# Boeing Alert Service Bulletin 737-26A1137: SB-737-26A1137-00

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2015-0681; AD 2016-04-06 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Service Bulletin 737-26A1137](https://openairdocs.org/service-documents/boeing/737-26a1137.md)
- Title as filed: SB-737-26A1137-00
- Pages: 37
- PDF: https://openairdocs.org/files/sha256/46/25/46257590c63cad3a297a96a2fc2651994592683008c49d69e9da6350f0ecddc8
- Page: https://openairdocs.org/service-documents/boeing/737-26a1137/file/46257590c63c

## Text

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### Page 1

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-26A1137
Original Issue: May 22, 2014
ATA System: 2616 2127
SUBJECT: FIRE PROTECTION - Cargo Bay Smoke Detection - Equipment Cooling System Smoke
Clearance Mode Operational Test for Cargo Smoke Protection
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). An export license may be required before it is used for development, production or use by foreign
persons from specific countries. The controller of this data has the individual responsibility to abide by all export
laws.
9E991ECCN:
BOEING PROPRIETARY, CONFIDENTIAL AND/OR TRADE SECRET
Copyright © 2014 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,
BBJ, DC-8, DC-9, DC-10, KC-10, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and
Boeing liveries are all trademarks owned by The Boeing Company; and no trademark license is granted in
connection with this document unless provided in writing by Boeing.
Original Issue: May 22, 2014
737-26A1137
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2.0

### Page 2

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### Page 3

Table of Contents
Summary ...................................................... 5
1. PLANNING INFORMATION ........................................ 9
A. Effectivity ................................................ 9
1. Airplanes ............................................. 9
2. Spares Affected ........................................ 2 8
B. Concurrent Requirements ...................................... 2 8
C. Reason ................................................ 2 8
D. Description .............................................. 2 9
E. Compliance .............................................. 2 9
F. Approval ............................................... 3 0
G. Manpower .............................................. 3 0
H. Weight and Balance Changes .................................... 3 1
I. Electrical Load Data ......................................... 3 1
J. References .............................................. 3 1
1. Existing Data: ......................................... 3 1
2. Data Supplied with this Service Bulletin: ........................... 3 1
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 3 1
K. Publications Affected ........................................ 3 1
L. Interchangeability and Intermixability of Parts ........................... 3 2
M. Software Accomplishment Summary ................................ 3 2
2. MATERIAL INFORMATION ........................................ 3 3
A. Material - Price and Availability ................................... 3 3
B. Industry Support Information .................................... 3 3
C. Parts Necessary for Each Airplane ................................. 3 3
1. Kits/Parts: ........................................... 3 3
2. Parts and Materials Supplied by the Operator: ........................ 3 3
3. Parts Modified and Reidentified: ............................... 3 3
4. Parts Removed and Not Replaced: .............................. 3 3
D. Parts Necessary to Change Spares ................................. 3 3
E. Special Tooling - Price and Availability ............................... 3 3
F. Special Tooling Necessary to do this Service Bulletin ....................... 3 3
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 5
A. GENERAL INFORMATION ..................................... 3 5
B. WORK INSTRUCTIONS ....................................... 3 6
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PROPRIETARY - Copyright © Unpublished
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Original Issue: May 22, 2014
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### Page 5

Commercial 
Airplanes
737
Service Bulletin
ALERT
SummaryNumber: 737-26A1137Original Issue: May 22, 2014
ATA System: 2616 2127
SUBJECT: FIRE PROTECTION - Cargo Bay Smoke Detection - Equipment Cooling System Smoke
Clearance Mode Operational Test for Cargo Smoke Protection
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
CONCURRENT REQUIREMENTS
Refer to Paragraph 1.B., Concurrent Requirements.
BACKGROUND
This service bulletin gives instructions to do the Smoke Clearance Mode - Operational Test at the repeat intervals
on airplanes equipped with the reconfigured low pressure air distribution system during a cargo fire event. The
repeat operational testing of the Equipment Cooling System and Low Pressure Environmental Control System
(ECS) will reduce the probability of a latent failure which could result in smoke and/or fire in the airplane.
