# Boeing Alert Service Bulletin 737-53A1166: U.S. DOT/FAA - Service Information - SB-737-53-1166-01

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- Document: [Boeing Alert Service Bulletin 737-53A1166](https://openairdocs.org/service-documents/boeing/737-53a1166.md)
- Title as filed: U.S. DOT/FAA - Service Information - SB-737-53-1166-01
- Pages: 63
- PDF: https://openairdocs.org/files/sha256/5e/88/5e88d93dec1d3a3912853e5b678df02a0449ef5be02f8cfeaaa155cca5320bd8
- Page: https://openairdocs.org/service-documents/boeing/737-53a1166/file/5e88d93dec1d

## Text

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### Page 1

Commercial
Airplane
Group
737
Service Bulletin
Number: 737-53A1166 Revision Transmittal SheetDate: June 30, 1994
Revision 1: May 25, 1995
ATA System: 5311
SUBJECT: FUSELAGE - FRAMES - BODY STATION 727 OUTBOARD CHORD AT STRINGER 18A,
INSPECTION AND PREVENTIVE MODIFICATION
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
Federal Aviation Administration (FAA) Notice of Proposed Rule Making, FAA Docket Number
94-NM-159-AD, is related to this service bulletin.
No more work is necessary on airplanes changed as shown in the initial release of this service bulletin.
SUMMARY
This revision is sent to add a stringer 18A outer chord repair. In addition, instructions have been added, to
trim "Time Limited Repair" parts, to eliminate interference with fasteners.
Paragraph I.A., Effectivity, shows changes of airplane operators. Each operator should examine the
Effectivity paragraph for changes.
Vertical lines are put on the left edge of each page, except in Paragraph I.A., Effectivity, to show the location
of important changes.
Pages with a revision number and date, but no vertical lines, have no important changes.
REVISION HISTORY
Initial Release: June 30, 1994
Revision 1: May 25, 1995
BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207

### Page 2

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### Page 3

Commercial
Airplane
Group
737
Service Bulletin
Number: 737-53A1166 SummaryDate: June 30, 1994
Revision 1: May 25, 1995
ATA System: 5311
SUBJECT: FUSELAGE - FRAMES - BODY STATION 727 OUTBOARD CHORD AT STRINGER 18A,
INSPECTION AND PREVENTIVE MODIFICATION
BACKGROUND
Four operators sent reports of cracks in the
outboard chord of the frame at Body Station (BS)
727 where Stringer 18A is attached. The reports
were of eight airplanes with 39,000 to 54,100 flight
hours and 56,200 to 73,200 flight cycles. The
cracks were caused by fatigue that was started by
fretting of adjacent parts. Operators have also sent
reports of cracks in the outboard chord of Stringer
18-A.
The changes shown in this service bulletin will
decrease the probability of these cracks. This area
is a primary structural element. Operation with
cracks in the frame will decrease the structural
integrity of this area.
As part of a service bulletin validation program, the
inspection, frame chord replacement, and preventive
modification was completed on airplane PG576
(Group 2) before the initial release of this bulletin.
ACTION
Make an inspection of the outboard chord of the
frame at BS 727 where Stringer 18A is attached.
Look for cracks. Do the inspection at the times
given in the Compliance section.
Also, make an inspection of the outboard chord of
Stringer 18A at Station 727. If cracks are found in
the outboard chord of Stringer 18A, do the repair.
If cracks are found in the outboard chord of the
frame at BS 727, install the time limited repair or
replace the chord and, optionally, install the
preventive modification. If no cracks are found,
install the preventive modification or do the
inspection again. Do the inspection at the times
given in the Compliance section until the preventive
modification is installed. If the preventive
modification is installed, no more inspections per
this bulletin are necessary.
More work is necessary for operators that have
replaced the outboard chord of the frame at BS 727
as shown in Service Bulletin 737-53-1088. Refer to
Compliance.
COMPLIANCE
This bulletin has a Flight Safety Inspection Program
that is the minimum necessary to keep the structural
integrity of the outboard chord.
For airplanes with 27,000 flights to 50,000 flights, do
the inspection initially within 4,500 flights after you
get this bulletin. Do the inspection again at intervals
of 15,000 flights until the airplane collects more than
50,000 flights.
For airplanes with 50,000 flights to 60,000 flights, do
the inspection initially within 2,500 flights after you
get this bulletin. Do the inspection again at intervals
of 7,500 flights until the airplane collects more than
60,000 flights.
For airplanes with 60,000 flights to 70,000 flights, do
the inspection initially within 1,500 flights after you
get this bulletin. Do the inspection again at intervals
of 5,000 flights until the airplane collects more than
70,000 flights.
For airplanes with more than 70,000 flights, do the
inspection initially within 500 flights after you get this
bulletin. Do the inspection again at intervals of
3,000 flights.
For airplanes with the lower part of the chord
replaced by SB 737-53-1088, do the inspection at
the intervals shown above.
For airplanes with the upper part of the chord
replaced by SB 737-53-1088, do the inspection
initially within 30,000 flight cycles after the chord
was replaced. Do the inspection again at the
intervals shown above for flight cycles after the
chord was replaced.
BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207 Summary Page 1 of 2

### Page 4

BOEING SERVICE BULLETIN 737-53A1166
EFFECTIVITY
All 737-100 and 737 -200 airplanes, Line Numbers
1-999, in 4 groups.
MANPOWER
Refer to Paragraph I.F. Manpower.
MATERIAL INFORMATION
Boeing Supplied Kits
Refer to Paragraph I.G., Material - Price and
Availability.
EDGE OF FLANGE
EXAMINE FORWARD
AROUND TWO FASTENER HEADS
EXAMINE SURFACE OF S−18A
EXAMINE AREA AROUND
TWO FASTENER HOLES
A FLAT STRAP)
THE OUTER CHORD OF
STRINGER 18−A IS
STRINGER 18−A
(ON SOME AIRPLANES
TYPICAL
CRACK
LEFT SIDE SHOWN
RIGHT SIDE OPPOSITE
(WING−TO−BODY FAIRING NOT SHOWN)
STA
727
C79178
Jun 30/94
REV 1: May 25/95 Summary Page 2 of 2

### Page 5

Commercial
Airplane
Group
737
Service Bulletin
Number: 737-53A1166
Date: June 30, 1994
Revision 1: May 25, 1995
ATA System: 5311
SUBJECT: FUSELAGE - FRAMES - BODY STATION 727 OUTBOARD CHORD AT STRINGER 18A,
INSPECTION AND PREVENTIVE MODIFICATION
THIS SERVICE BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN
IN PARAGRAPH I.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.
I. 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.
IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER
AER LINGUS (ARL)
2 PY322
3 PK641-PK642
AERO CONTROLS, INC (AEO)
2 PG629
AERO COSTA RICA (AOR)
3 PK872-PK873
AEROLINEAS ARGENTINAS (ARG)
2 PH705-PH708 PH741-PH742 PY007
3 PH743 PK102-PK103 PK464
AIR ALGERIE (ALG)
3 PK361 PK631 PK633-PK634 PL717-PL725 PY051 PY053
AIR ATLANTA ICELANDIC (AID)
2 PY346
AIR FOYLE LTD. (FOY)
3 PJ108 PJ113
AIR FRANCE (AFA)
3 PL502-PL503 PN101-PN112
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### Page 6

BOEING SERVICE BULLETIN 737-53A1166
AIR GABON S.A. (GBN)
3 PY191
AIR GUINEE (GNE)
3 PY651
AIR MADAGASCAR (MAD)
2 PG375
3 PL793
AIR NEW ZEALAND, LTD. (ANZ)
3 PJ117-PJ119 PK214 PL621-PL623 PY741
AIR SOUTH, INC. (SOT)
2 PG210 PG215
3 PK221 PK351 PK353 PK462 PK466
AIR TANZANIA (TNZ)
3 PY611-PY612
AIR TOULOUSE INTERNATIONAL (TOL)
2 PL716
AIR UKRAINE (UKA)
3 PK354
AIR ZAIRE (ZAI)
3 PY111 PY113
AIRCORP (CRP)
2 PG037
AIRTRAN AIRWAYS, INC. (CQT)
2 PG438
3 PK028
ALASKA AIRLINES (ASA)
3 PY112 PY134-PY135 PY270 PY461-PY462
ALBATROS AIRLINES (ABS)
2 PG251 PG253
ALIADRIATICA (ADH)
3 PK432
ALL NIPPON AIRWAYS CO. LTD. (ANA)
2 PG584-PG586
3 PK711-PK716
ALOHA (ALO)
2 PG046
3 PK286-PK287 PK691-PK695 PY231 PY242 PY451
AMC AVIATION (AMF)
3 PK254
Jun 30/94 737-53A1166
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### Page 7

