### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53A1166 

## Revision Transmittal Sheet 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 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

### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53A1166 

## Summary 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

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

### 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 727C79178

Jun 30/94 REV 1: May 25/95 Summary Page 2 of 2

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 Page 1 of 51

### 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 REV 1: May 25/95 2

### 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 REV 1: May 25/95 3

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 4

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 5

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 6

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 7

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 8

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 9

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 10

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 11

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 12

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 13

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 14

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 15

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 16

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 17

### 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

Jun 30/94 737-53A1166 REV 1: May 25/95 18

### 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)

Jun 30/94 737-53A1166 REV 1: May 25/95 19

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 20

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 21

### 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 4x8x0.15 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 1.25 x 6 x0.18 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

Jun 30/94 737-53A1166 REV 1: May 25/95 22

### 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 FlightSafety 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 23

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 24

### 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).

Jun 30/94 737-53A1166 REV 1: May 25/95 25

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 26

### 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.

Jun 30/94 737-53A1166 REV 1: May 25/95 27

### BOEING SERVICE BULLETIN 737-53A1166

Illustration Table of Contents Title Page FIGURE 1. INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION . . . . . . . . . . . . . . . . . . . 32 FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . 35 FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS . . . . . . . . . . . . . . . . . . . . . . . . . 39 FIGURE 5. INSTALL THE TIME LIMITED REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 FIGURE 6. MAKE STRINGER 18A REPAIR PARTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Jun 30/94 737-53A1166 REV 1: May 25/95 28

### BOEING SERVICE BULLETIN 737-53A1166

(WING-TO-BODY FAIRING NOT SHOWN) RIGHT SIDE OPPOSITE LEFT SIDE SHOWN SEE DETAIL IC79635

FIGURE 1. INSPECTION

Jun 30/94 SHEET 1 OF 3 737-53A1166 REV 1: May 25/95 29

### BOEING SERVICE BULLETIN 737-53A1166



## DETAIL II 2

3 6 5 4 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 727C79638

FIGURE 1. INSPECTION

Jun 30/94 SHEET 2 OF 3 737-53A1166 REV 1: May 25/95 30

### 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

Jun 30/94 SHEET 3 OF 3 737-53A1166 REV 1: May 25/95 31

### 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

AD23274

FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION

Jun 30/94 SHEET 1 OF 3 737-53A1166 REV 1: May 25/95 32

### BOEING SERVICE BULLETIN 737-53A1166

5

2

3

1 6

7

7

4



## VIEW A-A INBD S-17

S-18

S-19

S-20D23551

The step numbers shown below agree with the numbers shown inside the circle symbols in the figure.

FIGURE 2. ACCESS FOR THE PREVENTIVE MODIFICATION

Jun 30/94 SHEET 2 OF 3 737-53A1166 REV 1: May 25/95 33

### 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

Jun 30/94 SHEET 3 OF 3 737-53A1166 REV 1: May 25/95 34

### 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 IR07300

FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR

Jun 30/94 SHEET 1 OF 4 737-53A1166 REV 1: May 25/95 35

### BOEING SERVICE BULLETIN 737-53A1166



### SEE DETAIL III 5

2

3 S-20 SEE DETAIL III 4 S-19 S-18A

WL 190

INBD

RIGHT SIDE SIMILAR

LEFT SIDE SHOWN



## DETAIL IIR07463

FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR

Jun 30/94 SHEET 2 OF 4 737-53A1166 REV 1: May 25/95 36

### 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

5R07478

FIGURE 3. ACCESS FOR THE TIME LIMITED REPAIR

Jun 30/94 SHEET 3 OF 4 737-53A1166 REV 1: May 25/95 37

### 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

Jun 30/94 SHEET 4 OF 4 737-53A1166 REV 1: May 25/95 38

### BOEING SERVICE BULLETIN 737-53A1166



## VIEW A-A A

A 1 1R07508

FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS

Jun 30/94 SHEET 1 OF 3 737-53A1166 REV 1: May 25/95 39

### BOEING SERVICE BULLETIN 737-53A1166



### 7

8 6 3

4 2

5

6R07515

FIGURE 4. MAKE THE TIME LIMITED REPAIR PARTS

Jun 30/94 SHEET 2 OF 3 737-53A1166 REV 1: May 25/95 40

### 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 1.25 x 6 x0.18 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