A subsequent review by Boeing found that there was no maintenance procedure available to inspect the
components used to reconfigure the air distribution system. Without the maintenance procedure, failures of
components could possibly be latent for periods greater than required to meet certification requirements. A cargo
fire event in conjunction with a latent failure of the air distribution system can possibly result in smoke penetration
to occupied areas. The amount of smoke and toxicity of the smoke that could reach the occupied areas is
unknown.
Boeing Service Bulletins 737-26-1121 and either 737-21-1135 or 737-21-1163 are related to 737-26-1122.
Accomplishment of the changes in the Boeing Service Bulletins 737-26-1121, 737-21-1135 or 737-21-1163 will
not cause a failure of the test in this service bulletin. Boeing Service Bulletin 737-26A1083 is related to
737-21-1135.
Boeing Service Related Problem (SRP) 737-SRP-26-0079 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
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### Page 6

ReferenceAffectedPlanning Data
Paragraph 1.E., Compliance and Paragraph
1.F., Approval
YesAD Related
Paragraph 1.H., Weight and Balance ChangesNoWeight and Balance Change
Paragraph 1.I., Electrical Load DataNoElectrical Load Changed
Paragraph 1.K., Publications AffectedYesPublications Affected
Paragraph 1.K., Publications AffectedYesAirplane Flight Operations Affected (Flight Crew
Operations Manual and/or FAA Approved Air-
plane Flight Manual)
Paragraph 2.C.1., Kits/PartsNoKits/Parts Required
Paragraph 2.C.2., Parts and Materials Supplied
by the Operator
NoOperator Supplied Parts/Material
Paragraph 2.F., Special Tooling Necessary to
do this Service Bulletin
NoSpecial Tooling Required
ACTION
Get access into the flight compartment and main electronics equipment compartment. As an alternate location
to the flight compartment to make sure of the Recirculation Fan's operation, between the left and right air
conditioning (AC) pack compartments, open the access panel to the ground conditioned air connection duct.
Do the Smoke Clearance Mode - Operational Test to make sure the cargo smoke system operates correctly. If
the Smoke Clearance Mode - Operational Test result is not satisfactory, do the troubleshooting procedure on
the Equipment Cooling and Low Pressure ECS systems to find and replace faulty component.
EFFECTIVITY
All 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER Airplanes. Refer to Paragraph 1.A., Effectivity,
for the list of affected airplanes.
COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service
bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin
mandatory.
Refer to Paragraph 1.E., Compliance.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the Operational Test given in this service bulletin.
MANPOWER
Elapsed HoursTotal Task HoursAirplanes
2.504.00Each 737 Airplane
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### Page 7 (OCR)

ALERT
MATERIAL INFORMATION
None.
Original Issue: May 22, 2014
BOEING SERVICE BULLETIN 737-26A1137
ALERT
IN FLIGHT COMPARTMENT AND MAIN
ELECTRONICS COMPARTMENT:
-DO SMOKE CLEARANCE MODE
OPERATIONAL TEST
-IF TEST RESULTS NOT SATISFACTORY,
TROUBLESHOOT SYSTEM COMPONENTS
BELOW AC MIX AIR COMPARTMENT:
-AS AN ALTERNATE LOCATION TO FLIGHT
COMPARTMENT TO MAKE SURE OF RECIRCULATION
FAN'S OPERATION, OPEN ACCESS PANEL 191E
-MAKE SURE THERE IS AIR FLOW DURING SMOKE
CLEARANCE MODE TEST
2302407
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### Page 9

Commercial 
Airplanes
737
Service Bulletin
ALERT
Number: 737-26A1137
Original Issue: May 22, 2014
ATA System: 2616 2127
SUBJECT: FIRE PROTECTION - Cargo Bay Smoke Detection - Equipment Cooling System Smoke
Clearance Mode Operational Test for Cargo Smoke Protection
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
This service bulletin is applicable to 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER,
line numbers 1 through 9999 in three Groups. The Variable Numbers and Group Information for
the applicable airplanes is given below.
Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
NOTE: Variable numbers for airplanes scheduled to be delivered more than a year after the
Original Issue date of this service bulletin are not listed in the table below. MyBoeingFleet
(MBF) will show current listing of the affected airplanes.