BOEING SERVICE BULLETIN 737-53A1166
AMERICA WEST AIRLINES, INC. (AMW)
2 PC004 PG036 PL801
3 PK283 PK696 PL081 PL172 PL551-PL562
AMERICANA DE AVIATION S. A. (AMY)
2 PG276
AMIRI FLIGHT (ABD)
3 PK495
AMORA FLIGHT CHARTER SERVICES (FCA)
2 PG047
ANGOLA AIR CHARTER (AOH)
2 PG431
ANGOLA AIRLINES (ANG)
3 PK661 PK664 PY162
ANSETT WORLDWIDE AVIATION SERVICES (AWW)
1 PA001 PA003-PA004
ARAMCO ASSOCIATED CO. (ARM)
3 PL151 PY241 PY243-PY244
ARKIA ISRAELI AIRLINES, LTD (ARK)
2 PG575
ASEAN AVIATION (L) INC. (ASJ)
2 PG578-PG583
3 PK920
AVENSA (AVN)
3 PK042-PK043
AVIATECA (AVT)
2 PL736-PL737 PL740-PL741
AVIOGENEX AIR TRANSPORT (AVG)
3 PL501 PL506
BOURAQ INDONESIA AIRLINES (PTB)
2 PL742
3 PK501 PK913 PK918 PK931 PL743-PL744
BRITISH AIRWAYS (BAB)
3 PK731-PK749 PK771-PK772 PK774-PK777 PK779
CALDWELL AIRCRAFT TRADING CO. (CAS)
2 PG402
CAMBODIAN INTERNATIONAL AIRLINES (CAK)
2 PJ072
CAMEROON AIRLINES (CAM)
2 PY046-PY047
Jun 30/94 737-53A1166
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### Page 8

BOEING SERVICE BULLETIN 737-53A1166
CANADIAN AIRLINES INTERNATIONAL LTD. (CDI)
2 PY303-PY304
3 PK358 PK671-PK675 PK677-PK680 PK822 PK881 PK884
PL401-PL417 PL764-PL770 PM141-PM142 PY151-PY154 PY421-PY422 PY441
CANAIR CARGO (CAZ)
3 PK026-PK027
CARNIVAL AIR (CVL)
2 PG305 PG312 PL712
3 PJ007-PJ008
CASINO EXPRESS (CIN)
2 PG279 PG436
3 PK461
CAYMAN AIRWAYS (CAY)
3 PJ009 PK222
COMAIR (CML)
2 PG353-PG354 PG356
3 PK355
CONSOLIDATED PRESS HOLDINGS (CPH)
3 PJ109
CONTINENTAL AIRLINES, INC. (CAL)
1 PA006-PA009 PA011 PG199
2 PA012 PA014 PA016-PA020 PG056 PG064 PG225
PG433 PG501-PG505 PG621-PG625 PG627-PG628 PG630 PG704
3 PL001
COPA COMPANIA PANAMENA DE AVIATION S.A. (COP)
2 PY341
3 PJ107 PJ112 PK465 PK617 PL745 PY201
CROATIA AIRLINES (CRH)
3 PK904 PK906-PK907 PK928 PK932
DAMANIA AIRWAYS LTD. (DAI)
3 PL451-PL452 PN081-PN082
DELTA AIR LINES, INC. (DAL)
3 PK611 PK613 PK623-PK624 PL221
4 PN131-PN135
E G AND G (EGN)
3 PL763
E-SYSTEMS (ESM)
2 PG208
EAS EUROPE AIRLINES (EUR)
3 PK203 PK215 PK282 PK359 PK564 PK612
EAST WEST AIRLINES (INDIA) (BOM)
3 PK615-PK616 PK819 PK824 PL171
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### Page 9

BOEING SERVICE BULLETIN 737-53A1166
EDRESS, SHIEKH M. (SME)
3 PL505
EGYPTAIR (EGP)
3 PK255 PK257-PK258
EL AL ISRAEL AIRLINES, LTD. (ELA)
3 PL631-PL632
EURALAIR (ERA)
2 PG026 PG028-PG029 PY004 PY006
FAR EASTERN AIR TRANSPORT (FAT)
1 PA002 PA005
2 PG055 PG226 PG228 PG230
3 PK562
FAUCETT (COMPANIA DE AVIATION S.A. (FCT)
2 PC002 PG034 PG213 PL711
3 PK241 PL758
FLIGHTSTAR AVIATION CORPORATION (FST)
2 PG274
FRENCH POSTAL OFFICE (FPO)
2 PY302 PY344
3 PY101-PY103
FRONTIER AIRLINES (FRO)
2 PG304 PG306 PG308 PG310-PG311
GARUDA INDONESIAN AIRWAYS (GIA)
3 PK917 PK929-PK930
GATARI AIR SERVICE (GRI)
3 PL441
GB AIRWAYS (GBA)
3 PJ110-PJ111
GE CAPITAL AVIATION SERVICES, INC. (GEH)
1 PG272
2 PG218-PG219 PG651-PG652
GOVERNMENT OF BRAZIL (BRZ)
3 PK068-PK069
GOVERNMENT OF MEXICO (MXG)
2 PC005 PG223
GOVERNMENT OF SHARJAH (SHJ)
3 PL581
GPA GROUP LTD. (GUI)
3 PK252 PK614
GULF AIR (GUL)
3 PK467-PK468
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### Page 10

BOEING SERVICE BULLETIN 737-53A1166
HAPAG LLOYD (HAP)
3 PL504
INDIAN AIR FORCE (IDF)
2 PH712-PH713
4 PM016-PM017
INDIAN AIRLINES (IND)
2 PH709 PH711
3 PH021 PH024 PK231-PK233 PK235-PK240 PM001-PM006 PY631
INDONESIAN AIR FORCE (IDO)
3 PL601-PL602
4 PL603
INTEGRATED RESOURCES (INH)
1 PG271
2 PG273 PG403
3 PK697
INTERNATIONAL AIR LEASES (IAL)
2 PG048 PJ001
INTERNATIONAL AIRLINE SUPPORT GROUP (ASG)
2 PG021
INTERNATIONAL PACIFIC TRADING CO. (IPT)
2 PG572 PG574 PJ102
IRAN AIR (IRN)
2 PH731 PY021
3 PK391 PY022
IRAQI AIRWAYS (IRQ)
3 PY141-PY142
JAPAN TRANSOCEAN AIR CO., LTD. (SWL)
3 PK521 PK523-PK525
JETALL HOLDING CORPORATION (JEL)
2 PY002 PY005
KENYA AIRWAYS (KEN)
3 PK253 PK256
LACSA (LAC)
3 PK357 PK871
LADECO (LDE)
2 PL802
3 PJ004-PJ006 PK029 PK212 PK281 PK826 PK830
LAN-CHILE S.A. (LAN)
3 PK360 PK825 PL025-PL026 PL028
LAPA (LAZ)
2 PG355
3 PK047 PK051 PK463
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### Page 11

BOEING SERVICE BULLETIN 737-53A1166
LINA CONGO (LNA)
3 PY411
LINHAS AEREAS DE MOZAMBIQUE (LAM)
2 PH703 PY031
LITHUANIAN AIRLINES (LIJ)
3 PK563
LUFTHANSA GERMAN AIRLINES (DLH)
2 PY345
3 PK901-PK903 PK911-PK912 PK914-PK916 PK919 PK921-PK923 PK926-PK927
MAGNICHARTERS (MAM)
2 PG224
3 PJ003
MALEV HUNGARIAN AIRLINES (HGA)
3 PK284-PK285 PK636-PK637 PK827
MANDALA AIRLINES (MND)
3 PK874 PK924-PK925 PL027 PL061 PL421 PN002
MARKAIR, INC. (ALK)
3 PK632 PL611
4 PY056-PY057
MODILUFT (MOU)
3 PK905 PK908-PK910
MONTELY II (MOY)
2 PJ031
NASA (NAS)
1 PA099
NATIONAL AIRLINES (NAW)
2 PJ104
3 PJ105-PJ106
NICA (NICARAGUENCE DE AVIACION) (NIC)
3 PK823
NIGERIA AIRWAYS, LTD. (NIA)
3 PL781-PL782 PL785-PL788
NORDIC EAST (NOE)
2 PJ002
NWT AIR (NTA)
2 PX701
3 PY132-PY133 PY281
OLYMPIC AIRWAYS (OLY)
3 PK301-PK304 PK307-PK310 PM021-PM023
P. T. AIRFAST (PTF)
2 PG204 PG278 PY343
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### Page 12

BOEING SERVICE BULLETIN 737-53A1166
PETROLAIR SYSTEMS S. A. (PTS)
3 PL471
PLUNA (PLU)
3 PL201-PL203
PRESIDENTIAL AIR (PRB)
2 PC003
REPUBLIC OF NIGER (NIR)
3 PY166
ROYAL AIR MAROC (RAM)
3 PK271-PK274 PY671
4 PY672
RYANAIR (RYR)
3 PJ114-PJ115 PK503 PK801-PK804 PN001
SABENA S.A. (SAB)
3 PK041 PK044-PK046 PK048-PK050 PK052-PK053 PK431 PK433
PY272-PY275
SAETA S.A. (SAE)
3 PK211 PK561
SAHARA INDIAN AIRLINES (SAQ)
3 PK820
SAHSA (SERVICIO AEREO DE HONDURAS,S.A.) (SAH)
2 PJ071
SAKHALIN AIRLINES (SKH)
2 PG214
SAUDI ARABIAN AIRLINES CORP. (SVA)
2 PL726-PL728 PY036-PY037
3 PK311-PK317 PL729-PL735
SAUDI ROYAL FLIGHT (SRF)
3 PK318
SERVICIOS AEREOS RUTAS ORIENTE, (SARO) (SEV)
2 PA015 PA021-PA022 PJ032
SHAHEEN AIR INTERNATIONAL (SHK)
3 PK514
SHANNONAIR LEASING LTD. (SLE)
3 PK352
SIERRA PACIFIC AIRLINES (SRP)
3 PK627
SOUTH AFRICAN AIRWAYS (SAA)
3 PL101-PL113
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### Page 13

