### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53-1120 

## Revision Transmittal Sheet Date: July 6, 1989 Revision 1: May 13, 1993 ATA System: 5321

SUBJECT: FUSELAGE - BODY STATION 520 FLOOR BEAM INSPECTION, REPAIR AND PREVENTIVE CHANGE This revision includes all pages of the service bulletin. COMPLIANCE INFORMATION RELATED TO THIS REVISION On 737-100, 737-200, 737-200C, 737-300, 737-400 airplanes, make changes to a repair that was installed by the initial release. On 737-100, 737-200, 737-300, 737-400 airplanes, check the preventive change done by the initial release of this service bulletin. If necessary, make the changes shown to get the clearances given in this revision. Refer to Paragraph I.D. for compliance information. SUMMARY The 737-100 and 737-200 Airplanes are in Groups 1, 2 and 3. The 737-300 and 737-400 Airplanes are in Groups 7 and 8. The 737-200C Cargo Airplanes are in Groups 4, 5 and 6. The table on page 54 of the Accomplishment Instructions gives the work instructions for each channel location. Do only those work instructions that are applicable to the airplane group. Revision 1 is sent to : 1. Give different floor beam repair kits and make changes to a floor beam repair that was installed by the initial release. 2. Make changes to the cargo posts and the electrical bracket (These changes are necessary to install the channel with a pivot link). 3. Change the crack limits. 4. Delete the reference to a letter check ("C" check). 5. Give a different inspection threshold and repeat inspection interval in flight cycles. 6. Add a floor beam eddy current inspection (done before a preventwrive change or repair is made). 7. Give other instructions and information as shown in Paragraph I.B., Reason. Included in this revision is the information that Notice of Status Change 737-53-1120NSC2 (NSC2), NSC4 and NSC5 told the operator was necessary to change the floor beam. The electrical bracket information given in NSC5 is made better. The information in NSC1 and NSC3 has changed and is not included in Revision 1. 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. REVISION HISTORY Initial Release: July 6, 1989 Revision 1 May 13, 1993

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

### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53-1120 

## Summary Date: July 6, 1989 Revision 1: May 13, 1993 ATA System: 5321

SUBJECT: FUSELAGE - BODY STATION 520 FLOOR BEAM INSPECTION, REPAIR AND PREVENTIVE CHANGE BACKGROUND 28 operators gave reports of fatigue cracks in the Body Station (BS) 520 floor beam area. In these reports, 109 airplanes were found with cracks in the floor beam area. Seven of these airplanes were found with cracks in at least one of the channels in the floor beam. Four of these airplanes were found with cracks in at least one of the intercostals that attach to the floor beam. The largest crack in the floor beam was 8.5 inches long. The largest crack in the channel was 2.5 inches long. The largest crack in the intercostal was three inches long. These airplanes had between 7700 and 69,900 flight hours and between 4700 and 67,000 flight cycles. Three operators gave reports of cracks in the channel only. Boeing Structural Item Interim Advisory (SIIA) 737-140 is related to this service bulletin. These fatigue cracks occur when the intercostal link puts a force on the floor beam channel. This occurs because of the thermal contraction of the fuselage skin during flight that causes relative movement between the floor beam and wing box in the forward-aft direction. The pivot link installed in this service bulletin permits relative movement to occur without this force. Fatigue cracks are thus prevented. Revision 1 gives different floor beam repair kits and makes changes to a floor beam repair that was installed by the initial release. Revision 1 also makes changes to the cargo posts and the electrical bracket. ACTION (PRR34556) Make an inspection of the channel location for cracks. Install a channel with a pivot link if cracks are found in the channel only. Install a channel with a pivot link, two repair angles and two fillers below the floor beam flange if cracks are found in the adjacent floor beam area. If no cracks are found in the channel or in the adjacent floor beam area, install a channel with a pivot link only or repeat the inspection procedure until a channel with a pivot link is installed. Make an inspection of the adjacent intercostal if cracks are found in the floor beam. Repair or replace an intercostal if it is cracked. Refer to Paragraph I.C. if a preventive change or a repair was done at a channel location by the initial release. COMPLIANCE Boeing recommends that the operator make an inspection of the floor beam and the channels for cracks before the airplane gets 4500 flight cycles. Refer to the compliance information in Figure 1 for the repeat inspection interval. For airplanes with more than 4500 flight cycles, do the above inspection no later than 4500 flight cycles after you get this service bulletin. Refer to Paragraph I.D. if a preventive change or a repair was done at a channel location by the initial release. EFFECTIVITY All 737-100, 737-200 and 737-200 cargo airplanes. 737-300 and 737-400 airplanes in line positions 1 through 1717. MANPOWER Refer to Paragraph I.F. MATERIAL INFORMATION Boeing Supplied Kits and Operator Supplied Parts.

BOEING COMMERCIAL AIRPLANE GROUP P.O. BOX 3707 SEATTLE, WASHINGTON 98124-2207 Summary Page 1 of 2

### BOEING SERVICE BULLETIN 737-53-1120



### WING BOX

REPLACE THE CHANNEL AND REPAIR THE FLOOR BEAM IF NECESSARY MAKE AN INSPECTION FOR CRACKS

CARGO AIRPLANES SIMILAR (NO CHANNEL AT BL 0) EXISTING CHANNEL LOCATION ON A PASSENGER AIRPLANE SHOWN, INTERCOSTAL LINK

WING BOX BS 520

FLOOR BEAM

FWD INBD REPAIR OR REPLACE INTERCOSTAL IF NECESSARY BS 520

NO SEAT TRACK AT BL 0B54180

Jul 6/89 REV 1: May 13/93 Summary Page 2 of 2

### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53-1120 Date: July 6, 1989 Revision 1: May 13, 1993 ATA System: 5321

SUBJECT: FUSELAGE - BODY STATION 520 FLOOR BEAM INSPECTION, REPAIR AND PREVENTIVE CHANGE
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. An equivalent change is on subsequent production airplanes. Refer to PRR34556 for data about this change. IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER AER LINGUS (ARL)

1 PG255 PG573 PG575 3 PK029 PK614 PK641-PK642 4 PY322-PY323 6 PY281 7 PP951-PP952 AEROLINEAS ARGENTINAS (ARG)

1 PH705-PH708 2 PH741-PH742 3 PH743 PK102-PK103 5 PY007 AIR ALGERIE (ALG)

3 PK361 PK631 PK633-PK634 PL717-PL725 5 PY051-PY052 6 PY053 AIR ATLANTA ICELANDIC (AID)

1 PG047 PJ104 3 PJ004 PL027 4 PY002 5 PY381 AIR CHINA (BEJ)

3 PM281-PM283 7 PP521-PP522 AIR COLUMBUS (COB)

7 PP904 PP907

Jul 6/89 737-53-1120 REV 1: May 13/93 Page 1 of 316

### BOEING SERVICE BULLETIN 737-53-1120
AIR EUROPA (ARE)

7 PM382 PP501-PP502 PP831 PP835 PP840 PP846 AIR FRANCE (AFA)

3 PL502-PL503 PN101-PN117 7 PP902 PP910-PP912 AIR GABON S.A. (GBN)

6 PY191 AIR GUINEE (GNE)

6 PY651 AIR HOLLAND CHARTER B.V. (HOL)

7 PP504 AIR LANKA, LTD. (LNK)

1 PH701 3 PK252 AIR MADAGASCAR (MAD)

1 PG375 2 PL793 AIR MALTA (MLT)

3 PL621-PL626 AIR NAMIBIA (NAM)

3 PN492 AIR NAURU (NAU)

3 PK356 PK581 6 PY286 AIR NEW ZEALAND, LTD. (ANZ)

3 PJ009 PK047 PK051 PK211 PK213-PK214 PK216-PK220 PM181 6 PY741 AIR NIPPON CO., LTD. (ANK)

2 PG582 AIR SWEDEN (TIS)

1 PJ002 2 PJ003 AIR TANZANIA (TNZ)

6 PY611-PY612 AIR UK (LEISURE) (UKL)

8 PW001 AIR ZAIRE (ZAI)

6 PY111 PY113 AIR ZIMBABWE (ZMB)

3 PN431-PN433

Jul 6/89 737-53-1120 REV 1: May 13/93 2

### BOEING SERVICE BULLETIN 737-53-1120
ALASKA AIRLINES (ASA)

6 PY112 PY134-PY135 PY270 PY461-PY463 ALL NIPPON AIRWAYS CO. LTD. (ANA)

2 PG584-PG586 3 PK711-PK716 ALOHA (ALO)

1 PG046 3 PK286-PK287 PK305 PK691-PK695 PK697 4 PY001 6 PY231 PY242 PY451 7 PP730 PP733 PP825-PP826 ALYEMDA DEM. YEMEN AIRLINES (ALY)

6 PY409-PY410 AMERICA WEST AIRLINES, INC. (AMW)

1 PC004 PG036 PL801 3 PK283 PK565 PK625-PK626 PK696 PL081 PL172 PL551-PL562 7 PP181-PP187 PP189 PP192 PP194-PP197 PP732 PP891-PP899 PP901 PP903 PP931-PP934 ANGOLA AIRLINES (ANG)

3 PK661 PK664-PK666 6 PY162 ANSETT AIRLINES OF AUSTRALIA (ANS)

7 PQ026-PQ041 ANSETT WORLDWIDE AVIATION SERVICES (AWW)

1 PA001 PA003-PA004 ARAMCO ASSOCIATED CO. (ARM)

3 PL151 PL456 6 PY241 PY243-PY244 ASEAN AVIATION (L) INC. (ASJ)

1 PG578 2 PG579-PG581 PG583 ASIANA AIRLINES (AAR)

8 PW005 PW007-PW009 PW011 PW013 AUSTRALIAN AIRLINES LIMITED (AUS)

7 PQ001-PQ014 AVENSA (AVN)

3 PK042-PK043 7 PM383 AVIATECA (AVT)

1 PG201 2 PL737 PL740-PL741 7 PP352 PP379 PP384 PP948

Jul 6/89 737-53-1120 REV 1: May 13/93 3

### BOEING SERVICE BULLETIN 737-53-1120
AVIATION SALES CO., INC. (ASC)

1 PG224 PG331 PG401 PG572 4 PY342 PY344 AVIOGENEX AIR TRANSPORT (AVG)

3 PL501 PL506 PN501-PN502 BAVARIA (BAV)

3 PL455 BOSPHORUS AIRLINES (BHY)

7 PP773 PP775 BOURAQ INDONESIA AIRLINES (PTB)

1 PJ001 PL803 2 PL742 BRAATHENS S.A.F.E. (BRT)

1 PJ072 3 PJ006-PJ008 PK882 PN451-PN453 PN455 BRITANNIA AIRWAYS, INC. (BRI)

1 PJ101 PJ103 2 PJ105-PJ106 PL716 3 PJ108 PJ110-PJ111 PJ113-PJ115 PJ117-PJ119 PK215 PK801-PK804 BRITISH AIRWAYS (BAB)

3 PK731-PK765 PK771-PK777 PK779 PK820 PL421 7 PP351 PP353 PP380 8 PW091-PW092 PW111-PW112 BRITISH MIDLAND (BMA)

7 PP908-PP909 PP915-PP916 PQ281 8 PW004 PW006 PW501 CAMEROON AIRLINES (CAM)

3 PM171 5 PY046-PY047 CANADIAN AIRLINES INTERNATIONAL LTD. (CDI)

1 PG651-PG652 2 PK026 PL761-PL762 3 PK027-PK028 PK221 PK358 PK671-PK675 PK677-PK681 PK822 PK881 PK884 PL401-PL417 PL764-PL770 PM141-PM142 4 PY303 5 PY304 6 PY151-PY154 PY421-PY422 PY441 CARNIVAL AIR (CVL)

1 PG302 PG305 PG312 2 PL712 8 PW061 CASINO EXPRESS (CIN)

1 PG279 PG436 CAYMAN AIRWAYS (CAY)

3 PK222 PK561 PK622

Jul 6/89 737-53-1120 REV 1: May 13/93 4

### BOEING SERVICE BULLETIN 737-53-1120
CHINA AIR LINES, INC. (CHI)

3 PN472-PN474 CHINA SOUTHERN AIRLINES (GUN)

3 PK636-PK637 PM251-PM254 PN405 CHINA SOUTHWEST AIRLINES (XIN)

7 PP631-PP634 CHINA XINHUA AIRLINES (XIH)

6 PY401 PY594-PY595 CITICORP NORTH AMERICA (CIC)

3 PK082 CONTINENTAL AIRLINES, INC. (CAL)

1 PA006-PA014 PA016-PA020 PG056 PG064 PG199 PG225 PG229 PG432-PG433 PG501-PG505 PG621-PG625 PG627-PG628 PG630 PG704 2 PG441-PG442 3 PL001 7 PP671-PP699 PP701-PP726 COPA COMPANIA PANAMENA DE AVIATION S.A. (COP)

1 PC001 3 PJ107 PJ112 4 PY341 CORSE AIR INTERNATIONAL (COR)

7 PP838 CROATIA AIRLINES (CRH)

3 PK904 PK906-PK907 DELTA AIR LINES, INC. (DAL)

3 PK611 PK613 PK623-PK624 PK632 PL221 PL611 PN131-PN163 PN401-PN404 PN407-PN420 7 PP231-PP243 DRAGONAIR (DRG)

3 PK357 PK617 PK871-PK873 DUKE FARMS (DFI)

7 PP991 E G AND G (EGN)

1 PG037 PG208 PG210 PG215 PG431 3 PL763 EAST WEST AIRLINES (INDIA) (BOM)

3 PK615-PK616 PK819 PK824 PL171 PL758 EDRESS, SHIEKH M. (SME)

3 PL505 EGYPTAIR (EGP)

3 PK254-PK255 PK257-PK258

Jul 6/89 737-53-1120 REV 1: May 13/93 5

### BOEING SERVICE BULLETIN 737-53-1120
EL AL ISRAEL AIRLINES, LTD. (ELA)

3 PL631-PL632 ETHIOPIAN AIRLINES, CORP. (ETH)

3 PN512 EURALAIR (ERA)

1 PG026 PG028-PG029 4 PY004 PY006 EUROPE AERO SERVICE (EUR)

3 PK203 PK282 PK359 PK564 PK612 FAR EASTERN AIR TRANSPORT (FAT)

1 PA002 PA005 PG055 PG226 PG228 PG230 3 PK562 PN481 FAUCETT (COMPANIA DE AVIATION S.A. (FCT)

1 PC002 PG034 PG213 2 PL711 FORTUNE AVIATION (FOR)

3 PK432 FRENCH POSTAL OFFICE (FPO)

4 PY302 6 PY101-PY103 7 PS641 GARUDA INDONESIAN AIRWAYS (GIA)

7 PQ282 GATARI AIR SERVICE (GRI)

3 PL441 GERMANIA FLUGGESELLSCHAFT MBH (GER)

7 PP503 PP506-PP507 PQ231-PQ236 GOVERNMENT OF BRAZIL (BRZ)

3 PK068-PK069 GOVERNMENT OF MEXICO (MXG)

1 PC005 PG223 GOVERNMENT OF SHARJAH (SHJ)

3 PL581 GPA GROUP LTD. (GUI)

3 PK241 PK354-PK355 7 PP301 PP303-PP305 PP827 PP833-PP834 GULF AIR (GUL)

3 PK461-PK468 HAPAG LLOYD (HAP)

3 PL504 8 PW511-PW514

Jul 6/89 737-53-1120 REV 1: May 13/93 6

### BOEING SERVICE BULLETIN 737-53-1120
HEAVYLIFT AIRCRAFT ENGINEERING (HVL)

3 PJ109 ICELANDAIR (ICE)

8 PW561 INDIAN AIR FORCE (IDF)

1 PH712 2 PH713 3 PM016-PM017 INDIAN AIRLINES (IND)

1 PH709 PH711 3 PH021-PH022 PH024 PK231-PK233 PK235-PK240 PM001-PM006 6 PY631 INDONESIAN AIR FORCE (IDO)

3 PL601-PL603 INTEGRATED RESOURCES (INH)

1 PG271 PG273 PG629 INTER EUROPEAN AIRWAYS (IER)

7 PP841-PP842 INTERNATIONAL AIR LEASES (IAL)

1 PG043 PG048 PG253 INTERNATIONAL PACIFIC TRADING CO. (IPT)

1 PG574 PJ102 IRAN AIR (IRN)

2 PH731 3 PK391 5 PY021-PY022 IRAQI AIRWAYS (IRQ)

6 PY141-PY142 ISTANBUL AIRLINES (IST)

8 PW002 JUGOSLOVENSKI AEROTRANSPORT (JAT)

7 PP771-PP772 PP774 PP776-PP779 KENYA AIRWAYS (KEN)

3 PK253 PK256 KLM ROYAL DUTCH AIRLINES (KLM)

7 PP861-PP873 KOREAN AIR FORCE (KAF)

7 PP221 LADECO (LDE)

1 PL802 3 PJ005 PK212 PK281 PK826 PK830 7 PP946

Jul 6/89 737-53-1120 REV 1: May 13/93 7

### BOEING SERVICE BULLETIN 737-53-1120
LAN-CHILE S.A. (LAN)

3 PK360 PK825 PL025 PL028 LAUDA AIR LUFTFAHRT AG (LAL)

7 PP851-PP852 LINA CONGO (LNA)

6 PY411 LINHAS AEREAS DE MOCAMBIQUE (LAM)

1 PH703 5 PY031 LITHUANIAN AIRLINES (LIJ)

3 PK563 LUFTHANSA GERMAN AIRLINES (DLH)

3 PK901-PK903 PK905 PK908-PK938 5 PY345-PY346 7 PQ051-PQ068 PQ086-PQ092 MAERSK AIR (MRS)

7 PP505 MALAYSIAN AIRLINES SYSTEM BERHAD (MAS)

3 PL743-PL747 6 PY201 MALEV HUNGARIAN AIRLINES (HGA)

3 PK284-PK285 PK827 MANDALA AIRLINES (MND)

3 PN001-PN002 MARKAIR, INC. (ALK)

3 PN493 6 PY056-PY057 PY592-PY593 7 PQ226 8 PW502 MONARCH AIRLINES, LTD. (MON)

7 PM381 PP821 PP823-PP824 PP832 PP913-PP914 MONTELY II (MOY)

1 PJ031 MORRIS AIR (MOR)

7 PP164-PP165 PP201-PP205 PP378 PP382 PP727 NASA (NAS)

1 PA099 NICA (NICARAGUENCE DE AVIACION) (NIC)

3 PK823 NIGERIA AIRWAYS, LTD. (NIA)

2 PL781-PL782 3 PL784-PL788

Jul 6/89 737-53-1120 REV 1: May 13/93 8

### BOEING SERVICE BULLETIN 737-53-1120
NORDAM (NOP)

3 PK352 NWT AIR (NTA)

4 PX701 6 PY132-PY133 OLYMPIC AIRWAYS (OLY)

3 PK301-PK304 PK307-PK310 PM021-PM023 P. T. AIRFAST (PTF)

1 PG204 PG278 4 PY343 PAKISTAN INTERNATIONAL AIRLINES CORP. (PIA)

7 PP281-PP286 PAN AMERICAN WORLD AIRWAYS, INC. (PAA)

1 PG020-PG021 PEGUSUS CAPITAL CORPORATION (PSS)

7 PP162 PETROLAIR SYSTEMS S. A. (PTS)

3 PL471 PHILIPPINE AIRLINES, INC. (PAL)

7 PP935-PP936 PLUNA (PLU)

3 PL201-PL203 POLARIS AIRCRAFT LEASING CORP. (PLS)

1 PG202 PG205 PG207 PG211 PG216 PG218 PG272 3 PL061 7 PP188 PP190-PP191 PP302 POLY TECHNOLOGIES, INC. (PTI)

7 PP728-PP729 POLYNESIAN AIRLINES (PLY)

7 PP947 PRIVATE FLIGHT DIRECTORATE (ABU DHABI) (ABD)

3 PK495 REPUBLIC OF NIGER (NIR)

6 PY166 ROYAL AIR MAROC (RAM)

3 PK271-PK274 6 PY671-PY672 SABENA S.A. (SAB)

3 PK041 PK044-PK046 PK048-PK050 PK052-PK053 PK431 PK433 6 PY272-PY275 7 PP961-PP967

Jul 6/89 737-53-1120 REV 1: May 13/93 9

### BOEING SERVICE BULLETIN 737-53-1120
SAHSA (SERVICIO AEREO DE HONDURAS,S.A.) (SAH)

1 PJ032 PJ071 2 PL736 PL738 SAUDI ARABIAN AIRLINES CORP. (SVA)

2 PL726-PL728 3 PK311-PK317 PL729-PL735 5 PY036-PY037 SAUDI ROYAL FLEET (SRF)

3 PK318 SERVICIOS AEREOS RUTAS ORIENTE, (SARO) (SEV)

1 PA015 PA021-PA022 3 PK351 PK353 SHANNONAIR LEASING LTD. (SLE)

3 PK451-PK452 SIERRA PACIFIC AIRLINES (SRP)

1 PC003 PG217 PG577 3 PK627 7 PP169 PP381 SINGAPORE AIRLINES, LTD (SIA)

7 PQ222 SOUTH AFRICAN AIRWAYS (SAA)

1 PG353-PG356 3 PL101-PL113 SOUTHEAST PACIFIC AIRWAYS (SOU)

1 PG219 SOUTHWEST AIRLINES CO. (SWA)

3 PK091-PK099 PK541-PK560 PK621 PK628-PK630 PM051-PM066 7 PP101-PP145 PP161 PP163 PP166-PP168 PP193 PP731 PP822 SOUTHWEST-SWAL (SWL)