Jun 30/94 SHEET 3 OF 3 737-53A1166 REV 1: May 25/95 41

### 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

FWDR07523

FIGURE 5. INSTALL THE TIME LIMITED REPAIR

Jun 30/94 SHEET 1 OF 5 737-53A1166 REV 1: May 25/95 42

### BOEING SERVICE BULLETIN 737-53A1166



### 3 1

10 11

1 98

1 1 2 1

WL 190 S-18A S-19

S-20 4 7 1

INBD

RIGHT SIDE SIMILAR

LEFT SIDE SHOWN



## DETAIL II B B

A AR07532

FIGURE 5. INSTALL THE TIME LIMITED REPAIR

Jun 30/94 SHEET 2 OF 5 737-53A1166 REV 1: May 25/95 43

### BOEING SERVICE BULLETIN 737-53A1166



### 1 4

FWD INBD



## VIEW A-A 1 3
STA 727

7 1
5 1 1 2

1 6R07567

FIGURE 5. INSTALL THE TIME LIMITED REPAIR

Jun 30/94 SHEET 3 OF 5 737-53A1166 REV 1: May 25/95 44

### BOEING SERVICE BULLETIN 737-53A1166



### 1 5 1 7 1 6



## VIEW B-B LOOKING OUTBOARD FWD S-20 STA 727

S-18

S-18A
S-19 1 2R07646

FIGURE 5. INSTALL THE TIME LIMITED REPAIR

Jun 30/94 SHEET 4 OF 5 737-53A1166 REV 1: May 25/95 45

### 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

Jun 30/94 SHEET 5 OF 5 737-53A1166 REV 1: May 25/95 46

### BOEING SERVICE BULLETIN 737-53A1166



### LEFT SIDE SHOWN, RIGHT SIDE OPPOSITE 2.00R-2.50R

4 3

0.90 C,D C,D

3 4.20 1.20 0.14 .62R 

## VIEW C-C 9` 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` 1 0.05 FORM AFTER MACHINING 0.10

2.00R-2.50R 0.25 0.25 9.25 0.10



## VIEW A-A 2 1 0.46 2.96 3.00

4.947.50 1.252.50 .62R A,B A,B 14.35R37837

FIGURE 6. MAKE STRINGER 18A REPAIR PARTS

Jun 30/94 SHEET 1 OF 5 737-53A1166 REV 1: May 25/95 47

### 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 1.25R37960

FIGURE 6. MAKE STRINGER 18A REPAIR PARTS

Jun 30/94 SHEET 2 OF 5 737-53A1166 REV 1: May 25/95 48

### BOEING SERVICE BULLETIN 737-53A11663.201.5011.298.517.016.154.640.132.842.864.344.3611.203.251.583.092.770.233.055TYPICAL0.94-1 SHOWN,-2 OPPOSITESEE DETAIL IHOLE LAYOUT4 LOCATIONS0.28RR37979

FIGURE 6. MAKE STRINGER 18A REPAIR PARTS

Jun 30/94 SHEET 3 OF 5 737-53A1166 REV 1: May 25/95 49

### BOEING SERVICE BULLETIN 737-53A116657.626.634.303.32TYPICAL0.38TYPICAL0.380.25 IN. 1.50JOG UPOMLBEND 90`X.12R-1 SHOWN,-2 OPPOSITEHOLE LAYOUTDETAIL IR38342

FIGURE 6. MAKE STRINGER 18A REPAIR PARTS

Jun 30/94 SHEET 4 OF 5 737-53A1166 REV 1: May 25/95 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 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

Jun 30/94 SHEET 5 OF 5 737-53A1166 REV 1: May 25/95 51

### 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 REV 1: May 25/95 Page 1 of 6

### 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 REV 1: May 25/95 Page 2 of 6

### 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 REV 1: May 25/95 Page 3 of 6

### 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 oranysuitable alternativewhich containsthe 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 Page 4 of 6

### BOEING SERVICE BULLETIN 737-53A1166

DISCREPANT STRUCTURE REPORT SIDE 1 1 REPORT DATA A.T.A. INDEX REPORT NO.