BOEING SERVICE BULLETIN 737-53A1166
SOUTHWEST AIRLINES CO. (SWA)
3 PK082 PK091-PK099 PK541-PK560 PK621 PK628-PK630 PM051-PM062
SUDAN (SUD)
3 PY156-PY157
T A PORTUGUESES (TAP)
3 PK971 PK973-PK974 PN083
4 PN084-PN086
TACA INTERNATIONAL AIRLINES, INC. (TAC)
2 PG059 PG352
3 PK213 PK223 PK882 PY131
TAESA (TES)
3 PK622 PK625-PK626
TAT EUROPEAN AIRLINES (TTR)
2 PY003 PY301 PY321 PY361-PY362
THAI AIR FORCE (TAF)
4 PK519
THAI AIRWAYS INT'L PUBLIC CO., LTD. (TII)
3 PK511
TITAN CHARTER AVIATION INC. (TCA)
2 PL761
3 PL762
TRANSAERO (TRX)
3 PK451-PK452 PK773
TRANSAVIA AIRLINES (TAV)
2 PG074
3 PK502 PK504 PK821
TRANSMILE AIR SERVICES (TML)
2 PY323 PY342 PY381
TUNISAIR (TUN)
3 PK861-PK863 PY621
UKRAINE INTERNATIONAL AIRLINES (UKR)
3 PK635
UNITED AIR LINES, INC. (UAL)
1 PG001-PG004 PG006-PG008
2 PG009-PG013 PG015-PG019 PG022-PG025 PG027 PG030 PG032
PG038-PG040 PG045 PG051-PG054 PG057 PG060-PG063 PG065-PG072
PG075
3 PK201-PK202 PL002-PL023
UNITED STATES AIR FORCE (USF)
3 PJ201-PJ219
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### Page 14

BOEING SERVICE BULLETIN 737-53A1166
USAIR, INC. (USA)
2 PG073 PG301 PG303 PG307 PG313-PG314 PG474
3 PK288-PK289 PK591-PK599 PK601-PK610 PK883 PM101-PM117 PN021-PN028
4 PM118-PM119 PN029-PN038
USL CAPITAL (USL)
2 PY001
VANGUARD AIRLINES (VAG)
2 PG041-PG042 PG206 PG576 PL803
VARIG AIRLINES (VAR)
3 PK111-PK116 PK118-PK120 PK141-PK146 PL453-PL454
VARSA (VAB)
2 PG351
VASP (VSP)
2 PG435 PG437 PG439-PG440 PG471-PG473 PL756 PX071
3 PH011-PH013 PK061-PK062 PK065-PK067 PK356 PK581 PY286
VENEZUELA - GOVERNMENT OF (VNZ)
3 PK070
VISCOUNT AIR SERVICE INC. (VAS)
2 PG201 PG203 PG209 PG212 PG216-PG217 PG220-PG222
PJ101 PJ103
3 PK305-PK306
YEMEN AIRWAYS (YEM)
3 PK341
ZAMBIA AIRWAYS (ZAM)
3 PK291
IDENTIFICATION BY VARIABLE NUMBER
GROUP 1
PA001-PA011 PA099 PG001-PG008 PG199 PG271-PG272
GROUP 2
PA012-PA022 PA231-PA232 PC001-PC005 PG009-PG075 PG201-PG230 PG251-PG255
PG273-PG279 PG301-PG314 PG331-PG332 PG351-PG356 PG375 PG401-PG403
PG431-PG442 PG471-PG475 PG501-PG505 PG571-PG586 PG621-PG630 PG651-PG652
PG701-PG705 PH701-PH715 PH731-PH732 PH741-PH742 PJ001-PJ002 PJ031-PJ032
PJ071-PJ072 PJ101-PJ104 PL711-PL712 PL716 PL726-PL728 PL736-PL742
PL756 PL761 PL801-PL803 PX071 PX701 PY001-PY008
PY021 PY031 PY036-PY037 PY046-PY047 PY301-PY304 PY321-PY323
PY341-PY346 PY361-PY362 PY381
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### Page 15

BOEING SERVICE BULLETIN 737-53A1166
GROUP 3
PH001 PH011-PH013 PH021-PH024 PH743 PJ003-PJ009 PJ105-PJ119
PJ201-PJ219 PK026-PK029 PK041-PK053 PK061-PK070 PK081-PK082 PK091-PK099
PK101-PK103 PK111-PK120 PK141-PK146 PK201-PK204 PK211-PK215 PK221-PK223
PK231-PK241 PK251-PK258 PK271-PK274 PK281-PK289 PK291 PK301-PK318
PK341 PK351-PK361 PK391 PK431-PK433 PK451-PK452 PK461-PK469
PK495 PK501-PK504 PK511-PK514 PK521-PK525 PK541-PK564 PK581
PK591-PK599 PK601-PK617 PK621-PK637 PK641-PK642 PK661-PK664 PK671-PK680
PK691-PK697 PK711-PK716 PK731-PK749 PK771-PK779 PK801-PK804 PK819-PK827
PK830 PK861-PK863 PK871-PK874 PK881-PK884 PK901-PK932 PK971-PK974
PL001-PL028 PL061 PL081 PL101-PL113 PL151 PL171-PL172
PL201-PL203 PL221 PL401-PL417 PL421 PL441 PL451-PL454
PL471 PL491 PL501-PL506 PL551-PL562 PL581 PL601-PL602
PL611 PL621-PL623 PL631-PL632 PL717-PL725 PL729-PL735 PL743-PL745
PL758 PL762-PL770 PL781-PL788 PL793 PM001-PM006 PM021-PM023
PM051-PM062 PM101-PM117 PM141-PM142 PN001-PN002 PN021-PN028 PN081-PN083
PN101-PN112 PY022 PY048 PY051-PY053 PY101-PY103 PY111-PY113
PY131-PY135 PY141-PY143 PY151-PY154 PY156-PY157 PY161-PY162 PY166
PY191 PY201 PY221-PY222 PY231 PY241-PY244 PY270-PY275
PY281 PY286 PY401 PY411 PY421-PY422 PY441
PY451 PY461-PY462 PY611-PY612 PY621 PY631 PY651
PY671 PY741
GROUP 4
PK519 PL603 PM016-PM017 PM118-PM119 PN029-PN038 PN084-PN086
PN131-PN135 PY056-PY057 PY672
2. Spares
None
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### Page 16

