3
G. Manpower .............................................. 2 4
H. Weight and Balance Changes .................................... 2 5
I. Electrical Load Data ......................................... 2 6
J. References .............................................. 2 6
1. Existing Data .......................................... 2 6
2. Data supplied with this Service Bulletin ............................ 2 6
3. Installation Drawings Used in the Preparation of this Service Bulletin ............ 2 6
K. Publications Affected ........................................ 2 6
L. Interchangeability and Intermixability of Parts ........................... 2 7
2. MATERIAL INFORMATION ........................................ 2 9
A. Material - Price and Availability ................................... 2 9
B. Industry Support Information .................................... 2 9
C. Parts Necessary For Each Airplane ................................. 3 0
1. Kits/Parts ............................................ 3 0
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 2
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 3
A. GENERAL INFORMATION ..................................... 3 3
B. WORK INSTRUCTIONS ....................................... 3 4
FIGURE 1: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY [Group 1, Configuration 1] . 39
FIGURE 2: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY [Group 1, Configuration 2; Group
2 ]  ................................................ 4 1
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1 [Group 1, Configuration
1 ]  ................................................ 4 4
FIGURE 4: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 2 [Group 1, Configuration
1 ]  ................................................ 4 9
FIGURE 5: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 3 [Group 1, Configuration
1 ]  ................................................ 5 2
FIGURE 6: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 4 [Group 1, Configuration
1 ]  ................................................ 5 5
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FIGURE 7: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 5 [Group 1, Configuration
1 ]  ................................................ 5 8
FIGURE 8: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 6 [Group 1, Configuration
1 ]  ................................................ 6 1
FIGURE 9: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1 [Group 1, Configuration
2; Group 2] ........................................... 6 6
FIGURE 10: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 2 [Group 1, Configuration
2; Group 2] ........................................... 7 1
FIGURE 11: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 3 [Group 1, Configuration
2; Group 2] ........................................... 7 4
FIGURE 12: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 4 [Group 1, Configuration
2; Group 2] ........................................... 7 7
FIGURE 13: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 5 [Group 1, Configuration
2; Group 2] ........................................... 8 0
FIGURE 14: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 6 [Group 1, Configuration
2; Group 2] ........................................... 8 3
FIGURE 15: TAPERED FILLER FABRICATION (FOR SLAT CAN) .................... 8 8
FIGURE 16: TAPERED FILLER AND SLAT CAN INSTALLATION .................... 9 0
FIGURE 17: SLAT CAN REPAIR ...................................... 9 3
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Commercial 
Airplanes
737
Service Bulletin
Revision Transmittal SheetNumber: 737-57A1301Original Issue: February 05, 2008
Revision 3: August 11, 2011
ATA System: 5754
SUBJECT: WINGS - Flight Surfaces - Leading Edge Slats - Main Track Downstop Assembly
Inspection and Modification
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
More work is necessary on the airplane(s) changed in accordance with the original issue, Revision 1 or Revision
2 of this service bulletin. A new foreign object debris (FOD) inspection has been added with a decreased
compliance time.
Federal Aviation Administration (FAA) Airworthiness Directive 2008-06-29, is related to this service bulletin.
REASON FOR REVISION
This revision is sent to add a new detailed inspection for Fod in the slat can, to inform operators of the option
to replace a damaged slat can instead of repairing it and that the slat can needs to be replaced if they find a
crack. The general information note section was update to include the new standard notes.
These sections were changed:
1. Summary - Background, Added new service history for FOD findings and referenced the new SRP.
2. Paragraph 1.B. Concurrent Requirements, removed the old requirement and change it to None.
3. Paragraph 1.C. Reason, Added new service history for FOD findings and referenced the new SRP.
4. Paragraph 1.E. Compliance, Revised Table 2 and added Table 3. Provided option to replace a damaged
slat can instead of repairing it and provided a disposition for a cracked slat can.
5. Paragraph 1.F. Approval, Updated the revision level of the service bulletin in the AMOC paragraphs.
6. Paragraph 2.E. Special Tooling, revised the tool number to 2MIT65C37853-59 (this is equivalent to
MIT65C37853-59 Rev B).
7. Paragraph 3.A. General Information, Updated the notes to the current standard.
8. Paragraph 3.B. Work Instruction, Part 2 and Part 3, Provided option to replace a damaged slat can instead
of repairing it and provided a disposition for a cracked slat can. In Part 3, step 1.a. added the word, detailed
in front of inspection. In Part 4 and Part 5 deleted step 3 FOD inspection.
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9. Figures 1 and 2 note (a) added the word, detailed in front of inspection.
10. Figures 3 thru 14 note (f), revised the tool number to 2MIT65C37853-59 (this is equivalent to MIT65C37853-59
Rev B).
11. Through out the SB were the words part, object or debris are used the word (FOD) has been added.
Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location
of important changes.
Pages with no vertical lines have no important changes.
REVISION HISTORY
February 05, 2008Original Issue:
September 24, 2009Revision 1:
January 17, 2011Revision 2:
August 11, 2011Revision 3:
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Commercial 
Airplanes
737
Service Bulletin
SummaryNumber: 737-57A1301Original Issue: February 05, 2008
Revision 3: August 11, 2011
ATA System: 5754
SUBJECT: WINGS - Flight Surfaces - Leading Edge Slats - Main Track Downstop Assembly
Inspection and Modification
CONCURRENT REQUIREMENTS
None.
BACKGROUND
Since 1985, Boeing has received 32 reports of fuel leaking from the slat track housing (slat can) on 737-300,
-400, and -500 airplanes due to a number of causes. In all 32 cases, there were no reports of a fire as a result
of the fuel leaks. In five of the reports, the fuel leak was known to be caused by loose or broken downstop
assembly hardware falling into the slat can and then subsequently being driven into the slat can by the retracting
slat track. This service bulletin calls for a detailed inspection of the downstop assembly on the main tracks of
the number 2, 3, 4, and 5 slats and the inboard track of the number 1 and 6 slats. An incorrectly installed downstop
assembly can allow downstop hardware to fall off of the slat track and into the slat can, which could lead to a
fuel leak and fire when the slat is retracted and the hardware is pushed into the slat can.
An additional 3 reports were received from operators in 2010 of fuel leaks that had been caused by FOD - foreign
object debris found in the slat can.
Service History
FOD ReportedReport Date
Hi-Lok - Slat can had
been replaced 9
months prior.
2/3/2010
Loose washer4/30/2010
Extra downstop10/17/2010
Boeing Service Related Problem (SRP) 737-SRP-57-0208 is related to this service bulletin.
Boeing Service Related Problem (SRP) 737-SRP-57-0249 is related to this service bulletin.
ACTION (PRR 35005-290RS)
Do a detailed inspection of the main track downstop assemblies on the number 2, 3, 4, and 5 slats and the
inboard track of the number 1 and 6 slats. Make sure that each downstop assembly has all the parts installed,
that they are installed in the correct order, and that they are undamaged. Disassembly of the downstop is not
required to accomplish this inspection.
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— If the parts are not in the correct order but are undamaged, then remove the downstop assembly and install
the parts correctly.
— If the downstop assembly has a cracked or broken locator, then install a new locator.
— If the downstop assembly has a damaged part or if the downstop assembly has a missing part, then replace
the damaged or missing part and do a detailed inspection for loose objects (FOD) in the slat can and a
detailed inspection for damage to the slat can.
To terminate repeat inspections on slats one through six:
– Install new downstop assembly hardware. Special tooling is available from Boeing to assist with the installation
of the downstop assembly hardware.
– Do a One-time inspection of the slat can for damage and debris (FOD). If there is damage, then:
– install a tapered filler as required and repair the slat can, OR
– replace the slat can. Install a tapered filler as required.
EFFECTIVITY
737-300, -400, and -500 airplanes. Refer to Paragraph 1.A.1, Airplanes, for the list of affected airplanes.
COMPLIANCE
Refer to Paragraph 1.E., Compliance.
Federal Aviation Administration Airworthiness Directive FAA AD 2008-06-29, is related to this service bulletin.
INDUSTRY SUPPORT INFORMATION
Boeing Industry Support information is provided in Program Letter BPL 6-1151-737-PGM-190 dated March 9,
2009. Additional copies of program letters are available from Boeing Warranty & Product Assurance Contracts.
MANPOWER
Refer to Paragraph 1.G., Manpower.
MATERIAL INFORMATION
None.
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BOEING SERVICE BULLETIN 737-57A1301
LEFT WING SHOWN
(RIGHT WING IS EQUIVALENT)
FWD INBD
DO A DETAILED INSPECTION FOR
CORRECT PARTS AND CORRECT ORDER