3 PK521 PK523-PK528 PN454 PN456 SUDAN (SUD)

6 PY156-PY157 SULTANAIR (SLR)

1 PG251 T A PORTUGUESES (TAP)

3 PK971 PK973-PK974 PL451-PL452 PN081-PN086 6 PY721 7 PP984 PQ301-PQ303 TACA INTERNATIONAL AIRLINES, INC. (TAC)

1 PG059 PG352 3 PK223 PN491 6 PY131

Jul 6/89 737-53-1120 REV 1: May 13/93 10

### BOEING SERVICE BULLETIN 737-53-1120
TAESA (TES)

8 PW010 TAT EUROPEAN AIRLINES (TTR)

4 PY003 PY301 PY321 PY361-PY362 TEA BASEL (TEB)

7 PP845 PQ224-PQ225 THAI AIR FORCE (TAF)

3 PK519 THAI AIRWAYS INTERNATIONAL, INC. (TII)

3 PK511 PK514-PK515 TRANS EUROPEAN AIRWAYS ITALIA S.P.A. (TEI)

7 PQ221 PQ223 TRANSAVIA AIRLINES (TAV)

1 PG074 3 PK501-PK504 PK821 7 PP801-PP806 TRANSBRASIL AIRLINES INC. (TBL)

7 PP836-PP837 PP843-PP844 PP847-PP848 PQ241-PQ243 TRANSMED (TRZ)

8 PW012 TRANSTAR (AFM)

1 PG274 PG276 PG403 3 PK306 TUNIS AIR (TUN)

3 PK861-PK863 6 PY621 UNITED AIR LINES, INC. (UAL)

1 PG001-PG004 PG006-PG013 PG015-PG019 PG022-PG025 PG027 PG030 PG032-PG033 PG038-PG040 PG045 PG051-PG054 PG057 PG060-PG063 PG065-PG072 PG075 3 PK201-PK202 PL002-PL023 7 PQ101-PQ157 UNITED STATES AIR FORCE (USF)

2 PJ201 3 PJ202-PJ219 USAIR, INC. (USA)

1 PG041-PG042 PG073 PG206 PG301 PG303-PG304 PG306-PG311 PG313-PG314 PG474 PG576 3 PK288-PK289 PK591-PK599 PK601-PK610 PK883 PM101-PM119 PN021-PN043 7 PP001-PP010 PP012-PP049 PP376-PP377 PP383 PP401-PP440 PP471-PP475 8 PV001-PV010 PV012-PV017 VARIG (CRU)

3 PK141-PK146

Jul 6/89 737-53-1120 REV 1: May 13/93 11

### BOEING SERVICE BULLETIN 737-53-1120
VARIG AIRLINES (VAR)

3 PK111-PK116 PK118-PK120 PL453-PL454 7 PP839 PP905-PP906 PP981-PP982 PQ251-PQ255 VARSA (VAB)

1 PG351 VASP (VSP)

1 PG435 PG437 PG439-PG440 PG471-PG473 2 PL756 3 PH011-PH013 PK061-PK062 PK065-PK067 4 PX071 VENEZUELA - GOVERNMENT OF (VNZ)

3 PK070 VISCOUNT AIR SERVICE INC. (VAS)

1 PG203 PG209 PG212 PG220-PG222 VIVA AIR (VIV)

7 PP391-PP393 PP983 WHIRLPOOL FINANCIAL CORP (ZZW)

1 PG214 XIAMEN AIRLINES CO. LTD. (XIA)

3 PK635 PK874 PM255 PN521 YEMEN AIRWAYS (YEM)

3 PK341 YUNNAN PROVINCIAL IMPORT & EXPORT CORP. (YUN)

7 PP651-PP652 ZAMBIA AIRWAYS (ZAM)

3 PK291 PL026 IDENTIFICATION BY VARIABLE NUMBER GROUP 1 PA001-PA022 PA099 PA231-PA232 PC001-PC005 PG001-PG075 PG199 PG201-PG230 PG251-PG255 PG271-PG279 PG301-PG314 PG331-PG332 PG351-PG356 PG375 PG401-PG403 PG431-PG440 PG471-PG475 PG501-PG505 PG571-PG578 PG621-PG630 PG651-PG652 PG701-PG705 PH701-PH712 PJ001-PJ002 PJ031-PJ032 PJ071-PJ072 PJ101-PJ104 PL801-PL803 GROUP 2 PG441-PG442 PG579-PG586 PH713-PH715 PH731-PH732 PH741-PH742 PJ003 PJ105-PJ106 PJ201 PK026 PL711-PL712 PL716 PL726-PL728 PL736-PL742 PL756 PL761-PL762 PL781-PL782 PL793

Jul 6/89 737-53-1120 REV 1: May 13/93 12

### BOEING SERVICE BULLETIN 737-53-1120

GROUP 3 PH001 PH011-PH013 PH021-PH024 PH743 PJ004-PJ009 PJ107-PJ119 PJ202-PJ219 PK027-PK029 PK041-PK053 PK061-PK070 PK081-PK082 PK091-PK099 PK101-PK103 PK111-PK120 PK141-PK146 PK201-PK204 PK211-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-PK515 PK519 PK521-PK528 PK541-PK565 PK581 PK591-PK599 PK601-PK617 PK621-PK637 PK641-PK642 PK661-PK666 PK671-PK681 PK691-PK697 PK711-PK716 PK731-PK765 PK771-PK779 PK801-PK804 PK819-PK827 PK830 PK861-PK863 PK871-PK874 PK881-PK884 PK901-PK938 PK971-PK974 PL001-PL028 PL061 PL081 PL101-PL113 PL151 PL171-PL172 PL201-PL203 PL221 PL401-PL417 PL421 PL441 PL451-PL456 PL471 PL491 PL501-PL506 PL551-PL562 PL581 PL601-PL603 PL611 PL621-PL626 PL631-PL632 PL717-PL725 PL729-PL735 PL743-PL747 PL758 PL763-PL770 PL783-PL788 PM001-PM006 PM016-PM017 PM021-PM023 PM051-PM066 PM101-PM119 PM141-PM142 PM171 PM181 PM251-PM255 PM281-PM283 PN001-PN002 PN021-PN043 PN081-PN086 PN101-PN117 PN131-PN163 PN401-PN420 PN431-PN433 PN451-PN456 PN471-PN474 PN481 PN491-PN493 PN501-PN502 PN511-PN512 PN521 GROUP 4 PX071 PX701 PY001-PY006 PY301-PY303 PY321-PY323 PY341-PY344 PY361-PY362 GROUP 5 PY007-PY008 PY021-PY022 PY031 PY036-PY037 PY046-PY047 PY051-PY052 PY304 PY345-PY346 PY381 GROUP 6 PY048 PY053 PY056-PY057 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 PY409-PY411 PY421-PY422 PY441 PY451 PY461-PY463 PY591-PY595 PY611-PY612 PY621 PY631 PY651 PY671-PY672 PY721 PY741 GROUP 7 PM381-PM383 PP001-PP049 PP101-PP145 PP161-PP169 PP181-PP197 PP201-PP205 PP221 PP231-PP243 PP281-PP286 PP301-PP305 PP351-PP353 PP376-PP384 PP391-PP393 PP401-PP440 PP471-PP475 PP501-PP507 PP521-PP522 PP631-PP634 PP651-PP652 PP671-PP699 PP701-PP733 PP771-PP779 PP801-PP806 PP821-PP827 PP831-PP848 PP851-PP852 PP861-PP873 PP891-PP899 PP901-PP916 PP931-PP936 PP946-PP948 PP951-PP952 PP961-PP967 PP981-PP984 PP991 PQ001-PQ014 PQ026-PQ041 PQ051-PQ068 PQ086-PQ092 PQ101-PQ157 PQ221-PQ226 PQ231-PQ236 PQ241-PQ243 PQ251-PQ255 PQ281-PQ282 PQ301-PQ303 PS641 GROUP 8 PV001-PV017 PW001-PW013 PW061 PW091-PW092 PW111-PW112 PW501-PW502 PW511-PW514 PW561 2. Spares None.

Jul 6/89 737-53-1120 REV 1: May 13/93 13

### BOEING SERVICE BULLETIN 737-53-1120

B. Reason 28 operators gave reports of fatigue cracks in the Body Station (BS) 520 floor beam area. In these reports, 109 airplanes were found with cracks in the floor beam area. Seven of these airplanes were found with cracks in at least one of the channels in the floor beam. Four of these airplanes were found with cracks in at least one of the intercostals that attach to the floor beam. The largest crack in the floor beam was 8.5 inches long. The largest crack in the channel was 2.5 inches long. The largest crack in the intercostal was three inches long. These airplanes had between 7,700 and 69,900 flight hours and between 4700 and 67,000 flight cycles. Three operators gave reports of cracks in the channel only. Boeing Structural Item Interim Advisory (SIIA) 737-140 is related to this service bulletin. These fatigue cracks occur when the intercostal link puts a force on the floor beam channel. This occurs because of the thermal contraction of the fuselage skin during flight that causes relative movement between the floor beam and wing box in the forward-aft direction. The pivot link installed in this service bulletin permits relative movement to occur without this force. Fatigue cracks are thus prevented. NOTE: In Revision 1, the airplane effectivity is divided in groups that are different from the initial release. Revision 1 is sent to : 1. Give different floor beam repair kits and make changes to a floor beam repair that was installed by the initial release. 2. Make changes to the cargo posts and the electrical bracket (These changes are necessary to install the channel with a pivot link). 3. Change the crack limits. 4. Delete the reference to a letter check ("C" check). 5. Give a different inspection threshold and repeat inspection interval in flight cycles. 6. Add a floor beam eddy current inspection (done before a preventive change or repair is made). 7. Give these other instructions and information : - Steps to get sufficient clearance between the intercostal link and the channel with a pivot link

(This prevents a force on the channel which can cause cracks to occur from the relative movement between the intercostal link and the channel) - Inspection, repair and replacement steps for the four intercostals that attach to the floor beam - More information to stop-drill the cracks - Instructions to install parts for the pivot link joint that are larger in width than those specified in

the initial release (737-200C Airplanes only) - Instructions to spotface the channels with pivot links (737-200C Airplanes only) - Instructions to make a special channel radius filler if the channel with the pivot link cannot be

installed - Instructions to make a special channel with a pivot link if the channel with a pivot link given in the

kit cannot be installed with the above channel radius filler - Instructions to add a corrosion inhibitor to the floor beam areas where changes are made by

Revision 1. Included in this revision is the information that Notice of Status Change 737-53-1120NSC2 (NSC2), NSC4 and NSC5 told the operator was necessary to change the floor beam. The electrical bracket information given in NSC5 is made better. The information in NSC1 and NSC3 has changed and is not included in Revision 1. 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. Boeing Structural Item Interim Advisory (SIIA) 737-140 is related to this service bulletin.

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### BOEING SERVICE BULLETIN 737-53-1120
C. Description The airplane effectivity in Revision 1 is divided in 8 groups. The airplane model, the "cross section" of the cargo post and the "cross section" of the electrical bracket give the airplane group as shown in the table below: NOTES: 1. 737-100, 200, 300, and 400 Airplanes (Passenger) have five channel - intercostal link locations. 2. 737-200C Cargo Airplanes have four channel - intercostal link locations. 3. "Cross Section" is the shape of the cargo post and the electrical bracket Airplane Groups Table
Airplane Group Airplane Model "Cross Section" of Cargo Post Located at Body

Station 520, Left and Right Buttock Line 24.75 "Cross Section" of Electrical Bracket at

Body Station 520, Right Buttock Line 45.50 1 all 737-100's and all 737-200's "I" "L" "Hat" "Z" 2 3 4 all 737-200C's "I" "L" "Hat" "Z" 5 6 7 737-300 through line position 1717 This cargo post does not exist at the Body

Station 520 Floor Beam This electrical bracket does not exist at the Body Station

520 Floor Beam 8 737-400 through line position 1717 No more work is necessary on Group 4, 5, 6 channel locations that had a preventive change done by the initial release. If no preventive change or repair was done at a channel location by the initial release (no pivot link was installed), make an inspection of the channel and the adjacent floor beam for cracks. Install a channel with a pivot link if cracks are found in the channel only. Install a channel with a pivot link, two repair angles and two fillers below the floor beam flange if cracks are found in the adjacent floor beam area. If no cracks are found in the channel or in the adjacent floor beam, install a channel with a pivot link only or repeat the inspection procedure until a channel with a pivot link is installed. Make an inspection of the adjacent intercostal if floor beam cracks are found. Repair or replace a cracked intercostal.

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### BOEING SERVICE BULLETIN 737-53-1120
On Group 1, 2, 3, 7, 8 channel locations repaired by the initial release (a channel with a pivot link was installed on one repair angle), make an inspection of the repair installation. If no cracks are found in the channel and no more cracks are found in the floor beam area, remove the bolt that attaches the repair angle to the floor beam flange. Install a radius filler and the larger diameter bolt. Make an inspection of the adjacent intercostal for cracks. Repair or replace a cracked intercostal. Refer to the Accomplishment Instructions if more cracks are found in the adjacent floor beam area or if cracks are found in the channel. NOTE: Before Revision 1 was released, no Group 1, 2, 3, 7, 8 operators gave reports of cracks in channel locations repaired by the initial release. However, the crack inspection steps are given as a precaution. An intercostal link that has insufficient clearance with the channel can put a force on the channel that can cause it to crack. On Group 4, 5, 6 channel locations repaired by the initial release, remove the repair installation and make an inspection of the adjacent floor beam area for more cracks. Stop-drill any cracks if more are found. Replace the repair angle with two repair angles and install the same channel. Install two radius fillers below the floor beam flange. Make an inspection of the adjacent intercostal for cracks. Repair or replace a cracked intercostal. On Group 1, 2, 3, 7, 8 Airplanes, check the channel locations that had a preventive change done by the initial release of this service bulletin (a channel with a pivot link was installed). Make any necessary changes to get the clearances shown in this revision. Refer to Figure 2 for more information. NOTE: Before Revision 1 was released, no Group 1, 2, 3, 7, 8 operators gave reports of cracks in channel locations that had a preventive change done by the initial release of this service bulletin. However, the crack inspection steps given in Figure 2 are given as a precaution. An intercostal link that has insufficient clearance with the channel can put a force on the channel that can cause it to crack. 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. Inspection and maintenance alternatives are shown in diagrams in Section III., ACCOMPLISHMENT INSTRUCTIONS (Figure 1 and Figure 2). 2. If more cracks are found in channel locations that were changed by the initial release, or if the damaged area is more than the specified limits, write to Boeing for repair instructions. Give the size and location of the damage. When possible, send sketches and photographs. If the damage includes corrosion, send data on the length, width, and largest depth of clean up. SEND TO: BOEING COMMERCIAL AIRPLANE GROUP ATTENTION: MANAGER, AIRLINE SUPPORT D. Compliance No more work is necessary on Group 4, 5, 6 channel locations that had a preventive change done by the initial release. If no preventive change or repair was done at a channel location by the initial release, (no pivot link was installed), Boeing recommends that the operator inspect the channel and the adjacent floor beam area for cracks before the airplane gets 4500 flight cycles. For airplanes with more than 4500 flight cycles , do the above inspection no later than 4500 flight cycles after you get this service bulletin. Figure 1 gives the repeat inspection interval and more compliance information.

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### BOEING SERVICE BULLETIN 737-53-1120
On Group 1, 2, 3, 7, 8 channel locations repaired by the initial release, Boeing recommends that the operator make changes to the repair installation no later than 4500 flight cycles after you get this service bulletin. No more work, as shown in Revision 1 of this service bulletin, is necessary if the changes to the repair installation are made. On Group 4, 5, 6 Airplanes channel locations repaired by the initial release, Boeing recommends that the operator replace the repair installation no later than 4500 flight cycles after you get this service bulletin. No more work, as shown in Revision 1 of this service bulletin, is necessary at the channel location if the repair installation is replaced. On Group 1, 2, 3, 7, 8 channel locations that had a preventive change done by the initial release, Boeing recommends that the operator make an inspection of the channel and the adjacent floor beam area for cracks and the correct clearances no later than 4500 flight cycles after you get this service bulletin. Figure 2 gives more information. E. Approval This service bulletin was examined by the Federal Aviation Administration (FAA). The repairs and changes specified in this service bulletin comply with the applicable Federal Aviation Regulations (FAR) and are FAA approved. F. Manpower Manpower data for access is given for each airplane. Separate manpower data is given for each channel location and intercostal that is changed. The manpower data for access together with the data for the changes give the total value for each airplane. This estimates below are 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 cure the materials - Time to make the parts - Time to find the tools. 1. Manpower data for Group 1, 2, 3, 4, 5, 6, 7, 8 Airplanes if no preventive change or repair was done at a channel location by the initial release (No pivot link was installed) NOTES: 1. Before the close visual inspection is done on each airplane, approximately five man-hours and one person is necessary to open access from below the passenger cabin floor, do an inspection of every channel location, and close access (Refer to Part I, Accomplishment instructions). 2. Before the changes in the table below are made, approximately eight man-hours and two persons are necessary to open access to all of the channel locations from above the passenger cabin floor on each airplane (Refer to Part V or Part VI, Accomplishment instructions). 3. Approximately eight man-hours and one person is necessary to repair an intercostal web if it is cracked (Refer to the 737-100/200 Structural Repair Manual Subject 51-40-2 or refer to the 737-300/400/500 Structural Repair Manual Subject 51-70-13).

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### BOEING SERVICE BULLETIN 737-53-1120
4. Approximately thirteen man-hours and one person is necessary to replace an intercostal web or an intercostal top chord if it is cracked (Figure 22 or 23). 5. After the changes in the table below are made, approximately eight man-hours and two persons are necessary to close access on each airplane (Refer to Part V or Part VI, Accomplishment instructions). Manpower for the Channel Location Shown Task Number of Persons Man-Hours Elapsed Time (Hours) Group 1, 2, 3, Repair : (Figure 19, 20, 21, 28) At Left or Right Buttock Line 45.50 At Left or Right Buttock Line 24.75 1 1 18 21 18 21 Group 1, 2, 3 Preventive Change : (Figure19, 20, 21, 25) At Left or Right Buttock Line 45.50 At Left or Right Buttock Line 24.75 1 1 12 15 12 15 Group 4, 5, 6 Repair : (Figure 19, 20, 21, 41) At Left or Right Buttock Line 45.50 At Left or Right Buttock Line 24.75 1 1 16 19 16 19 Group 4, 5, 6 Preventive Change : (Figure19, 20, 21, 27) At Left or Right Buttock Line 45.50 At Left or Right Buttock Line 24.75 1 1 16 19 16 19 Group 7, 8 Repair : (Figure 28) At Left or Right Buttock Line 45.50 or 24.75 1 15 15 Group 7, 8 Preventive Change : (Figure 25) At Left or Right Buttock Line 45.50 or 24.75 1 9 9 2. Manpower data for Group 1, 2, 3, 7, 8 Airplanes that had a preventive change done at a channel location by the initial release (A channel with a pivot link was installed) NOTES: 1. On each airplane, approximately five man-hours one person is necessary to open access from below the passenger cabin floor, do an inspection of every channel location, and close access (Refer to Part II, Accomplishment instructions). 2. At each channel location, approximately one man-hour and one person is necessary to change the clearance (Refer to Figure 5). 3. Manpower data is not given for work necessary if cracks are found in a channel or if more cracks are found in the floor beam.