NOTE: The Variable Number table below includes all affected airplanes up to Line Number 5263.
Affected airplanes after Line Number 5263 will be added to the service bulletin's
MyBoeingFleet.com (MBF) "get effectivity" result when they are added to the MBF Fleet
Profile Page.
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### Page 10

DESCRIPTIONCONFIGURATIONGROUP
737-600/-700/-800 Line Numbers 1 Through 1700 Included in Boeing
Service Bulletin 737-26-1122
-1
737-600/-700/-800 Line Numbers 1 Through 1700 Included in Boeing
Service Bulletin 737-26-1122 and Had Not Accomplished Boeing
Service Bulletin 737-26-1122
1
737-600/-700/-800 Line Numbers 1 Through 1700 Included in Boeing
Service Bulletin 737-26-1122 and Had Accomplished Boeing Service
Bulletin 737-26-1122
2
737-700/-700C/-900 Line Numbers 1 Through 1700 Not Included in
Boeing Service Bulletin 737-26-1122
-2
737-600/-700/-700C/-800/-900/-900ER Line Numbers 1701 and All
Line Numbers After 1701
-3
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
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GroupVariable Number
1YA541 - YA552
1YA571 - YA578
1YA601 - YA615
1YA621 - YA622
1YA626 - YA631
1YA635 - YA636
1YA641 - YA642
1YA645 - YA650
1YA656 - YA659
1YA666 - YA667
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 - YA976
3YA977 - YA978
1YB001 - YB006
1YB101 - YB132
1YB151 - YB153
1YB156 - YB157
3YB158
1YB161 - YB164
1YB171 - YB172
1YB181 - YB184
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GroupVariable Number
1YB201 - YB208
1YB271
1YB276
1YB301 - YB310
1YB371 - YB380
3YB381 - YB392
1YB501 - YB502
1YB521 - YB525
3YB526
1YB541 - YB544
1YB551
1YB561 - YB573
3YB574 - YB580
1YB581 - YB586
3YB587 - YB598
1YB601 - YB629
3YB630
1YB631 - YB632
3YB633 - YB636
1YB651
1YB656
3YB671 - YB672
1YB851 - YB859
3YB860
1YB861 - YB863
1YB871 - YB873
3YB874
1YB881 - YB888
3YB889 - YB893
1YB901 - YB903
1YB911
3YB961 - YB975
3YB981
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GroupVariable Number
3YB986 - YB998
1YC001 - YC030
1YC051 - YC083
3YC084
1YC091 - YC094
3YC095
1YC101 - YC104
1YC111 - YC113
1YC121
1YC126 - YC127
1YC136 - YC141
1YC146 - YC147
1YC151 - YC156
1YC166 - YC171
1YC176 - YC178
3YC179
1YC186 - YC189
3YC190
1YC201 - YC203
1YC206 - YC207
1YC301 - YC305
1YC321 - YC385
3YC386 - YC387
1YC391 - YC394
1YC396
1YC401 - YC417
1YC421 - YC422
1YC426 - YC428
1YC436 - YC437
3YC438 - YC439
1YC441 - YC448
1YC451 - YC455
1YC459
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GroupVariable Number
1YC461 - YC467
1YC471 - YC499
1YC501 - YC526
1YC571 - YC583
1YC587 - YC589
1YC591 - YC593
1YC601 - YC655
1YC681 - YC696
1YC701 - YC715
1YC720 - YC725
1YC727 - YC741
3YC742 - YC750
1YC751 - 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 - YD107
3YD108 - YD117
1YD121 - YD126
1YD151 - YD159
1YD171 - YD172
1YD201 - YD203
1YD206 - YD209
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GroupVariable Number
1YD216 - YD219
1YD251 - YD254
1YD256 - YD257
1YD261
1YD301 - YD334
1YD391
1YD401 - YD410
1YD412
3YD413 - YD422
1YD481 - YD485
3YD491 - YD499
2YD501 - YD512
2YD531 - YD535
2YD541 - YD547