SEE  (STACKUP). IF PARTS OR STACKUP
IS NOT CORRECT, THEN DO A
DETAILED INSPECTION FOR LOOSE
OBJECTS IN THE SLAT CAN.
TO TERMINATE REPEAT INSPECTIONS,
REPLACE DOWNSTOP COMPONENTS AND
DO ONE-TIME DETAILED INSPECTION
OF SLAT CAN
FWDI
INBD
SLAT NUMBER 3 SHOWN  1475105
(TYPICAL)
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Commercial 
Airplanes
737
Service Bulletin
Number: 737-57A1301
Original Issue: February 05, 2008
Revision 3: August 11, 2011
ATA System: 5754
SUBJECT: WINGS - Flight Surfaces - Leading Edge Slats - Main Track Downstop Assembly
Inspection and Modification
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
This service bulletin is for the airplanes shown below.
DESCRIPTIONCONFIGURATIONGROUP
737-300 airplanes Line Number 1001 - 1517-1
that have not done the downstop changes as given in Service Bulletin
737-57-1175
1
that have done the downstop changes as given in Service Bulletin
737-57-1175
2
737-300 airplanes Line Number 1518 and on, and all 737-400 and
-500 airplanes
-2
Airplane Models:
737-300, 737-400, 737-500
GroupVariable Number
2PJ301 - PJ302
2PJ551 - PJ561
2PJ601 - PJ615
2PJ811
2PJ816 - PJ817
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GroupVariable Number
2PM381 - PM399
2PM401 - PM417
2PM541 - PM564
1PP001 - PP043
2PP044 - PP054
1PP101 - PP126
2PP127 - PP160
1PP161 - PP169
1PP181 - PP189
2PP190 - PP199
1PP201 - PP204
2PP205
1PP221
1PP231 - PP243
1PP281 - PP286
1PP301 - PP305
1PP351 - PP353
1PP376 - PP384
2PP391 - PP393
1PP401 - PP432
2PP433 - PP440
1PP471 - PP475
1PP501 - PP504
2PP505 - PP520
1PP521 - PP522
1PP631 - PP634
1PP651 - PP652
1PP671 - PP699
1PP701 - PP729
2PP730 - PP733
1PP771 - PP777
2PP778 - PP779
1PP801 - PP804
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GroupVariable Number
2PP805 - PP808
1PP821 - PP827
1PP831 - PP838
2PP839 - PP845
1PP846 - PP848
1PP851 - PP852
1PP861 - PP870
2PP871 - PP877
1PP891 - PP899
1PP901 - PP909
2PP910 - PP930
1PP931 - PP935
2PP936
1PP946 - PP948
1PP951 - PP952
1PP961 - PP965
2PP966 - PP967
1PP981 - PP982
2PP983 - PP990
1PP991
2PP993
1PQ001 - PQ012
2PQ013 - PQ016
1PQ026 - PQ037
2PQ038 - PQ041
1PQ051 - PQ065
2PQ066 - PQ085
1PQ086 - PQ090
2PQ091 - PQ092
1PQ101 - PQ118
2PQ119 - PQ199
2PQ201 - PQ202
2PQ221 - PQ230
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GroupVariable Number
1PQ231 - PQ232
2PQ233 - PQ237
1PQ241 - PQ242
2PQ243
2PQ251 - PQ267
2PQ281 - PQ299
2PQ301 - PQ307
2PQ331 - PQ332
2PQ341 - PQ348
2PQ361 - PQ373
2PQ391 - PQ395
2PQ401 - PQ418
2PQ421
2PQ431 - PQ438
2PQ447 - PQ448
2PQ451
2PQ454
2PQ471 - PQ475
2PQ479 - PQ481
2PQ486 - PQ487
2PQ491 - PQ493
2PQ771 - PQ772
2PQ791 - PQ793
2PQ801 - PQ805
2PQ931 - PQ935
2PQ951
2PQ971 - PQ997
2PR001 - PR017
2PR021 - PR034
2PR041 - PR045
2PR061 - PR072
2PR077 - PR082
2PR091 - PR092
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GroupVariable Number
2PR096
2PR101
2PR121 - PR122
2PR131 - PR132
2PR141 - PR143
2PR161 - PR172
2PR181
2PS601 - PS631
2PS636 - PS638
2PS641 - PS644
2PS651 - PS657
2PS666 - PS669
2PS691 - PS692
2PS701 - PS706
2PS751 - PS799
2PS811
2PS836 - PS837
2PS841 - PS846
2PS851 - PS852
2PS856
2PS861 - PS863
2PS866 - PS868
2PS871 - PS874
2PS896 - PS897
2PS901 - PS941
2PS956 - PS957
2PS961 - PS963
2PS971 - PS978
2PT001 - PT015
2PT021 - PT031
2PT041 - PT064
2PT101 - PT105
2PT121 - PT138
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GroupVariable Number
2PT146 - PT148
2PT161 - PT170
2PT181 - PT188
2PT211 - PT220
2PT295
2PT301 - PT309
2PT331 - PT360
2PT381 - PT399
2PT401 - PT438
2PT501 - PT517
2PT561 - PT565
2PT581 - PT586
2PT611 - PT621
2PT641 - PT644
2PT651 - PT656
2PT671 - PT672
2PT681 - PT685
2PT701 - PT703
2PT716 - PT717
2PT721 - PT725
2PT801 - PT834
2PT851 - PT854
2PT871 - PT886
2PT901 - PT930
2PT971 - PT973
2PT981 - PT985
2PT996
2PU001 - PU025
2PU301
2PU311 - PU313
2PV001 - PV055
2PV201 - PV209
2PV226 - PV229
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GroupVariable Number
2PV231 - PV237
2PV271 - PV272
2PV281 - PV287
2PV296
2PV301 - PV302
2PV351
2PV356 - PV357
2PW001 - PW054
2PW061 - PW068
2PW072
2PW086 - PW088
2PW091 - PW094
2PW101 - PW102
2PW106
2PW111 - PW120
2PW156 - PW157
2PW161 - PW171
2PW201 - PW252
2PW261 - PW268
2PW271 - PW276
2PW278
2PW281 - PW293
2PW296
2PW301 - PW327
2PW401 - PW408
2PW411 - PW418
2PW421 - PW424
2PW431 - PW435
2PW441 - PW450
2PW461 - PW467
2PW501 - PW504
2PW511 - PW522
2PW524 - PW550
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GroupVariable Number
2PW556 - PW557
2PW561 - PW564
2PW571 - PW576
2PW591 - PW596
2PW611 - PW622
2PW631 - PW637
2PW661 - PW662
2PW681 - PW683
2PW701 - PW702
2PW711 - PW717
2PW741 - PW742
2PW761
2PW771
2PW831
2PW851 - PW856
2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
Since 1985, Boeing has received 32 reports of fuel leaking from the slat track housing (slat can) on
737-300, -400, and -500 airplanes due to a number of causes. In all 32 cases, there were no reports
of a fire as a result of the fuel leaks. In five of the reports, the fuel leak was known to be caused by
loose or broken downstop assembly hardware falling into the slat can and then subsequently being
driven into the slat can by the retracting slat track. This service bulletin calls for a detailed inspection
of the downstop assembly on the main tracks of the number 2, 3, 4, and 5 slats and the inboard track
of the number 1 and 6 slats. An incorrectly installed downstop assembly can allow downstop hardware
to fall off of the slat track and into the slat can, which could lead to a fuel leak and fire when the slat is
retracted and the hardware is pushed into the slat can.
An additional 3 reports were received from operators in 2010 of fuel leaks that had been caused by
FOD - foreign object debris found in the slat can.
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Service History
FOD ReportedReport Date
Hi-Lok - Slat can had
been replaced 9
months prior.
2/3/2010
Loose washer4/30/2010
Extra downstop10/17/2010
Revision 2 is sent to change the compliance time, remove the clearance inspection from the compliance,
change the upper range for the tapered filler thickness, clarify the distance between allowable damage
limit of the slat can, and provide further clarification on the installation of the tapered filler and slat can
in the event that the slat can is found to be damaged.
Revision 3 is sent to add a new detailed inspection for FOD in the slat can, to inform operators of the
option to replace a damaged slat can instead of repairing it and to inform operators that the slat can
needs to be replaced if they find a crack. The general information note section was update to include
the new standard notes.
Boeing Service Related Problem (SRP) 737-SRP-57-0208 is related to this service bulletin.
Boeing Service Related Problem (SRP) 737-SRP-57-0249 is related to this service bulletin.
D. Description
Do a detailed inspection of the main track downstop assemblies on the number 2, 3, 4, and 5 slats and
the inboard track of the number 1 and 6 slats. Make sure that each downstop assembly has all the
parts installed, that they are installed in the correct order, and that they are undamaged. Also torque
the nut/bolt and perform a detailed inspection to verify that the bolt chamfer protrudes beyond the outer
surface of the nut. Disassembly of the downstop is not required to accomplish these inspections.
— If the parts are not in the correct order but are undamaged, then remove the downstop assembly
and install the parts correctly.
— If the downstop assembly has a cracked or broken locator, then install a new locator.
— If the downstop assembly has a damaged part or if the downstop assembly has a missing part,
then replace the damaged or missing part and do a detailed inspection for loose objects (FOD) in
the slat can and a detailed inspection for damage to the slat can.
— If you find a loose part (FOD) in the slat can, remove it
— If the slat can is damaged, repair or replace the slat can.
— If the entire chamfered portion of the bolt does not protrude beyond the outer surface of the nut
after you torque it, then you must remove the downstop assembly and reinstall the parts.
To terminate repeat inspections on slats one through six:
– Install new downstop assembly hardware. Special tooling is available from Boeing to assist with
the installation of the downstop assembly hardware.
– Do a One-time inspection of the slat can for damage and debris (FOD). If there is damage, then:
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– install a tapered filler as required and repair the slat can, OR
– replace the slat can. Install a tapered filler as required.
Revision 2 -
No more work is necessary on airplanes inspected in accordance with Revision 1 of this service bulletin,
however more work is necessary on airplanes inspected in accordance with the original issue of this
service bulletin. The following items were added in Revision 1: an inspection to look for possible
interference of the slat main track with the slat can, a slat can blendout repair, and the replacement of
downstop assembly hardware on the slat main tracks of slats one through six in order to terminate
repeat inspections.
Revision 3 - More work is necessary on airplanes changed in accordance with Revision 1 and Revision
2 of this service bulletin. A new foreign object debris (FOD) inspection has been added with a decreased
compliance time. Prior inspection for FOD per any Table at any Revision of this Service Bulletin meets
the intent of this new compliance time requirement.
The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
302, 402737-300
Group 2:
Affected Maintenance Zones
ZoneModel
302, 402737-300, 737-400, 737-500
E. Compliance
Federal Aviation Administration Airworthiness Directive FAA AD 2008-06-29 is related to this service
bulletin.
Table 1: Slats 2, 3, 4, and 5 and the Inboard Track of the Number 1 and 6 Slats, Main Track Downstop
Assemblies - Detailed Inspection
Repeat
Interval
(Not to
Exceed)
Compliance TimeActionCondition
4500
flight cy-
cles(a)
Within 90 days after the date
of the original issue of this
service bulletin
Do a detailed inspection of the downstop
assemblies as given in Paragraph 3.B
Work Instructions, Part 2, Step 1
Group 1, Configuration
1