BOEING SERVICE BULLETIN 737-53A1166
B. Reason
Boeing Supplemental Structural Inspection Document D6-37089, Section 8.2, SSI Number F.29, is
related to this service bulletin.
Boeing Structural Item Interim Advisory (SIIA) 737-131 is related to this service bulletin.
The changes shown in this service bulletin will decrease the probability of cracks in the frame at Body
Station (BS) 727 where Stringer 18A is attached. This area is a primary structural element.
Operation with cracks in the frame will decrease the structural integrity of this area. Unscheduled
downtime can be necessary to replace a frame that has a crack.
Four operators sent reports of cracks in the outboard chord of the frame at BS 727. The reports were
of eight airplanes with 39,000 to 54,100 flight hours and 56,200 to 73,200 flight cycles. The cracks
were found in the chord at the lower row of fasteners where Stringer 18A is attached. The cracks
were in a forward and aft direction and measured approximately 1.4 to 3.0 inches in length. The
cracks were caused by fatigue that was started by fretting of adjacent parts. Operators have also
sent reports of cracks in the outboard chord of Stringer 18-A.
Revision 1 is sent to add a stringer 18A outer chord repair. In addition, instructions have been added,
to trim "Time Limited Repair" parts, to eliminate interference with fasteners.
As part of a service bulletin validation program, the inspection, frame chord replacement, and
preventive modification was completed on airplane PG576 before the initial release of this bulletin.
Airplane PG576 had the configuration of a Group 2 airplane.
C. Description
The airplane effectivity is divided in 4 groups because of differences in airplane configuration. There
is a preventive modification kit for each of the airplane configurations.
Do the inspections that follow at the times given in the Compliance section.
Make a visual inspection of the edge of the forward flange of the outboard chord of the frame at BS
727. Look for cracks.
Make an inspection of the outboard chord under Stringer 18-A. Use the Pulse Echo Shear Wave
(PESW) Inspection procedure. Look for cracks in the area of the two forward lower fastener holes in
the chord where Stringer 18A is attached.
NOTES:
1. Airplanes with 60,000 to 70,000 cycles can omit the next step only at the initial inspection at
1500 flights after you get this bulletin.
2. Airplanes with more than 70,000 cycles can omit the next step only at the initial inspection at
500 flights after you get this bulletin.
Remove the two forward lower fasteners. Make an inspection of the fastener holes in the outboard
chord of BS 727. Use a high frequency eddy current (HFEC) inspection procedure. Look for cracks.
Also, make an inspection of the outboard surface of the outboard chord of Stringer 18A at Station
727. Examine the surface around the heads of two fasteners. Use a high frequency eddy current
(HFEC) inspection procedure. Look for cracks. If cracks are found in the outboard chord of Stringer
18A, do the repair.
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BOEING SERVICE BULLETIN 737-53A1166
If cracks are found in the outboard chord of the frame at BS 727, install the time limited repair or
replace the chord. Refer to Boeing Service Bulletin 737-53-1088 for instructions to replace the chord.
When you replace the chord, Boeing recommends that you also install the preventive modification.
At the operators option, the preventive modification can be installed later.
The repair is time limited. Within 4500 flight cycles, but not more than 18 months, after the repair was
installed, replace the chord as specified in Boeing Service Bulletin 737-53-1088. The repair chord
takes the place of the forward splice angle of the chord replacement kit per Service Bulletin
737-53-1088. When you replace the chord, Boeing recommends that you also install the preventive
modification. At the operators option, the preventive modification can be installed later.
If no cracks are found, install the preventive modification or repeat the inspection at the times given in
the Compliance section until the preventive modification is installed.
If the preventive modification is installed, no more inspections, per this service bulletin, are
necessary.
More work is necessary for operators that have replaced the chord as shown in Service Bulletin
737-53-1088. Refer to the Compliance section.
Revision 1 - no more work is necessary on airplanes changed as shown in the initial release of this
service bulletin.
An evaluation form is attached to this service bulletin. Please use this form to tell us what you think
of the quality of this service bulletin.
NOTES:
1. The changes given in Boeing Service Bulletin 737-53A1039, "Fuselage - Skin Lap Joint
Inspection and Repair", can be made on applicable airplanes before or during the changes
given in this service bulletin.
2. The changes given in Boeing Service Bulletin 737-53-1066, "Fuselage - Stringer 18A Shear
Beam Inspection, Repair and Modification", can be made on applicable airplanes before or
during the changes given in this service bulletin.
3. The changes given in Boeing Service Bulletin 737-53-1076, "Fuselage - Circumferential Butt
Splices and Bonded Doublers Inspection, Repair and Modification", can be made on applicable
airplanes before or during the changes given in this service bulletin.
4. The changes given in Boeing Service Bulletin 737-53-1077, "Fuselage - Skin Inspection,
Repair, and Modification Aft of Body Station 727 Between Stringer S-18 and S-21", can be
made on applicable airplanes before or during the changes given in this service bulletin.
5. The changes given in Boeing Service Bulletin 737-53-1089, "Fuselage - Skin Cracks at Stringer
17 Inspection and Preventive Modification", can be made on applicable airplanes before or
during the changes given in this service bulletin.
6. The changes given in Boeing Service Bulletin 737-53-1124, "Fuselage - Bonded Doublers
(Tear Straps) - Inspection and Repair - For Delamination above Stringer 26 Between Stations
259 and1016", can be made on applicable airplanes before or during the changes given in this
service bulletin.
PLEASE SEND A REPORT OF YOUR INSPECTION PROGRAM. ALSO, SEND THE INSPECTION
RESULTS WHEN EACH INSPECTION IS COMPLETE. REFER TO THE FLIGHT SAFETY SECTION
IN THE ADDENDUM.
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BOEING SERVICE BULLETIN 737-53A1166
D. Compliance
This bulletin has a Flight Safety Inspection Program that is the minimum necessary to keep the
structural integrity of the outboard chord.
For airplanes with 27,000 flights to 50,000 flights, do the inspection initially within 4,500 flights after
you get this bulletin. Do the inspection again at intervals of 15,000 flights until the airplane collects
more than 50,000 flights.
For airplanes with 50,000 flights to 60,000 flights, do the inspection initially within 2,500 flights after
you get this bulletin. Do the inspection again at intervals of 7,500 flights until the airplane collects
more than 60,000 flights.
For airplanes with 60,000 flights to 70,000 flights, do the inspection initially within 1,500 flights after
you get this bulletin. Do the inspection again at intervals of 5,000 flights until the airplane collects
more than 70,000 flights.
For airplanes with more than 70,000 flights, do the inspection initially within 500 flights after you get
this bulletin. Do the inspection again at intervals of 3,000 flights.
For airplanes with the lower part of the chord replaced by Service Bulletin 737-53-1088, do the
inspection at the intervals shown above.
For airplanes with the upper part of the chord replaced by Service Bulletin 737-53-1088, do the
inspection initially within 30,000 flight cycles after the chord was replaced. Do the inspection again at
the intervals shown above for flight cycles after the chord was replaced.
Federal Aviation Administration (FAA) Notice of Proposed Rule Making, FAA Docket Number
94-NM-159-AD, is related to this service bulletin.
E. Approval
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes
specified in this service bulletin comply with the applicable Federal Aviation Regulations (FAR) and
are FAA approved. The service bulletin and the FAA approval were based on the airplane in its
original Boeing delivery configuration or as modified by other FAA 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.
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BOEING SERVICE BULLETIN 737-53A1166
F. Manpower
The data below shows an estimate of the man-hours necessary to do the inspection, repair, and
preventive modification for each airplane. This estimate is for direct labor only, done by an
experienced crew. Adjust the estimate with operator man-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 examine the work
- Time to make the parts
- Time to find the tools.
Inspection:
Task Number of Persons Man-Hours Elapsed Time (Hours)
Open Access 1 1 1
Inspection 1 1.5 1.5
Close Access 1 1 1
TOTAL FOR INSPECTION 3.5 3.5
Time Limited Repair for the Outer Chord of BS 727 Frame.
Task Number of Persons Man-Hours Elapsed Time (Hours)
Open Access 2 6 3
Install Repair 2 30 15
Close Access 2 6 3
TOTAL FOR REPAIR 42 21
Preventive Modification.
Task Number of Persons Man-Hours Elapsed Time (Hours)
Open Access 2 32 16
Preventive
Modification
2 40 20
Close Access 2 27 13.5
TOTAL FOR MODIFICATION 99 49.5
Stringer 18A Repair
Task Number of Persons Man-Hours Elapsed Time (Hours)
Open Access 2 8 4
Install Repair 2 26 13
Close Access 2 8 4
TOTAL FOR REPAIR 42 21
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BOEING SERVICE BULLETIN 737-53A1166
G. Material - Price and Availability
Boeing can supply the kits shown in Paragraphs II.A., Parts Necessary For Each Airplane as shown
below. Kit availability is shown in the Reorder Lead Time (ROLT). ROLT is calculated from the date
Boeing gets the purchase order.
Kit Number Name
ROLT
(weeks)
Unit Price thru
Jan 26/96
65C37277-1 Top Kit, Left Side 32 $1759
65C37277-2 Top Kit, Right Side 32 $1759
65C37277-3 Top Kit, Left Side 32 $1825
65C37277-4 Top Kit, Right Side 32 $1825
65C37277-5 Top Kit, Left Side 32 $1840
65C37277-6 Top Kit, Right Side 32 $1840
65C37277-7 Top Kit, Left Side 32 $1805
65C37277-8 Top Kit, Right Side 32 $1805
65C37565-1 (a) Top Kit, Left Side 36 $1460
65C37565-2 (a) Top Kit, Right Side 36 $1460
65C37565-3 (a) Top Kit, Left Side 36 $1460
65C37565-4 (a) Top Kit, Right Side 36 $1460
65C37565-5 (a) Top Kit, Left Side 36 $1631
65C37565-6 (a) Top Kit, Right Side 36 $1631
65C37565-7 (a) Top Kit, Left Side 36 $1631
65C37565-8 (a) Top Kit, Right Side 36 $1631
(a) As an option, instructions to make theStringer 18A repair parts are provided in
Figure 6 of this service bulletin.
The kits are subject to the terms and conditions of the Boeing standard purchase order
acknowledgment. After the Unit Price date, new price (and ROLT ) data is applicable. Prices are in
United States Dollars. Terms: Net 30 days.
Send purchase orders and letters about the supply data to the Director of Spares and refer to this
service bulletin number.
H. Special Tools - Price and Availability
None
I. Weight and Balance
Task
Change in Weight
(Pounds)
Change in Moment
(Pound-Inches)
Preventive Modification +3.70 +2690
Time Limited Repair +6.50 +4755
Stringer 18A Repair:
Repair Kit 65C37565-1,-2,-3,-4 (a) +1.52 +1105
Repair Kit 65C37565-5,-6,-7,-8 (b) +1.90 +1381
(a) For airplanes without the preventive modification installed.
(b) For airplanes with the preventive modification installed.
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BOEING SERVICE BULLETIN 737-53A1166
J. References
1. Existing Data:
a. 737 Maintenance Manual Subjects 26-21-11, 27-51-261, 53-23-1
b. 737 Structural Repair Manual Subjects 51-10-1, 51-10-2, 51-20-1, 51-20-4
c. 737 Nondestructive Test Manual D6-37239, Part 4, Subject 53-10-01
d. 737 Nondestructive Test Manual D6-37239, Part 6, Subject 51-00-00, Figure 1
e. 737 Maintenance Planning Data Manual D6-17594-2, Section 6-02
f. Boeing Service Bulletin 737-53-1088, "Fuselage - Body Station 727 Bulkhead, Outboard Chord
Inspection and Replacement"
2. Data supplied with this service bulletin:
a. Drawings:
Drawing Number Sheet DCN ADCN Title
65C37277 PL - 1 Strap Installation - Station 727 Bulkhead,
1 - - S-18 to S-20, Preventive Modification (Top Kit)
65C37565 PL (a) A - Strap Installation - S-18A Outboard Chord
1 (a) - - Repair - Station 727
(a) Sent with Revision 1.
3. Installation Drawings:
Drawing Number Title
65-48654 Frame Installation - Aft Wing/Body Fairing, Station 729.38
65-46877 Strap and Beam Installation - Stringer 18A, Station 639 to Station 747
These drawings were used to prepare this service bulletin. These drawings are not necessary to
make the specified changes, and are not supplied with this service bulletin. These drawings may
not be applicable to all airplane configurations or operators.
4. Process Data:
Boeing Process Specifications referred to on the drawings are not given in this service bulletin
since these procedures are frequently used as standard shop practices.
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BOEING SERVICE BULLETIN 737-53A1166
K. Publications Changed
Publication Chapter-Section
737 Structural Repair Manual 53-10-2
737 Non-Destructive Test Manual Part 4
L. Electrical Load Data
Not changed
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BOEING SERVICE BULLETIN 737-53A1166
II. MATERIAL INFORMATION
A. Parts Necessary For Each Airplane
1. To get the kits shown below, refer to Paragraph I.G., Material - Price and Availability.
NOTES:
1. One Preventive Modification Kit and if required, one S-18A Repair Kit, and the operator
supplied materials specified in Paragraph II.A.2., Parts and Materials Supplied by the
Operator, are necessary for each side of the airplane.
2. As an option, the Stringer 18A repair parts, included in the 65C37565 Repair Kits, can be
made by the operator. Refer to Figure 6.
65C37277 - STRAP INSTALLATION - STATION 727 BULKHEAD, S-18 TO S-20,
PREVENTIVE MODIFICATION (TOP KIT)
-4 -3 -2 -1
Quantity Part Number Name
. . . - 65C37277-1 (a) (e) Preventive Modification Kit (Left Side)
. . - . 65C37277-2 (a) (e) Preventive Modification Kit (Right Side)
. - . . 65C37277-3 (b) (e) Preventive Modification Kit (Left Side)
- . . . 65C37277-4 (b) (e) Preventive Modification Kit (Right Side)
65C37277 - STRAP INSTALLATION - STATION 727 BULKHEAD, S-18 TO S-20,
PREVENTIVE MODIFICATION (TOP KIT)
-8 -7 -6 -5
Quantity Part Number Name
. . . - 65C37277-5 (c) (e) Preventive Modification Kit (Left Side)
. . - . 65C37277-6 (c) (e) Preventive Modification Kit (Right Side)
. _ . . 65C37277-7 (d) (e) Preventive Modification Kit (Left Side)
- . . . 65C37277-8 (d) (e) Preventive Modification Kit (Right Side)
65C37565 - STRAP INSTALLATION - STATION 727 BULKHEAD, S-18A OUTBOARD
CHORD REPAIR (TOP KIT)
-4 -3 -2 -1
Quantity Part Number Name
. . . - 65C37565-1 (b) (f) (h) Repair Kit (Left Side)
. . - . 65C37565-2 (b) (f) (h) Repair Kit (Right Side)
. - . . 65C37565-3 (c) (f) (h) Repair Kit (Left Side)
- . . . 65C37565-4 (c) (f) (h) Repair Kit (Right Side)
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BOEING SERVICE BULLETIN 737-53A1166
65C37565 - STRAP INSTALLATION - STATION 727 BULKHEAD, S-18 TO S-20,
PREVENTIVE MODIFICATION (TOP KIT)
-8 -7 -6 -5
Quantity Part Number Name
. . . - 65C37565-5 (b) (g) (h) Repair Kit (Left Side)
. . - . 65C37565-6 (b) (g) (h) Repair Kit (Right Side)
. _ . . 65C37565-7 (c) (g) (h) Repair Kit (Left Side)
- . . . 65C37565-8 (c) (g) (h) Repair Kit (Right Side)
a. For Group 1 airplanes.
b. For Group 2 airplanes.
c. For Group 3 airplanes.
d. For Group 4 airplanes.
e. Refer to Drawing 65C37277, sent with the initial release of this bulletin, for the list of parts.
f. For airplanes without the 65C37277 Preventive Modification installed.
g. For airplanes with the 65C37277 Preventive Modification installed.
h. Refer to Drawing 65C37565, sent with this bulletin, for the list of parts.
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BOEING SERVICE BULLETIN 737-53A1166
2. Parts and Materials Supplied by the Operator for the Preventive Modification:
Quantity Part Number (Specification) Name
As necessary BMS 5-92, or equivalent Adhesive
As necessary BMS 5-95, or equivalent Sealant
As necessary BMS 10-11, Type 1, or equivalent Primer
As necessary BMS 10-11, Type 2, or equivalent,
Color BAC702 White
Gloss Enamel
3. Parts and Materials Supplied by the Operator if the Preventive Modification is not installed:
NOTE: Refer to 737 Structural Repair Manual Chapter 51 for alternative fasteners.
Quantity Part Number (Specification) Name
2 BACB30MB8A( ) (a) (b) (e) Hi-Lok
2 BACB30MC8A( ) (a) (c) (e) Hi-Lok
2 BACC30X8 (a) (b) (c) Collar
2 BACB30MD8A( ) (a) (d) (e) Hi-Lok
2 BACC30AC8 (a) (d) Collar
(a) Use if the chord is not replaced and the preventive modification is not installed. Use oversize
fasteners if necessary (refer to III. Accomplishment Instructions). Only two fasteners are
necessary at each installation. Choose the appropriate size.
(b) Standard size.
(c) For 1/64 oversize.
(d) For 1/32 oversize.
(e) Choose the grip length the same as the fastener that is removed. Refer to Figure 1.
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BOEING SERVICE BULLETIN 737-53A1166