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### BOEING SERVICE BULLETIN 737-53-1120
3. Manpower data for Group 1, 2, 3, 4, 5, 6, 7, 8 Airplanes with channel locations repaired by the initial release (A channel with a pivot link was installed on one repair angle) NOTES: 1. Before the changes in the table below are made, approximately eight man-hours and two persons are necessary to open access to all of the channel locations from above the passenger cabin floor on each airplane (Refer to Part III or IV, Accomplishment instructions). 2. Approximately eight man-hours and one person is necessary to repair an intercostal web if it is cracked (Refer to the 737-100/200 Structural Repair Manual Subject 51-40-2 or refer to the 737-300/400/500 Structural Repair Manual Subject 51-70-13). 3. Approximately thirteen man-hours and one person is necessary to replace an intercostal web or an intercostal top chord if it is cracked (Figure 22, 23, or 24). 4. After the changes in the table below are made, approximately eight man-hours and two persons are necessary to close access on each airplane (Refer to Part III or IV, Accomplishment instructions). 5. Manpower data is not given for work necessary if cracks are found in a channel or if more cracks are found in the floor beam. Manpower for Each Channel Location Task Number of Persons Man-Hours Elapsed Time (Hours) Group 1, 2, 3, 7, 8 : Examine the Channel and Floor Beam (Figure 7) 1 1 1 Examine the adjacent Intercostal Web and Top Chord (Figure 10) 1 0.5 0.5 Change the Repair Installation (Figure 46) 1 12 12 TOTAL FOR EACH GROUP 1, 2, 3, 7, 8 CHANNEL LOCATION 13.5 13.5 Group 4, 5, 6 : Examine the Channel and Floor Beam (Figure 48) 1 1 1 Examine the adjacent Intercostal Web and Top Chord (Figure 10) 1 0.5 0.5 Install Two Repair Angles (Figure 48) 1 9 9 TOTAL FOR EACH GROUP 4, 5, 6 CHANNEL LOCATION 10.5 10.5

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### BOEING SERVICE BULLETIN 737-53-1120
G. Material - Price and Availability Boeing can supply the kits shown in Paragraph II.A.1, Parts and Materials Supplied by Boeing as shown below. If there is a limit to the quantity of available kits, a supply sequence is given by Spares. More kits become available as shown in the Reorder Lead Time (ROLT). ROLT is calculated from the date Boeing gets the purchase order.
Kit Number Name Date Quantity ROLT (weeks) Unit Price thru Oct 22/93 65C34688-26 Supplemental Kit Feb 5/92 284 19 No Charge 65C34978-28 Supplemental Kit Nov 20/91 20 24 No Charge 65C27712-1 Collector Kit Apr 21/93 25 49 $6698.00 65C27712-2 Collector Kit Apr 21/93 25 49 $6287.00 65C34978-26 Collector Kit Mar 10/92 25 30 $13,134.00 65C34978-27 Collector Kit Mar 10/92 25 30 $12,749.00 Boeing can supply the kits and the intercostal parts listed in Paragraph II.A.1, Parts and Materials Supplied by Boeing as shown below. Kit and part availability is shown in the Reorder Lead Time (ROLT). ROLT is calculated from the date Boeing gets the purchase order.
Kit (Part) Number Name ROLT (weeks) Unit Price thru Oct 22/93 65C34688-25 Supplemental Kit 49 No Charge 65C34688-24 Floor Beam Top Kit 19 $5076.00 65C34688-2 Channel Subkit 48 Boeing Spares Catalog Item 65C34688-3 Channel Subkit 48 $452.00 65C34688-27 Repair Subkit 22 $713.00 65C34688-8 Cargo Post Top Kit 26 $1621.00 65C34688-9 Cargo Post Top Kit 24 $1151.00 65C34978-25 Floor Beam Top Kit 28 $11,468.00 65C34978-23 Channel Subkit 25 $1704.00 65C34978-22 Repair Subkit 22 $4,652.00 65C34978-31 Repair Subkit 22 $663.00 65C34978-32 Repair Subkit 22 $774.00 65C34978-33 Repair Subkit 22 $774.00 65C34978-34 Repair Subkit 22 $714.00 65C34978-6 Cargo Post Top Kit 17 $1,665.00 65C34978-7 Cargo Post Top Kit 22 $1,221.00 65C35994-1 Electrical Bracket Top Kit 16 $1.00 65C35994-2 Electrical Bracket Top Kit 16 $1.00 65C35994-3 Electrical Bracket Top Kit 22 $59.10 65C35994-4 Electrical Bracket Top Kit 16 $59.10 65C34688-33 Intercostal Web 18 $63.20 65C34688-34 Intercostal Top Chord 15 $70.00

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### BOEING SERVICE BULLETIN 737-53-1120
(Continued)
Kit (Part) Number Name ROLT (weeks) Unit Price thru Oct 22/93 65C34688-35 Intercostal Web 23 $63.20 65C34688-36 Intercostal Top Chord 16 $70.00 65C34688-37 Intercostal Top Chord 15 $70.00 69-51452-7 Intercostal Web 54 $71.70 Prices shown as "No Charge" change to "Charge" after the Unit Price date. The kits and the parts 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 NOTE: The table below gives the weight and balance data for one (1) channel location. Add the weight and balance data for all the channel locations to get the total weight and balance data for the airplane.

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### BOEING SERVICE BULLETIN 737-53-1120
Weight and Balance for One Channel Location Airplane

Group Changes Made at A Channel Location Change in Weight (Pounds) Change in Moment (Pound-Inches) Kit Installed Figure Where Changes are Shown +(-) +(-)

1, 2, 3, 7, 8 65C34688-2 25 +0.2 (f), (g) +104 (h), (i) 65C34688-3 65C34688-2 installed with 65C34688-27 28, 47 +0.8 (f), (g) +416 (h), (i) 65C34688-2 installed with 65C34688-4 and 65C34688-25 (c) 65C34688-26 (c) 46 0 0 1(a) 65C34688-8 (d) 19, 20 +0.2 +104 3 (b) 65C35994-3 55, 56 0 0 1, 2 (b) 65C35994-1 53, 54 0 0 2, 3 (a) 65C34688-9 (d) 19, 21 +1.0 +520

4, 5, 6 65C34978-23 27 +0.5 +260 65C34978-2 installed with 65C34978-24 (c)

65C34978-23 installed with 65C34978-22 (e) 41 +1.1 +572 65C34978-2 installed with 65C34978-24 (c) and 65C34978-22 (e) 41, 48 4 (a) 65C34978-6 (d) 19, 20 +0.2 +104 4, 5 (b) 65C35994-2 57 0 0 5, 6 (a) 65C34978-7 (d) 19, 21 +1.0 +520

6 (b) 65C35994-4 58 0 0 (a) Installation is at Left or Right Buttock Line 24.75 only. (b) Installation is at Right Buttock Line 45.50 only. (c) This is a supplemental kit. (d) The kit has all the parts necessary for installation at both locations.

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### BOEING SERVICE BULLETIN 737-53-1120
(e) The 65C34978-22 Repair Subkit has a different subkit for each location : - 65C34978-31 Repair Subkit at Right BL 45.50. - 65C34978-32 Repair Subkit at Right BL 24.75. - 65C34978-33 Repair Subkit at Left BL 24.75. - 65C34978-34 Repair Subkit at Left BL 45.50. (f) Add +0.2 Pounds to the value shown in the table if it is necessary to install a Channel Assembly "A", "B", or "C" because the Channel 69-77845-3 cannot be installed. (g) Add +0.1 Pounds to the value shown in the table if it is necessary to install a Channel Radius Filler "A" in the Channel 69-77845-3. (h) Add +104 Pound-Inches to the value shown in the table if it is necessary to install a Channel Assembly "A", "B", or "C" because the Channel 69-77845-3 cannot be installed. (i) Add +52 Pound-Inches to the value shown in the table if it is necessary to install a Channel Radius Filler "A" in the Channel 69-77845-3. J. References 1. Existing Data: a. Engineering Change Memo PRR34556, PRR35012R, PRR34990-R, MRR3539-649 b. 737-100/200 Maintenance Manual Subjects : 25-22-0, 25-27-100, 25-52-111, 53-21-00. c. 737-300/400/500 Maintenance Manual Subjects : 25-22-0, 25-27-15, 53-21-00. d. 737 -100/200 Structural Repair Manual Subjects : 51-30-5, 51-30-8, 51-30-4, 51-30-1, 51-30-2 51-30-3, 51-10-6, 51-20-4, 51-30-2, 51-10-2, 51-20-4, 51-40-2, 51-70. e. 737 -300/400/500 Structural Repair Manual Subjects : 51-40-05, 51-40-08, 51-40-04, 51-40-01, 51-40-02, 51-40-03, 51-10-02, 51-20-01, 51-20-05, 51-40-02, 51-30-03, 51-70-13. f. 737 Nondestructive Test Manual Part 6 Subject 51-00-00, Figure 1, 4, 11, and 16 g. 737-140 Structural Item Interim Advisory h. Boeing Standard Overhaul Practices Manual : 20-50-01, 20-30-03, 20-50-12, 20-41-02, 20-43-03, 20-60-02, 20-50-10, 20-43-01.

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### BOEING SERVICE BULLETIN 737-53-1120
2. Data supplied with this service bulletin: None 3. Installation Drawings: Drawing Number Title 65C34688 Pivot Link Instl - Sta 520, Top Kit 65C34978 Pivot Link Instl - Sta 520, Top Kit 65-54906 Beam Instl- Cargo Floor Sta 500 thru 520 65-46803 Beam Instl- Passenger Floor Sta 500 and 520 65-49714 Wire Provisions Instl - Raceway E and F Cargo Compartment 65-46814 Seat Track and Floor Stabilizer Instl - Section 43 65-54966 Seat Track and Floor Stabilizer Instl - Section 43 65-45410 Floor Beam Instl - Wing Center Section 65-67140 Floor Beam Instl - Wing Center Section, Cargo 69-51452 Shear Web Instl - Floor Stabilizer, BL 24.75 and 45.50, Sta 500B - 520 65-49631 Bulkhead Instl - Rear Wall Fwd Cargo Compartment 65-52962 Shroud Closure Instl - Auxiliary Heat, Fwd Cargo, Compartment 69-77845 Channel - Link Support, Floor Beam, Sta 520 These drawings were used to prepare this service bulletin. These drawings are not necessary to make the changes specified, and are not supplied with this service bulletin. These drawings may not be applicable to all airplane configurations or operators. K. Publications Changed Publication Chapter-Section 737 Illustrated Parts Catalog 25-52, 53-10, 57-10
L. Electrical Load Data Not changed

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### BOEING SERVICE BULLETIN 737-53-1120

II. MATERIAL INFORMATION A. Parts Necessary For Each Airplane 1. Parts And Materials Supplied by Boeing NOTE: To get the kits and the intercostal parts supplied by Boeing, refer to Paragraph I.G., Material - Price and Availability a. Locations Where the Kits Can Be Installed (marked with an "X") : 65C34688-24 Floor Beam Top Kit Airplane

Group Subkit Subkit Name Buttock Line (BL) Location On The Floor Beam Left BL

45.50 Left BL 24.75 BL 0.00 Right BL 24.75 Right BL 45.50

1,2,3,7,8 65C34688-2 Channel X X - X X
65C34688-3 Channel - - X - - 65C34688-27 Repair X X - X X 65C34978-25 Floor Beam Top Kit Airplane Group Subkit Subkit Name Buttock Line (BL) Location On The Floor Beam Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 4, 5, 6 65C34978-23 Channel X X X X 65C34978-22 (a) Repair (e) (d) (c) (b) Cargo Post Kits Airplane

Group Top Kit Buttock Line (BL) Location On The Floor Beam Left BL 45.50 Left BL 24.75 BL 0.00 Right BL 24.75 Right BL 45.50 1 65C34688- 8 - X - X - 2 and 3 65C34688- 9 - X - X - 4 65C34978-6 - X - X - 5 and 6 65C34978-7 - X - X -

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### BOEING SERVICE BULLETIN 737-53-1120

Electrical Bracket Kits Airplane

Group Top Kit Buttock Line (BL) Location On The Floor Beam Left BL 45.50 Left BL 24.75 BL 0.00 Right BL 24.75 Right BL 45.50 1 and 2 65C35994-1 - - - - X 3 65C35994-3 - - - - X 4 and 5 65C35994-2 - - - - X 6 65C35994-4
- - - - X (a) The 65C34978-22 Repair Subkit has a different subkit for each location. (b) Install the 65C34978-31 Repair Subkit at Right BL 45.50. (c) Install the 65C34978-32 Repair Subkit at Right BL 24.75. (d) Install the 65C34978-33 Repair Subkit at Left BL 24.75. (e) Install the 65C34978-34 Repair Subkit at Left BL 45.50. b. Obsolete and Supplemental Kits : Group 1, 2, 3, 4, 5, 6, 7,8 Airplanes Airplane Group Obsolete Kit Supplemental Kits New Kit

1, 2, 3, 7, 8 65C34688-1 (Not Installed) Three 65C34688-27 Together With One 65C34688-25 65C34688-24 (a) 65C34688-4 (Not Installed) (b) 65C34688-25 (b) 65C34688-27 65C34688-4

(Installed) 65C34688-26 None 4, 5, 6 65C34978-1 (c) 65C34978-28 65C34978-25 (d) 65C34978-3 (c) None 65C34978-22 65C34978-2 65C34978-24 65C34978-23 (a) The new 65C34688-24 Top Kit has four 65C34688-27 Repair Subkits. Only One 65C34688-4 Repair Subkit was given in the 65C34688-1 Floor Beam Top Kit. (b) Keep the 69-77942-1 Repair Angle, ten (10) Hi - Loks BACB30VT6K3 and nine (9) BACC30BL6 Collars from the 65C34688-4 Repair Subkit. These parts, together with a 65C34688-25 Supplemental Kit, are equivalent to a 65C34688-27 Repair Subkit. (c) Discard the 65C34978-3 Repair Subkit. The 65C34978-3 Repair Subkit is in the 65C34978-1kit.

Jul 6/89 737-53-1120 REV 1: May 13/93 26

### BOEING SERVICE BULLETIN 737-53-1120
(d) The new Floor Beam Top Kit 65C34978-25 contains four Repair Subkits. Only one repair subkit was given in the 65C34978-1 Floor Beam Top Kit. c. Kits Necessary if No Preventive Change or Repair was done by the Initial Release to the Airplane ( No pivot links were installed on the airplane) :

Airplane Group Kits Necessary For Each Airplane Alternative #1 Alternative # 2 (b) Floor Beam Top Kit Cargo Post Top Kit (a) Electrical Bracket Top Kit Collector Kit 1 65C34688-24 65C34688-8 65C35994-1 65C27712-1 65C27712-2 65C34688-9 65C35994-3 2 3 4 65C34978-25 65C34978-6 65C35994-2 65C34978-26 65C34978-27 65C34978-7 65C35994-4 5 6 7, 8 65C34688-24 None None None (a) One Cargo post top kit contains all the parts necessary to change the cargo posts at both Left and Right Buttock Line 24.75. (b) All the changes shown in this service bulletin can be made at all locations on the floor beam with this collector kit. d. Kits Necessary for the Channel Locations Repaired by the Initial Release ( A channel with a pivot link was installed on one repair angle) : Airplane Group Kits Necessary For Each Channel Location With A Repair Angle Floor Beam Top Kit Electrical Bracket Top Kit 1 65C34688-26 If no more cracks are found in the floor beam or 65C34688-27 If more cracks are found in the floor beam 65C35994-1 if cracks are found in the channel 65C35994-3 if cracks are

found in the channel None 2, 3 7, 8 4, 5, 6 65C34978-24 together with one of the repair subkits in the 65C34978-22 Kit None

Jul 6/89 737-53-1120 REV 1: May 13/93 27

### BOEING SERVICE BULLETIN 737-53-1120
e. Kits Necessary for the Channel Locations That had a Preventive Change Done by the Initial Release (A channel with a pivot link was installed) Airplane Group Kits Necessary For Each Channel Location With A Pivot Link Floor Beam Top Kit Electrical Bracket Top Kit 1, 2 65C34688-27 if cracks are found in the floor beam 65C35994-1 if cracks are found in the channel 65C35994-3 if cracks are

found in the channel 3 4, 5, 6 None None

7, 8 65C34688-27 if cracks are found in the floor beam f. Replacement Parts for Cracked Intercostal Webs or Cracked IntercostalTop Chords: NOTES: 1. The parts shown below can be supplied by the operator. Refer to Paragraph II.A.2., Parts and Materials Supplied by the Operator. 2. A new intercostal web is not necessary if the cracks can be repaired with the steps shown in the 737-100/200 Structural Repair Manual Subject 51-40-2 or the 737-300/400 Structural Repair Manual Subject 51-70-13. 3. On Group 4, 5, 6 Airplanes, the intercostal top chord that is available from Boeing Spares has pilot holes. Boeing recommends that the operator make the replacement for this part. Refer to Paragraph II.A.2., Parts and Materials Supplied by the Operator, for the list of materials necessary to make this part. Airplane Group Part Number Name 1, 2, 3

(a) 65C34688-33 Intercostal Web 65C34688-34 Intercostal Top Chord 7, 8 (b) 65C34688-35 Intercostal Web 65C34688-36 (c) or 65C34688-37 (d) Intercostal Top Chord 4, 5, 6 69-51452-7 Intercostal Web (a) Does not include : PA099, PA001-PA015, PA231-PA232, PA016-PA022 and PC001-PC005 (b) Includes : PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005 (c) On Group 8 Airplanes at Left or Right Buttock Line 45.50.

Jul 6/89 737-53-1120 REV 1: May 13/93 28

### BOEING SERVICE BULLETIN 737-53-1120
(d) On Group 7 Airplanes and on PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005 Airplanes at Left or Right Buttock Line 24.75 or 45.50 and on Group 8 Airplanes at Left or Right Buttock Line 24.75.

Jul 6/89 737-53-1120 REV 1: May 13/93 29

### BOEING SERVICE BULLETIN 737-53-1120
g. List of Kits for Group 1, 2, 3, 7, 8 Airplanes COLLECTOR KITS 65C27712 "Collector - Top Kit, Sta 520 Retrofit" -2 -1 Quantity Part Number Name . - 65C27712-1 Collector Kit - Group 1 Airplanes - . 65C27712-2 (a) Collector Kit - Group 2 and 3 Airplanes 1 1 65C34688-24 Floor Beam Top Kit . 1 65C34688-8 Cargo Post Top Kit - "I" Section 1 . 65C34688-9 Cargo Post Top Kit - "Hat" Section 1 1 65C35994-1 Electrical Bracket Top Kit 1 . 65C35994-3 Electrical Bracket, Top Kit - With Clip (a) Only one of the two electrical bracket top kits in this collector kit is used on each airplane. Discard the kit parts not used or keep the kit parts for spares. FLOOR BEAM TOP KIT

65C34688 "Pivot Link Instl - Sta 520, Top Kit" -3 -2 -27 -24 Quantity Part Number Name . . . - 65C34688-24 Floor Beam Top Kit . . - 4 65C34688-27 (b) Repair Subkit . - . 4 65C34688-2 (a) Channel Subkit - Outboard - . . 1 65C34688-3 (a) Channel Subkit - BL 0.00 . 1 . . 65C34688-5 Channel-Pivot Link Assembly-Outboard 1 . . . 65C34688-6 Channel-Pivot Link Assembly - BL 0.00 . . 1 . 65C34688-28 Intercostal Angle . . 1 . 66-13222-10 Channel Radius Filler . . 2 . 66-13222-9 Flange Radius Filler . . 1 . 69-77942-1 Aft Repair Angle . . 1 . 69-77942-2 Forward Repair Angle 1 1 . . AN960C516 Washer 1 1 . . BACB28AK05-128 Plain Bushing 2 2 . . BACB28AT07B010C Flanged Bushing . . 3 . BACB30MY6K3Y Hi - Lok 9 9 . . BACB30MY6K5Y Hi - Lok . . 5 . BACB30MY6K6X Hi - Lok . . 5 . BACB30MY6K8X Hi - Lok 1 1 . . BACB30NR5DK21 Pivot Bolt

Jul 6/89 737-53-1120 REV 1: May 13/93 30

### BOEING SERVICE BULLETIN 737-53-1120
(Continued) FLOOR BEAM TOP KIT 65C34688 "Pivot Link Instl - Sta 520, Top Kit" -3 -2 -27 -24 . . 3 . BACB30NX6K10X Hi - Lok . . 4 . BACB30NX6K4 Hi - Lok . . 3 . BACB30NX6K5X Hi - Lok 5 5 . . BACB30NX6K8X Hi - Lok . . 3 . BACB30NX6K9X Hi - Lok . . 2 . BACB30NY10K11 Hi - Lok . . 9 . BACB30NY6K4 Hi - Lok . . 5 . BACB30NY6K8X Hi - Lok . . 2 . BACB30NY8K11 Hi - Lok . . 6 . BACB30VT6K2 Hi - Lok . . 10 . BACB30VT6K3 Hi - Lok . . 3 . BACB30VT6K4 Hi - Lok . . 15 . BACB30VT6K5 Hi - Lok . . 9 . BACC30BH6 Collar . . 34 . BACC30BL6 Collar . . 10 . BACC30M6 Collar 9 9 3 . BACC30R6 Collar . . 2 . BACC30X10 Collar 5 5 27 . BACC30X6 Collar . . 2 . BACC30X8 Collar 1 1 . . BACN10JD5CD Nut . . 3 . BACN10YD6 Nut . . 3 . BACS12GM3-15 Screw . . 2 . BACS40R007D030F Shim 1 1 . . MS24665-134 Pin (a) Use the Hi -Loks and collars supplied with the repair subkit to attach the channel to the repair angle. Discard the fasteners that are not used or keep them for spares. (b) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares. SUPPLEMENTAL KIT 65C34688 "Pivot Link Instl - Sta 520, Top Kit" Quantity Part Number Name - 65C34688-25 (a) Supplemental Kit 1 65C34688-28 Intercostal Angle 1 66-13222-10 Channel Radius Filler 2 66-13222-9 Flange Radius Filler

Jul 6/89 737-53-1120 REV 1: May 13/93 31

### BOEING SERVICE BULLETIN 737-53-1120
(Continued) SUPPLEMENTAL KIT 65C34688 "Pivot Link Instl - Sta 520, Top Kit" Quantity Part Number Name 1 69-77942-2 Forward Repair Angle 3 BACB30MY6K3Y Hi - Lok 5 BACB30MY6K6X Hi - Lok 5 BACB30MY6K8X Hi - Lok 3 BACB30NX6K10X Hi - Lok 4 BACB30NX6K4 Hi - Lok 3 BACB30NX6K5X Hi - Lok 3 BACB30NX6K9X Hi - Lok 2 BACB30NY10K11 Hi - Lok 9 BACB30NY6K4 Hi - Lok 5 BACB30NY6K8X Hi - Lok 2 BACB30NY8K11 Hi - Lok 6 BACB30VT6K2 Hi - Lok 3 BACB30VT6K4 Hi - Lok 15 BACB30VT6K5 Hi - Lok 9 BACC30BH6 Collar 15 BACC30BL6 Collar 10 BACC30M6 Collar 2 BACC30X10 Collar 19 BACC30X6 Collar 2 BACC30X8 Collar 3 BACN10YD6 Nut 3 BACS12GM3-15 Screw 2 BACS40R007D030F Shim (a) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares. SUPPLEMENTAL KIT 65C34688 "Pivot Link Instl - Sta 520, Top Kit"

Quantity Part Number Name - 65C34688-26 (a) Supplemental Kit 1 66-13222-10 Channel Radius Filler 1 66-13222-9 Flange Radius Filler 3 BACB30NX6K9Y Hi-Lok 2 BACB30NY10K11 Hi - Lok 3 BACB30NY6K8Y Hi - Lok 6 BACC30AC6 Collar

Jul 6/89 737-53-1120 REV 1: May 13/93 32

### BOEING SERVICE BULLETIN 737-53-1120
(Continued) SUPPLEMENTAL KIT 65C34688 "Pivot Link Instl - Sta 520, Top Kit"

Quantity Part Number Name 2 BACC30X10 Collar (a) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares. CARGO POST TOP KITS 65C34688 "Pivot Link Instl - Sta 520, Top Kit" -17 -16 -11 -10 -9 -8 Quantity Part Number Name
.....- 65C34688-8 (a) Cargo Post Top Kit - "I" Section

....-. 65C34688-9 (a) Cargo Post Top Kit - "Hat" Section . . . - . 1 65C34688-10 Cargo Post Subkit - LBL 24.75 . . - . . 1 65C34688-11 Cargo Post Subkit - RBL 24.75 . - . . 1 . 65C34688-16 Cargo Post Subkit - LBL 24.75 - . . . 1 . 65C34688-17 Cargo Post Subkit - RBL 24.75 . . . .22 65C34688-20 Wide Filler . . . .22 65C34688-21 Radius Filler . . . .22 65C34688-22 Narrow Filler 22 . . . . 65C34688-23 Shim . . . .22 65C35842-1 Attach Bracket . . 1 1 . . 65C35842-2 Post End - "I" Section 11 . . . . 65C35842-3 Post End - "Hat" Section . . . .88 AN960JD416L Washer 77 . . . . BACB30FM6-17 Hi-Lok . . 6 6 . . BACB30FM6-6 Hi-Lok . . . .66 BACB30MB8-8 Hi-Lok . . . .22 BACB30MD6-8 Hi-Lok . . . .22 BACC30AC6 Collar 7766 . . BACC30M6 Collar . . . .66 BACC30X8 Collar . . . .22 MS20392-3C79 Pin . . . .22 MS24665-132 Pin, Cotter . . . .4. NAS43DD4-24 Spacer . . . . .4 NAS43DD4-45 Spacer . . . .44 NAS549E416 Washer (a) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares.