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Table 1: Slats 2, 3, 4, and 5 and the Inboard Track of the Number 1 and 6 Slats, Main Track Downstop
Assemblies - Detailed Inspection
Repeat
Interval
(Not to
Exceed)
Compliance TimeActionCondition
4500
flight cy-
cles(a)
Within 90 days after the date
of the original issue of this
service bulletin
Do a detailed inspection of the downstop
assemblies as given in Paragraph 3.B
Work Instructions, Part 2, Step 2
Group 1, Configuration
2; Group 2
-Before further flightDo a detailed inspection of the associat-
ed slat can as given in Paragraph 3.B
Work Instructions, Part 2, Step 3.a.
Parts missing
Parts damaged
AND
Replace damaged or missing parts as
given in Paragraph 3.B Work Instruc-
tions, Part 2, Step 3.b.
-Before further flightRemove loose part (FOD) as given in
Paragraph 3.B Work Instructions, Part
2, Step 3.a.(1).
Loose Part (FOD) in the
slat can
-Before further flightRepair the slat can as given in Para-
graph 3.B Work Instructions, Part 2, Step
3.a.(2)(a).
Slat can was found
damaged after detailed
inspection of the slat
can and remaining
thickness was 0.040
inches or greater.
As an option you may replace the slat
can with a new or serviceable slat can.
-Before further flightReplace slat can with a new or service-
able slat can as given in Paragraph 3.B
Work Instructions, Part 2, Step
3.a.(2)(b).
Slat can was found
damaged after detailed
inspection of the slat
can and remaining
thickness was less than
0.040 inches or if a
crack was found.
-Before further flightRemove and reinstall the parts as given
in Paragraph 3.B Work Instructions, Part
2, Step 4
Parts are installed in
the wrong order
-Within 90 days after the date
of the original issue of this
service bulletin.
Torque the nut and do a detailed inspec-
tion to verify that the bolt chamfer pro-
trudes fully beyond the nut as given in
Paragraph 3.B Work Instructions, Part
2, Step 5.
All Airplanes
-Before further flightRemove and reinstall the parts as given
in Paragraph 3.B Work Instructions, Part
2, Step 5.a.
Bolt chamfer does NOT
protrude fully beyond
the nut after the bolt/nut
is torqued
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Table 1: Slats 2, 3, 4, and 5 and the Inboard Track of the Number 1 and 6 Slats, Main Track Downstop
Assemblies - Detailed Inspection
Repeat
Interval
(Not to
Exceed)
Compliance TimeActionCondition
(a) Installation of new downstop assembly hardware in Table 2, one-time inspection of slat can for damage
and debris (FOD) in Table 2, and installation of tapered filler in Table 2, as required, terminates the
repeat inspections of the downstop assemblies.
Table 2: Slats 1 through 6, Main Track Downstop Assemblies - Modification
Repeat
Interval
(Not to
Exceed)
Compliance TimeActionCondition
(a)Within 6 years or 15,000 flight
cycles after the Revision 1
date of this service bulletin,
whichever comes first.
Replace bolt, washers and nut in down-
stop assembly as given in Paragraph
3.B Work Instructions, Part 4. Then do
a detailed inspection of the slat can and
slat main track as given in Paragraph
3.B Work Instructions, Part 3.
Group 1, Configuration
1
(a)Within 6 years or 15,000 flight
cycles after the Revision 1
date of this service bulletin,
whichever comes first.
Replace bolt, washer, nut, and stop fit-
ting as given in Paragraph 3.B Work In-
structions, Part 5. Then do a detailed
inspection of the slat can and slat main
track as given in Paragraph 3.B Work
Instructions, Part 3.
Group 1, Configuration
2, Group 2
(a)Before Further FlightInstall tapered filler as given in Para-
graph 3.B Work Instructions, Part 6, Step
4.
Slat Main Track has no
clearance to Slat Can
-Before Further FlightRepair the slat can as given in Para-
graph 3.B Work Instructions, Part 3, Step
1.a.(1)
Slat can was found
damaged after inspec-
tion and remaining
thickness was 0.040
inches or greater.
As an option you may replace the slat
can with a new or serviceable slat can.
-Before Further FlightReplace the slat can with a new or ser-
viceable slat can as given in Paragraph
3.B Work Instructions, Part 3, Step
1.a.(2).
Slat can was found
damaged after inspec-
tion and remaining
thickness was less than
0.040 inches or if a
crack was found.
-Before Further FlightRemove the debris (FOD)Debris (FOD) found in
slat can
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Table 2: Slats 1 through 6, Main Track Downstop Assemblies - Modification
Repeat
Interval
(Not to
Exceed)
Compliance TimeActionCondition
(a) Installation of new downstop assembly hardware, one-time inspection of slat can for damage and
debris (FOD), and installation of tapered filler, as required, terminates the repeat inspections of the
downstop assemblies in Table 1.
Table 3: Slats 1 through 6, Main Track Downstop Assemblies - Detailed Inspection for FOD.
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
-Within 2 years after
the Revision 3 date
of this service bul-
letin. (a)
Do a detailed inspection
of the slat can interior to
check for foreign object
debris (FOD) in accor-
dance with Paragraph 3.B
Work Instructions, Part 3.
All Airplanes
-Before further flightRemove the FODIf FOD is found in slat can
(a) Prior inspection of the slat can interior for damage and FOD as given in any Paragraph 3.B
Work Instructions of any revision of this Service Bulletin satisfies the inspection requirement
of Table 3.
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.
F. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified
in this service bulletin comply with the applicable regulations and are FAA approved, as well as European
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on
the airplane in its original Boeing delivery configuration or as modified by other approved Boeing
changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
This service bulletin has been approved by the FAA. In addition, the Manager of the FAA Seattle Aircraft
Certification Office approves the accomplishment of the applicable inspections, and investigative and
corrective actions specified in Table 1 of SB 737-57A1301, Revision 3, as an alternative method of
compliance (AMOC) to the inspections, and investigative and corrective actions required by paragraph
(f) of AD 2008-06-29.
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In addition, the Manager of the FAA Seattle ACO approves the installation of the downstop assembly
hardware modification, and accomplishment of the applicable inspections, and investigative and
corrective actions specified in Tables 2 and 3 of SB 737-57A1301, Revision 3, at each applicable slat
location, as an AMOC to the repeat inspections required by paragraph (f) of AD 2008-06-29.
All provisions of AD 2008-06-29 that are not specifically referenced in the preceding two paragraphs
remain in effect and must be complied with.
G. Manpower
Part 1 - Downstop Assembly Access
Elapsed HoursTask HoursNumber of PersonsTask
1.753.502Open Access
Part 2 - Detailed Inspection of the Downstop Assemblies
Elapsed HoursTask HoursNumber of PersonsTask
0.501.002Figure 1or 2
0.501.002Torque Nuts
1.753.502Close Access
2.755.50TOTAL FOR EACH
AIRPLANE
Part 3 - One-Time Detailed Inspection of Slat Can (All Groups)
Elapsed HoursTask HoursNumber of PersonsTask
0.501.002Inspect
1.753.502Close Access
2.254.50TOTAL FOR EACH
AIRPLANE
Part 4 - Downstop Assembly Modification - Slats 1-6 (Group 1, Configuration 1)
Elapsed HoursTask HoursNumber of PersonsTask
0.601.202Figure 3
0.601.202Figure 4
0.601.202Figure 5
0.601.202Figure 6
0.601.202Figure 7
0.601.202Figure 8
0.501.002Inspect
1.753.502Close Access
5.8511.70TOTAL FOR EACH
AIRPLANE
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Part 5 - Downstop Assembly Modification - Slats 1-6 (Group 1, Configuration 2; Group 2)
Elapsed HoursTask HoursNumber of PersonsTask
0.601.202Figure 9
0.601.202Figure 10
0.601.202Figure 11
0.601.202Figure 12
0.601.202Figure 13
0.601.202Figure 14
0.501.002Inspect
1.753.502Close Access
5.8511.70TOTAL FOR EACH
AIRPLANE
Part 6 - Tapered Filler Installation (All Groups)
Elapsed HoursTask HoursNumber of PersonsTask
3.7515.004Access
1.00(a)1.00(a)1Remove Slat Can
(b)(b)Figure 15
1.25(a)1.25(a)1Figure 16
3.009.003Close Access
6.7524.00TOTAL FOR EACH
AIRPLANE
(a) Time estimated is per slat can removed and not included in total shown. Multiply number of
slat cans removed by estimate given and add to total.
(b) Time to fabricate part not included in estimate. More time will be necessary to fabricate parts.
The table above shows an estimate of the task hours necessary to do this inspection and change 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.
H. Weight and Balance Changes
None.
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I. Electrical Load Data
Not changed.
J. References
1. Existing Data
a. Engineering Change Memo PRR 35005-290RS
b. Boeing Service Related Problem (SRP) 737-SRP-57-0208, 737-SRP-57-0249
c. Federal Aviation Administration (FAA) Airworthiness Directive 2008-06-29
d. Standard Overhaul Practices Manual (SOPM) 20-30-03, 20-41-02, 20-43-03, 20-50-19
e. 737 Non-Destructive Testing (NDT) Manual Part 4, 51-00-00
f. 737-300/400/500 Aircraft Maintenance Manual (AMM) 12-31-61, 27-81, 27-81-00, 27-81-21,
28-11-00, 28-11-11, 28-23-00
g. 737-300/400/500 Illustrated Parts Catalog (IPC) 57-11, 57-54
h. Boeing Service Bulletins 737-57-1175, 737-57-1156
i. Boeing Program Letter BPL 6-1151-737-PGM-190
2. Data supplied with this Service Bulletin
None.
3. Installation Drawings Used in the Preparation of this Service Bulletin
TitleDrawing Number
Slat Instl - Leading Edge, Wing65C26600
This drawing was used to prepare this service bulletin. This drawing is not necessary to make the
specified changes, and is not supplied with this service bulletin. This drawing may not be applicable
to all airplane configurations or operators.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
737-300/400/500 AMM 27-81737 Maintenance Manual
737-300/400/500 IPC 57-54, 737-
300/400/500 IPC 57-11
737 Illustrated Parts Catalog
2. Damage Tolerance Based Structural Inspections:
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Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
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BLANK PAGE