4. Parts and Materials Supplied by the Operator for the Time Limited Repair:
The table that follows shows the repair parts necessary at each installation.
NOTE: Refer to 737 Structural Repair Manual Chapter 51 for alternative fasteners.
Quantity Part Number (Specification) Name
1 4x8x 0.15 inch thick 7075-T0 Aluminum Alloy Sheet
1 AND10134-2008 x 20.8, 7075-T6
or equivalent
Extruded Angle
1 1.25 x 4.25 x 0.032 inch thick 7075-T6 Aluminum Alloy Sheet
1 1 . 2 5x6x 0.18 inch thick 7075-T6 Aluminum Alloy Sheet
1 1.4 x 8.2 x 0.18 inch thick 7075-T6 Aluminum Alloy Sheet
1 2.1 x 11.4 x 0.18 inch thick 7075-T6 Aluminum Alloy Sheet
1 1.2 x 8.7 x 0.18 inch thick 7075-T6 Aluminum Alloy Sheet
1 1.2 x 1.4 x 0.82 inch thick 7075-T6 Aluminum Alloy Sheet
As necessary BMS 5-95, or equivalent Sealant
As necessary BMS 10-11, Type 1, or equivalent Primer
As necessary BACB30MB8A( ) Hi-Lok
As necessary BACC30X8 Collar
B. Parts Necessary to Change Spares
None
C. Special Tools and Equipment
No special tools or equipment are necessary to do the change in this service bulletin. Also,
maintenance and overhaul tools in manuals shown in Paragraph I.J., References, can be necessary.
Examine operator tool supply to make sure all necessary tools are available.
D. Existing Parts Accountability
None
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BOEING SERVICE BULLETIN 737-53A1166
III. ACCOMPLISHMENT INSTRUCTIONS
NOTES:
1. The paragraphs identified with letters give the general work instructions and the necessary tests.
The instructions identified with numbers on the figures give the recommended sequence of steps.
2. 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 are given in 737 Structural Repair Manual Chapter 51
- Torque limits to tighten nuts and bolts are given in 737 Structural Repair Manual Chapter 51
- Edge margins for fasteners are given in 737 Structural Repair Manual Chapter 51
3. Fastener installation is given in 737 Structural Repair Manual Chapter 51.
4. Alternative fasteners are given in 737 Structural Repair Manual Chapter 51.
5. Obey all of the warnings and cautions given in the specified manual sections.
Part I Flight Safety Inspection Program
A. Do the inspections that follow at the thresholds specified in the Compliance section.
B. Fully extend the trailing edge flaps. Get access to the outboard side of the frame at Body Station (BS)
727 through the opening in the flap fairing. At the operators option, for more access, remove the
fairing for the inboard track of the inboard flap. Keep the fairing and all fasteners for installation.
C. Get access to the inboard side of the frame at BS 727 from inside the wheelwell. On the left side, at
the operators option for more access, disconnect the connectors for the gauge and the detonator on
the aft fire bottle.
D. Examine the outboard surface of the outboard chord of Stringer 18-A. Look for cracks in the surface
around the heads of the two fasteners immediately aft of BS 727. Refer to Figure 1.
E. If there are cracks in the outboard chord of Stringer 18-A, do the repair as specified in Part IV.
F. At the edge of the forward flange of the outboard chord of the frame at BS 727, inspect for cracks.
Refer to Figure 1.
G. If there are no cracks in the forward flange of the outboard chord of the frame at BS 727, go to Step H.
If there are cracks, go to Step L.
H. Use the Pulse Echo Shear Wave Inspection procedure in the area under the outboard chord of
Stringer 18-A. Look for cracks in the area of the two lower fastener holes. Refer to Figure 1.
I. If no cracks are detected by this procedure in the area of the two lower fastener holes in the outboard
chord of the frame at BS 727, go to Step J. If there are cracks, go to Step L.
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BOEING SERVICE BULLETIN 737-53A1166
NOTES:
1. Airplanes with 60,000 to 70,000 cycles can omit Steps J and K only at the initial inspection at
1500 flights after you get this bulletin.
2. Airplanes with more than 70,000 cycles can omit Steps J and K only at the initial inspection at
500 flights after you get this bulletin.
J. Get access to the two lower fasteners in the outboard chord of the frame at BS 727 where Stringer
18A is attached. Refer Figure 1.
K. Remove the two fasteners and inspect the fastener holes for cracks as shown in Figure 1.
L. If cracks are found in the outboard chord of the frame at BS 727, at the customers option install the
time limited repair (refer to Part III of the Accomplishment Instructions) or go to Step M. The time
limited repair is limited to a crack that extends from the forward edge of the chord, or from the forward
fastener hole, but does not extend past the second fastener hole. At the time specified in Part C.
Description, replace the chord. Refer to Step M. The repair chord takes the place of the forward
splice angle of the chord replacement kit per Service bulletin 737-53-1088. If the crack extends past
the second fastener hole go to Step M.
M. Replace the chord as shown in Boeing Service Bulletin 737-53-1088 (refer to Part II of the
Accomplishment Instructions). When you replace the chord, Boeing recommends that you also install
the preventive modification. At the customers option, the preventive modification can be installed
later. If you install the preventive modification, use the hole pattern shown for the chord replacement
(refer to 737-53-1088) to install the 69-78770-1 splice plate. If the preventive modification is not
installed, do the inspections again as specified in the Compliance section.
N. If no cracks are found, install the preventive modification as specified in Part II of the Accomplishment
Instructions or do the inspections again as specified in the Compliance section.
O. If the preventive modification is not installed, replace the fasteners removed in Step K (refer to Figure
1). If necessary, drill 1/64 or 1/32 inch oversize to remove any damage (such as scratches, nicks, or
ovality) in the fastener holes and install oversize fasteners (refer to Section II.A.2. Parts and Materials
Supplied by Operator). Do the inspections again, as specified in the Compliance section, until the
preventive modification is installed.
NOTE: Check the fastener holes before they are oversized to see if they are already oversize by the
incorporation of another service bulletin. If another service bulletin has been installed, use
the same size and type of fastener used in the other service bulletin. If necessary, drill 1/64
or 1/32 inch oversize to remove any damage (such as scratches, nicks, or ovality) in the
fastener holes and install oversize fasteners.
P. If disconnected in Step C, install the connectors for the gauge and the detonator on the aft fire bottle.
Q. If removed in Step B, Install the fairing for the inboard track of the inboard flap.
R. Return the airplane to serviceable condition.
S. Send a report of the inspection to Boeing. Refer to Paragraph C. Description and the Flight Safety
Section in the Addendum.
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BOEING SERVICE BULLETIN 737-53A1166
Part II Preventive Modification
A. Get access to the outboard side of the outboard chord at Body Station (BS) 727 between Stringers
S-17 and S-20. Also, get access to the outboard side of Stringers S-18A and S-19 from BS 709 to BS
747 (for 737 -100 airplanes) or 727A (for 737-200 airplanes). Refer to Figure 2.
To get the access, remove the parts that follow:
. The wing-to-body fairings (refer to AMM 53-51-21).
. The fairing support structure at BS 727 (refer to View A-A in Figure 2).
B. Get access to the inboard side of Stringer S-19 between BS 729 and 747 (for 737 -100 airplanes) or
727A (for 737-200 airplanes). To get the access, remove the cargo liner at the forward end of the
cargo compartment in the aft lower lobe.
NOTE: On some airplanes there may be an auxiliary fuel tank installed. If installed, remove the
auxiliary fuel tank to get access to the cargo liner (refer to 737 AMM 53-23-1).
C. In the wheel well, get access to the inboard side of Stringer S-18A between BS 709 and 727.
D. In the wheel well, get access to the inboard side of the outer chord at BS 727. To get the access,
remove the engine fire extinguisher bottles (refer to 737 AMM 26-21-11).
CAUTION: TO INSTALL THE PREVENTIVE MODIFICATION, SKIN PANEL ATTACHMENT
FASTENERS ARE REMOVED. THIS SKIN PANEL AND FASTENERS ARE THE
SUBJECT OF AIRWORTHINESS DIRECTIVES 88-22-11 R1, 89-09-03, 91-08-12 AND
92-25-09. MAKE SURE THAT THE INCORPORATION OF THIS SERVICE BULLETIN
DOES NOT CHANGE THE COMPLIANCE WITH THESE AIRWORTHINESS
DIRECTIVES.
NOTE: Airworthiness Directives 88-22-11 R1 and 89-09-03 refer to Boeing Service Bulletins
737-53-1039 and 737-53-1089. Airworthiness Directive 91-08-12 refers to Boeing Service
Bulletin 737-53-1124. Airworthiness Directive 92-25-09 refers to Boeing Service Bulletin
737-53-1076.
E. Install the preventive modification as shown in Drawing 65C37277.
NOTES:
1. At the customers option make the external strap, 69-78770-1, -2 opposite, from 4130 150-170
KSI or 15-5PH 150-170 KSI steel.
2. Service Bulletin 737-53-1077 installs a repair patch at BS 727 and Stringer 18A. If the repair
patch is installed, then the 69-78773-10 filler is not needed. If necessary, install an additional
filler forward of BS 727 to match the thickness of the repair patch. If necessary, also use a
tapered filler forward of BS 727, same as the 69-78773-7 tapered filler, but with the thickness
increased to match the repair patch. Keep the same taper ratio.
F. Install the cargo liner if that was removed in Step B. If removed in Step B, install the auxiliary fuel tank
(refer to 737 AMM 53-23-1).
G. Install the engine fire extinguisher bottles removed in Step D (refer to 737 AMM 26-21-11).
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BOEING SERVICE BULLETIN 737-53A1166
H. Install the wing-to-body fairing that was removed in Step A (refer to AMM 53-51-21).
NOTE: The preventive modification installs new structure to replace most of the fairing support
structure that was removed in Step A (refer to Figure 2).
I. Return the airplane to serviceable condition.
Part III Time Limited Repair
A. In the wheel well, get access to the inboard side of the outer chord at BS 727. To get the access,
remove the engine fire extinguisher bottles (refer to 737 AMM 26-21-11).
B. Get access to the aft side of the bulkhead at BS 727. To get the access, remove the cargo liner at the
forward end of the cargo compartment in the aft lower lobe.
NOTE: On some airplanes there may be an auxiliary fuel tank installed. If installed, remove the
auxiliary fuel tank to get access to the cargo liner (refer to 737 AMM 53-23-1).
C. Get access to the forward side of the bulkhead at BS 727. Remove the flap right angle gearbox and
associated brackets (refer to Figure 3).
D. On the forward side of the bulkhead at BS 727, find the horizontal stiffener at approximately Water
Line189. Trim the outboard part of the vertical side of the horizontal stiffener to allow installation of the
repair angle (refer to Figure 3).
E. Trim the aft part of the outboard vertical side of the Stringer S-18A Shear Beam to allow installation of
the repair angle (refer to Figure 3).
F. Drill a stop crack hole at the end of the crack (refer to 737 Structural Repair Manual 51-10-1).
NOTE: To prevent damage to the skin or S-18 structure, put a thin steel shim between the outer
chord at BS 727 and the skin.
G. Make the repair parts (refer to Figure 4).
H. Install the repair parts (refer to Figure 5).
I. Install the flap right angle gearbox and associated brackets removed in Step C (refer to Figure 5).
J. Install the cargo liner removed in Step B. If removed in Step B, install the auxiliary fuel tank (refer to
737 AMM 53-23-1).
K. Install the engine fire extinguisher bottles removed in Step A (refer to 737 AMM 26-21-11).
L. Return the airplane to serviceable condition.
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BOEING SERVICE BULLETIN 737-53A1166
Part IV - Stringer 18A - Outboard Chord Repair
A. Get access to the outboard side of Stringer S-18A, from BS 709 to BS 747 (for 737 -100 airplanes) or
727A (for 737-200 airplanes). Refer to Figure 2.
To get the access, remove the parts that follow:
. The wing-to-body fairings (refer to AMM 53-51-21).
. The fairing support structure at BS 727 (refer to View A-A in Figure 2).
B. In the wheel well, get access to the inboard side of Stringer S-18A between BS 709 and 727.
C. Do the stringer 18A outboard chord repair as specified in drawing 65C37565.
NOTES:
1. Drawing 65C37565 provides repair procedures for airplanes with and without the frame
outboard chord preventive modification installed.
2. The Stringer 18A repair parts can be purchased as Repair Kit 65C37565, refer to Paragraph
I.G., Material - Price and Availability, or, as an option, the Stringer 18A repair parts can be
made by the operator. Refer to Figure 6.
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BOEING SERVICE BULLETIN 737-53A1166
Illustration Table of Contents
Title Page
FIGURE 1. INSPECTION . . ............................................... 2 9
FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION . . ................. 3 2
FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR . . ....................... 3 5
FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS . . ....................... 3 9
FIGURE 5. INSTALL THE TIME LIMITED REPAIR ............................. 4 2
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS ............................ 4 7
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BOEING SERVICE BULLETIN 737-53A1166
(WING−TO−BODY FAIRING NOT SHOWN)
RIGHT SIDE OPPOSITE
LEFT SIDE SHOWN
SEE DETAIL I
C79635
FIGURE 1. INSPECTION
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BOEING SERVICE BULLETIN 737-53A1166
DETAIL II
2
3 654
TYPICAL
CRACK
STRINGER 18−A
1
DETAIL I
INBD
FWD
SEE DETAIL II
STRINGER 18−A IS
A FLAT STRAP)
THE OUTER CHORD OF
STRINGER 18−A
(ON SOME AIRPLANES
STA
727
STA
727
C79638
FIGURE 1. INSPECTION
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BOEING SERVICE BULLETIN 737-53A1166
The step number shown below agree with the numbers shown inside the circle symbols in the figure.
STEP TASK NAME PROCEDURE REFERENCES NOTES
1 Examine Outboard chord
of Stringer 18-A
High Frequency
Eddy Current
Inspection
NDT Part 6, 51-00-00,
Figure 4
Examine the outboard
surface of the outboard
chord around the
fastener head. Look for
cracks.
2 Examine Outboard chord
of frame
Close Visual
Inspection
Examine the edge of the
forward flange of the
outboard chord. Look for
cracks.
3 Examine Outboard chord
of frame
Pulse Echo
Shear Wave
Inspection
NDT Part 4, 53-10-01 Examine the area under
the outboard chord of
Stringer 18-A. Look for
cracks.
If there is no indication of a crack, go to Step 4.
STEP TASK NAME PART NUMBER QTY NOTES
4 Remove /
Discard
Lockbolt
Collar
BACB30GW8( )
BACC30K8
2
2
Measure the grip length of the
fastener that was removed.
STEP TASK NAME PROCEDURE REFERENCES NOTES
5 Examine Fastener Holes High Frequency
Eddy Current
Inspection
NDT Part 6, 51-00-00,
Figure 1
Examine the fastener
holes in the forward
flange of the outboard
chord. Look for cracks
If you do not install the preventive modification, go to Step 6.
STEP TASK NAME PART NUMBER QTY NOTES
6 Examine Hole 2 Look for damage.
Drill Oversize
hole
2 If necessary, drill oversize hole
to remove damage. Make sure that
the edge margin is not less than 1.5D
Install Hi-Lok BACB30MB8A( )
or
BACB30MC8A( )
or
BACB30MD8A( )
or equivalent.
(a)
(b)
(c)
2
2
2
Use the same grip length as the
fastener that was removed in Step 4.
(a) Standard size.
(b) 1/64 oversize.
(c) 1/32 oversize.
FIGURE 1. INSPECTION
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BOEING SERVICE BULLETIN 737-53A1166
S−19
S−18A
S−20
S−17
STA
716
STA
709
727A (737−200)
STA
747 (737−100)
STA
727
S−18
LEFT SIDE SHOWN
RIGHT SIDE OPPOSITE
(WING−TO−BODY FAIRING NOT SHOWN)
A
A
D23274
FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION
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BOEING SERVICE BULLETIN 737-53A1166
5
2
3
1
6
7
7
4
VIEW A−A
INBD
S−17
S−18
S−19
S−20
D23551
The step numbers shown below agree with the numbers shown inside the circle symbols in the figure.
FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION
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BOEING SERVICE BULLETIN 737-53A1166
STEP TASK NAME REFERENCES QTY NOTES
1 Remove /
Discard
Stiffener 1
2 Remove /
Keep
Tee Chord 1 Keep the tee chord to use
again.
3 Remove /
Discard
Web 1
4 Remove /
Discard
Angle 1
5 Remove /
Discard
Attach Angle 1
6 Remove /
Keep
Filler 1 Keep the filler to use again.
7 Remove /
Discard
Filler 2
FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION
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BOEING SERVICE BULLETIN 737-53A1166
1
DETAIL I
FLAP RIGHT ANGLE GEARBOX
RIGHT GEAR BOX SHOWN
LEFT GEARBOX SIMILAR
FWD
SEE DETAIL II
SEE DETAIL I
R07300
FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
SEE DETAIL III 5
2
3
S−20
SEE DETAIL III4
S−19
S−18A
WL 190
INBD
RIGHT SIDE SIMILAR
LEFT SIDE SHOWN
DETAIL II
R07463
FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR
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### Page 41