__ AIRLINE/AGENCY __________________ STATION MONTH DAY YEAR________
2 AIRCRAFT DATA MODEL ___________________ SERIES _____________ TAIL NO. ___________________________________ MFG. SERIAL NO. ____________________________ FLIGHT HOURS _________________ FLIGHT CYCLES _________________________
3 COMPONENT DATA (AS APPLICABLE AND AVAILABLE): NAME ________________________________________________ P/N _________________________ S/N ____________________________ IPC/DWG. REF. ________________________________________ SRM REF. ____________________________________________________ COMPLETE THE FOLLOWING IF KNOWN AND DIFFERENT FROM SECTION 2: COMPONENT FLIGHT HOURS SINCE NEW ____________________________ SINCE OVERHAUL ____________________________ COMPONENT FLIGHT HOURS SINCE NEW ____________________________ SINCE OVERHAUL ____________________________ 4 REPAIR DATA 

# [] PLANNED 

# [] COMPLETED
4A ACTION

___________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________ 4B REFERENCE ASSOCIATED WITH INSPECTION/REPAIR (SPECIFY NO., PAGE, FIGURE, ETC): SB_______________________ AD _______________________ IPC ________________________ SRM ______________________________ MPD_____________________ OTHER (E.G. SDR, MRR) __________________________________ SIIA ______________________________ STRUCTURAL SIGNIFICANT ITEM NO.

_________________SERIES 50 NO. __________________________ 5 SERVICE BULLETINS INCORPORATED IN AREA OF DISCREPANCY
SERVICE BULLETIN APPLICABLE SECTION DATE OF TOTAL FLIGHT HOURS AND NO. OF SERVICE BULLETIN INCORPORATION CYCLES AT INCORPORATION _________________ ____________________ ________________ __________ HOURS ________ FLIGHTS _________________ ____________________ ________________ __________ HOURS ________ FLIGHTS _________________ ____________________ ________________ __________ HOURS ________ FLIGHTS 6 INSPECTION DATA (COMPLETE KNOWN INFO., CHECK APPROPRIATE ITEMS FOR DISCREPANT STRUCTURE): CURRENT INSPECTION INTERVALS (FLIGHTS) _________________ _________________ ________________ ________________ CORRESPONDING INSPECTION LEVELS _________________ _________________ ________________ ________________ 6A WHEN DISCOVERED 6B INSPECTION LEVEL 6C DETECTION METHOD 

### [] SCHEDULED MAINTENANCE 

### [] OVERHAUL 

### [] UNSCHEDULED 

### [] SPECIAL/DIRECTED (AD, SB...) 

### [] SYMPTOM (FUEL/PRESS LEAK...) 

### [] RELATED FLEET EXPERIENCE 

### [] ACCIDENT INVESTIGATION 

### [] SSID 

### [] SERIES 50 

### []

______________________ 

### [] WALK - AROUND 

### [] GENERAL VISUAL

### L [] EXTERNAL SURVEILLANCE 

### [] INTERNAL SURVEILLANCE 

### [] DETAILED 

### [] SPECIAL 

### []

______________________ 

### [] VISUAL 

### [] MAG. VISUAL 

### [] DYE PENETRANT 

### [] ULTRASONIC 

### [] LOW FREQUENCY EDDY CURRENT 

### [] HIGH FREQUENCY EDDY CURRENT 

### [] BORESCOPE 

### [] MAGNETIC PARTICLE 

### [] TAP TEST 

### [] SOUND 

### [] SMELL 

### [] FEEL 

### [] X-RAY 

### [] PRESS. LOSS


### []

__________ 

### []

__________ 

### []

__________

Jun 30/94 ADDENDUM REV 1: May 25/95 Page 5 of 6

### BOEING SERVICE BULLETIN 737-53A1166

DISCREPANT STRUCTURE REPORT SIDE 2 7 DISCREPANCY DESCRIPTION:

______________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________ Attach sketch, photos and text as required to describe defect and specific location. When applicable give details of associated discrepancies on the same aircraft, related experience with this discrepancy on any aircraft, and previous modification (s) to the discrepant structure. 7A TYPE OF DISCREPANCY: 

### [] BENT 

### [] BROKEN 

### [] BUCKLED 

### [] BURNED 

### [] CLOGGED 

### [] CONTAMINATED 

### [] CORRODED 

### [] CRACKED 

### [] DEFORMED 

### [] DELAMINATED 

### [] DENTED 

### [] DETACHED 

### [] IMPROPERLY

ADJUSTED 

### [] LEAK 

### [] LOOSE 

### [] MISSING 

### [] OUT-OF-TOLERANCE 

### [] STUCK 

### [] WORN 

### [] WRINKLED 

### []

_________________ 

### []

_________________ 

### []

_________________ 

### []

_________________ 7B SIZE OF DISCREPANCY: 

### [] INCHES, OR 

### [] CENTIMETERS AREA__________________________ X ____________________________ DEPTH ________________________________________________ CRACK LENGTH INITIALLY DETECTED ________________________________________ DATE ____________________________________ FINAL MEASUREMENT (IF DIFFERENT) ________________________________________ DATE ____________________________________ 7C DISCREPANT PART: 