Jul 6/89 737-53-1120 REV 1: May 13/93 33

### BOEING SERVICE BULLETIN 737-53-1120

CHANNEL-PIVOT LINK ASSEMBLY 65C34688 "Pivot Link Instl - Sta 520, Top Kit" -6 -5 Quantity Part Number Name . - 65C34688-5 Channel-Pivot Link Assembly - . 65C34688-6 Channel-Pivot Link Assembly, BL 0.00 1 1 65C34622-3 Pivot Link 1 1 69-77845-3 Channel 1 1 AN960C516 Washer 1 1 BACB28AK05-170 Plain Bushing 2 2 BACB28AT07B009C Flanged Bushing 1 1 BACB30NR5DK28 Pivot Bolt 1 1 BACN10JD5CD Nut 1 1 MS24665-134 Pin

Jul 6/89 737-53-1120 REV 1: May 13/93 34

### BOEING SERVICE BULLETIN 737-53-1120
h. List of Kits for Group 4, 5, 6 Airplanes COLLECTOR KITS 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -27 -26 Quantity Part Number Name . - 65C34978-26 Collector Kit - Group 4 Airplanes - . 65C34978-27 (a) Collector Kit - Group 5 and 6 Airplanes . 1 65C34978-6 Cargo Post Top Kit - "I" Section 1 . 65C34978-7 Cargo Post Top Kit - "Hat" Section 1 1 65C34978-25 Floor Beam Top Kit 1 1 65C35994-2 Electrical Bracket Top Kit 1 . 65C35994-4 Electrical Bracket Top Kit - With Clip (a) Only one of the electrical bracket top kits in this collector kit is used on each airplane. Discard the kit parts not used or keep the kit parts for spares. FLOOR BEAM TOP KIT 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -25 -23 -22 Quantity Part Number Name - . . 65C34978-25 Floor Beam Top Kit 1 . - 65C34978-22 Repair Subkit 4 - . 65C34978-23 (a) Channel Subkit . . 1 65C34978-31 (b) Repair Subkit - RBL 45.50 . . 1 65C34978-32 (b) Repair Subkit - RBL 24.75 . . 1 65C34978-33 (b) Repair Subkit - LBL 24.75 . . 1 65C34978-34 (b) Repair Subkit - LBL 45.50 . 1 . 65C34978-4 Channel-Pivot Link Assembly . 2 . 65C34978-47 Channel Radius Filler . 1 . AN960C516 Washer . 1 . BACB28AK05-147 Plain Bushing . 2 . BACB28AT07B018C Flanged Bushing . 7 . BACB30MY6K6Y Hi-Lok . 3 . BACB30MY8K6Y Hi-Lok . 1 . BACB30NR5DK25 Pivot Bolt . 5 . BACB30NX8K8X Hi-Lok . 7 . BACC30R6 Collar . 3 . BACC30R8 Collar . 5 . BACC30X8 Collar . 1 . BACN10JD5CD Nut . 1 . MS24665-134 Pin

Jul 6/89 737-53-1120 REV 1: May 13/93 35

### BOEING SERVICE BULLETIN 737-53-1120
(a) Use the Hi -Loks and collars supplied with the repair subkit to attach the channel to the repair angle. Discard the fasteners that are not used or keep them for spares. (b) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares. REPAIR SUBKIT 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -34 -33 -32 -31 -22 Quantity Part Number Name
....- 65C34978-22 Repair Subkit . . . - 1 65C34978-31 Repair Subkit - RBL 45.50 . . - . 1 65C34978-32 Repair Subkit - RBL 24.75 . - . . 1 65C34978-33 Repair Subkit - LBL 24.75 - . . . 1 65C34978-34 Repair Subkit - LBL 45.50 . . . 1 . 65C34978-35 Aft Flange Filler . . . 1 . 65C34978-36 Forward Flange Filler . 1 1 . . 65C34978-37 Aft Flange Filler . 1 1 . . 65C34978-38 Forward Flange Filler 1.... 65C34978-41 Aft Flange Filler 1.... 65C34978-42 Forward Flange Filler 2111 . 65C34978-43 Pulley Filler 1.... 65C34978-44 Web Filler . 1 . . . 65C34978-45 Web Filler . . 1 . . 65C34978-46 Web Filler 1222 . 65C34978-48 Seat Track Filler 1 . . 1 . 65C34978-49 (a) Intercostal Channel . 1 1 . . 65C34978-50 (b) Intercostal Channel 1.... 69-77969-10 Aft Repair Angle - LBL 45.50 . . . 1 . 69-77969-3 Forward Repair Angle - RBL 45.50 . . . 1 . 69-77969-4 Aft Repair Angle - RBL 45.50 . . 1 . . 69-77969-5 Forward Repair Angle - RBL 24.75 . . 1 . . 69-77969-6 Aft Repair Angle - RBL 24.75 . 1 . . . 69-77969-7 Forward Repair Angle - LBL 24.75 . 1 . . . 69-77969-8 Aft Repair Angle - LBL 24.75 1.... 69-77969-9 Forward Repair Angle - LBL 45.50 2222 . BACB30MY6K3Y Hi-Lok 1 . . 1 . BACB30MY6K4 Hi-Lok 14 1 1 17 . BACB30MY6K5 Hi-Lok 3.... BACB30MY6K5Y Hi-Lok 2 14 13 . . BACB30MY6K6 Hi-Lok . 2 2 . . BACB30MY6K6Y Hi-Lok . . . 6 . BACB30MY6K8Y Hi-Lok 6 6 6 . . BACB30MY6K9Y Hi-Lok

Jul 6/89 737-53-1120 REV 1: May 13/93 36

### BOEING SERVICE BULLETIN 737-53-1120
(Continued) REPAIR SUBKIT 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -34 -33 -32 -31 -22

. 1 1 . . BACB30MY8K6Y Hi-Lok . . . 2 . BACB30MY8K8Y Hi-Lok 2 2 2 . . BACB30MY8K9Y Hi-Lok 1.... BACB30NW6K12Y Hi-Lok 2.... BACB30NW6K5Y Hi-Lok . . . 2 . BACB30NX8K10X Hi-Lok 2 2 2 . . BACB30NX8K11X Hi-Lok . . . 2 . BACB30NX8K8X Hi-Lok 2 2 2 . . BACB30NX8K9X Hi-Lok 2 . . 2 . BACB30NY8K12X Hi-Lok . 2 2 . . BACB30NY8K13X Hi-Lok 1 . . 2 . BACB30VU6K15 Hi-Lok . 2 2 . . BACB30VU6K16 Hi-Lok 3 . . 5 . BACB30VU6K4 Hi-Lok 5995 . BACB30VU6K5 Hi-Lok 2 . . 4 . BACB30VU6K8 Hi-Lok . 2 2 . . BACB30VU6K9 Hi-Lok 11 13 13 14 . BACC30BL6 Collar 17 17 14 18 . BACC30M6 Collar 12 8 8 6 . BACC30R6 Collar 2332 . BACC30R8 Collar 6666 . BACC30X8 Collar 2222 . BACN10KE3D Nut Plate 2 2 2 . . BACR15AD7D10 Rivet 4 4 4 . . BACR15BA3D4 Rivet . 4 4 . . BACR15BA3D6 Rivet 5555 . BACR15BB6D6 Rivet 4444 . BACR15CE3D4 Rivet . . . 4 . BACR15CE3D6 Rivet . 1 1 . . BACS12GP3K12 Screw 2112 . BACS12GP3K14 Screw 1222 . BACS40R009D010F Shim, Laminated (a) Some kits are supplied with the Intercostal Channel 69-33135-4. The Intercostal Channel 69-33135-4 can be used as an alternative to the Intercostal Channel 65C34978-49. The Intercostal Channel 69-33135-4 is made with pilot holes.

Jul 6/89 737-53-1120 REV 1: May 13/93 37

### BOEING SERVICE BULLETIN 737-53-1120
i. Some kits are supplied with the Intercostal Channel 69-33135-6. The Intercostal Channel 69-33135-6 can be used as an alternative to the Intercostal Channel 65C34978-50. The Intercostal Channel 69-33135-6 is made with pilot holes. SUPPLEMENTAL KIT 65C34978 "Pivot Link Instl - Sta 520, Top Kit" Quantity Part Number Name - 65C34978-28 Supplemental Kit 1 65C34978-22 Repair Subkit 4 65C34978-24 Supplemental Subkit SUPPLEMENTAL SUBKIT 65C34978 "Pivot Link Instl - Sta 520, Top Kit"

Quantity Part Number Name - 65C34978-24 Supplemental Subkit 2 65C34978-47 Channel Radius Filler 1 BACB28AK05-147 Plain Bushing 2 BACB28AT07B018C Flanged Bushing 7 BACB30MY6K6Y Hi-Lok 3 BACB30MY8K6Y Hi-Lok 1 BACB30NR5DK25 Pivot Bolt 5 BACB30NX8K8X Hi-Lok CARGO POST TOP KITS 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -9 -8 -15 -14 -7 -6 Quantity Part Number Name
.....- 65C34978-6 (a) Cargo Post Top Kit - "I" Section

....-. 65C34978-7 (a) Cargo Post Top Kit - "Hat" Section . . . - 1 . 65C34978-14 Cargo Post Subkit - LBL 24.75 . . - . 1 . 65C34978-15 Cargo Post Subkit - RBL 24.75 . - . . . 1 65C34978-8 Cargo Post Subkit - LBL 24.75 -. . . .1 65C34978-9 Cargo Post Subkit - RBL 24.75 . . . .22 65C34978-18 Wide Filler . . . .22 65C34978-19 Filler, Radius . . . .22 65C34978-20 Narrow Filler . . 2 2 . . 65C34978-21 Shim . . . .22 65C35842-1 Attach Bracket 11 . . . . 65C35842-2 Post End - "I" Section . . 1 1 . . 65C35842-3 Post End- "Hat" Section . . . .88 AN960JD416L Washer . . 7 7 . . BACB30FM6-17 Hi-Lok 66 . . . . BACB30FM6-6 Hi-Lok

Jul 6/89 737-53-1120 REV 1: May 13/93 38

### BOEING SERVICE BULLETIN 737-53-1120
(Continued) CARGO POST TOP KITS 65C34978 "Pivot Link Instl - Sta 520, Top Kit" -9 -8 -15 -14 -7 -6 . . . .66 BACB30MB8-10 Hi-Lok . . . .22 BACB30MD6-10 Hi-Lok . . . .22 BACC30AC6 Collar 6677 . . BACC30M6 Collar . . . .66 BACC30X8 Collar . . . . . 10 BACR15AD7D8 Rivet . . . .6. BACR15BA6D7 Rivet . . . .22 MS20392-3C79 Pin . . . .22 MS24665-132 Pin,Cotter . . . .4. NAS43DD4-24 Spacer . . . . .4 NAS43DD4-45 Spacer . . . .44 NAS549E416 Washer (a) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares. CHANNEL-PIVOT LINK ASSEMBLY 65C34978 "Pivot Link Instl - Sta 520, Top Kit" Quantity Part Number Name - 65C34978-4 Channel-Pivot Link Assembly 1 65C34622-3 Pivot Link 1 69-77976-1 Channel 1 AN960C516 Washer 2 AN960C716L Washer 1 BACB28AK05-231 Plain Bushing 2 BACB28AT07B034C Flanged Bushing 1 BACB30NF5D37 (a) Pivot Bolt 1 BACN10JD5CD Nut 1 MS24665-134 Pin (a) Some kits are supplied with a Pivot Bolt BACB30NR5DK37. The Pivot Bolt BACB30NR5DK37 is an alternative to the Pivot Bolt BACB30NF5D37.

Jul 6/89 737-53-1120 REV 1: May 13/93 39

### BOEING SERVICE BULLETIN 737-53-1120
j. Electrical Bracket Top Kits For Group 1, 2, 3, 4, 5, 6 Airplanes ELECTRICAL BRACKET TOP KITS 65C35994 "Bracket Instl - Wire Instl Support Sta 520, RBL 45.50 Top Kit" -4 -3 -2 -1 Quantity Part Number Name . . . - 65C35994-1 (a) Electrical Bracket Top Kit . . - . 65C35994-2 (a) Electrical Bracket Top Kit . - . . 65C35994-3 (a) Electrical Bracket Top Kit - With Clip - . . . 65C35994-4 (a) Electrical Bracket Top Kit - With Clip 1 1 . . 65C35994-5 Support Clip 1 1 . . AN960PD10 Washer 2 2 . . BACN10JC3 Nut . . 2 2 BACN10YD1 Nut-Clip 2222 BACR15BB6D7 Rivet 2222 NAS1801-3-7 Screw (a) The kit has more fasteners than are necessary for installation. Discard the fasteners that are not used or keep them for spares.

Jul 6/89 737-53-1120 REV 1: May 13/93 40

### BOEING SERVICE BULLETIN 737-53-1120

k. List of Obsolete Kits NOTE: 65C34688-1, 65C34688-4, 65C34978-1, 65C34978-2 and 65C34978-3, were available for the initial release of this service bulletin. These kits are not available for revision 1. 65C34688 "Pivot Link Instl - STA 520, Top Kit"

Quantity Part Number Name - 65C34688-1 Top Kit 4 65C34688-2 Kit Instl - Outboard 1 65C34688-3 Kit Instl-BL 0.00 1 65C34688-4 Kit Instl - Repair
65C34688 "Pivot Link Instl - Sta 520, Top Kit"

Quantity Part Number Name - 65C34688-4 Kit Instl-Repair 1 69-77942-1 Angle 9 BACB30MY6K6Y Hi-Lok 5 BACB30NX6K8X Hi-Lok 3 BACB30NY6K5X Hi-Lok 2 BACB30NY8K8X Hi-Lok 16 BACB30VT6K3 Hi-Lok 3 BACB30VU6K4 Hi-Lok 19 BACC30BL6 Collar 9 BACC30R6 Collar 8 BACC30X6 Collar 2 BACC30X8 Collar 65C34978 "Pivot Link Instl - Sta 520, Top Kit"

-3 -2 -1 Quantity Part Number Name . . - 65C34978-1 Kit Instl . - 4 65C34978-2 Kit Instl-Link - . 1 65C34978-3 Kit Instl-Repair . 1 . 65C34978-4 Link Assy 1 . . 69-77969-1 Angle . 1 . AN960C516 Washer . 1 . BACB28AK05-128 Bushing . 2 . BACB28AT07B010C Bushing 6 . . BACB30MY6K5Y Hi-Lok 7 7 . BACB30MY6K7Y Hi-Lok 3 3 . BACB30MY8K7Y Hi-Lok . 1 . BACB30NR5DK21 Bolt 5 . . BACB30NX8K11X Hi-Lok

Jul 6/89 737-53-1120 REV 1: May 13/93 41

### BOEING SERVICE BULLETIN 737-53-1120
(Continued)

. 5 . BACB30NX8K9X Hi-Lok 2 . . BACB30NY8K9X Hi-Lok 16 . . BACB30VT6K5 Hi-Lok 5 . . BACB30VU6K5 Hi-Lok 5 . . BACC30BL6 Collar 16 . . BACC30BL6 Collar 6 7 . BACC30R6 Collar 7 . . BACC30R6 Collar 3 3 . BACC30R8 Collar 2 5 . BACC30X8 Collar 5 . . BACC30X8 Collar . 1 . BACN10JD5CD Nut 2 . . BACR15CE6D3 Rivet . 1 . MS24665-134 Pin

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### BOEING SERVICE BULLETIN 737-53-1120
2. Parts and Materials Supplied by the Operator a. Parts and Materials : All Airplanes Airplane Group Maximum Quantity for each Airplane Part Number (Specification) Name 1, 2, 3 400 inch No. 212HD (3.00 inch wide) Permacel Tape (a)

4, 5, 6 8 BACB30FP6-3 Hex Drive Bolt 8 BACC30M6 Collar 112 MS20470D5-5 Rivet 20 MS20470D5-6 56 MS20470D5-7 760 inch No. 212HD (3.00 inch wide) Permacel Tape (a)

1, 2, 3, 4, 5, 6 4 MS20426D6-8

Rivet 8 MS20426D5-7 4 MS20427M5-7 4 BACR15BA5D7 2 BACR15BB5D6 2 BACR15BB6D10 16 BACR15BB6D9 1 0.04 X 2.5 X 0.90 (QQ-A-250/13) 7075-T6 clad aluminum sheet 2 MS24665-132 Cotter Pin 1 NAS43DD3-5FC Spacer Sleeve 1, 2, 3, 4, 5, 6, 7, 8 5 MS24665-134 Cotter Pin

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### BOEING SERVICE BULLETIN 737-53-1120
b. Materials : All Airplanes
Specification Name Maximum Surface Area Covered on each Airplane (Square-Feet) (*) Vendor Information Notes 737 Structural Repair Manual Subject (SRM) Boeing Standard Overhaul Practice Manual MIL-G-23827 Grease 1.0 - - -

BMS 3-23 Corrosion Inhibitor 7.0 -300/400/500 SRM 51-30-03 "Corrosion Inhibitors" or -300/400/500 SRM 51-20-01 - (p)

(Alodine 1200S) MIL-C-5541 Chemical Film Treatment 9.0 -100/200 SRM 51-20-3 "Protective Coatings" or -300/400/500 SRM 51-30-03 "Materials For

Protective Treatment" - (n)

- 20-41-02 "Mixing Instructions" - (o) BMS 10-11, Type I Primer BMS 10-11, Type II Enamel BMS 5-95, Class

B-1/2, -2 or -4 Faying Surface Salient 2.0 - 20-50-12 "Materials - Adhesives, Type 93" -
(*) Use the values shown in this column to calculate the quantity of material necessary.