BOEING SERVICE BULLETIN 737-53A1166
FWD
INBD
727
STA
5
4
VIEW A−A
FWD
VIEW B−B
INBD
DETAIL III
B
B
S−18A
A A
5
S−19
S−18A
WL 190
4
4
5
R07478
FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR
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### Page 42

BOEING SERVICE BULLETIN 737-53A1166
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
STEP TASK NAME PART NUMBER QTY NOTES
1 Remove/
Keep
Flap Right Angle
Gearbox
1 Keep the parts to use again.
Refer to AMM 27-51-261.
2 Remove/
Keep
Tee 65-48692-5 Left Side
65-48692-12 Right Side
1 Keep the tee to use again.
3 Remove/
Keep
Bracket 69-39436-2 Left Side
69-39437-2 Right Side
Keep the bracket to use again.
4 Trim
Apply
Apply
Shear Beam Web
Chemical Film
Treatment
(Alodine)
Primer
65-46877-( )
BMS 10-11, Type 1
1 Trim the aft part of the outboard
vertical side of the Shear Beam
Web to allow for the installation
of the Repair Angle.
Apply to cut area. Refer to 737
Structural Repair Manual
51-10-2
Apply one layer to cut area.
5 Trim
Apply
Apply
Horizontal
Stiffener
Chemical Film
Treatment
(Alodine)
Primer
65-46547-( )
BMS 10-11, Type 1
1 Trim the outboard part of the
vertical side of the Horizontal
Stiffener to allow for the
installation of the Repair Angle.
Apply to cut area. Refer to 737
Structural Repair Manual
51-10-2
Apply one layer to cut area.
FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
VIEW A−A
A
A
11
R07508
FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
7
8
6
3
4
2
5
6
R07515
FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS
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### Page 45