2YD561 - YD564
2YD571 - YD572
2YD591 - YD594
3YD595
2YD601 - YD612
3YD651 - YD655
1YE001 - YE020
1YE051
1YE101 - YE109
1YE151 - YE157
1YE171 - YE172
1YE201 - YE206
1YE301 - YE305
1YE321 - YE326
3YE371 - YE383
3YF001 - YF011
3YF021 - YF049
3YF051 - YF080
3YF086 - YF087
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GroupVariable Number
3YF106 - YF107
3YF111 - YF114
3YF116 - YF119
3YF121 - YF132
3YF176 - YF178
3YF191 - YF192
3YF201 - YF276
3YF401 - YF402
3YF431 - YF432
3YF436 - YF437
3YF441 - YF442
3YF451 - YF460
3YF501 - YF599
3YF601 - YF666
3YF701 - YF707
3YF801 - YF805
3YF831 - YF832
3YF836 - YF838
3YF871 - YF872
3YF901 - YF905
3YF921 - YF928
3YF951 - YF954
1YG001 - YG043
2YG044
1YG061 - YG064
1YG066
2YG067
1YG068
2YG069
1YG070 - YG073
2YG074
1YG075 - YG080
2YG081
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GroupVariable Number
1YG082 - YG083
2YG084
1YG085 - YG087
2YG088
1YG089
3YG091 - YG099
3YG101 - YG104
3YG111 - YG114
3YG116 - YG142
1YG201
3YG202 - YG205
1YG211
3YG212 - YG214
3YG221 - YG224
3YG251 - YG252
2YG501 - YG508
3YG509 - YG514
2YG601 - YG602
3YG701
3YG711
3YH001 - YH012
3YH031 - YH055
3YH071 - YH080
3YH101 - YH132
3YH201 - YH202
3YH206 - YH207
3YH301 - YH306
3YH321 - YH322
3YH501 - YH542
3YH551 - YH594
3YH601 - YH606
3YH611 - YH620
3YH631 - YH632
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GroupVariable Number
3YH636 - YH637
3YH641
3YH681
3YH701 - YH723
3YH751
3YH801 - YH831
3YH901 - YH904
3YH911
3YH951
1YJ001 - YJ004
3YJ005 - YJ010
1YJ011 - YJ013
1YJ021
1YJ471 - YJ480
1YJ501 - YJ517
1YJ531 - YJ545
3YJ546 - YJ579
1YJ591 - YJ593
3YJ594 - YJ599
1YJ631 - YJ632
1YJ671 - YJ682
3YJ683 - YJ694
1YJ801 - YJ853
3YJ854 - YJ860
1YJ861 - YJ867
1YJ871
3YJ872 - YJ880
1YJ901 - YJ902
3YJ903 - YJ904
3YJ908 - YJ910
1YJ911 - YJ919
3YJ920 - YJ929
1YJ931 - YJ936
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GroupVariable Number
3YJ937
1YJ941 - YJ943
3YJ944 - YJ956
3YJ961
3YJ976 - YJ977
1YK001 - YK007
1YK101 - YK104
1YK111 - YK112
1YK121 - YK122
1YK131 - YK132
3YK133
1YK136
3YK137 - YK139
3YK141 - YK142
3YK146 - YK148
3YK151 - YK154
3YK161 - YK167
3YK171
3YK176 - YK177
3YK186
3YK191
3YK196
3YK201 - YK202
1YK301 - YK304
3YK305 - YK314
1YK321 - YK330
3YK331 - YK340
1YK361 - YK364
3YK365 - YK378
1YK401 - YK405
3YK406
1YK426
3YK427
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GroupVariable Number
1YK431
3YK432 - YK450
1YK456 - YK458
3YK459 - YK467
3YK471 - YK473
3YK476
1YK480
3YK481 - YK487
3YK491 - YK493
3YK495 - YK499
3YK511 - YK516
3YK521 - YK530
3YK551 - YK571
3YK576 - YK577
3YK580 - YK585
3YK601 - YK602
3YK606 - YK607
3YK611 - YK616
3YK621 - YK634
3YK641 - YK644
3YK651 - YK665
3YK671 - YK672
3YK676 - YK677
3YK681 - YK686
3YK691
3YK695 - YK699
3YK701 - YK713
3YK716 - YK719
3YK721 - YK741
3YK751 - YK770
3YK776 - YK778
3YK781 - YK785
3YK791 - YK792
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GroupVariable Number
3YK796 - YK797
3YK801 - YK899
3YK901 - YK912
3YK918 - YK919
3YK921 - YK929
3YK941 - YK999
3YL001 - YL005
3YL011 - YL016
3YL021 - YL024
3YL051 - YL052
3YL056 - YL057
3YL061
3YL066 - YL069
3YL076 - YL077
3YL101 - YL137