### Page 29

2.    MATERIAL INFORMATION
A. Material - Price and Availability
Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary for Each Airplane as shown
below. If there is a limit to the quantity (QTY) of available kits, a supply sequence is given by Spares.
More kits become available as shown in the Reorder Lead Time (ROLT). ROLT is calculated from the
date Boeing gets the purchase order.
Reference this service bulletin and submit your purchase order by one of these methods:
1. Order on-line via ATA Spec 2000 or The Boeing PART Page
2. Fax to (206) 662-7145
REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST
RESPONDER AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE
INFORMATION
Group 1 Configuration 2, and Group 2
Unit Price thru
03/31/2011
ROLT
(Weeks)
QTYDateNameKit Number
$3,124.0072 Weeks1003/26/09(a)TOP KIT, RETROFIT -
DOWNSTOP REPLACE-
MENT
65C37853-59
(a) Approximately every 2 weeks, 100 kits will become available for 18 weeks.
Group 1 Configuration 1
Unit Price thru
03/31/2011
ROLT
(Weeks)
QTYDateNameKit Number
$1,080.0077 Weeks253/29/09(a)TOP KIT, RETROFIT -
DOWNSTOP REPLACE-
MENT
65C37853-61 (b)
(a) Approximately every 2 weeks, 25 kits will become available for 6 weeks.
(b) If it is unknown whether the downstop changes as given in service bulletin 737-57-1175 have
been accomplished, Boeing recommends that Kit Number 65C37853-59 be ordered.
B. Industry Support Information
Boeing Industry Support information is provided in Program Letter BPL 6-1151-737-PGM-190 dated
March 9, 2009. Additional copies of program letters are available from Boeing Warranty & Product
Assurance Contracts.
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C. Parts Necessary For Each Airplane
1. Kits/Parts
To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability.
Figure Kit
876543Top Kit
------65C37853-59
11111165C37853-61
Figure Kit
14131211109Top Kit
11111165C37853-59
------65C37853-61
Group 1, Configuration 2; Group 2:
KIT 65C37853-59
NOTES
Existing Part
NumberName
Figure
New Part Number
14131211109
QTY
BOLT22222265C33736-3
STOP FITTING44444469-73825-3
SELF-LOCKING
NUT
222222BACN10JC5CD
PIN, COTTER222222BACP18BC02A06P
WASHER, PLAIN444444NAS1149C0532B
Group 1, Configuration 1:
KIT 65C37853-61
NOTES
Existing Part
NumberName
Figure
New Part Number
876543
QTY
BOLT22222265C33736-3
SELF-LOCKING
NUT
222222BACN10JC5CD
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Group 1, Configuration 1:
KIT 65C37853-61
NOTES
Existing Part
NumberName
Figure
New Part Number
876543
QTY
NUT, CASTELLAT-
ED
222222BACN11N5CD
PIN, COTTER222222BACP18BC02A06P
WASHER, PLAIN444444NAS1149C0516R
2. Parts and Materials Supplied by the Operator
NotesNameQTYPart Number/ Specification
Corrosion Inhibiting Material4 OzBMS 3-38
(b)Tapered Filler-BACF3T03()
Chemical Conversion Coating-ALODINE 600
Corrosion Resistant Finish-BMS 10-20, TYPE II
Sealant-BMS 5-45
(a)Bolt-BACB30VT()K()X
Collar-BACC30BQ
(a) Replace existing fasteners with 1/64th oversize diameter fasteners. Fastener grip length
will vary and will have to be determined upon installation.
(b) Used to make tapered filler for slat can. Dimensions for slat can flange vary from approx-
imately 6.5 to 8.5 inches high by 4.5 inches wide.
3. Parts Modified and Reidentified
None.
4. Parts Removed and Not Replaced
Locators.
D. Parts Necessary to Change Spares
None.
E. Special Tooling - Price and Availability
No special tooling is necessary to do the change in this service bulletin. However, special tooling is
available to help with the installation of the downstop assembly hardware. Send a Purchase Order to
the Director of Spares. Give this service bulletin number and the date the tools will be used.
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Purchase Data:
Unit Price thru
03/31/2011
NameTool Kit Number
$437.00Miscellaneous Tool Main Slat
Downstop Installation Collector
2MIT65C37853-59
The kits are subject to the terms and conditions of the Boeing standard purchase order
acknowledgement. After the Price date, new price data is applicable. Prices are in United States dollars.
Terms: Net 30 days.
Reference this service bulletin number and submit purchase order by one of the methods that follow:
1. Order on-line via ATA Spec 2000 or Boeing Part Page
2. Fax to (206) 662-7145
3. Mail to:
Spares Customer Support - MC 36-65
Boeing Spares Department
P.O. Box 3707
Seattle, Washington 98124-2207 USA
(Service Bulletin 737-57A1301)
REFER TO THE BOEING PART PAGE ON MYBOEINGFLEET.COM OR CONTACT FIRST
RESPONDER AT FR@BOEING.COM FOR THE LATEST REORDER LEAD TIME (ROLT) AND PRICE
INFORMATION
F. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. Maintenance
and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator tool supply to make sure all necessary tools are available.
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3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL
PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,
METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE
DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
2. Obey all of the warnings and cautions given in the specified manual sections.
3. Unless shown differently, these dimensions and tolerances are used:
– Linear dimensions are in inches
– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus
or minus 0.03 inch
– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
– Angular tolerance is plus or minus 2 degrees
– Hole dimensions for standard solid rivets and fasteners are in Structural Repair
Manual (SRM) Chapter 51
– Torque limits to tighten nuts and bolts are in SRM Chapter 51
4. Use the approved fastener and process material substitutions in accordance with
SRM Chapter 51.
5. If the length of any fastener specified in this service bulletin does not meet installation
standards given in SRM Chapter 51, then a fastener of the same specification, or
an approved substitute, with a length which meets the installation standards given
in SRM Chapter 51 may be used. In addition, washers may be installed for fastener
grip length in accordance with SRM Chapter 51.
6. A Detailed Inspection is defined as: An intensive examination of a specific item,
installation, or assembly to detect damage, failure, or irregularity. Available lighting
is normally supplemented with a direct source of good lighting at an intensity deemed
appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be
necessary. Surface cleaning and elaborate procedures may be required.
7. These work instructions refer to procedures included 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 "as
given in or in accordance with" are included in the instruction, the procedure in the
Boeing document must be used.
8. Boeing Service Letter 737-SL-51-042, Damage Reporting and Repair Plan/Design
Guidelines, is an acceptable procedure to request information from Boeing for
additional structural repair instructions. The Service Letter describes what information
must be provided to Boeing before a structural repair can be provided.
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9. Each location in this service bulletin where a detailed inspection is called out, a
borescope may be used.
10. The instructions in Paragraph 3.B., Work Instructions and the figures can include
operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated
Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing
Index contain data on versions of the tools or test equipment that you can use. It is
permitted to use replaced tools. It is not permitted to use superseded tools.
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. Where the work instructions include installation of a kept part, a new or serviceable
part with the same part number can be installed as an alternative to the kept part.
The removed part can be discarded if a new or serviceable part is installed.
13. This service bulletin includes functional test procedures for the systems changed by
this service bulletin. More functional tests can possibly be necessary in accordance
with standard maintenance practices because of interruption to other airplane systems.
14. Some Boeing parts are supplied in a temporary configuration. Those parts are
identified with a 'U', 'W', or 'Y' in place of the '-' (dash) in the part number. It is