BOEING SERVICE BULLETIN 737-53A1166
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
NOTE: Make the repair parts shown in the table that follows. Trim the repair parts to match the existing
equivalent airplane parts. Make sure that the fastener hole edge margin is not less than the
equivalent airplane part.
STEP TASK NAME MATERIAL QTY NOTES
1 Make
Heat Treat
Repair Angle
Repair Angle
AND10134-2008 x 20.8
7075-T0,
or equivalent.
Heat Treat to T-6
1
2 Make Shim 1.25 x 4.25 x 0.032 inch thick
7075-T6 Aluminum Alloy Sheet.
1
3 Make Repair Strap 1 . 2 5x6x 0.18 inch thick
7075-T6 Aluminum Alloy Sheet.
1
4 Make Filler 1.4 x 8.2 x 0.18 inch thick
7075-T6 Aluminum Alloy Sheet.
1
5 Make Filler 1.2 x 1.4 x 0.15 inch thick
7075-T6 Aluminum Alloy Sheet
1
6 Make
Bend
Heat Treat
Repair Angle
Vertical Wall
Repair Angle
4 x 8.2 x 0.15 inch thick
7075-T0 Aluminum Alloy Sheet.
Heat treat to T-6.
1 Refer to 737 Structural
Repair Manual 51-20-1.
Use a minimum bend radius
of 0.44. Chamfer the aft
vertical edge 0.10 x 45
degrees to match the
Repair Angle made in Step
1.
Also, bend the vertical wall
so it will align with the filler
made in Step 4 and the
Repair Angle made in Step
1.
7 Make Shim 2.1 x 11.4 x 0.18 inch thick
7075-T6 Aluminum Alloy Sheet.
1
8 Make Shim 1.2 x 8.7 x 0.18 inch thick
7075-T6 Aluminum Alloy Sheet.
1
FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
SEE DETAIL I
SEE DETAIL II
DETAIL I
FLAP RIGHT ANGLE GEARBOX
RIGHT GEAR BOX SHOWN
LEFT GEARBOX SIMILAR
12
FWD
R07523
FIGURE 5. INSTALL THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
31
10 11
1 9
81
1
21
WL 190
S−18A
S−19
S−20
4 71
INBD
RIGHT SIDE SIMILAR
LEFT SIDE SHOWN
DETAIL II
B
B
A A
R07532
FIGURE 5. INSTALL THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
1 4
FWD
INBD
VIEW A−A
13
STA
727
71
51
1 2
1 6
R07567
FIGURE 5. INSTALL THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
15
1 7
16
VIEW B−B
LOOKING OUTBOARD
FWD
S−20
STA
727
S−18
S−18A
S−19
1 2
R07646
FIGURE 5. INSTALL THE TIME LIMITED REPAIR
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### Page 50