3YL201 - YL237
3YL241 - YL242
3YL271 - YL272
3YL281 - YL284
3YL301 - YL303
3YL311 - YL314
3YL316 - YL321
3YL351 - YL353
3YL371 - YL374
3YL401
3YL421 - YL429
3YL431 - YL444
3YL461 - YL478
3YL501 - YL509
3YL531 - YL534
3YL541 - YL551
3YL561 - YL579
3YL591 - YL598
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GroupVariable Number
3YL601 - YL606
3YL611 - YL612
3YL616 - YL617
3YL621
3YL626
3YL631 - YL634
3YL636 - YL637
3YL661 - YL664
3YL676 - YL691
3YL696 - YL697
3YL701 - YL707
3YL731
3YL751 - YL752
3YL756 - YL757
3YL761 - YL780
3YL796 - YL797
3YL801 - YL815
3YL901 - YL910
3YL921 - YL940
3YL951 - YL968
1YM101
3YM102 - YM103
1YM201 - YM202
3YM203 - YM244
1YM251 - YM259
3YM260 - YM299
3YM301 - YM399
3YM401 - YM415
3YM471
3YM481 - YM484
3YM501 - YM515
3YM521 - YM522
3YM541
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GroupVariable Number
3YM551 - YM553
3YM571 - YM572
3YM581 - YM582
3YM591 - YM599
3YM631 - YM634
3YM641 - YM652
3YM671 - YM674
3YM691 - YM699
3YM701 - YM710
3YM761 - YM765
3YM771 - YM779
3YN001 - YN016
3YN021 - YN024
3YN061
3YN071 - YN082
3YN091 - YN092
3YN101 - YN112
3YN121
3YN126
3YN201 - YN202
3YN211 - YN219
3YN231 - YN236
3YN261
3YN501
3YN531 - YN534
3YN551 - YN562
3YN581 - YN583
3YN591
3YN601 - YN606
3YN651 - YN653
3YN701 - YN702
3YN741 - YN746
3YN756
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GroupVariable Number
3YQ001 - YQ003
3YQ011 - YQ021
3YQ026 - YQ029
3YQ036 - YQ045
3YQ201 - YQ207
3YQ231
3YQ241 - YQ251
3YQ281 - YQ284
3YQ291 - YQ296
3YQ301 - YQ302
3YQ321 - YQ324
3YQ331 - YQ334
3YQ346 - YQ347
3YQ401 - YQ403
3YQ451 - YQ454
3YQ456
3YQ461
3YQ471
3YQ501 - YQ514
3YR001 - YR037
3YR051 - YR087
3YR091 - YR098
3YR101 - YR105
3YR111 - YR119
3YR126 - YR144
3YR166 - YR182
3YR186 - YR198
3YR201 - YR204
3YR231 - YR294
3YR296 - YR297
3YR301 - YR334
3YR338 - YR339
3YR361 - YR366
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GroupVariable Number
3YR371 - YR373
3YR376
3YR381 - YR382
3YR386 - YR387
3YR391
3YR396 - YR398
3YR401 - YR405
3YR411 - YR413
3YR416 - YR418
3YR421 - YR424
3YR426 - YR438
3YR441 - YR449
3YR451 - YR455
3YR457 - YR499
3YR501 - YR506
3YR511 - YR520
3YR526 - YR544
3YR546 - YR551
3YR556 - YR562
3YR571 - YR580
3YR591 - YR592
3YR601 - YR605
3YR616 - YR648
3YR651 - YR658
3YR661 - YR663
3YR671 - YR672
3YR676 - YR677
3YR701 - YR769
3YR771 - YR796
3YR801 - YR816
3YR831 - YR838
3YR841 - YR849
3YR851 - YR883
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GroupVariable Number
3YR901 - YR903
3YR931 - YR934
3YR938 - YR944
3YR951 - YR970
3YR981 - YR994
3YS001 - YS002
3YS006 - YS009
3YS031 - YS032
3YS051 - YS073
3YS101 - YS120
3YS126 - YS130
3YS151 - YS160
3YS166 - YS189
3YS191 - YS194
3YS196 - YS197
3YS201 - YS209
3YS221 - YS225
3YS231 - YS236
3YS271 - YS282
3YS301 - YS333
3YS351 - YS362
3YS371 - YS374
3YS381 - YS383
3YS401
3YS451
3YS456 - YS457
3YS462
3YS501 - YS502
3YS506
3YS511
3YS551 - YS553
3YS561 - YS575
3YS581 - YS589
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GroupVariable Number
3YS591 - YS595
3YS601 - YS680
3YS686 - YS690
3YS701 - YS708
3YS721 - YS750
3YS761 - YS762
3YS771 - YS780
3YS806 - YS810
3YS816 - YS818