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### BOEING SERVICE BULLETIN 737-53-1120
c. Also Supply these Parts and Materials if the Channel Locations on Group 4, 5, 6 Airplanes were Repaired by the Initial Release ( A channel with a pivot link was installed on one repair angle) : Maximum Quantity for each Airplane Part Number (Specification) Name 2 BACB30MA6-5 3/64 Oversize Hex Drive Bolt 4 BACB30MA6-6 24 BACB30MA6-9 8 BACB30MA8-9 8 BACB30MD8-11

Hex Drive Bolt 8 BACB30MD8-9 17 BACB30FP6-5 12 BACB30FP6-6 4 BACB30FQ6-9 4 BACB30FQ6-8 2 BACB30FQ6-4 6 BACB30FQ6-5 2 BACB30FN6-6 47 BACC30M6 Collar 16 BACC30AC8 30 BACC30Y6 8 BACC30Y8 d. Parts : For each Intercostal Web or Top Chord that is Cracked : Airplane

Group Part Number Name Clad Aluminum Sheet for the Part Fasteners Dimensions Specifications 1, 2, 3

(l) 65C34688-33 Web 0.025 X 5.75 X 17.75 2024-T3 (QQ-A-250/5)
(i) 65C34688-34 Top Chord 0.05 X 1.80 X 17.75 7075-O (QQ-A-250/13)
7, 8 (m) 65C34688-35 Web 0.025 X 5.75 X 19.63 2024-T3 (QQ-A-250/5) 65C34688-36 Top Chord (j) 0.05 X 2.00 X 19.63 7075-O (QQ-A-250/13) 65C34688-37 Top Chord (k) 0.05 X 1.80 X 19.63 7075-O (QQ-A-250/13)

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### BOEING SERVICE BULLETIN 737-53-1120
(Continued) Airplane

Group Part Number Name Clad Aluminum Sheet for the Part Fasteners Dimensions Specifications 4, 5, 6 69-51452-7 Web 0.025 X6.13 X 17.50 2024-T3 (QQ-A-250/5) Included in 2.a Intercostal Top Chord "A" Top Chord "A" 0.05 X 1.71 X 17.50 7075-O (QQ-A-250/13) e. Parts and Materials : For Special Conditions on Group 1, 2, 3, 7, 8 Airplane 1. No Preventive Change or Repair was done at a Channel Location by the Initial Release ( No pivot link was installed) : Special Condition Parts And Material Information The fastener heads in a channel make contact with the channel radius. (*) Refer to (b) for the list of parts and materials to use at each channel location with this condition The fastener heads in a channel make contact with

the sides of the channel. (*) Refer to (c) for the list of parts and materials to use at each channel location with this condition (*) This condition is shown in Figure 25, View D-D and in Figure 28, View D-D. 2. The Channel Location was Repaired by the Initial Release ( A channel with a pivot link was installed on one repair angle) : Special Condition Parts And Material Information The clearance is not sufficient

between a channel that was installed as shown in the initial release and the seat track fastener that is installed in this Revision 1 Refer to (d) for the list of parts to use at each channel location with this condition

Cracks are found in a channel Refer to (d) and (e) for the list of parts and materials to use at each channel location with this condition More cracks are found in the floor beam adjacent to a channel Refer to (f) for the list of parts to use at each channel location with this condition Cracks are found in the channel and more cracks are found in the floor beam adjacent to the channel Refer to (e) and (f) for the list of parts and materials to use at each channel location with this condition

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### BOEING SERVICE BULLETIN 737-53-1120
3. The Channel Location had a Preventive Change Done by the Initial Release (A channel with a pivot link was installed) : Special Condition Parts And Material Information
Cracks are found in the Channel Refer to (g) and (e) for the list of parts to use at each channel location with this condition Cracks are found in the floor beam adjacent to a channel Refer to (h) for the list of parts to use at each channel location with this condition (a) Permacel Division Johnson and Johnson. US Highway No 1 PO Box 671, New Brunswick, New Jersey 08903 Vendor Code No. V99742. (b) Get these parts and materials to make one (1) Channel Radius Filler "A" :

- One (1) BAC1511-1550 X 4.6 inch extrusion for the Channel Radius Filler "A" made from 2024-T3511 aluminum (QQ-A-200/3) or One (1) 0.16 X 4.6 X 1.5 inch sheet made from bare 2024-T3 aluminum (QQ-A-250/4) - Eight (8) BACB30KK6-8 Hex Drive Bolts to install a channel without a repair angle 0r Four (4) BACB30FP6-9 Hex Drive Bolts and (4) BACB30FP6-10 Hex Drive Bolts to install a channel on a repair angle. - Eight (8) BACC30R6 Collars to install a channel without a repair angle 0r Eight (8) BACC30M6 Collars to install a channel on a repair angle. (c) Get these parts and materials to make one (1) Channel Assembly "A", "B", or "C" : Quantity for Each Channel Assembly Part Number (Specification) Name
1 0.10 x 6.7 x 6.1 inch sheet of clad 7075-O aluminum

(QQ-A-250/13) Material For Channel "A"

1 0.19 x 3.4 x 1.8 inch sheet of clad 7075-T6 aluminum

(QQ-A-250/13) Material For Plate "A" 1 BACB28AT07B028C Flanged Bushing 1 BACB28AT07B009C Flanged Bushing

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### BOEING SERVICE BULLETIN 737-53-1120
(Continued)

2 0.16 X 0.9 X 1.75 inch sheet of bare 2024-T3 aluminum (QQ-A-250/4) Material For Channel Radius Filler "B" or "C" 4 BACR15BB6D9 Rivet 1 0.04 X 2.4 X 0.84 7075-T6 clad aluminum sheet (QQ-A-250/13) 2 BACR15BB6D10 Rivet (d) Get these hex drive bolts and collars for each channel or channel assembly:

- Two (2) BACB30MD6-9 - Eight (8) BACB30MA6-6 (3/64 Oversize) - Two (2) BACC30AC6 - Eight (8) BACC30Y6 (e) Get these parts and materials to make one (1) Channel Assembly "D" or "E" : - One (1) 0.10 x 6.70 x 6.10 inch sheet of clad 7075-O aluminum sheet (QQ-A-250/13) - Two (2) Flanged Bushing BACB28AT07B009C. (f) Get these hex drive bolts and collars for each channel or channel assembly:

- Two (2) BACB30LY6-8 - Two (2) BACB30LX6-4 - Two (2) BACB30MD6-9 - Two (2) BACB30MD6-10 - Four (4) BACB30MA6-6 (3/64 Oversize) - Four (4) BACB30MA6-8 (3/64 Oversize) - Fourteen (14 ) BACB30FP6-5 - Six (6) BACC30AC6 - Eight (8) BACC30Y6 - Fourteen (14 ) BACC30M6 - Two (2) BACC30X6 (g) Get these hex drive bolts and collars for each channel assembly:

- Four (4) BACB30MD6-8 - Eight (8) BACB30MA6-5 (3/64 Oversize) - Four (4) BACC30AC6 - Eight (8) BACC30Y6

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### BOEING SERVICE BULLETIN 737-53-1120
(h) Get these hex drive bolts and collars for each channel or channel assembly:

- Two (2) BACB30MD6-9 - Two (2) BACB30MD6-10 - Four (4) BACB30MA6-6 (3/64 Oversize) - Four (4) BACB30MA6-8 (3/64 Oversize) - Four (4) BACC30AC6 - Eight (8) BACC30Y6 (i) Get these rivets, hex drive bolts and collars :

- Sixteen (16) BACR15FT5D6 - Thirty Seven (37) BACR15FT5D4 - Two (2) BACB30FP6-3 - Two (2) BACC30M6 (j) Use on Group 8 Airplanes only at Left or Right Buttock Line 45.50. (k) Use on Group 7 and on PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005 Airplanes at Left or Right Buttock Line 24.75 or 45.50 and on Group 8 Airplanes at Left or Right Buttock Line 24.75. (l) Does not include : PA099, PA001-PA015, PA231-PA232, PA016-PA022 and PC001-PC005 (m) Includes : PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005 (n) Refer to the Boeing Standard Overhaul Practice Manual 20-43-01 for information on the chromic acid anodize procedure, which is an alternative to the chemical film treatment operation. (o) The application of an enamel layer is an alternative step. (p) There was no vendor information for this material in the 737-100/200 Structural Repair Manual at the time that this service bulletin was released.

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### BOEING SERVICE BULLETIN 737-53-1120
B. Parts Necessary to Change Spares None C. Special Tools and Equipment None D. Existing Parts Accountability The parts shown below are changed by this service bulletin. Quantity is the number of parts changed at each channel location.

Existing Part Number RUC Name Quantity New Part Number PNC RC 69-51476-1 DIS Channel Assembly 1 65C34978-4 S A 69-51476-2 Channel Assembly 1 65C34978-4 66-23250-1 Channel 1 65C34688-6 66-22187-1 Channel 1 65C34688-5 69-33135-4 Channel Stiffener 1 65C34978-49 (c) 69-33135-6 Channel Stiffener 1 65C34978-50 (c) 69-51475-3 Channel Filler 2 65C34978-47 65-46803-9 Channel Filler 1 66-13222-10 (c) 65-46803-7 Tee 1 65C34688-28 Intercostal Angle (c) 65-67140-24 RWK Intercostal Link 1 65C34978-29 or 65C34978-30 (c) R A
65-45410-77 65-45410-78 65-45410-123 65-45410-330 65-45410-365 65-45410-396 65-45410-579 RWK Intercostal Link 1 65C34688-30 or 65C34688-29 (c) R A

65-49631-9 (a) 65-49631-10 (a) 65-49631-502 (a) 65-49631-501 (a) 65-49631-9 (a) 65-49631-10 (a) 65-49631-502 (a) 65-49631-501(a) 65-77435-2 (a) 65-77435-1 (a) 65-77435-2 (a) 65-77435-1 (a) RWK Cargo Post 1 65C34688-13 65C34688-12 65C34688-14 65C34688-15 65C34978-11 65C34978-10 65C34978-12 65C34978-13 65C34688-18 65C34688-19 65C34978-16 65C34978-17 R A

65-49714-8 (b) RWK (d) Support Clip 1 Support Clip "A" (e), (f) N A 65-49714-8 (b) DIS (d) Support Clip 1 Support Clip "B" (e) Support Clip "C" (f) N A

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### BOEING SERVICE BULLETIN 737-53-1120
(Continued) Existing Part Number RUC Name Quantity New Part Number PNC RC 65-49714-33 (b) DIS Support Clip 1 65C35994-5 S A 65-49714-12 (b) RWK Electrical Bracket 1 65C35994-6 R A 65-49714-32 (b) 65-49714-36 (b) RWK Electrical Bracket 1 65C35994-8 R A (a) Existing at Left or Right Buttock Line 24.75 only. (b) Existing at Right Buttock Line 45.50 only. (c) For the repair only. (d) RWK or DIS the Support Clip 65-49714-8. (e) Change the Support Clip 65-49714-8 or make a Support Clip "B". The Support Clip 65-49714-8 with changes becomes Support Clip "A". (f) Use Support Clip "C" if Channel Assembly "B" is installed as shown in this revision 1. (g) Use if the fastener heads in a channel make contact with the sides of the channel. This condition is shown in Figure 25 and 28. RUC Recommended Use Code DIS - Discard the part. RWK - Make the change as specified in this service bulletin. PNC Part Number Code N - There is no equivalent Boeing part number for the changed part. Show on the part that this service bulletin has been done. R - This is the part number after the change. S - This is the new equivalent or replacement part number. RC Replacement Code A - Replacement not permitted. Do not replace a new part with an existing part. B - Removed part. No replacement.

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### BOEING SERVICE BULLETIN 737-53-1120

BLANK PAGE

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### BOEING SERVICE BULLETIN 737-53-1120

III. ACCOMPLISHMENT INSTRUCTIONS NOTES: 1. The paragraphs identified with letters give the general work instructions. The instructions identified with numbers on the figures give the recommended sequence of steps. 2. In this service bulletin : - Edge margin is the distance from the center of a fastener hole in a part to the edge of the part - Edge distance is the distance from the edge of a fastener hole in a part to the edge of the part. 3. Unless specified differently, these dimensions and tolerances are used: - All linear dimensions are in inches - Tolerance on linear dimensions other than rivet and bolt edge margin is plus or minus 0.03 inch - Angular tolerance is plus or minus 2 degrees - Tolerance on rivet and bolt edge margin or edge distance is plus or minus 0.05 inch - Fastener hole dimensions are found in the 737 Structural Repair Manual Chapter 51 - The torque limits for nuts and bolts are found in the 737 Structural Repair Manual Chapter 51. 4. Refer to the 737 Structural Repair Manual Subject 51-30-1, 51-30-3 (737-100/200) and 51-40-01, 51-40-03 (737-300/400/500) for information on alternative fasteners. 5. Unless specified differently, restore all bare aluminum surfaces, except fastener holes, with the same finish as on the adjacent surface. 6. Refer to the "Substitute Sealants" figure in the 737 Structural Repair Manual, Subjects 51-20-4 (737-100/200) and 51-20-05 (737-300/400/500) for a list of alternative sealants. 7. Refer to the 737 Structural Repair Manual "Safety Procedures" for working with chemicals, Subject 51-10-6 (737-100/200), 51-10-02 (737-300/400/500). Also obey all warnings and cautions in these and all other manual subjects and numbers specified in this service bulletin : - Solvent cleaning steps Boeing Standard Overhaul Practices Manual 20-30-03. - Chemical film treatment 737 Structural Repair Manual Subject 51-10-2 (737-100/200), 51-20-01 (737-300/400/500) and Boeing Standard Overhaul Practices Manual 20-43-03 - Chromic acid anodize Boeing Standard Overhaul Practices Manual 20-43-01. - Repair sealing 737 Structural Repair Manual Subject 51-20-4 (737-100/200), 51-20-05 (737-300/400/500) and Boeing Standard Overhaul Practices Manual 20-50-12. - Application of primers Refer to the Boeing Standard Overhaul Practices Manual

and paints 20-41-02. 8. Remove initial layers of corrosion inhibiting compound (BMS 3-23 or equivalent) from surfaces that are fay sealed (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01). 9. Remove initial layers of sealant from surfaces that are fay sealed.

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### BOEING SERVICE BULLETIN 737-53-1120
10. On Group 1, 2, 3, 4, 5, 6, 7, 8 Airplanes (all airplane groups) use the table below. It tells you which part of the work instructions are necessary for each channel location. Work Instructions for Each Channel Location Airplane

Group Work Done To the Channel Location By The Initial Release Work Instructions
1, 2, 3, 4, 5, 6, 7, 8 No preventive change or repair was made at the channel location (no pivot link was installed) See Figure 1 for the work instruction alternatives

1, 2, 3, 7, 8 A repair was made at the channel location (a channel with a pivot link was installed on one repair angle) Inspect the adjacent intercostal and make changes to the repair installation as shown in Part III Inspect the adjacent intercostal

and replace the repair angle

with two repair angles as shown in

Part IV 4, 5, 6

1, 2, 3, 7, 8 A preventive change was made at the channel location (a channel with a pivot link was installed) See Figure 2 for the work instruction alternatives No more work is necessary as shown in this service bulletin at that channel location 4, 5, 6

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### BOEING SERVICE BULLETIN 737-53-1120

Part I: Inspection - No Pivot Link was Installed on : Group 1, 2, 3, 7, 8 Airplanes At Left or Right Buttock Line 24.75 or 45.50 or Buttock Line 0.00 or Group 4, 5, 6, Airplanes At Left or Right Buttock Line 24.75 or 45.50 NOTES: 1. Do this part if no changes were made to the channel location by the initial release. 2. No repair instructions are given in this service bulletin at Buttock Line 0.00. A. (not shown) Gain access through the air conditioning distribution bay to the aft side of the floor beam. This can be done through the forward cargo compartment if the rear cargo wall is removed. Keep the cargo wall and the fasteners. B. Refer to Figure 3 to make an inspection for cracks in the channel and the aft side of the floor beam. 1. If no cracks are found in the floor beam, do the preventive change as shown in Part V or repeat the inspection in this Part I (Figure 1 gives the repeat inspection interval). 2. Do Part V if cracks are found in the channel only. 3. If cracks are found in the floor beam only or in both the floor beam and the channel, do the repair in Part VI (Refer to the note above if floor beam cracks are found at Buttock Line 0.00). C. (not shown) Install the cargo wall if only the inspection was done.

Part II: Inspection and Changes - Pivot Link Was Installed on Group 1, 2, 3, 7, 8 Airplanes At Left or Right Buttock Line 24.75 or 45.50, or Buttock Line 0.00 NOTE: Do this part if a preventive change was made at the channel location by the initial release. A. (not shown) Gain access through the air conditioning distribution bay to the aft side of the floor beam. This can be done through the forward cargo compartment if the rear cargo wall is removed. Keep the cargo wall and the fasteners. B. Refer to Figure 5 to make an inspection for cracks in the channel and on the aft side of the floor beam. C. Refer to Part VII if cracks are found in the channel only. D. If cracks are found in the floor beam only or in both the floor beam and the channel, do the repair in Part VIII. NOTE: No repair instructions are given in this service bulletin at Buttock Line 0.00. E. If no cracks are found in the channel or on the floor beam, make an inspection of the clearances shown in Figure 5.

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### BOEING SERVICE BULLETIN 737-53-1120
F. If the clearance between the edge of the pivot bolt and the edge of the channel is the only clearance that is not correct, make the changes to the channel as shown in Figure 5 to get the correct clearance. G. If the clearance between the seat track ends or if the clearance between the forward edge of the intercostal link and the fastener heads is not correct, gain access to the work area from above the passenger cabin floor : 1. (not shown) Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. 2. Do the steps in Figure 6 to get the correct clearances. H. (not shown) Install the cargo wall in the forward cargo compartment, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part III: Inspection and Changes - A Channel With A Pivot Link Was Installed on One Repair Angle on Group 1, 2, 3, 7, 8 Airplanes At Left or Right Buttock Line 24.75 or 45.50 NOTE: Do this part if a repair was made at the channel location by the initial release. A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top chord of the intercostal, and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. B. (not shown) On Group 1, 2, 3 Airplanes at Right Buttock Line 45.50, remove and keep the electrical bracket and the fasteners that attach it to the support clip on the channel. Also remove and keep the fasteners that attach the electrical bracket to the wing box structure. C. Refer to Figure 17 to remove the intercostal link. D. Refer to Figure 7 to make an inspection for cracks in the channel and in the floor beam. Look for more cracks that started after the repair steps in the initial release of this service bulletin were done. E. (not shown) On Group 1 and 2 Airplanes with channels that were cracked at Right Buttock Line 45.50, remove the support clip from the channel and keep it. The support clip attaches the electrical bracket to the channel. F. (not shown) On Group 1, 2, 3 Airplanes at Left or Right Buttock Line 24.75, remove and keep the cargo posts if cracks are found in the channel or if more cracks are found in the floor beam. G. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. H. If no more cracks are found in the floor beam, make the changes to the aft repair angle as shown in Figure 46.

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### BOEING SERVICE BULLETIN 737-53-1120
Also do one of these steps : - If cracks are found in the intercostal web or in the top intercostal chord on Group 1, 2, 3

Airplanes (does not include PA099, PA001-PA015, PA231-PA232, PA016-PA022 and PC001-PC005), do the steps in Figure 22. - If cracks are found in the intercostal web or in the top intercostal chord on Group 7, 8 Airplanes

(also includes PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005), do the steps in Figure 23. - If no cracks are found in the intercostal web and the top intercostal chord, no more work, as

specified in this service bulletin, is necessary on the intercostal web or on the top intercostal chord. I. Do these steps if more cracks are found in the floor beam or in both the floor beam and the channel : 1. Stop-drill the crack ends as shown in Figure 8. 2. Install two repair angles with the channel as shown in Figure 47. J. (not shown) On Group 1, 2, 3 Airplanes at Right Buttock Line 45.50, install the electrical bracket if it has not been done. K. (not shown) On Group 1, 2, 3 Airplanes at Left or Right Buttock Line 24.75, install the cargo posts L. (not shown) Install the cargo wall in the forward cargo compartment, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part IV: Inspection and Changes - A Channel With A Pivot Link Was Installed on One Repair Angle on Group 4, 5, 6 Airplanes At Left or Right Buttock Line 24.75 or 45.50 NOTE: Do this part if a repair was made at the channel location by the initial release. A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top intercostal chord, and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. B. (not shown) At Left or Right Buttock Line 24.75, remove and keep the cargo posts. C. (not shown) At Right Buttock Line 45.50, remove and keep the electrical bracket and the fasteners that attach it to the support clip on channel. Also remove and keep the fasteners that attach the electrical bracket to the wing box structure. D. Refer to Figure 18 to remove the intercostal link, the channel with a pivot link, and the repair angle from the floor beam. E. Refer to Figure 48 to make an inspection for cracks in the floor beam. Look for more cracks that started after the repair steps in the initial release of this service bulletin were done. F. If more cracks are found in the floor beam, stop-drill the crack ends as shown in Figure 9.

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### BOEING SERVICE BULLETIN 737-53-1120
G. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. H. Install two repair angles with the channel as shown in Figure 48.

I. (not shown) At Right Buttock Line 45.50, install the electrical bracket. J. (not shown) At Left or Right Buttock Line 24.75, install the cargo posts. K. (not shown) Install the shroud panels or the ceiling lining panels in the forward cargo compartment if they were removed. Refer to the 737-100 and -200 Boeing Maintenance Manual Subject 25-52-111 for the shroud panels or the ceiling lining panel installation instructions. Install the cargo wall, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part V: Preventive Change - Group 1, 2, 3, 4, 5, 6, 7, 8 Airplanes NOTE: You can do this part if no changes were made to the channel location by the initial release. A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top intercostal chord and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. B. Remove the cargo posts at Left or Right Buttock Line 24.75 : - On Group 1 and 4 Airplanes, refer to Figure 11 - On Group 2, 3, 5, 6 Airplanes, refer to Figure 12 C. Remove and keep the electrical bracket at Right Buttock Line 45.50 : - On Group 1, 2, 4, 5 Airplanes, refer to Figure 13 - On Group 3, 6, refer to Figure 14 D. Refer to Figure 15 to remove the intercostal link and the channel without a pivot link. E. On Group 1, 2, 3, 4, 5, 6 Airplanes at Left or Right Buttock Line 24.75, refer to Figure 19. This figure gives the steps to change the forward cargo compartment adjacent to the floor beam where the cargo posts will be attached. F. Make the changes to the cargo post ends at Left or Right Buttock Line 24.75 : - On Group 1 and 4 Airplanes, refer to Figure 20. - On Group 2, 3, 5, 6 Airplanes, refer to Figure 21. NOTE: These changes are made to give sufficient clearance between the pivot link and the top end of the cargo posts. G. Refer to Figure 4 to make another inspection for cracks in the floor beam.

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### BOEING SERVICE BULLETIN 737-53-1120
NOTE: No repair instructions are given in this service bulletin at Buttock Line 0.00. H. Do one of these steps if no cracks are found in Figure 4 : - On Group 1, 2, 3, 7, 8 Airplanes, install the channel with a pivot link as shown in Figure 25. - On Group 4, 5, 6, Airplanes, install the channel with a pivot link as shown in Figure 27. I. Do these steps if cracks are found in Figure 4 : 1. Stop-drill the crack ends : - On Group 1, 2, 3, 7, 8 Airplanes, stop-drill the crack ends as shown in Figure 8 - On Group 4, 5, 6 Airplanes, stop-drill the crack ends as shown in Figure 9. 2. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. 3. Install two repair angles with the channel that has a pivot link : - On Group 1, 2, 3, 7, 8 Airplanes, refer to Figure 28 - On Group 4, 5, 6 Airplanes, refer to Figure 41 J. (not shown) Install the shroud panels or the ceiling lining panels in the forward cargo compartment if they were removed. Refer to the 737-100 and -200 Boeing Maintenance Manual Subject 25-52-111 for the shroud panels or the ceiling lining panel installation instructions. Install the cargo wall, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part VI : Repair - Group 1, 2, 3, 4, 5, 6, 7, 8 Airplanes NOTE: You can do this part if no changes were made to the channel location by the initial release. A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top intercostal chord and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. B. Remove the cargo posts at Left or Right Buttock Line 24.75: - On Group 1 and 4 Airplanes, refer to Figure 11 - On Group 2, 3, 5, 6 Airplanes, refer to Figure 12

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### BOEING SERVICE BULLETIN 737-53-1120
C. Remove and keep the electrical bracket at Right Buttock Line 45.50: - On Group 1, 2, 4, 5 Airplanes, refer to Figure 13 - On Group 3, 6, refer to Figure 14 D. Refer to Figure 15 to remove the intercostal link and the channel without a pivot link. E. On Group 1, 2, 3, 4, 5, 6 Airplanes , refer to Figure 19. This figure gives the steps to change the forward cargo compartment adjacent to the floor beam where the cargo posts will be attached. F. Make the changes to the cargo post ends at Left or Right Buttock Line 24.75 : - On Group 1 and 4 Airplanes, refer to Figure 20. - On Group 2, 3, 5, 6 Airplanes, refer to Figure 21. NOTE: These changes are made to give sufficient clearance between the pivot link and the top end of the cargo posts. G. Refer to Figure 4 to make another inspection for cracks in the floor beam. H. On Group 4, 5, 6 Airplanes, stop-drill the crack ends as shown in Figure 9.