### [] FRAME/BULKHEAD 

### [] PRESSURE BULKHEAD 

### [] FRAME AROUND OPENING 

### [] WINDOW FORGING 

### [] KEEL BEAM 

### [] FLOOR 

### [] WING CENTER SECTION 

### [] WING DRY-BAY AREA/COMPT. 

### [] SPAR 

### [] RIB 

### [] LANDING GEAR BEAM 

### [] FLAP TRACK 

### [] FAIRING 

### []

_______________________________________ 

### [] SKIN 

### [] PLATE/PANEL 

### [] CHORD 

### [] STRINGER NO. 

### [] BEAM 

### [] STRUT/BRACE 

### [] LINK/ROD 

### [] LONGERON 

### [] FITTING 

### [] BRACKET/CLIP 

### [] STOP 

### [] FASTENER 

### []

________________________________ 

### []

________________________________ 

### [] JOINT/SPLICE 

### [] LUG 

### [] WELD 

### [] BOND 

### [] OPEN HOLE 

### [] FASTENER HOLE 

### [] CUT-OUT 

### [] ACCESS/LIGHTENING HOLE 

### [] NOTCH/GROOVE 

### [] DISCONTINUITY 

### [] BASIC MATERIAL 

### [] BUSHING 

### [] PIN 

### []

____________________________ 7D LOCATION OF DISCREPANT PART: GENERAL LOCATION (E.G., BILGE, UNDER GALLEY) ______________________________________________________________________ 

### [] BODY STA. NO. __________ 

### [] WING STA. NO. ___________ 

### [] VERT. STAB. STA. ________ 

### [] HORIZ.STAB.STA. ________ 

### [] NACELLE/PYLON COMPARTMENT _________ 

### [] NOSE LANDING GEAR 

### [] MAIN LANDING GEAR 

### [] WING LANDING GEAR 

### [] BODY LANDING GEAR 

### [] DOOR/ACCESS PANEL 

### [] RUDDER 

### [] ELEVATOR 

### [] AILERON 

### [] FLAP 

### [] SLAT 

### [] SPOILER 

### [] TAB (ALSO CHECK ABOVE) 

### []

________________________ 

### []

________________________ 

### [] INTERIOR 

### [] INBOARD 

### [] LEFT 

### [] FORWARD 

### [] UPPER 

### [] LEADING EDGE 

### [] MIDDLE 

### [] EXTERIOR 

### [] OUTBOARD 

### [] RIGHT 

### [] AFT 

### [] LOWER 

### [] TRAILING EDGE 

### [] SIDE 

### [] SPECIFIC LOCATION __________________________________

________________________________________________________

________________________________________________________

INSPECTED BY REPAIRED BY
ORIGINATED BY DATE

Jun 30/94 ADDENDUM REV 1: May 25/95 Page 6 of 6

### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53A1166 

## Evaluation Form Date: June 30, 1994 Revision 1: May 25, 1995 ATA System: 5311 Prepared By: Steve Lemon

SUBJECT: FUSELAGE - FRAMES - BODY STATION 727 OUTBOARD CHORD AT STRINGER 18A, INSPECTION AND PREVENTIVE MODIFICATION
Use this evaluation form to tell us what you think of the quality of this service bulletin. We will use the data that you give us to improve the quality of our service bulletins. Please include data about these or other items: - Did this service bulletin meet your estimate of quality? - How easy is this service bulletin to understand? - Are the Planning Information, Material Information and Accomplishment Instructions satisfactory? - Will you do this service bulletin fully? If not, please tell us why. - Is the Manpower estimate satisfactory? NOTE: Please do not use this evaluation form to tell us to make changes to your manuals. To make these changes, please use a Publication Change Request (PCR) form. Please give us this data: OPERATOR: TODAY'S DATE: PREPARED BY: TITLE: ORGANIZATION: TELEX CODE: TELEPHONE NUMBER:

COMMENTS:

If you have other comments please use the other side. Thank you for the time you used to complete this form. Give the completed evaluation form to your Boeing Field Service Representative or send the evaluation form directly to this address: T. J. Taylor, Manager Service Bulletin Engineering Boeing Commercial Airplane Group P.O. Box 3707, Mail Stop 20-85 Seattle, WA 98124-2207

BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207 Page 1 of 1