3YS823 - YS825
3YS851 - YS856
3YS876
3YS881 - YS882
3YS901 - YS909
3YS911 - YS917
3YS961 - YS965
3YS991 - YS993
3YT001 - YT004
3YT006
3YT031 - YT032
3YT036 - YT037
3YT061 - YT068
3YT101 - YT106
3YT126 - YT127
3YT136 - YT138
3YT176 - YT179
3YT201
3YT251 - YT267
3YT301
3YT306 - YT307
3YT311 - YT312
3YT401 - YT403
3YT411 - YT414
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GroupVariable Number
3YT461 - YT468
3YT601 - YT606
3YT761 - YT769
3YT891 - YT894
3YU001 - YU029
3YU201 - YU207
2. Spares Affected
None.
B. Concurrent Requirements
The service bulletins listed below must be done before or at the same time as this service bulletin:
Group 1:
DescriptionService BulletinCompany
FIRE PROTECTION - Lower Cargo Com-
partment Smoke Detection - Forward Cargo
Compartment Smoke Penetration Electrical
Changes
737-26-1122, Revision 1 (a)Boeing
(a) Incorporation of this service bulletin is necessary to make sure the Smoke Clearance
Mode - Operational Test result is satisfactory.
C. Reason
This service bulletin gives instructions to do the Smoke Clearance Mode - Operational Test at the
repeat intervals on airplanes equipped with the reconfigured low pressure air distribution system during
a cargo fire event. The repeat operational testing of the Equipment Cooling System and Low Pressure
Environmental Control System (ECS) will reduce the probability of a latent failure which could result in
smoke and/or fire in the airplane.
A subsequent review by Boeing found that there was no maintenance procedure available to inspect
the components used to reconfigure the air distribution system. Without the maintenance procedure,
failures of components could possibly be latent for periods greater than required to meet certification
requirements. A cargo fire event in conjunction with a latent failure of the air distribution system can
possibly result in smoke penetration to occupied areas. The amount of smoke and toxicity of the smoke
that could reach the occupied areas is unknown.
Boeing Service Bulletins 737-26-1121 and either 737-21-1135 or 737-21-1163 are related to
737-26-1122. Accomplishment of the changes in the Boeing Service Bulletins 737-26-1121, 737-21-1135
or 737-21-1163 will not cause a failure of the test in this service bulletin. Boeing Service Bulletin
737-26A1083 is related to 737-21-1135.
Boeing Service Related Problem (SRP) 737-SRP-26-0079 is related to this service bulletin.
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D. Description
Get access into the flight compartment and main electronics equipment compartment. As an alternate
location to the flight compartment to make sure of the Recirculation Fan's operation, between the left
and right air conditioning (AC) pack compartments, open the access panel to the ground conditioned
air connection duct. Do the Smoke Clearance Mode - Operational Test to make sure the cargo smoke
system operates correctly. If the Smoke Clearance Mode - Operational Test result is not satisfactory,
do the troubleshooting procedure on the Equipment Cooling and Low Pressure ECS systems to find
and replace faulty component.