I. On Group 1, 2, 3, 7, 8 Airplanes, stop-drill the crack ends as shown in Figure 8. J. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. K. On Group 4, 5, 6 Airplanes, refer to Figure 41 to install two repair angles with the channel that has a pivot link. L. Group 1, 2, 3, 7, 8 Airplanes - Refer to Figure 28 to install two repair angles with the channel that has a pivot link. M. (not shown) Install the shroud panels or the ceiling lining panels in the forward cargo compartment if they were removed. Refer to the 737-100 and -200 Boeing Maintenance Manual Subject 25-52-111 for the shroud panels or the ceiling lining panel installation instructions. Install the cargo wall, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part VII :Replacement of a Channel With A Pivot Link - Group 1, 2, 3, 7, 8 Airplanes A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top intercostal chord, and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. B. (not shown) On Group 1, 2, 3 Airplanes at Left or Right Buttock Line 24.75, remove and keep the cargo posts.

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### BOEING SERVICE BULLETIN 737-53-1120
C. (not shown) On Group 1, 2, 3 Airplanes at Right Buttock Line 45.50, remove and keep the electrical bracket. D. (not shown) On Group 1 and 2 Airplanes at Right Buttock Line 45.50, remove the support clip from the channel and keep it. The support clip attaches the electrical bracket to the channel. E. Refer to Figure 16 to remove the intercostal link and the channel with a pivot link. F. Refer to Figure 4 to make another inspection for cracks in the floor beam. NOTE: No repair instructions are given in this service bulletin at Buttock Line 0.00. G. If no cracks are found in Figure 4, install another channel as shown in Figure 26. H. Do these steps if cracks are found in Figure 4 : 1. Stop-drill the crack ends as shown in Figure 8. 2. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. 3. Refer to Figure 47 to install two repair angles with the channel. I. (not shown) On Group 1, 2, 3 Airplanes, install the cargo posts at Left or Right Buttock Line 24.75. J. (not shown) Install the cargo wall in the forward cargo compartment, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

Part VIII: Repair -If a Preventive Change was Made by the Initial Release (a Pivot Link was Installed), Group 1, 2, 3, 7, 8 Airplanes A. (not shown) Gain access through the passenger cabin to the channel, the intercostal link, the intercostal web, the top intercostal chord, and to the part of the floor beam where the work will be done. Remove the seats, carpets and floor panels necessary to gain this access. Refer to the 737-100 and -200 Boeing Maintenance Manual Subjects 25-22-0, 25-27-100, and 53-21-00. Refer to the 737-300 and -400 Boeing Maintenance Manual Subjects 25-22-0, 25-27-15, and 53-21-00. B. (not shown) On Group 1, 2, 3 Airplanes at Left or Right Buttock Line 24.75, remove and keep the cargo posts. C. (not shown) On Group 1, 2, 3 Airplanes at Right Buttock Line 45.50, remove and keep the electrical bracket and the fasteners that attach it to the support clip on the channel. Also remove and keep the fasteners that attach the electrical bracket to the wing box structure. D. Refer to Figure 16 to remove the intercostal link and the channel with a pivot link. E. Refer to Figure 4 to make another inspection for cracks in the floor beam. F. Stop-drill the crack ends as shown in Figure 8. G. On Group 1 and 2 Airplanes with channels that were cracked at Right Buttock Line 45.50, remove the support clip from the channel and keep it. The support clip attaches the electrical bracket to

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### BOEING SERVICE BULLETIN 737-53-1120

the channel. H. Refer to Figure 10 to make an inspection for cracks in the adjacent intercostal web and top intercostal chord. I. Refer to Figure 47 to install two repair angles with the channel. J. (not shown) On Group 1, 2, 3 Airplanes, install the electrical bracket at Right Buttock Line 45.50 if it has not been done. K. (not shown) On Group 1, 2, 3 Airplanes, install the cargo posts at Left or Right Buttock Line 24.75. L. (not shown) Install the cargo wall in the forward cargo compartment, the floor panels, the carpets, and the seats. Put the airplane back to the normal condition for operation.

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### BOEING SERVICE BULLETIN 737-53-1120

Illustration Table of Contents Title Page FIGURE 1. COMPLIANCE AND WORK INSTRUCTION ALTERNATIVES IF NO PREVENTIVE CHANGE OR REPAIR WAS MADE BY THE INITIAL RELEASE, GROUP 1,2,3,4,5,6,7,8 AIRPLANES . . . . . . . . . . . . . . . . . 68 FIGURE 2. WORK INSTRUCTION ALTERNATIVES IF A PREVENTIVE CHANGE WAS MADE BY THE INITIAL RELEASE, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 FIGURE 3. CLOSE VISUAL INSPECTION - CHANNELS WITH NO PIVOT LINKS AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,4,5,6,7,8 AIRPLANES, OR 0.00, GROUP 1,2,3,7,8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 FIGURE 4. CRACK INSPECTION - BEFORE CHANGES ARE MADE AT A CHANNEL LOCATION, GROUP 1,2,3,4,5,6,7,8 AIRPLANES . . . . . . . 71 FIGURE 5. CHANNEL WITH A PIVOT LINK - INSPECTION AND CHANGES TO THE CHANNEL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . . . 74 FIGURE 6. CHANNEL- CHANGES TO THE SEAT TRACK, INTERCOSTAL LINK, AND THE CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 OR 0.00, GROUP 1,2,3,7,8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 FIGURE 7. CRACK INSPECTION - REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 . . 80 FIGURE 8. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 1,2,3,7,8 AIRPLANES. . . . . . . . . . . . . . . . 83 FIGURE 9. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . 87 FIGURE 10. CRACK INSPECTION - INTERCOSTAL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 GROUP 1,2,3,4,5,6,7,8 AIRPLANES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 FIGURE 11. CARGO POST REMOVAL - GROUP 1 AND 4 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 FIGURE 12. CARGO POST REMOVAL - GROUP 2,3,5,6 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 FIGURE 13. ELECTRICAL BRACKET REMOVAL - GROUP 1,2,4,5 AIRPLANES, RIGHT BUTTOCK LINE 45.00 . . . . . . . . . . . . . . . . . . . . 97 FIGURE 14. ELECTRICAL BRACKET REMOVAL - GROUP 3,6 AIRPLANES, RIGHT BUTTOCK LINE 45.00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 FIGURE 15. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITHOUT A PIVOT LINK, GROUP 1,2,3,4,5,6,7,8 AIRPLANES . . . . . 99 FIGURE 16. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITH A PIVOT LINK, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . 101 FIGURE 17. INTERCOSTAL LINK REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 1,2,3,7,8 . . . . . . . 103
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Illustration Table of Contents (Continued) Title Page FIGURE 18. INTERCOSTAL LINK, CHANNEL AND REPAIR ANGLE REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 4,5,6 AIRPLANES. . . . . . . . . . . . . . . . . . . . 105 FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES . . . . . . . . . . 107 FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES . . . . . . . . . . 113 FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES . . . . . . . 118 FIGURE 22. INTERCOSTAL CHANGES - GROUP 1,2,3 AIRPLANES (DOES NOT INCLUDE PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005. . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 FIGURE 23. INTERCOSTAL CHANGES - GROUP 7,8 AIRPLANES (INCLUDES PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 FIGURE 24. INTERCOSTAL - REPAIR, REPLACEMENT OR INSTALLATION, GROUP 4,5,6 AIRPLANES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 . . . 153 FIGURE 29. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES. . . . . . . . . 166 FIGURE 30. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES. . . . . . . . . 168 FIGURE 31. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES. . . . . . . . 170 FIGURE 32. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES. . . . . . . . 172 FIGURE 33. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES . . . . . . . . . . . . 174

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### BOEING SERVICE BULLETIN 737-53-1120
Illustration Table of Contents (Continued) Title Page FIGURE 34. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 7 AIRPLANES . . . . . . . . . . . . 176 FIGURE 35. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75 GROUP 7 AIRPLANES . . . . . . . . . . . 178 FIGURE 36. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES. . . . . . . . . . . 180 FIGURE 37. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES . . . . . . . . . . . . 182 FIGURE 38. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES . . . . . . . . . . . . 184 FIGURE 39. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES. . . . . . . . . . . 186 FIGURE 40. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES. . . . . . . . . . . 188 FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 FIGURE 42. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 FIGURE 43. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 FIGURE 44. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 FIGURE 45. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES . . . . . . . . . . . . . . . . 223 FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 FIGURE 49. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

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Illustration Table of Contents (Continued) Title Page FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 FIGURE 52. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 FIGURE 53. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 FIGURE 54. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . 266 FIGURE 55. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 FIGURE 56. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES. . . . . . . . . . . . . . . . . . . . . . . . . . . 273 FIGURE 57. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 . . . . . . 276 FIGURE 58. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 . . . . . . . 279 FIGURE 59. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2. . . . . . . . . . . 282 FIGURE 60. ELECTRICAL BRACKET INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 . . . . . . . 284 FIGURE 61. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3 OR CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 FIGURE 62. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 AIRPLANES . . . . . . . . . . . . . . . . . . . . . . . . . 289 FIGURE 63. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 AIRPLANES. . . . . . . . . . . . . . . . . . . . . . . . . . . 291 FIGURE 64. OPERATOR MADE PART - CHANNEL RADIUS FILLER "A". . . . . . . 293 FIGURE 65. OPERATOR MADE PART - CHANNEL RADIUS FILLER "B". . . . . . . 294 FIGURE 66. OPERATOR MADE PART - CHANNEL RADIUS FILLER "C". . . . . . . 295 FIGURE 67. OPERATOR MADE PART - SUPPORT CLIP "B" . . . . . . . . . . . . . . . . 296 FIGURE 68. OPERATOR MADE PART - SUPPORT CLIP "C". . . . . . . . . . . . . . . . 297 FIGURE 69. OPERATOR MADE PART - INTERCOSTAL WEB 65C34688-33. . . . 298

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Illustration Table of Contents (Continued) Title Page FIGURE 70. OPERATOR MADE PART - INTERCOSTAL WEB 65C34688-35. . . . 299 FIGURE 71. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 FIGURE 72. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 FIGURE 73. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 FIGURE 74. OPERATOR MADE PART - INTERCOSTAL WEB 69-51452-7 . . . . . 304 FIGURE 75. OPERATOR MADE PART - INTERCOSTAL TOP CHORD "A" . . . . . 305 FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 FIGURE 77. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "D" AND "E" . . 313

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* NO REPAIR INSTRUCTIONS ARE GIVEN IN THIS SERVICE BULLETIN AT BL 0 OR REPAIR WAS MADE NO PREVENTIVE CHANGE

NO NO

DO PART V "PREVENTIVE CHANGE" 4500 MORE FLIGHT CYCLES BEFORE THE AIRPLANE GETS

AS SHOWN IN REVISION 1 OF NO MORE WORK IS NECESSARY
THE CHANNEL LOCATION THIS SERVICE BULLETIN AT DO PART VI "REPAIR" (*) DO PART I "INSPECTION" (*)

BY THE INITIAL RELEASE

YES NO YES

YES ? BEAM CRACKED

THE FLOOR IS

NO

? BEAM CRACKED

THE FLOOR IS ? CRACKED CHANNEL IS THE

REPEAT PART I "INSPECTION"802255

FIGURE 1. COMPLIANCE AND WORK INSTRUCTION ALTERNATIVES IF NO PREVENTIVE CHANGE OR REPAIR WAS MADE BY THE INITIAL RELEASE, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 68

### BOEING SERVICE BULLETIN 737-53-1120

A PREVENTIVE CHANGE WAS MADE BY THE INITIAL RELEASE

YES

YES AS SHOWN IN REVISION 1 OF NO MORE WORK IS NECESSARY
THE CHANNEL LOCATION THIS SERVICE BULLETIN AT
NO NO

A CHANNEL WITH A PIVOT LINK" DO PART VII "REPLACEMENT OF YES

YES ? BEAM CRACKED

THE FLOOR IS

A CRACKED CHANNEL) (PART VIII ALSO REPLACES

DO PART VIII "REPAIR"

? CORRECT CLEARANCES ALL OF THE ARE

AS SHOWN IN PART II CORRECT THE CLEARANCES NO
CLEARANCES AS SHOWN MAKE AN INSPECTION FOR IN PART II NO

? BEAM CRACKED

THE FLOOR IS ? CRACKED CHANNEL IS THE CRACKS AS SHOWN IN PART II CHANNEL AND FLOOR BEAM FOR MAKE AN INSPECTION OF THE802247

FIGURE 2. WORK INSTRUCTION ALTERNATIVES IF A PREVENTIVE CHANGE WAS MADE BY THE INITIAL RELEASE, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 69

### BOEING SERVICE BULLETIN 737-53-1120

FWD INBD BS 520

2 2 2 520

1 BS

PASSENGER AIRPLANES SHOWN

CARGO AIRPLANES SIMILAR ON GROUP 1, 2, 3, 7 AND 8 AIRPLANES NO SEAT TRACK AT BL 0

FLOOR PANEL FLOOR PANEL

TYPICAL CRACK IN WEB

CHANNEL TYPICAL CRACK TYPICAL CRACK IN WEB-TO-FLANGE RADIUS IN WEB INTERCOSTAL LINK
OF FLOOR BEAM TOP FLANGE TYPICAL CRACK IN RADIUS OF CHANNEL FLOOR PANELA98707The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make a close visual inspection for cracks in the channel. 2. Make a close visual inspection for cracks on the aft side of in the floor beam. Also look for cracks in the top flange of the floor beam.

FIGURE 3. CLOSE VISUAL INSPECTION - CHANNELS WITH NO PIVOT LINKS AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,4,5,6,7,8 AIRPLANES, OR 0.00, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 70

### BOEING SERVICE BULLETIN 737-53-1120

FWD 1 1 1 1

1 N0 SEAT TRACK AT BL 0 ON GROUP 1, 2, 3, 7 AND 8 AIRPLANES

PASSENGER AIRPLANES SHOWN

CARGO AIRPLANES SIMILAR WASHER RADIUS FILLER BOLT

A

A NUT B B BS 520

FLOOR BEAM WEB INTERCOSTAL802098

FIGURE 4. CRACK INSPECTION - BEFORE CHANGES ARE MADE AT A CHANNEL LOCATION, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 71

### BOEING SERVICE BULLETIN 737-53-1120

3 32

2

3 42

5 0.5 EDDY CURRENT INSPECT

INTERCOSTAL CHANNEL ON GROUP 4, 5 AND 6 AIRPLANES LINK INTERCOSTAL L C

C

LOOKING AFT 

## VIEW B-B LINK INTERCOSTAL L

INTERCOSTAL TEE ON GROUP 1, 2, 3, 7 AND 8 AIRPLANES 

## VIEW A-A LOOKING FORWARD 2.00 TYPICAL

CHECK FOR CRACKS

CHECK FOR CRACKS WEB-TO-FLANGE RADIUS WEB-TO-FLANGE RADIUS

TOP FLANGE OF FLOOR BEAM TOP FLANGE OF FLOOR BEAM

WEB WEBC19377

FIGURE 4. CRACK INSPECTION - BEFORE CHANGES ARE MADE AT A CHANNEL LOCATION, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 72

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make sure that the bolt, the nut, the washer and the radius filler are removed from both the forward and the aft side of the floor beam flange. NOTES: 1. Keep the bolts, nuts, washers and radius fillers for possible later use. 2. The bolts, nuts, washers and radius fillers are installed only at Left Buttock Line 24.75 and 45.50 and at Right Buttock Line 24.75 and 45.50. 2. Make a close visual inspection for cracks on the part of the floor beam that was covered by the channel and the radius filler. NOTE: Most floor beam cracks start at the centerline of the intercostal link. 3. Make a close visual inspection for cracks on the forward side of the floor beam. Also look for cracks in the top flange of the floor beam. 4. Make an eddy current inspection of the aft side of the floor beam surface to find cracks that cannot be seen visually. Inspect the surface of the web and the web-to-flange radius inside the area shown (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 4). 5. Make an eddy current inspection of these two existing fastener holes for small cracks (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 1, Figure 11 or Figure 16). NOTE: The floor beam cannot be repaired with the instructions given in this service bulletin if small cracks are found in these fastener holes with the eddy current inspection given in this circle note step.

FIGURE 4. CRACK INSPECTION - BEFORE CHANGES ARE MADE AT A CHANNEL LOCATION, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 73

### BOEING SERVICE BULLETIN 737-53-1120

FWD INBD 520 BS

2 2 2

1 NO SEAT TRACK AT BL 0 FLOOR PANEL

FLOOR PANEL
INTERCOSTAL LINK TOP FLANGE OF FLOOR BEAM

PIVOT LINK IN WEB



## CHANNEL AT INTERCOSTAL LINK LOCATIONS CHECK FOR CRACKS RADIUS IN WEB-TO-FLANGE CHECK FOR CRACKS

CRACKS IN WEB CHECK FOR

RADIUS OF CHANNEL CHECK FOR CRACKS IN RADIUS FILLER

A AA98762

FIGURE 5. CHANNEL WITH A PIVOT LINK - INSPECTION AND CHANGES TO THE CHANNEL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 74

### BOEING SERVICE BULLETIN 737-53-1120

9 5

6 4 3 8

3 4

FWDSTA 520 4

CHANNEL RADIUS FILLER AND FASTENER HEAD

INTERCOSTAL LINK
PIVOT BOLT

PIVOT LINK FLOOR PANEL FLOOR PANEL



## VIEW A-A BEAM FLOOR

CHANNEL SEAT TRACK ENDS

0.06 0.19B00960

FIGURE 5. CHANNEL WITH A PIVOT LINK - INSPECTION AND CHANGES TO THE CHANNEL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 75

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. Channel and Floor Beam - Inspection for Cracks at Left and Right Buttock Line 24.75 and 45.50 1. Make a close visual inspection for cracks in the channel. 2. Make a close visual inspection for cracks on the aft side of in the floor beam. Also look for cracks in the top flange of the floor beam. Inspection for Clearance at Buttock Line 0.00 3. Make sure that there is a minimum horizontal clearance of 0.20 inch between the following: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads that are installed on the

channel radius filler. Inspection for Clearance at Left or Right Buttock Line 24.75 or 45.50 4. Make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends above every channel that has a pivot link. Make sure that the clearances at the following locations are more than the clearance at the seat track ends: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads that are installed on the

channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Changes to the Channel 5. Remove and discard the pin that is inserted in the bolt. Remove and keep the nut, the washer, the pivot bolt and the plain bushing. 6. Move the pivot link away from the intercostal link. 7. (Not shown) Insert a thin sheet of metal between the channel and the intercostal link. This is done to protect the surface of the intercostal link from damage. 8. Cut and remove material from the channel until the correct clearance is obtained. The maximum distance that the cut edge can be made from the original edge is 0.20 inch. 9. Connect the pivot link to the intercostal link. Install the fasteners that were kept. These fasteners include the Pivot Bolt BACB30NR5DK21, the Plain Bushing BACB28AK05-128, the Washer AN960C516 and the Nut BACN10JD5CD. Install a Pin MS24665-134 (operator supplied) through the nut and the bolt.