permitted to install parts identified with a 'U', 'W', or 'Y' as an alternative to the '-'
(dash) part number. Boeing Drawing 005W0900 contains more data.
B. WORK INSTRUCTIONS
Part 1 - Downstop Assembly Access
1. If necessary, remove the applicable access panels on the lower surface of the wing leading edge
to gain access to the two main tracks of slats 1 through 6. Refer to 737-300/400/500 AMM 27-81-21
as an accepted procedure.
2. The downstop assembly can be inspected by using a one inch extendable mirror, or similar mirror,
placed between the two ribs. The downstop assembly can also be viewed through the access hole
in the ribs on each side of the slat track. The downstop assembly can also be viewed using a
borescope through the drain holes in the lower access panels or elsewhere as necessary.
Disassembly of the downstop is not required to accomplish this inspection.
If it is necessary to line up the downstop assembly with the access holes in the ribs, you can use
the following procedure:
a. Pressurize hydraulic system B by toggling the hydraulic system B electric motor pump switch,
located on the P5-8 panel, to ON.
b. Place the flap handle to detent 40.
c. Allow the leading edge slats to fully extend.
d. Toggle the hydraulic system B electric motor pump switch to OFF.
e. Place the flap handle to detent 5.
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f. Turn on, and then immediately turn off (pulse), the hydraulic system B electric motor pump
switch.
g. If the downstop has not moved far enough to line up with the access holes in the ribs, then
pulse the hydraulic system B electric motor pump switch again. Repeat this step until the
downstop assembly lines up with the access holes.
NOTE: Successive start up cycles (pulses) of the hydraulic system B electric motor pump
can overheat the pump and damage it. Do not let the pump get too hot to touch. If
the pump gets hot and/or the overheat light on the P5-8 panel is illuminated, wait
until the pump is cool enough to touch and the warning light goes off before pulsing
or turning on the pump.
h. Once the downstop assembly lines up with the access holes, place the flap handle to detent
40.
As an option to using the above procedure, you can deactivate the slats, disconnect the actuator
from the slat, and move the slat manually to line up the downstop assemblies with the access
holes. Refer to 737-300/400/500 AMM 27-81-21 and 737-300/400/500 AMM 27-81-00 as an
accepted procedure.
Part 2 - Detailed Inspection of the Downstop Assemblies
1. Group 1, Configuration 1:
For slat 2, 3, 4, and 5 and the inboard track of the number 1 and 6 slats: do a detailed inspection
of the downstop assembly for each main track as given in FIGURE 1.
2. Group 1, Configuration 2; Group 2:
For slat 2, 3, 4, and 5 and the inboard track of the number 1 and 6 slats: do a detailed inspection
of the downstop assembly for each main track as given in FIGURE 2.
3. If a downstop assembly part is missing or if a downstop assembly part is damaged, then:
a. Do a detailed inspection of the inside of the slat can. Look for loose parts (FOD) and look for
damage to the wall of the slat can.
(1) If you find a loose part (FOD) in the slat can, remove it.
(2) If the slat can is damaged:
NOTE: To determine the Wall thickness, refer to 737 NDT Part 4, 51-00-00, Figure 2
or Figure 3, as an accepted procedure.
(a) If the minimum wall thickness of the slat can in the damaged region is greater than
or equal to .040 inches, then remove the slat. Refer to 737-300/400/500 AMM
27-81-21 as an accepted procedure. Do a blendout repair as given in FIGURE 17.
As an option you may replace the slat can with a new or serviceable slat can.
(b) If the minimum wall thickness of the slat can in the damaged region is less than .040
inches or if a crack was found, then do the following:
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1) Defuel the fuel tank common to the damaged slat can. Refer to 737-300/400/500
AMM 28-23-00 as an accepted procedure.
2) Gain access to the slat can. If necessary:
a) Remove applicable wing access doors. Refer to 737-300/400/500 AMM
28-11-11 and 737-300/400/500 AMM 12-31-61 as accepted procedures.
b) Remove applicable lower wing panels. Refer to 737-300/400/500 AMM
27-81-21 and 737-300/400/500 AMM 12-31-61 as an accepted procedure.
c) Remove slat (if necessary). Refer to 737-300/400/500 AMM 27-81-21 as
an accepted procedure.
3) Remove and replace the slat can with a new or serviceable slat can.
4) Reinstall wing access doors and lower wing panels and slat (if removed). Refer
to 737-300/400/500 AMM 27-81-21 as an accepted procedure.
b. If a downstop assembly part is missing or damaged, then replace the part. Refer to
737-300/400/500 AMM 27-81-21 as an accepted procedure.
4. If downstop assembly parts are in the wrong order, remove the downstop assembly and reinstall
the parts. Refer to 737-300/400/500 AMM 27-81-21 as an accepted procedure.
NOTE: FIGURE 1 and FIGURE 2 show the bolt head on a particular side of the slat track.
However, the bolt head can be installed on either side of the slat track. For FIGURE 2
downstop assemblies, the locator must be installed on the same side of the slat track as
the bolt head.
5. Hold the bolt head and torque the nut to 50 - 75 pound inches. After torquing the nut, do a detailed
inspection to verify that the entire chamfered portion of the bolt protrudes beyond the outer surface
of the nut.
a. If the entire chamfered portion of the bolt does not protrude beyond the outer surface of the
nut after you torque it, then you must remove the downstop assembly and reinstall the parts.
Refer to 737-300/400/500 AMM 27-81-21 as an accepted procedure. It is acceptable to use
a thinner washer under the nut.
6. Install any access panels that were removed.
7. If the slats were deactivated, put them back into a serviceable condition. Refer to 737-300/400/500
AMM 27-81-00 as an accepted procedure.
8. Put the airplane back to a serviceable condition.
Part 3 - One-Time Detailed Inspection of Slat Can (All Groups)
1. Do a detailed inspection for any damage to the interior surface of the slat can for the inboard and
outboard tracks of slats 2 through 5, and the inboard tracks of slats 1 and 6. Also do a detailed
inspection for debris (FOD).
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a. If there is damage to the slat can, then do a detailed inspect the wall thickness in the damaged
region.
NOTE: To determine the Wall thickness, refer to 737 NDT Part 4, 51-00-00, Figure 2 or
Figure 3, as an accepted procedure.
(1) If the minimum wall thickness of the slat can in the damaged region is greater than or
equal to .040 inches, then remove the slat. Refer to 737-300/400/500 AMM 27-81-21 as
an accepted procedure. Do a blendout repair as given in FIGURE 17. As an option you
may replace the slat can with a new or serviceable slat can.
(a) If there is damage on the interior surface of the slat can, this is an indication that
there may be no clearance between the slat can and the track. Do an inspection for
clearance. If there is no clearance between the bottom of the slat can and slat main
track, then install a tapered filler as given in Part 6 of the accomplishment instructions.
(2) If the minimum wall thickness of the slat can in the damaged region is less than .040
inches or if a crack was found, then replace the slat can with a new or serviceable slat
can.
b. If debris (FOD) is found, remove it.
2. Put the airplane back to a serviceable condition.
Part 4 - Downstop Assembly Modification - Slats 1-6 (Group 1, Configuration 1)
1. Gain access to downstops for slats 1 through 6. Refer to Part 1 as an accepted procedure.
2. Install the new downstop assembly hardware as given in:
SLAT NUMBERFIGURE
13
24
35
46
57
68
Keep the existing downstops and reinstall them with the new nut, washers, bolt, and cotter pin.
Optional tooling is available from Boeing to assist in installing the new downstop assembly hardware.
Refer to Paragraph 2.E., Special Tooling - Price and Availability.
NOTE: Be careful in handling the small parts. Do not drop them.
3. Return the airplane to a serviceable condition.
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### Page 38