The work in this service bulletin is done in the maintenance zone(s) given below.
Group 1:
Affected Maintenance Zones
ZoneModel
112, 113, 114, 117, 118, 125, 126737-600, 737-700, 737-800
Group 2:
Affected Maintenance Zones
ZoneModel
112, 113, 114, 117, 118, 125, 126737-700, 737-700C, 737-900
Group 3:
Affected Maintenance Zones
ZoneModel
112, 113, 114, 117, 118, 125, 126737-600, 737-700, 737-700C,
737-800, 737-900, 737-900ER
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.
Table: Smoke Clearance Mode - Operational Test
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
9000 flight hours.Within 51 months
after the original is-
sue date of this
service bulletin.
Do a Smoke Clearance
Mode - Operational Test
in accordance with Para-
graph 3.B., Work Instruc-
tions.
Group 1, Configuration 1
Airplanes.
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Table: Smoke Clearance Mode - Operational Test
Repeat Interval
(Not to Exceed)
Compliance TimeActionCondition
9000 flight hours.Within 10 months
after the original is-
sue date of this
service bulletin.
Do a Smoke Clearance
Mode - Operational Test
in accordance with Para-
graph 3.B., Work Instruc-
tions.
Group 1, Configuration 2,
Group 2 and Group 3 Air-
planes.
-Before further
flight.
Do a system fault isola-
tion in accordance with
Paragraph 3.B., Work In-
structions.
If the Smoke Clearance
Mode - Operational Test
result is not satisfactory.
F. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified
in this service bulletin comply with the applicable regulations and are FAA approved, as well as European
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on
the airplane in its original Boeing delivery configuration or as modified by other approved Boeing
changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected
by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this service bulletin.
G. Manpower
The table below shows an estimate of the task hours necessary to do this 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 find the tools.
Elapsed HoursTask-HoursNumber of Per-
sons
Task
0.500.501Open Access
1.503.002Test (a)
0.500.501Close Access
2.504.00TOTAL FOR EACH AIRPLANE
(a) The task hour does not include time that is possibly needed to troubleshoot
wiring and components if test result is not satisfactory.
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This estimate does not include the task hour data given in the service bulletins in Paragraph 1.B.,
Concurrent Requirements.
H. Weight and Balance Changes
None.
I. Electrical Load Data
Not changed.
J. References
1. Existing Data:
a. Boeing Service Bulletin 737-21-1135, 737-21-1163, 737-26-1121, 737-26-1122, 737-26A1083
b. Boeing Service Related Problem (SRP) 737-SRP-26-0079
c. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19
d. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 06-41-00, 21-27-00, 21-31-01,
24-22-00, 52-51-00
e. 737-600/700/800/900 Fault Isolation Manual (FIM) 21-25-801, 21-25-802, 21-27-805,
21-27-806, 21-27-807, 21-27-808, 21-27-809, 21-27-810, 21-27-811
2. Data Supplied with this Service Bulletin:
None.
3. Installation Drawings Used in the Preparation of this Service Bulletin:
None.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
8-20737 Flight Crew Operations Manual
21-27737 Aircraft Maintenance Manual
21-25, 21-27737 Fault Isolation Manual
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.
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L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
M. Software Accomplishment Summary
Not affected.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
None.
B. Industry Support Information
Boeing warranty remedies are not available for the Operational Test given in this service bulletin.
C. Parts Necessary for Each Airplane
1. Kits/Parts:
None.
2. Parts and Materials Supplied by the Operator:
None.
3. Parts Modified and Reidentified:
None.
4. Parts Removed and Not Replaced:
None.
D. Parts Necessary to Change Spares
None.
E. Special Tooling - Price and Availability
None.
F. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance
and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine
operator tool supply to make sure all necessary tools are available.
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### Page 35

3.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL
PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,
METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE
DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR
OTHER ELECTRICAL DAMAGE.
NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for
definition of the acronyms.