BOEING SERVICE BULLETIN 737-53A1166
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
STEP TASK NAME PART NUMBER QTY NOTES
1 Install
Drill
Remove
Deburr
Apply
Apply
Repair parts
Fastener holes
Repair parts
Fastener holes
Chemical film
treatment (Alodine)
Primer BMS 10-11, Type 1
Temporarily install repair parts.
Remove sharp edges.
Refer to 737 Structural Repair
Manual 51-10-2.
2 Install Repair Angle (a) (refer to Figure 4, Step 1) 1 Install parts with BMS 5-95 fay
surface sealant. Refer to 737
Structural Repair Manual
51-20-4.
Install with BACB30 MB
fasteners the same size as
was removed. If necessary,
use oversize fasteners.
For new fastener locations, use
BACB30MB8-( ) fasteners.
Install fasteners wet with BMS
5-95 sealant.
3 Install Shim (b) (refer to Figure 4, Step 2) 1
4 Install Repair Strap (b) (refer to Figure 4, Step 3) 1
5 Install Filler (refer to Figure 4, Step 4) 1
6 Install Filler (refer to Figure 4, Step 5)
7 Install Repair Angle (refer to Figure 4, Step 6) 1
8 Install Shim (refer to Figure 4, Step 7) 1
9 Install Shim (refer to Figure 4, Step 8) 1
10 Install Bracket 69-39436-2 Left Side
69-39436-2 Right Side
1 Install the bracket removed in
Step 3 of Figure 3.
11 Install Tee 65-48692-5 Left Side
65-48692-12 Right Side
1 Install the tee removed in Step
2 of Figure 3.
12 Install Flap Right Angle
Gearbox
1 Install the Flap Right Angle
Gearbox removed in Step 1 of
Figure 3.
Refer to AMM 27-51-261.
(a) If necessary, the inboard edge of the repair angle can be trimmed to remove interference with
fasteners through the Repair Strap, (Step 4), Shim (Step 3), and Tee, (Step 11).
(b) The fastener at the inboard edge of the Repair Strap and Shim, as shown in the initial installation, can
be difficult to install. Trim the Repair Strap and Shim so that installation does not require removal of
this fastener. Detail II has been revised to show the changed installation.
FIGURE 5. INSTALL THE TIME LIMITED REPAIR
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BOEING SERVICE BULLETIN 737-53A1166
LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE
2.00R−2.50R
43
0.90
C,DC,D
3
4.201.20
0.14
.62R VIEW C−C9°
2
0.25 0.25
9.25 0.10
VIEW B−B
0.10
0.21 FORM AFTER
MACHINING
.50R 2 LOCATIONS
4
1.20 3.70
0.14
.62R
VIEW D−D
9°
10.05 FORM AFTERMACHINING
0.10
2.00R−2.50R
0.25 0.25
9.25 0.10
VIEW A−A
210.46
2.96
3.00
4.94
7.50 1.25
2.50
.62R
A,BA,B
14.35
R37837
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
11.42
6
2.68
2.34
2.46
16.66
7
15.86
.62R
.50R
2.62
8
.62R
2.34
1.25
1.25
19.06
9
.50R
2.62
2.34
1.25
R37960
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
3.20
1.50
11.29
8.51
7.01
6.15
4.64
0.13
2.84
2.86
4.34
4.36
11.20
3.25
1.58
3.09
2.77
0.23
3.05
5
TYPICAL
0.94
−1 SHOWN,−2 OPPOSITE
SEE DETAIL I
HOLE LAYOUT
4 LOCATIONS
0.28R
R37979
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
5
7.62
6.63
4.30
3.32
TYPICAL0.38 TYPICAL0.38
0.25 IN. 1.50
JOG UPOML
BEND 90°X.12R
−1 SHOWN,−2 OPPOSITE
HOLE LAYOUT
DETAIL I
R38342
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS
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BOEING SERVICE BULLETIN 737-53A1166
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
STEP TASK NAME MATERIAL QTY NOTES
1 Make Strap
65C37566-5, Left
65C37566-6, Right
3.1 x 14.4 x 0.25 inch thick
7075-T6 Bare Plate
1 For Group 2 airplanes.
See View A-A
2 Make Strap
65C37566-7, Left
65C37566-8, Right
3.1 x 14.4 x 0.25 inch thick
7075-T6 Bare Plate
1 For Group 3 airplanes.
See View B-B
3 Make Filler
65C37566-9
1.0 x 5.5 x 0.14 inch thick
2024-T3 Bare Sheet
1 See View C-C
4 Make Filler
65C37566-10
1.0 x 5.0 x 0.14 inch thick
2024-T3 Bare Sheet
1 See View D-D
5 Make
Heat Treat
Splice Angle
69-87822-1, Left
69-87822-2, Right
Splice Angle
3.3 x 11.4 x 0.063 inch thick
2024-0 Clad Sheet
Heat Treat to T42
1 -
6 Make Strap
65C37566-4
2.8 x 11.5 x 0.10 inch thick
7075-T6 Clad Sheet
1 -
7 Make Strap
65C37566-3
2.5 x 16.7 x 0.10 inch thick
7075-T6 Clad Sheet
1 -
8 Make Strap
65C37566-2
2.7 x 16.0 x 0.10 inch thick
7075-T6 Clad Sheet
1 -
9 Make Strap
65C37566-1
2.7 x 19.2 x 0.10 inch thick
7075-T6 Clad Sheet
1 -
FIGURE 6. MAKE STRINGER 18A REPAIR PARTS
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(No text on this page.)

### Page 57

BOEING SERVICE BULLETIN 737-53A1166
ADDENDUM
FLIGHT SAFETY SECTION
INSPECTION TO ENSURE STRUCTURAL INTEGRITY OF AIRFRAME
A structural reassessment of the 737 airplane has been conducted under the requirements of Federal
Aviation Administration (FAA) Advisory Circular 91-56 in accordance with Federal Aviation Regulation (FAR)
25.571, as amended in 1978, to ensure safe operation of 737 airplanes throughout their operational life.
Table I provides a summary of the inspections specified in Accomplishment Instructions, Part I - Flight Safety
Inspection Program and the Compliance Section, that are recommended for the detection of cracks prior to
their reaching critical lengths. Failure to detect cracks prior to their reaching critical length may result in
failure of the outboard chord of the frame at BS 727.
Any cracked structure should be replaced prior to further flight unless specifically approved by your cognizant
regulatory agency.
Please report any discrepancies to Boeing Customer Support Engineering using the reporting system
described in the addendum.
Jun 30/94 ADDENDUM
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### Page 58

BOEING SERVICE BULLETIN 737-53A1166
TABLE I - CHORD INSPECTION
Inspection
(See 737 Non
Destructive Test
Manual)
Airplane Condition Inspection Threshold
(Flight Cycles)
Repeat Inspection
Interval (Flight Cycles)
until Preventive
Modification is installed
Close visual inspection
of the the outboard
chord of the frame at
BS 727. Examine the
edge of the forward
flange.
Pulse Echo Shear
Wave inspection of the
outboard chord of the
frame at BS 727.
Examine area where
Stringer 18A is
attached.
High Frequency Eddy
Current inspection of
the outboard chord of
the frame at BS 727.
Examine two fastener
holes (i) (j).
High Frequency Eddy
Current inspection of
the outboard surface
of Stringer 18-A.
Examine around the
heads of two fastener
holes.
Service Bulletin
Modification not
accomplished.
Service Bulletin
737-53-1088 frame
replacement not
accomplished.
or
Service Bulletin
Modification not
accomplished.
Lower part of frame
replaced per Service
Bulletin 737-53-1088.
27,000 to 50,000 (a) 15,000 (e)
50,000 to 60,000 (b) 7,500 (f)
60,000 to 70,000 (c) 5,000 (g)
70,000 (d) 3,000
Service Bulletin
Modification not
accomplished.
Upper part of frame
replaced per Service
Bulletin 737-53-1088.
30,000 (after the
chord was replaced).
Use the intervals shown
above for flight cycles
after the chord was
replaced.
Close visual inspection
of the the outboard
chord of the frame at
BS 727. Examine the
edge of the forward
flange. (h)
Service Bulletin
Modification
accomplished.
Next scheduled
structural inspection.
Refer to the 737
Maintenance Planning
Data Manual
D6-17594-2, Section
6-02.
Use your Maintenance
Program Interval for
scheduled structural
inspections.
Refer to the 737
Maintenance Planning
Data Manual
D6-17594-2, Section
6-02.
Jun 30/94 ADDENDUM
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### Page 59

BOEING SERVICE BULLETIN 737-53A1166
(a) For airplanes at this threshold, do the inspection initially within 4,500 flights after you get this bulletin.
(b) For airplanes at this threshold, do the inspection initially within 2,500 flights after you get this bulletin.
(c) For airplanes at this threshold, do the inspection initially within 1,500 flights after you get this bulletin.
(d) For airplanes at or over this threshold, do the inspection initially within 500 flights after you get this
bulletin.
(e) Use these intervals until the airplane collects more than 50,000 flights.
(f) Use these intervals until the airplane collects more than 60,000 flights.
(g) Use these intervals until the airplane collects more than 70,000 flights.
(h) Fully extend the trailing edge flaps. Get access to the outboard side of the frame at BS 727 through the
opening in the flap fairing. Get access to the inboard side of the frame at BS 727 from inside the
wheelwell.
(i) Airplanes with 60,000 to 70,000 cycles can omit this step only at the initial inspection at 1500 flights after
you get this bulletin.
(j) Airplanes with more than 70,000 cycles can omit this step only at the initial inspection at 500 flights after
you get this bulletin.
Jun 30/94 ADDENDUM
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### Page 60

BOEING SERVICE BULLETIN 737-53A1166
Boeing requests that operators use the following Structural Significant Item (SSI) Reporting System to report
any discrepancies that are found in accomplishing a Flight Safety Inspection.
1. Upon recognition of discrepancy, the following information should be telegraphed to Boeing:
Heading: ATTENTION - SSI DISCREPANCY - SERVICE BULLETIN RELATED
- Service Bulletin number
- Airplane serial number on which discrepancy was found
- Identification of structural item found damaged
- Flight cycles and hours on damaged item
- Location and description of damage including direction and size
- When discovered and inspection method used
Send telegram through Boeing Field Service Representative or directly to:
737 Customer Support Engineering
2. An Operator's Follow-Up Report containing all available pertinent data, relative to the structural
discrepancy, shall be sent to Boeing. A summary of the information that should be reported is shown in
the DISCREPANT STRUCTURE REPORT form attached. Operators may use this form or any suitable
alternative which contains the same information.
3. All data and reports dealing with the Flight Safety Inspection Program shall be submitted either through
a Boeing Field Service Representative or directly to:
The Boeing Commercial Airplane Group
P.O. Box 3707
Seattle, Washington 98124-2207, USA
Attn: 707/727/737 Service Engineering Director
Org. M-7201 Mail Stop 2H-84
4. All reports will be reviewed promptly.
5. The Boeing Company will summarize the results of all reported significant data for distribution
semi-annually to operators and appropriate Airworthiness Authorities.
Jun 30/94 ADDENDUM
REV 1: May 25/95 P a g e4o f6

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