Part 5 - Downstop Assembly Modification - Slats 1-6 (Group 1, Configuration 2; Group 2)
1. Gain access to downstops for slats 1 through 6. Refer to Part 1 as an accepted procedure.
2. Install the new downstop assembly hardware as given in:
SLAT NUMBERFIGURE
19
210
311
412
513
614
Remove all downstop assembly hardware and replace with new hardware. Optional tooling is
available from Boeing to assist in installing the new downstop assembly hardware. Refer to
Paragraph 2.E., Special Tooling - Price and Availability.
NOTE: Be careful in handling the small parts. Do not drop them.
3. Return the airplane to a serviceable condition.
Part 6 - Tapered Filler Installation (All Groups)
1. Defuel the fuel tank common to the damaged slat can. Refer to 737-300/400/500 AMM 28-23-00
as an accepted procedure.
2. Gain access to the slat can(s) that failed the clearance inspection in Part 3. If necessary:
a. Remove applicable wing access doors. Refer to 737-300/400/500 AMM 28-11-11 and
737-300/400/500 AMM 12-31-61 as accepted procedures.
b. Remove applicable lower wing panels. Refer to 737-300/400/500 AMM 27-81-21 and
737-300/400/500 AMM 12-31-61 as an accepted procedure.
c. Remove slat (if necessary). Refer to 737-300/400/500 AMM 27-81-21 as an accepted
procedure.
3. Fabricate a tapered filler as given in FIGURE 15.
4. Remove the slat can from the front spar and install the tapered filler and the slat can as given in
FIGURE 16.
5. Reinstall wing access doors and lower wing panels and slat (if removed). Refer to 737-300/400/500
AMM 27-81-21 as an accepted procedure.
6. Return the airplane to a serviceable condition.
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### Page 39 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
LEFT WING SHOWN
(RIGHT WING IS EQUIVALENT)
FWD SINBD
SEE
1 SEE B
FADE
INBD
SLAT NUMBER 3 SHOWN  1475106
(TYPICAL)
FIGURE 1: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY
(SHEET 1 OF 2)
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### Page 40