2. Obey all of the warnings and cautions given in the specified manual sections.
3. Unless shown differently, these dimensions and tolerances are used:
– Linear dimensions are in inches
– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus
or minus 0.03 inch
– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
– Angular tolerance is plus or minus 2 degrees
– Hole dimensions for standard solid rivets and fasteners are in Structural Repair
Manual (SRM) Chapter 51
– Torque Values:
— Values for structural fasteners are given in 737 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 737
Airplane Maintenance Manual (AMM).
— Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
— Values for engine maintenance tasks are included in Chapter 70 of 737
Airplane Maintenance Manual (AMM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
4. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,
and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.
5. These work instructions refer to procedures included in other Boeing documents.
When the words "refer to" are used and the operator has an accepted alternative
procedure, the accepted alternative procedure can be used. When the words "in
accordance with" are included in the instruction, the procedure in the Boeing document
must be used.
6. If it is necessary to remove more parts for access, you can remove those parts. If
you can get access without removing identified parts, it is not necessary to remove
all of the identified parts. Jacking and shoring limitations must be observed.
7. 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.
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8. If shading is used, shaded areas in Figures are to separate the non-critical and
non-authoritative information from the critical and authoritative information.
9. Use of colors in Figures is based on guidance from the ATA e-Business Program
(ATA) iSpec 2200.
10. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS
are in Paragraph 1.E., Compliance.
11. Some steps in the Work Instructions are identified as Required for Compliance (RC).
If this service bulletin is mandated by an Airworthiness Directive (AD), then the steps
identified as RC must be done to comply with the AD. Alternative procedures for
steps not identified with RC can be used if the RC steps can still be done as specified,
and the airplane can be put back in a serviceable condition. An Alternative Method
of Compliance (AMOC) is not necessary for deviations to steps that are not identified
as RC.
B. WORK INSTRUCTIONS
1. Do these steps to get access.
a. Below the main electronics equipment compartment, open the Access Door 117A. Refer to
737-600/700/800/900 AMM 06-41-00 as an accepted procedure.
b. In the main electronics equipment compartment, get access to the Cabin Pressure Controller.
For the Cabin Pressure Controller location, refer to 737-600/700/800/900 AMM 21-31-01 as
an accepted procedure.
c. Below the AC mix air compartment, open the ECS Panel 191E to get access to the Ground
Conditioned Air Connection Duct. Refer to 737-600/700/800/900 AMM 06-41-00 as an accepted
procedure.
NOTE: This is an alternate location to the flight compartment to make sure of the Recirculation
Fan's operation.
d. Get access into the flight compartment. Refer to 737-600/700/800/900 AMM 52-51-00 as an
accepted procedure.
2. Do these steps to make sure the Cargo Fire Protection system operates correctly:
a. In the flight compartment, apply electrical power to the airplane. Refer to 737-600/700/800/900
AMM 24-22-00 as an accepted procedure.
b. RC - In the flight compartment and main electronics equipment compartment, do the AMM
task 21-27-00-700-807, Smoke Clearance Mode - Operational Test. Refer to
737-600/700/800/900 AMM 21-27-00 as an accepted procedure.
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c. If the Smoke Clearance Mode - Operational Test result is not satisfactory, do a system fault
isolation to find and replace faulty component. Refer to 737-600/700/800/900 FIM 21-25-801,
737-600/700/800/900 FIM 21-25-802, 737-600/700/800/900 FIM 21-27-805,
737-600/700/800/900 FIM 21-27-806, 737-600/700/800/900 FIM 21-27-807,
737-600/700/800/900 FIM 21-27-808 , 737-600/700/800/900 FIM 21-27-809,
737-600/700/800/900 FIM 21-27-810 and 737-600/700/800/900 FIM 21-27-811 as accepted
procedures.
d. Remove electrical power from the airplane if electrical power is not necessary. Refer to
737-600/700/800/900 AMM 24-22-00 as an accepted procedure.
3. Do these steps to close access.
a. Below the main electronics equipment compartment, close the Access Door 117A. Refer to
737-600/700/800/900 AMM 06-41-00 as an accepted procedure.
b. Below the AC mix air compartment, close the Low Pressure ECS Panel 191E if it was opened.
Refer to 737-600/700/800/900 AMM 06-41-00 as an accepted procedure.
4. Put the airplane back to a serviceable condition.
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