FIGURE 5. CHANNEL WITH A PIVOT LINK - INSPECTION AND CHANGES TO THE CHANNEL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 76

### BOEING SERVICE BULLETIN 737-53-1120

A

A NO SEAT TRACK AT BL 0

LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR FWD INBD 4 PIVOT LINK 3 FLOOR BEAM

STRAP 10 6 520 BS

7 INTERCOSTAL LINK

WING BOX PLAIN BUSHING 9 5 PIN 11 PIN

PLAIN BUSHING

CHANNELB01603

FIGURE 6. CHANNEL- CHANGES TO THE SEAT TRACK, INTERCOSTAL LINK, AND THE CHANNEL

WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 OR 0.00, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 77

### BOEING SERVICE BULLETIN 737-53-1120

2 1 1 2 8

FWD520 STA 1

CHANNEL PIVOT LINK



## VIEW A-A SEAT TRACK ENDS

INTERCOSTAL LINK FASTENER HEAD CHANNEL RADIUS FILLER AND

PIVOT BOLT

PIVOT JOINT FLOOR BEAM 0.19 0.06B01612

FIGURE 6. CHANNEL- CHANGES TO THE SEAT TRACK, INTERCOSTAL LINK, AND THE CHANNEL

WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 OR 0.00, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 78

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. At Left or Right Buttock Line 24.75 or 45.50, make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends above every channel that has a pivot link. Make sure that the following clearances are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads that are installed on the

channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient. See View A-A. 2. At Buttock Line 0.00, make sure that there is a minimum horizontal clearance of 0.20 inch between the following: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads that are installed on the

channel radius filler. Make a mark at the location where material will be removed if the clearance is not sufficient. 3. Remove and discard the pin that is inserted in the bolt. Remove and keep the nut, the washer, the pivot bolt and the plain bushing. 4. Move the pivot link away from the intercostal link. 5. Remove and keep the fasteners that connect the intercostal link to the wing box. Discard the pin. 6. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 7. Remove and keep the intercostal link. 8. Cut and remove material from the seat track end, the channel, or the intercostal link where the marks were made. On the channel, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. On the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 9. Connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. Install a Pin MS24665-134 (operator supplied) through the nut and the bolt. 10. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 11. Connect the pivot link to the intercostal link. Install the fasteners that were kept. These fasteners include the Pivot Bolt BACB30NR5DK21, the Plain Bushing BACB28AK05-128, the Washer AN960C516 and the Nut BACN10JD5CD. Install the Pin MS24665-134 through the nut and the pivot bolt.
FIGURE 6. CHANNEL- CHANGES TO THE SEAT TRACK, INTERCOSTAL LINK, AND THE CHANNEL

WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 OR 0.00, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 79

### BOEING SERVICE BULLETIN 737-53-1120

FWD B B NO SEAT TRACK AT BL 0 BEAM FLOOR

REPAIR ANGLE 6 INTERCOSTAL

6 TYPICAL CRACK IN RADIUS OF CHANNEL1

CHANNEL RADIUS FILLER 6 1 CHANNEL A BS 520

AB02583

FIGURE 7. CRACK INSPECTION - REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 80

### BOEING SERVICE BULLETIN 737-53-1120

9 7 8 10 2 5 10 5

4 3 2

7

7 3 3

0.5 EDDY CURRENT INSPECT LOOKING AFT 

## VIEW A-A CHECK FOR CRACKS

WEB CHECK FOR CRACKS TYPICAL 2.00



## VIEW B-B LOOKING FORWARD LINK INTERCOSTAL L C INTERCOSTAL TEE RADIUS FILLER LINK INTERCOSTAL L C

CRACK WITH STOP DRILL

WEB WEB

FLOOR BEAM TOP FLANGE OF

WEB-TO-FLANGE RADIUS WEB-TO-FLANGE RADIUS FLOOR BEAM TOP FLANGE OF

CHECK FOR CRACKSB03070

FIGURE 7. CRACK INSPECTION - REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 81

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make a close visual inspection for cracks on the channel. 2. Remove the radius filler, the bolt, the nut, and the washer from below the forward side of the floor beam flange. 3. Make a close visual inspection for cracks on the forward side of the floor beam. Look for more cracks that started after the repair steps in the initial release of this service bulletin were done. Also look for more cracks in the top flange of the floor beam. NOTE: Most floor beam cracks start at the centerline of the intercostal link. 4. It is not necessary to do more work on floor beam cracks that were stop-drilled with the steps in the initial release of this service bulletin. 5. If no more floor beam cracks are found, apply a layer of sealant (BMS 5-95) to the faying surfaces and install the Bolt BACB30FL5-6, the Radius Filler 66-13222-1, the Washer AN960-D516 and the Nut NAS679-A5. Do these Steps Below if more Floor Beam Cracks are Found 6. Remove the channel, the channel radius filler and the repair angle. Keep the channel radius filler and the channel. However, discard the channel if it is cracked. Discard the repair angle. 7. Make a close visual inspection for cracks on the part of the floor beam that was covered by the repair angle. 8. Also make an eddy current inspection on the same side of the floor beam surface to find cracks that cannot be seen visually. Inspect the surface of the web and the web-to-flange radius inside the area shown (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 4). 9. Make an eddy current inspection of these two existing fastener holes for small cracks (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 1,or Figure 11). NOTE: The floor beam cannot be repaired with the instructions given in this service bulletin if small cracks are found in these fastener holes with the eddy current inspection given in this circle note step. 10. Discard the radius filler, the bolt and the nut that were removed from the floor beam flange.

FIGURE 7. CRACK INSPECTION - REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 82

### BOEING SERVICE BULLETIN 737-53-1120

FWD A

A NO SEAT TRACK AT BL 0 SEAT TRACK

WEB-TO-FLANGE RADIUS BOTTOM SIDE OF THE FLANGE FLOOR BEAM WEB 520 BS

INTERCOSTAL801794

FIGURE 8. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 83

### BOEING SERVICE BULLETIN 737-53-1120

6 9

8 9 5 9 4 4 1 FOR THE MARK

CRACK ENDS NEAR THE TOP FLANGE

3 2

3 PROBE 0.090 MINIMUM FOR THE INSPECTION 0.130 MINIMUM 6 7

TYPICAL CRACK 1 4

CRACK ENDS NEAR THE OTHER LIMITS CRACK INSPECTION PROBE CRACK ENDS NOT ADJACENT TO THE LIMITS INSPECTION PROBE CRACK INSPECTION PROBE
0.130 MINIMUM



## VIEW B-B

VIEW A-A LIMITS FOR THE CRACK ENDS SEAT TRACK SEAT TRACK

B

B

TYPICAL 1.28 2.58 2.70 0.025

1.28 0.62 1.40 TYPICAL



## VIEW A-A LIMITS FOR ANY PART OF A CRACK NOT AT THE CRACK ENDS

1.15 0.49801799

FIGURE 8. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 84

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Some airplanes have an existing fastener installed at any of these two locations. Remove and discard this fastener if it is installed. 2. Limits For Any Part Of the Crack Not At The Ends - Make sure that the cracks are in the limits shown on the aft side of in the floor beam. The areas of the floor beam in the crack limits include the web and part of the web-to-flange radius. The floor beam cannot be repaired with the instructions given in this service bulletin if the cracks are not in these limits and if cracks are found in the floor beam flange. 3. Eddy Current Inspection Of The Floor Beam Surface For The Crack Ends - Do an eddy current inspection of the cracks on the web surface to find the crack ends (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 4). The crack ends are located by the position of the inspection probe where the indicator meter deflections stop. The crack ends can be found near the center of the circular area defined by the trace of the inspection probe. Make sure that the center of the inspection probe is located in the limits shown when an indication is made. The floor beam cannot be repaired with the instructions given in this service bulletin if the crack ends (The center of the inspection probe) are not in these limits. 4. A minimum distance of 0.125 inch is permitted between the edge of a new stop-drill hole and the edge of one of the existing fastener holes shown. The floor beam cannot be repaired with the instructions given in this service bulletin if this minimum distance cannot be kept. Stop-drill instructions are given in subsequent circle note steps. 5. Stop-Drill Procedure For Crack Ends Not Adjacent To The Limits - Stop-drill the crack end where the inspection probe is located when an indication is made. Make an initial 3/16 inch diameter stop-drill hole. Locate the 3/16 inch diameter drill within the circular area defined by the trace of the inspection probe. Locate the center of the stop-drill as near as possible to the center of the inspection probe. 6. Location of A Stop-Drill For Crack Ends Near The Top Flange - This circle note step is for crack ends that are found when the inspection probe is near the bottom side of the top flange. Make a mark for the center of the 3/16 inch diameter stop-drill where the inspection probe is located when an indication is made. Locate the mark within the circular area defined by the trace of the inspection probe and 0.130 inch minimum from the bottom side of the flange. NOTE: The next circle note step gives the instructions to stop-drill the crack ends at the mark. Keep the above minimum distance between the center of the stop-drill and the bottom side of the flange. The repair cannot be done with these service bulletin instructions if these limits are not kept. 7. Stop-Drill Procedure For Crack Ends Near The Top Flange - A pilot hole can be made at the location where the 3/16 inch stop-drill will be made. Locate the center of the drill on the mark. Keep the angle between the centerline of the drill and the floor beam web as close as possible to 90 degrees. This is done to prevent contact between the drill and the bottom side of the flange. Scratches or damage the bottom side of the flange are not permitted. Increase the diameter of the pilot hole to 3/16 inch. Make sure to keep the minimum distance as given in the last Circle Note Step.

FIGURE 8. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 85

### BOEING SERVICE BULLETIN 737-53-1120
8. Stop-Drill Procedure For Crack Ends Near The Other Limits - Stop-drill the crack end where the inspection probe is located when an indication is made. Make an initial 3/16 inch diameter stop-drill hole. Locate the 3/16 inch diameter drill within the circular area defined by the trace of the inspection probe. Locate the center of the stop-drill as near as possible to the center of the inspection probe. Make sure that the center of the stop drill hole is in the limits shown. NOTE: Except for the limits near the top flange, the limits for the center of the stop drill holes are the same as the limits for the center of the inspection probe. 9. Eddy Current Inspection Of A Stop-Drill Hole - Make an eddy current inspection of the 3/16 inch diameter stop-drill hole to see if the crack end continues on the other side of the stop-drill hole (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 1 or Figure 11). a. If the crack end is not found (The crack is too small to cause an indication), increase the diameter of the hole to 1/4 inch. This is done to remove the small crack that did not cause an indication. The hole diameter cannot be increased if any of these conditions occur: - Another increase of the hole diameter could cause the drill to damage or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure. b. If the crack end is found, increase the diameter of the stop-drill hole in 1/16 inch increments after each inspection of the hole. Increase the diameter until the crack end cannot be found with the eddy current inspection or until any of these conditions occur: - Another increase of the hole diameter could cause the drill to damage or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure. The repair cannot be done with the instructions in this bulletin if any of the above conditions occur. c. Increase the hole diameter by an additional 1/16 inch increment if the crack end was not found with the last eddy current inspection. This is done to remove a small crack end that did not cause an indication. The hole diameter cannot be increased if any of these conditions occur: - Another increase of the hole diameter could cause the drill to damaged or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure.

FIGURE 8. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 86

### BOEING SERVICE BULLETIN 737-53-1120

FWD A A SEAT TRACK BS 520

FLOOR BEAM WEB

BOTTOM SIDE OF THE FLANGE WEB-TO-FLANGE RADIUS INTERCOSTAL801803

FIGURE 9. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 87

### BOEING SERVICE BULLETIN 737-53-1120

9

6 1 6 1 4 1 4 1 3

5

10 11 11 7 11 8 0.165 MINIMUM 0.130 MINIMUM FOR

THE TOP FLANGE CRACK ENDS NEAR FOR THE MARK 3 PROBE THE INSPECTION 8 2

CRACK INSPECTION PROBE CRACK CRACK ENDS NEAR THE OTHER LIMITS

INSPECTION PROBE 0.165 INSPECTION PROBE

MINIMUM



## VIEW B-B

CRACK ENDS NOT ADJACENT TO THE LIMITS 1.64



## VIEW A-A LIMITS FOR THE CRACK ENDS 1.40 B

B 1.53

1.77 0.06



## VIEW A-A LIMITS FOR ANY PART OF A CRACK NOT AT THE CRACK ENDS SEAT TRACK

SEAT TRACK

TYPICAL CRACK801792

FIGURE 9. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 88

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Some airplanes have an existing fastener hole at any of these four locations. Remove and discard the fastener if it is installed. 2. Limits For Any Part Of the Crack Not At The Ends - Make sure that the cracks are in the limits shown on the aft side of in the floor beam. The areas of the floor beam in the crack limits include the web and part of the web-to-flange radius. The floor beam cannot be repaired with the instructions given in this service bulletin if the cracks are not in these limits and if cracks are found in the floor beam flange. 3. Eddy Current Inspection Of The Floor Beam Surface For The Crack Ends - Do an eddy current inspection of the cracks on the web surface to find the crack ends (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 4). The crack ends are located by the position of the inspection probe where the indicator meter deflections stop. The crack ends can be found near the center of the circular area defined by the trace of the inspection probe. Make sure that the center of the inspection probe is located in the limits shown when an indication is made. The floor beam cannot be repaired with the instructions given in this service bulletin if the crack ends (The center of the inspection probe) are not in these limits. 4. A minimum distance of 0.125 inch is permitted between the edge of a new stop-drill hole and the edge of the fastener hole if it exist at one of the two locations shown. A minimum distance of 0.125 inch is permitted between the edge of a new stop-drill hole and the edge of the fastener hole if it exist at one of the two locations shown. The floor beam cannot be repaired with the instructions given in this service bulletin if this minimum distance cannot be kept. Stop-drill instructions are given in subsequent circle note steps. 5. A minimum distance of 0.125 inch is permitted between the edge of a new stop-drill hole and the edge of the holes for the 1/4 inch hex drive bolts at any one of the four locations shown. The floor beam cannot be repaired with the instructions given in this service bulletin if this minimum distance cannot be kept. Stop-drill instructions are given in subsequent circle note steps. 6. A minimum distance of 0.41 inch is permitted between the edge of a new stop-drill hole and the edge of the fastener hole if it exist at one of the two locations shown. The floor beam cannot be repaired with the instructions given in this service bulletin if this minimum distance cannot be kept. Stop-drill instructions are given in subsequent circle note steps. 7. Stop-Drill Procedure For Crack Ends Not Adjacent To The Limits - Stop-drill the crack end where the inspection probe is located when an indication is made. Make an initial 3/16 inch diameter stop-drill hole. Locate the 3/16 inch diameter drill within the circular area defined by the trace of the inspection probe. Locate the center of the stop-drill as near as possible to the center of the inspection probe. 8. Location of A Stop-Drill For Crack Ends Near The Top Flange - This circle note step is for crack ends that are found when the inspection probe is near the bottom side of the top flange. Make a mark for the center of the 3/16 inch diameter stop-drill where the inspection probe is located when an indication is made. Locate the mark within the circular area defined by the trace of the inspection probe and 0.165 inch minimum from the bottom side of the flange. NOTE: The next circle note step gives the instructions to stop-drill the crack ends at the mark. Keep the above minimum distance between the center of the stop-drill and the bottom side of the flange. The repair cannot be done with these service bulletin instructions if these limits are not kept.

FIGURE 9. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 89

### BOEING SERVICE BULLETIN 737-53-1120
9. Stop-Drill Procedure For Crack Ends Near The Top Flange - A pilot hole can be made at the location where the 3/16 inch stop-drill will be made. Locate the center of the drill on the mark. Keep the angle between the centerline of the drill and the floor beam web as close as possible to 90 degrees. This is done to prevent contact between the drill and the bottom side of the flange. Scratches or damage the bottom side of the flange are not permitted. Increase the diameter of the pilot hole to 3/16 inch. Make sure to keep the minimum distance as given in the last circle note step. 10. Stop-Drill Procedure For Crack Ends Near The Other Limits - Stop-drill the crack end where the inspection probe is located when an indication is made. Make an initial 3/16 inch diameter stop-drill hole. Locate the 3/16 inch diameter drill within the circular area defined by the trace of the inspection probe. Locate the center of the stop-drill as near as possible to the center of the inspection probe. Make sure that the center of the stop drill hole is in the limits shown. NOTE: Except for the limits near the top flange, the limits for the center of the stop drill holes are the same as the limits for the center of the inspection probe. 11. Eddy Current Inspection Of A Stop-Drill Hole - Make an eddy current inspection of the 3/16 inch diameter stop-drill hole to see if the crack end continues on the other side of the stop-drill hole (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 1 or Figure 11). a. If the crack end is not found (The crack is too small to cause an indication), increase the diameter of the hole to 1/4 inch. This is done to remove the small crack that did not cause an indication. The hole diameter cannot be increased if any of these conditions occur: - Another increase of the hole diameter could cause the drill to damage or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure. b. If the crack end is found, increase the diameter of the stop-drill hole in 1/16 inch increments after each inspection of the hole. Increase the diameter until the crack end cannot be found with the eddy current inspection or until any of these conditions occur: - Another increase of the hole diameter could cause the drill to damage or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure. The repair cannot be done with the instructions in this bulletin if any of the above conditions occur. c. Increase the hole diameter by an additional 1/16 inch increment if the crack end was not found with the last eddy current inspection. This is done to remove a small crack end that did not cause an indication. The hole diameter cannot be increased if any of these conditions occur: - Another increase of the hole diameter could cause the drill to damaged or scratch the bottom

side of the top flange - Another increase of the hole diameter exceeds the minimum distance permitted between the

edge of the stop-drill hole and the edge of an existing fastener hole as shown in this figure.

FIGURE 9. CRACK LENGTHS, CRACK LIMITS AND STOP-DRILL HOLE INSTRUCTIONS - GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 90

### BOEING SERVICE BULLETIN 737-53-1120

1 500 OR

500D 500B OR BS 520 BS

INTERCOSTAL WEB

FWD FLOOR BEAM WEB A

A



## VIEW A-A ALL INTERCOSTALS SIMILAR TO THIS VIEW INTERCOSTAL TOP CHORD INTERCOSTAL TEE OR INTERCOSTAL ANGLE, INTERCOSTAL CHANNEL 520 BS

TYPICAL CRACKS802236The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make a close visual inspection for cracks. Examine all of the surfaces on the intercostal web and the top intercostal chord where there is access.

FIGURE 10. CRACK INSPECTION - INTERCOSTAL AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50 GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 91

### BOEING SERVICE BULLETIN 737-53-1120

2 CHANNEL

3 BS 520 FLOOR BEAM

INTERCOSTAL LINK

BS 520 FRAME ELECTRICAL BRACKET (RBL ONLY) 5 BOTTOM ANGLE CARGO POST

SIDE ANGLE BEAM TEE

4 2

LBL 24.75 LOCATION ON PASSENGER AIRPLANES SHOWN RBL LOCATION SIMILAR ON ALL AIRPLANES A

A

INBD FWDB09550

FIGURE 11. CARGO POST REMOVAL - GROUP 1 AND 4 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 Jul 6/89 737-53-1120 REV 1: May 13/93 92

### BOEING SERVICE BULLETIN 737-53-1120

520 STA

FLOOR BEAM CHANNEL INTERCOSTAL INTERCOSTAL LINK

1

CARGO POST MARK

FWD 0.35 3.45 1.30

BEAM TEE



## VIEW A-A801094

FIGURE 11. CARGO POST REMOVAL - GROUP 1 AND 4 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 Jul 6/89 737-53-1120 REV 1: May 13/93 93

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make the marks shown (These will be used to change the post in another figure). See View A-A for the locations. 2. Remove and discard the rivets that connect the post to the adjacent structure. 3. Remove and discard the fasteners that connect the top of the post to the channel. 4. Remove and keep the screw, nut and washer that connect the bottom of the post to the Body Station 520 frame. 5. Remove and keep the post.

FIGURE 11. CARGO POST REMOVAL - GROUP 1 AND 4 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 Jul 6/89 737-53-1120 REV 1: May 13/93 94

### BOEING SERVICE BULLETIN 737-53-1120

2 2 3

4 5 1

BOTTOM ANGLE

SIDE ANGLE FLOOR BEAM

CARGO POST

(RBL ONLY) ELECTRICAL BRACKET

BS 520 FRAME BEAM ANGLE 3.45 CHANNEL INTERCOSTAL LINK 520 BS

LBL 24.75 LOCATION ON PASSENGER AIRPLANES SHOWN ALL OTHER BL LOCATIONS SIMILAR ON ALL AIRPLANES FWD INBDB08818

FIGURE 12. CARGO POST REMOVAL - GROUP 2,3,5,6 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 Jul 6/89 737-53-1120 REV 1: May 13/93 95

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make the mark shown. It will be used to change the post in another figure. 2. Remove and discard the rivets that connect the post to the adjacent structure. 3. Remove and discard the fasteners that connect the top of the post to the channel. 4. Remove and keep the screw, nut and washers that connect the bottom of the post to the Body Station 520 frame. 5. Remove and keep the post.

FIGURE 12. CARGO POST REMOVAL - GROUP 2,3,5,6 AIRPLANES, LEFT AND RIGHT BUTTOCK LINE 24.75 Jul 6/89 737-53-1120 REV 1: May 13/93 96

### BOEING SERVICE BULLETIN 737-53-1120

2 1

1 3

PASSENGER AIRPLANES SHOWN

CARGO AIRPLANES SIMILAR INBD

FWD ELECTRICAL BRACKET SUPPORT CLIP
LINK INTERCOSTAL RBL 45.5

STRAP BEAM FLOOR

WING BOX BS 520

CHANNELB11061The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the fasteners from the forward and the aft end of the electrical bracket. 2. Make a mark to identify the forward end of the electrical bracket. Remove and keep the electrical bracket. It will be changed and installed in another figure. 3. Remove and keep the support clip. Steps are given to change it and to install it in another figure.

FIGURE 13. ELECTRICAL BRACKET REMOVAL - GROUP 1,2,4,5 AIRPLANES, RIGHT BUTTOCK LINE 45.00 Jul 6/89 737-53-1120 REV 1: May 13/93 97

### BOEING SERVICE BULLETIN 737-53-1120

SUPPORT CLIP

PASSENGER AIRPLANES SHOWN

CARGO AIRPLANES SIMILAR FWD INBD STRAP 3

1 520 BS

WING BOX FLOOR BEAM

CHANNEL INTERCOSTAL LINK RBL 45.50

ELECTRICAL BRACKET 2
1B11059The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the fasteners from the forward and the aft end of the electrical bracket. 2. Make a mark to identify the forward end of the electrical bracket. Remove and keep the electrical bracket. It will be changed and installed in another figure. 3. Do not remove or keep the support clip. It will be discarded with the channel in another figure.