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for each slat track.
MORE DATAQTYNAMETASKSTEP
(a)1BoltInspect1
(a)1WasherInspect
(a)2Stop FittingInspect
(a)1WasherInspect
(a)1NutInspect
(a) Verify parts are installed in the correct order as shown. Disassembly of the downstop is not required to
accomplish this detailed inspection.
FIGURE 1: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY
(SHEET 2 OF 2)
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### Page 41 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 2; Group 2.
LEFT WING SHOWN
(RIGHT WING IS EQUIVALENT)
FWD INBD
SEE
O SEE 100
TOMI
SONI
SLAT NUMBER 3 SHOWN  1475133
(TYPICAL)
FIGURE 2: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY
(SHEET 1 OF 3)
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### Page 42 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
1 ASSEMBLY  STOP FITTING
1 LOCATOR
1) STOP FITTING
> WASHER
) NUT
STOP FITTING  TYPICAL INSTALLATION - SLAT NUMBER 2 THROUGH 5
ASSEMBLY  AND OUTBOARD TRACK - SLAT NUMBER 1
AND OUTBOARD TRACK - SLAT NUMBER 6
1 LOCATOR
) STOP FITTING
1 WASHER  ASSEMBLY  STOP FITTING
> NUT
FWD '  • INBD  LOCATOR 1
STOP FITTING 1
INBOARD TRACK - SLAT NUMBER 1  WASHER
NUT (1
INBD<  • FWD
INBOARD TRACK - SLAT NUMBER 6  1475140
FIGURE 2: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY
(SHEET 2 OF 3)
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### Page 43

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for each slat track.
MORE DATAQTYNAMETASKSTEP
(a)1NutInspect1
(a)1WasherInspect
(a)1Stop FittingInspect
(d) (a) (b)1LocatorInspect
(a) (c)1Stop Fitting Assem-
bly
Inspect
(a) Verify parts are installed in the correct order as shown. Disassembly of the downstop is not required to
accomplish this detailed inspection.
(b) Make sure the locator isn't bent or damaged.
(c) The washer under the head of the bolt in the Stop Fitting Assembly may be difficult to see. Proper instal-
lation of this washer does not need to be confirmed.
(d) On the inboard track of slats 1 and 6, the locator cannot be rotated from what is shown.
FIGURE 2: DETAILED INSPECTION OF THE DOWNSTOP ASSEMBLY
(SHEET 3 OF 3)
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### Page 44 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
FWD <  → INBD
SEE
OUTBOARD SLAT
MAIN TRACK  SLAT NUMBER 1
SEE
INBOARD SLAT
MAIN TRACK
1) STOP FITTING  1 BOLT
@WASHER
1 NUT
SLAT
1 WASHER  STOP FITTING  MAIN  TRACK
SEE
DOWNSTOP
ASSEMBLY
FWD <
INBOARD SLAT MAIN TRACK
(BEFORE MODIFICATION)
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1
(SHEET 1 OF 5)
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### Page 45 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2) COTTER PIN
BOLT
WASHER
STOP
FITTING
WASHER
SELF-LOCKING  STOP  - SLAT
NUT  FITTING  MAIN
TRACK
FWD T
DOWNSTOP
ASSEMBLY
INBOARD SLAT MAIN TRACK
(AFTER MODIFICATION)
TYPICAL INSTALLATION
1798256
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1
(SHEET 2 OF 5)
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### Page 46 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
BOLT
WASHER
STOP
FITTING
FWD <
WASHER
NUT  STOP
FITTING
- SLAT
MAIN
TRACK
SEE
DOWNSTOP
ASSEMBLY
OUTBOARD SLAT MAIN TRACK
(BEFORE MODIFICATION)
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1
(SHEET 3 OF 5)
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### Page 47 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2 COTTER PIN
(г)
BOLT
(2)
WASHER
STOP
FWD  FITTING
• SLAT
NUT  MAIN
TRACK
DOWNSTOP
ASSEMBLY
OUTBOARD SLAT MAIN TRACK
(AFTER MODIFICATION)
TYPICAL INSTALLATION
1814441
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1
(SHEET 4 OF 5)
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### Page 48

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for each slat.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
2-NutRemove1
2-WasherRemove
469-73825-2Stop FittingRemove / Keep
2-WasherRemove
(e)2-BoltRemove
(a) (e)265C33736-3BOLTInstall (New)2
2NAS1149C0516RWASHER, PLAINInstall (New)
(b)469-73825-2Stop FittingInstall (Kept)
(b)-BMS 3-38Corrosion Inhibiting
Material
Apply
2NAS1149C0516RWASHER, PLAINInstall (New)
(c) (g)2BACN10JC5CDSELF-LOCKING NUTInstall (New)
Optional(c) (g)2BACN11N5CDNUT, CASTELLATEDInstall (New)
(d) (f)2BACP18BC02A06PPIN, COTTERInstall (New)
(a) Optional - Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip or similar pen.
(b) Apply corrosion inhibiting material to bolt shank and inner faces of both downstop fittings.
(c) Torque the nut to 50-75 inch-pounds.
(d) Using marked line as reference, rotate bolt so that cotter pin can be installed. Install cotter pin approxi-
mately as shown in the illustration. Be careful not to damage the bolt threads when installing the cotter
pin.
(e) The downstop assembly can be installed with the bolt head on either the inboard side or the outboard
side of the slat main track.
(f) Optional Tool 2MIT65C37853-59 will ease installation of the downstop assembly and cotter pin. Refer to
Paragraph 2.E., Special Tooling - Price and Availability.
(g) BACN11N5CD Castellated Nut Optional if tolerance stack-up does not allow the cotter pin to be installed
using a BACN10JC5CD nut.
FIGURE 3: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 1
(SHEET 5 OF 5)
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BOEING SERVICE BULLETIN 737-57A1301

### Page 49 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
FWD <  → INBD
SEE
OUTBOARD SLAT  SLAT NUMBER 2
MAIN TRACK
SEE A
INBOARD SLAT
MAIN TRACK
1 STOP FITTING  1 BOLT
1 WASHER
1 NUT
SLAT
1 WASHER  STOP FITTING  TRACK  MAIN
SEE
DOWNSTOP
FWDY  ASSEMBLY
BEFORE MODIFICATION  1798046
FIGURE 4: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 2
(SHEET 1 OF 3)
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### Page 50 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2) COTTER PIN
BOLT
WASHER
FWD T  STOP
FITTING
WASHER
SELF-LOCKING  STOP  • SLAT
NUT  FITTING  MAIN
TRACK
DOWNSTOP
ASSEMBLY
AFTER MODIFICATION
TYPICAL INSTALLATION
1816650
FIGURE 4: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 2
(SHEET 2 OF 3)
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### 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 each slat.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
2-NutRemove1
2-WasherRemove
469-73825-2Stop FittingRemove / Keep
2-WasherRemove
(e)2-BoltRemove
(a) (e)265C33736-3BOLTInstall (New)2
2NAS1149C0516RWASHER, PLAINInstall (New)
(b)469-73825-2Stop FittingInstall (Kept)
(b)-BMS 3-38Corrosion Inhibiting
Material
Apply
2NAS1149C0516RWASHER, PLAINInstall (New)
(c) (g)2BACN10JC5CDSELF-LOCKING NUTInstall (New)
Optional(c) (g)2BACN11N5CDNUT, CASTELLATEDInstall (New)
(d) (f)2BACP18BC02A06PPIN, COTTERInstall (New)
(a) Optional - Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip or similar pen.
(b) Apply corrosion inhibiting material to bolt shank and inner faces of both downstop fittings.
(c) Torque the nut to 50-75 inch-pounds.
(d) Using marked line as reference, rotate bolt so that cotter pin can be installed. Install cotter pin approxi-
mately as shown in the illustration. Be careful not to damage the bolt threads when installing the cotter
pin.
(e) The downstop assembly can be installed with the bolt head on either the inboard side or the outboard
side of the slat main track.
(f) Optional Tool 2MIT65C37853-59 will ease installation of the downstop assembly and cotter pin. Refer to
Paragraph 2.E., Special Tooling - Price and Availability.
(g) BACN11N5CD Castellated Nut Optional if tolerance stack-up does not allow the cotter pin to be installed
using a BACN10JC5CD nut.
FIGURE 4: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 2
(SHEET 3 OF 3)
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BOEING SERVICE BULLETIN 737-57A1301

### Page 52 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
FWD<  • INBD
SEE  SLAT NUMBER 3
OUTBOARD SLAT
MAIN TRACK
SEE
INBOARD SLAT
MAIN TRACK
1 STOP FITTING  1 BOLT
1 WASHER
1 NUT
SLAT
~ WASHER  1 STOP FITTING  MAIN
TRACK
SEE
• DOWNSTOP
ASSEMBLY
FWD .
BEFORE MODIFICATION  1798048
FIGURE 5: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 3
(SHEET 1 OF 3)
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### Page 53 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2 COTTER PIN
(г)
BOLT
(2)
(2)  WASHER
STOP
FITTING
• SLAT
NUT  MAIN
TRACK
DOWNSTOP
ASSEMBLY
B
AFTER MODIFICATION
TYPICAL INSTALLATION
1818304
FIGURE 5: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 3
(SHEET 2 OF 3)
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### Page 54

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for each slat.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
2-NutRemove1
2-WasherRemove
469-73825-2Stop FittingRemove / Keep
2-WasherRemove
(e)2-BoltRemove
(a) (e)265C33736-3BOLTInstall (New)2
2NAS1149C0516RWASHER, PLAINInstall (New)
(b)469-73825-2Stop FittingInstall (Kept)
(b)-BMS 3-38Corrosion Inhibiting
Material
Apply
2NAS1149C0516RWASHER, PLAINInstall (New)
(c) (g)2BACN10JC5CDSELF-LOCKING NUTInstall (New)
Optional(c) (g)2BACN11N5CDNUT, CASTELLATEDInstall (New)
(d) (f)2BACP18BC02A06PPIN, COTTERInstall (New)
(a) Optional - Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip or similar pen.
(b) Apply corrosion inhibiting material to bolt shank and inner faces of both downstop fittings.
(c) Torque the nut to 50-75 inch-pounds.
(d) Using marked line as reference, rotate bolt so that cotter pin can be installed. Install cotter pin approxi-
mately as shown in the illustration. Be careful not to damage the bolt threads when installing the cotter
pin.
(e) The downstop assembly can be installed with the bolt head on either the inboard side or the outboard
side of the slat main track.
(f) Optional Tool 2MIT65C37853-59 will ease installation of the downstop assembly and cotter pin. Refer to
Paragraph 2.E., Special Tooling - Price and Availability
(g) BACN11N5CD Castellated Nut Optional if tolerance stack-up does not allow the cotter pin to be installed
using a BACN10JC5CD nut.
FIGURE 5: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 3
(SHEET 3 OF 3)
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BOEING SERVICE BULLETIN 737-57A1301

### Page 55 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
SLAT NUMBER 4  SEE A
OUTBOARD SLAT
MAIN TRACK
SEE
INBD <  → FWD
INBOARD SLAT
MAIN TRACK
1
1) WASHER  BOLT
1 STOP FITTING
1 WASHER 1 STOP FITTING  MAIN  SLAT
NUT  TRACK
SEE
FWD
BEFORE MODIFICATION  1798052
FIGURE 6: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 4
(SHEET 1 OF 3)
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### Page 56 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2 COTTER
PIN
BOLT
(2)  WASHER
STOP
FWD T  FITTING
WASHER
SELF-LOCKING  STOP  - SLAT
NUT  FITTING  MAIN
TRACK
DOWNSTOP
ASSEMBLY
AFTER MODIFICATION
TYPICAL INSTALLATION  1818462
FIGURE 6: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 4
(SHEET 2 OF 3)
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### 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 each slat.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
2-NutRemove1
2-WasherRemove
469-73825-2Stop FittingRemove / Keep
2-WasherRemove
(e)2-BoltRemove
(a) (e)265C33736-3BOLTInstall (New)2
2NAS1149C0516RWASHER, PLAINInstall (New)
(b)469-73825-2Stop FittingInstall (Kept)
(b)-BMS 3-38Corrosion Inhibiting
Material
Apply
2NAS1149C0516RWASHER, PLAINInstall (New)
(c) (g)2BACN10JC5CDSELF-LOCKING NUTInstall (New)
Optional(c) (g)2BACN11N5CDNUT, CASTELLATEDInstall (New)
(d) (f)2BACP18BC02A06PPIN, COTTERInstall (New)
(a) Optional - Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip or similar pen.
(b) Apply corrosion inhibiting material to bolt shank and inner faces of both downstop fittings.
(c) Torque the nut to 50-75 inch-pounds.
(d) Using marked line as reference, rotate bolt so that cotter pin can be installed. Install cotter pin approxi-
mately as shown in the illustration. Be careful not to damage the bolt threads when installing the cotter
pin.
(e) The downstop assembly can be installed with the bolt head on either the inboard side or the outboard
side of the slat main track.
(f) Optional Tool 2MIT65C37853-59 will ease installation of the downstop assembly and cotter pin. Refer to
Paragraph 2.E., Special Tooling - Price and Availability
(g) BACN11N5CD Castellated Nut Optional if tolerance stack-up does not allow the cotter pin to be installed
using a BACN10JC5CD nut.
FIGURE 6: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 4
(SHEET 3 OF 3)
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: February 05, 2008
737-57A1301Revision 3 August 11, 2011
57 of 94
BOEING SERVICE BULLETIN 737-57A1301

### Page 58 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
This Figure applies only to: Group 1, Configuration 1.
SLAT NUMBER 5  SEE (A
OUTBOARD SLAT
MAIN TRACK
SEE A
INBD  → FWD
INBOARD SLAT
MAIN TRACK
1 WASHER
1 BOLT
1 STOP FITTING
• SLAT
WASHER  MAIN
NUT  STOP
FITTING
SEE
ASSEMBLY
FWD <
BEFORE MODIFICATION  (A  1798050
FIGURE 7: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 5
(SHEET 1 OF 3)
Original Issue: February 05, 2008
Revision 3 August 11, 2011  BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.

### Page 59 (OCR)

BOEING SERVICE BULLETIN 737-57A1301
2) COTTER
PIN
(2)
BOLT
WASHER
FWD <  STOP
FITTING
WASHER
STOP  SLAT
SELF-LOCKING  FITTING  MAIN
NUT  TRACK
DOWNSTOP
ASSEMBLY
AFTER MODIFICATION
TYPICAL INSTALLATION  1818521
FIGURE 7: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 5
(SHEET 2 OF 3)
Original Issue: February 05, 2008
Revision 3 August 11, 2011  737-57A1301
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.  59 of 94

### 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 each slat.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
2-NutRemove1
2-WasherRemove
469-73825-2Stop FittingRemove / Keep
2-WasherRemove
(e)2-BoltRemove
(a) (e)265C33736-3BOLTInstall (New)2
2NAS1149C0516RWASHER, PLAINInstall (New)
(b)469-73825-2Stop FittingInstall (Kept)
(b)-BMS 3-38Corrosion Inhibiting
Material
Apply
2NAS1149C0516RWASHER, PLAINInstall (New)
(c) (g)2BACN10JC5CDSELF-LOCKING NUTInstall (New)
Optional(c) (g)2BACN11N5CDNUT, CASTELLATEDInstall (New)
(d) (f)2BACP18BC02A06PPIN, COTTERInstall (New)
(a) Optional - Mark reference line on threaded end of bolt to show cotter pin hole using felt-tip or similar pen.
(b) Apply corrosion inhibiting material to bolt shank and inner faces of both downstop fittings.
(c) Torque the nut to 50-75 inch-pounds.
(d) Using marked line as reference, rotate bolt so that cotter pin can be installed. Install cotter pin approxi-
mately as shown in the illustration. Be careful not to damage the bolt threads when installing the cotter
pin.
(e) The downstop assembly can be installed with the bolt head on either the inboard side or the outboard
side of the slat main track.
(f) Optional Tool 2MIT65C37853-59 will ease installation of the downstop assembly and cotter pin. Refer to
Paragraph 2.E., Special Tooling - Price and Availability
(g) BACN11N5CD Castellated Nut Optional if tolerance stack-up does not allow the cotter pin to be installed
using a BACN10JC5CD nut.
FIGURE 7: SLAT MAIN TRACK DOWNSTOP ASSEMBLY MODIFICATION - SLAT 5
(SHEET 3 OF 3)
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: February 05, 2008
737-57A1301Revision 3 August 11, 2011
60 of 94
BOEING SERVICE BULLETIN 737-57A1301

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