FIGURE 14. ELECTRICAL BRACKET REMOVAL - GROUP 3,6 AIRPLANES, RIGHT BUTTOCK LINE 45.00 Jul 6/89 737-53-1120 REV 1: May 13/93 98

### BOEING SERVICE BULLETIN 737-53-1120

PASSENGER AIRPLANES SHOWN

CARGO AIRPLANES SIMILAR CHANNEL 61

FWD INBD 520 BS

WING BOX 3

2
7 8 CHANNEL RADIUS FILLERS 7 8
4 INTERCOSTAL LINK CHANNEL RADIUS FILLERS

STRAP FLOOR BEAM NO SEAT TRACK AT BL 0 ON GROUP 1, 2, 3, 7 AND 8 AIRPLANES802166

FIGURE 15. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITHOUT A PIVOT LINK, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 99

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. NOTE: The channel will be replaced with a new channel that has a pivot link in another figure. 1. Remove and discard the fasteners that connect the intercostal link to the channel. 2. Remove and keep the fasteners that connect the intercostal link to the wing box. Discard the cotter pin. 3. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 4. Remove and keep the intercostal link. It will be changed and installed in another figure. 5. (Not shown) On Group 4, 5, 6 Airplanes at Left Buttock Line 45.50, remove the left shroud panel and the left closure panel in the forward cargo compartment for work access. These panels are located adjacent to and forward of the floor beam. Discard the glass cloth tape from the edges. Keep the panels and the fasteners. Refer to the Boeing Maintenance Manual Subject 25-52-111. 6. Remove and discard the channel and the hex drive bolts that attach it to the floor beam. 7. On Group 1, 2, 3, 7, 8 Airplanes, remove and keep the channel radius fillers. 8. On Group 4, 5, 6 Airplanes, remove and discard the channel radius fillers.

FIGURE 15. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITHOUT A PIVOT LINK, GROUP 1,2,3,4,5,6,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 100

### BOEING SERVICE BULLETIN 737-53-1120

WING BOX NO SEAT TRACK AT BL 0LINK PIVOT

1

CHANNEL 5 6 7

2 3

7 STRAP LINK INTERCOSTAL 4 BEAM FLOOR BS 520

INBD FWD
ALL OTHER BL LOCATIONS SIMILAR LBL 24.75 LOCATION SHOWNB03190

FIGURE 16. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITH A PIVOT LINK, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 101

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and keep the pivot link and the fasteners at the pivot joints. Discard the cotter pins. 2. Remove and keep the fasteners that connect the intercostal link to the wing box. Discard the cotter pin. 3. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 4. Remove and keep the intercostal link. It will be installed in another figure. 5. Remove and discard the hex drive bolts that attach the channel to the floor beam. 6. keep the channel if it is not cracked. 7. Keep the channel radius fillers.

FIGURE 16. INTERCOSTAL LINK AND CHANNEL REMOVAL - A CHANNEL WITH A PIVOT LINK, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 102

### BOEING SERVICE BULLETIN 737-53-1120

NO SEAT TRACK AT BL 0LINK PIVOT

1

2 3 STRAP LINK INTERCOSTAL 4 BEAM FLOOR

WING BOX BS 520

REPAIR ANGLE
5

CHANNEL CHANNEL RADIUS FILLER

INBD FWD
ALL OTHER BL LOCATIONS SIMILAR LBL 24.75 LOCATION SHOWNB03270

FIGURE 17. INTERCOSTAL LINK REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 103

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and keep the pivot link and the fasteners at the pivot joints. Discard the cotter pins. 2. Remove and keep the fasteners that connect the intercostal link to the wing box. Discard the cotter pin. 3. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 4. Remove and keep the intercostal link. It will be changed and installed in another figure. 5. Remove and discard the channel radius filler at the top of the channel and the two hex drive bolts that attach it to the channel.

FIGURE 17. INTERCOSTAL LINK REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 104

### BOEING SERVICE BULLETIN 737-53-1120

10 6 RADIUS CHANNEL FILLER

RADIUS CHANNEL FILLER 6 ANGLE REPAIR 9 FLOOR BEAM

ALL OTHER BL LOCATIONS SIMILAR LBL 24.75 LOCATION SHOWN FWD INBD 1 8 520

LINK PIVOT

CHANNEL 7 4

2 BS

WING BOX INTERCOSTAL LINK STRAP 3B12134

FIGURE 18. INTERCOSTAL LINK, CHANNEL AND REPAIR ANGLE REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 105

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and keep the pivot link. Discard the Bolt BACB30NR5DK21 and the Plain Bushing BACB28AK05-128 at the joint where the pivot link is connected to the intercostal link. Discard the cotter pins. Keep the remaining fasteners at the pivot joints. 2. Remove and keep the fasteners that connect the intercostal link to the wing box. 3. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 4. Remove and keep the intercostal link. It will be changed and installed in another figure. 5. (Not shown) At Left Buttock Line 45.50, remove the left shroud panel and the left closure panel in the forward cargo compartment for work access. These panels are located adjacent to and forward of the floor beam. Discard the glass cloth tape from the edges. Keep the panels and the fasteners. Refer to the Boeing Maintenance Manual Subject 25-52-111. 6. Remove and discard the channel radius fillers. Remove the hex drive bolts carefully to prevent damage to the holes. 7. Remove and save the channel. Remove the hex drive bolts in the channel carefully to prevent damage to the holes. 8. Discard the hex drive bolts that attach the channel to the floor beam. 9. Remove and discard the repair angle and the fasteners that attach it to the floor beam. 10. Remove and discard the radius filler, the bolt, the nut, and the washer from the bottom side of the forward flange on the floor beam.

FIGURE 18. INTERCOSTAL LINK, CHANNEL AND REPAIR ANGLE REMOVAL - A CHANNEL WITH A PIVOT LINK INSTALLED ON A REPAIR ANGLE, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 106

### BOEING SERVICE BULLETIN 737-53-1120

520 STA LBL 24.75 SEE DETAIL I SEE DETAIL II RBL 24.75802165

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 107

### BOEING SERVICE BULLETIN 737-53-1120



## DETAIL I CHANGES TO CARGO COMPARTMENT AT LBL 24.75 FLOOR BEAM 24.75

LBL

BEAM TEE OR BEAM ANGLE BOTTOM CAPSTRIP TOP CAPSTRIP

PANEL SUPPORT PANEL LINING CEILING1STABILIZER STRAP

CLOSURE PANEL

RUBBER SHROUD RUBBER TAPE

A A

FWD INBD802164

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 108

### BOEING SERVICE BULLETIN 737-53-1120

3 4 6

3 4 STABILIZER STRAP 6 FLOOR BEAM

RUBBER SHROUD BOTTOM CAPSTRIP STABILIZER STRAP 24.75 LBL

24.75

LBL CHANGES TO AFT SIDE OF RUBBER SHROUD 

## VIEW A-A RUBBER TAPE

RUBBER TAPE RUBBER TAPE CLOSURE PANEL

LOOKING UP 

## VIEW B-B RUBBER SHROUD

CLOSURE PANEL 7 STABILIZER STRAP PANEL SUPPORT

7

TOP CAPSTRIP

TOP CAPSTRIP 0.4 0.2 TYPICAL 0.8 TYPICAL

TOP CAPSTRIP

INBD

INBD CUT 0.1 TYPICAL 2.8

CUT 0.2 TYPICAL B B

0.08 0.00 FLOOR BEAM CUT802170

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 109

### BOEING SERVICE BULLETIN 737-53-1120



## DETAIL II CHANGES TO CARGO COMPARTMENT AT RBL 24.75 BEAM ANGLE BEAM TEE OR

BOTTOM CAPSTRIP PANEL SUPPORT TOP CAPSTRIP STABILIZER STRAP RBL 24.75

FLOOR BEAM

PANEL 1 CEILING LINING CLOSURE PANEL

INBD AIR CONDITIONING DUCT
FOAM SEAL RUBBER SHROUD RUBBER TAPE

C C

FWDB08538

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 110

### BOEING SERVICE BULLETIN 737-53-1120

STABILIZER STRAP 7 CLOSURE PANEL CLOSURE PANEL

7



## VIEW D-D VIEW C-C

RBL RBL
RUBBER TAPE

3 4 FLOOR BEAM STABILIZER STRAP 24.75

24.75 CHANGES TO AFT SIDE OF RUBBER SHROUD

LOOKING UP RUBBER SHROUD

RUBBER TAPE CLOSURE PANEL 6 2 BOTTOM CAPSTRIP

RUBBER SHROUD

7
CLOSURE PANEL CUT RUBBER SHROUD 9

STABILIZER STRAP

CUT CLOSURE PANEL INBD

INBD 0.2 TYPICAL 0.8 TYPICAL TOP CAPSTRIP 0.4

TOP CAPSTRIP RIGHT SHROUD PANEL 0.1 TYPICAL 2.8

CUT

0.08 0.00 CUT 0.2 TYPICAL D D

FOAM SEAL

AIR CONDITIONING DUCT

FLOOR BEAM PANEL SUPPORT

FOAM SEAL802226

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 111

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove the ceiling lining panels that are adjacent to the floor beam between the right and left shroud panels. Discard the glass cloth tape from the edges. The location of the ceiling lining panels to be removed is between Body Station 520 and the adjacent forward floor beam. Keep the panels and the fasteners. Refer to the Boeing Maintenance Manual Subject 25-52-111 for removal instructions. 2. Remove the shroud panel at Right Buttock Line 24.75 adjacent to and forward of the panel support at Body Station 520. Discard the glass cloth tape from the edges. Keep the panels and the fasteners. Refer to the Boeing Maintenance Manual Subject 25-52-111 for removal instructions. 3. At Left Buttock Line 24.75, make two marks on the top capstrip. At Right Buttock Line 24.75, make one mark on the end of the top capstrip. Make the marks 0.2 inch from the edge of the strap. 4. Remove the top capstrip. Keep the fasteners. Cut the top capstrip at the marked locations. At Right Buttock Line 24.75, make sure to keep a minimum edge margin of 0.33 inch between the fastener hole in the top capstrip and the cut edge. 5. (not shown) Insert a thin sheet of metal between the top surface of the closure panels and the rubber tape on the bottom surface of the floor beam. Also insert a thin sheet of metal between the top surface of the closure panels and the stabilizer straps at Left and Right Buttock Line 24.75. This is done to protect the rubber tape and the straps from damage. 6. Install the top capstrip on the bottom of the floor beam. 7. Make the cuts shown and remove the material shown from the rubber shroud and the closure panels. Drill the 0.19 inch diameter relief holes in the rubber shroud. 8. (not shown) Remove the metal sheets that were used above. 9. Cut and remove the material shown from the foam seal near the Right Buttock Line 24.75 location.

FIGURE 19. CARGO COMPARTMENT - CHANGES AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3,4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 112

### BOEING SERVICE BULLETIN 737-53-1120

F E



### BOTTOM ANGLE 18 COTTER PIN

WASHER 11 WASHER

11 11

PIN
11 SPACER 11 SPACER 11 WASHER ATTACH BRACKET (SEE DETAIL I)

(RBL ONLY) ELECTRICAL BRACKET
CARGO POST 8 7

9 15 POST END ASSEMBLY

BS 520 FRAME SIDE ANGLE 16 16 10 BEAM TEE BS 520 FLOOR BEAM

RBL 24.75 LOCATION SIMILAR LBL 24.75 LOCATION SHOWN A

A

FWD INBD800978

FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 113

### BOEING SERVICE BULLETIN 737-53-1120

D D D DD

D



### 2 14
12 12



## VIEW A-A 1

17

POST END

CARGO POST RUBBER SHROUD EDGE OF SLOT

FLANGE BEAM TEE CAPSTRIP BOTTOM

SUPPORT PANEL

FWD ELECTRICAL BRACKET (RBL ONLY) ATTACH BRACKET

CHANGES TO THE CARGO POST 0.25 RADIUS

STIFFENER801096

FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 114

### BOEING SERVICE BULLETIN 737-53-1120

C B A B C A 

### 24.75 LBL/RBL



## DETAIL I 13 6

13

NARROW STABILIZER 13 5 13 4 24.75 LBL/RBL

WIDE STABILIZER 

## DETAIL I 13 6 13 3

13 0.45 MINIMUM EDGE MARGIN 0.45 EDGE MARGIN MINIMUM 0.45
MARGIN EDGE MIN INTERCOSTAL ANGLE

FWD 0.40 0.45
MARGIN EDGE MIN INTERCOSTAL ANGLE

FWD 0.40 BRACKET ATTACH BS 520 FLOOR BEAM

FILLER RADIUS 0.53 NARROW STABILIZER

WIDE FILLER FLANGE

FILLER NARROW

BRACKET ATTACH WIDE STABILIZER

0.53 BS 520 FLOOR BEAM

WIDE FILLER

FILLER RADIUS FLANGE801098

FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 115

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the cargo posts that were kept. Use the marks made when the cargo post was removed to cut and remove material from the area shown on the ends. See View A-A 2. Rubber stamp the new part numbers on the cargo posts as shown below (Refer to the Standard Overhaul Practices Manual 20-50-10): AIRPLANE

GROUP EXISTING PART NUMBER NEW PART NUMBER

1 65-49631-9 65C34688-13 65-49631-10 65C34688-12 65-49631-502 65C34688-14 65-49631-501 65C34688-15

4 65-49631-9 65C34978-11 65-49631-10 65C34978-10 65-49631-502 65C34978-12 65-49631-501 65C34978-13 3. Airplanes with wide stabilizers - Put the Wide Filler 65C34688-20 or 65C34978-18 below the stabilizer strap at the floor beam. 4. Airplanes with narrow stabilizers - Put the Narrow Filler 65C34688-22 or 65C34978-20 adjacent to the narrow stabilizer strap at the floor beam. 5. Airplanes with narrow stabilizers - Put the wide filler below the narrow filler and the narrow stabilizer strap. 6. Put the Attach Bracket 65C35842-1 below the wide filler and clamp the attach bracket to the floor beam. 7. Clamp the Post End Assembly 65C35842-2 to the top of the cargo post. 8. On Group 1 Airplanes, put the cargo post 65C34688-12 or 65C34688-14 at the Left Buttock Line 24.75 location. Put the cargo post 65C34688-13 or 65C34688-15 at the Right Buttock Line 24.75 location. On Group 4 Airplanes, put the cargo post 65C346978-10 or 65C346978-12 at the Left Buttock Line 24.75 location. Put the cargo post 65C346978-11 or 65C346978-13 at the Right Buttock Line 24.75 location. 9. Temporarily connect the bottom of the post to the Body Station 520 frame. Use the fasteners that were kept. These fasteners at the connection, include the Bolt NAS1103-3, the Nut NAS679A3W and the two Washers AN960PD10L. 10. Clamp the cargo post to the beam "Tee".

FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 116

### BOEING SERVICE BULLETIN 737-53-1120
11. Temporarily connect the attach bracket to the post end assembly that is clamped to the top end of the cargo post. Use a Pin MS20392-3C79, two Washers AN960JD416L on the surface of the attach bracket, two Washers NAS549E416 on the surface of the post end assembly, and two Spacers NAS43DD4-45 at the connection. 12. Adjust the location of the attach bracket and the post end assembly relative to each other to get these conditions : - The flange on the cargo post is parallel to the edge of the slot in the post end assembly within

0.01 inch along the length of the slot - The attach bracket does not put a load on the post end assembly. 13. Install the wide filler, the narrow filler, if it is used, the attach bracket and the Radius Filler 65C34688-21 or 65C34978-19. Keep a minimum edge margin of 0.33 inch at the locations shown. Apply a layer of sealant (BMS 5-95) to the faying surfaces and to the hex drive bolts. 14. Install the post end assembly on the cargo post end with six fasteners. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. Apply a layer of sealant (BMS 5-95) to the faying surfaces and to the hex drive bolts. 15. Connect the bottom of the post to the Body Station 520 frame. Make sure to install a Cotter Pin MS24665-132 (operator supplied) through the bolt. 16. Attach the cargo post to the beam "Tee" and to the side and bottom to the angles that are near the Body Station 520 frame. 17. Make more cuts to the rubber shroud as necessary to give it clearance with the post end. 18. Connect the top end of the cargo post to the attach bracket. Make sure to install a Cotter Pin MS24665-132 through the pin. 19. (Not shown) Use tape (Permacel) to cover the areas on the rubber shroud where material was cut and removed. The tape can be attached to both the rubber shroud and the aluminum structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a 0.247 - 0.250 inch diameter hole to match the hole in the floor beam structure. Install a hex drive bolt BACB30MB8-8 on Group 1 Airplanes and BACB30MB8-10 on Group 4 Airplanes. Use a collar BACC30X8. Install with the head on the top side of the floor beam flange. B. Drill a 0.247 - 0.250 inch diameter hole. Install a hex drive bolt BACB30MB8-8 on Group 1 Airplanes and BACB30MB8-10 on Group 4 Airplanes. Use a collar BACC30X8. Install with the head on the top side of the floor beam flange. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam structure. Install a hex drive bolt BACB30MD6-8 on Group 1 Airplanes and BACB30MD6-10 on Group 4 Airplanes. Use a collar BACC30AC6. Install with the head on the top side of the floor beam flange. D. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30FM6-6 with a collar BACC30M6. E. Install a rivet MS20426D6-8. F. Install a rivet MS20426D5-7.
FIGURE 20. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 1,4 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 117

### BOEING SERVICE BULLETIN 737-53-1120

E

F



### (SEE DETAIL I) ATTACH BRACKET WASHER 13

SPACER 13

10

17 11 9 9 16 SHIM 8 SPACER 13 PIN 13

13 WASHER

13 WASHER COTTER PIN 20

POST END

12 18

18 FLOOR BEAM BS 520

A

CARGO POST

BOTTOM ANGLE A

SIDE ANGLE

BS 520 FRAME (RBL ONLY) ELECTRICAL BRACKET

RBL 24.75 LOCATION SIMILAR

LBL 24.75 LOCATION SHOWN BEAM ANGLE

FWD INBD802209

FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 118

### BOEING SERVICE BULLETIN 737-53-1120

D

D DD D D D



### 16 1

3 14 1914 2

POST END ELECTRICAL BRACKET (RBL ONLY) RUBBER SHROUD EDGE OF SLOT ATTACH BRACKET

FWD BEAM ANGLE
FLANGE CAPSTRIP BOTTOM

SUPPORT PANEL



## VIEW B-B TYPICAL 0.15

TYPICAL 0.25R TYPICAL 1.00R TYPICAL 3.36 TYPICAL 2.61 LBL/RBL 24.75

CHANGES TO THE CARGO POST B

B MARK FLANGE POST CARGO



## VIEW A-A CARGO POST800049

FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 119

### BOEING SERVICE BULLETIN 737-53-1120

B C A C B A 

### 24.75 LBL/RBL

WIDE STABILIZER 

## DETAIL I 15 7 15 4

15 15 5 24.75 LBL/RBL



## DETAIL I 15 7

15

NARROW STABILIZER 15 6

0.45 0.45 0.45 0.45 INTERCOSTAL ANGLE

FWD 0.40 MARGIN MIN EDGE INTERCOSTAL ANGLE

FWD 0.40 MARGIN MIN EDGE

MARGIN EDGE MINIMUM MARGIN EDGE MINIMUM FLANGE

BRACKET ATTACH WIDE STABILIZER

0.53 BS 520 FLOOR BEAM

WIDE FILLER

FILLER RADIUS FILLER NARROW FLANGE

BRACKET ATTACH BS 520 FLOOR BEAM

FILLER RADIUS 0.53 TYPICAL NARROW STABILIZER

WIDE FILLER800996

FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 120

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the cargo posts that were kept. Use the marks made when the cargo post was removed to cut and remove material from the area shown on the ends. See View A-A 2. Make the marks shown. These are used to cut and remove material from the area shown on the cargo post flange. 3. Rubber stamp the new part numbers on the cargo posts as shown below (Refer to the Standard Overhaul Practices Manual 20-50-10): AIRPLANE

GROUP EXISTING PART NUMBER NEW PART NUMBER 2,3 65-77435-2 65C34688-18 65-77435-1 65C34688-19 5,6 65-77435-2 65C34978-16 65-77435-1 65C34978-17 4. Airplanes with wide stabilizers - Put the Wide Filler 65C34688-20 or 65C34978-18 below the stabilizer strap at the floor beam. 5. Airplanes with narrow stabilizers - Put the Narrow Filler 65C34688-22 or 65C34978-20 adjacent to the narrow stabilizer strap at the floor beam. 6. Airplanes with narrow stabilizers - Put the wide filler below the narrow filler and the narrow stabilizer strap. 7. Put the Attach Bracket 65C35842-1 below the wide filler and clamp the attach bracket to the floor beam. 8. Use the post end and the cargo post as a template to cut and remove material from the edges of the Shim 65C34688-23 or 65C34978-21. Remove the laminations from the shim until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 9. Clamp the Post End 65C35842-3 to the top of the cargo post. Put the Shim 65C34688-23 or 65C34978-21 between the inside of the cargo post and the post end. 10. On Group 2,3 Airplanes, put the cargo post 65C34688-18 at the Left Buttock Line 24.75 location. Put the cargo post 65C34688-19 at the Right Buttock Line 24.75 location. On Group 5,6 Airplanes, put the cargo post 65C34978-16 at the Left Buttock Line 24.75 location. Put the cargo post 65C34978-17 at the Right Buttock Line 24.75 location. 11. Temporarily connect the bottom of the post to the Body Station 520 frame. Use the fasteners that were kept. These fasteners at the connection include the Bolt NAS1104-3, the Nut NAS679A4W and the two Washers AN960PD416L. 12. Clamp the cargo post to the beam angle. 13. Temporarily connect the attach bracket to the post end assembly that is clamped to the top end of the cargo post. Use a Pin MS20392-3C79, two Washers AN960JD416L on the surface of the attach bracket, two Washers NAS549E416 on the surface of the post end assembly, and two Spacers NAS43DD4-24 at the connection. FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 121

### BOEING SERVICE BULLETIN 737-53-1120
14. Adjust the location of the attach bracket and the post end assembly relative to each other to get these conditions: - The flange on the cargo post is parallel to the edge of the slot in the post end assembly within

0.01 inch along the length of the slot - The attach bracket does not put a load on the post end assembly. 15. Install the wide filler, the narrow filler, if it is used, the attach bracket and the Radius Filler 65C34688-21 or 65C34978-19. Keep a minimum edge margin of 0.33 inch at the locations shown. Apply a layer of sealant (BMS 5-95) to the faying surfaces and to the hex drive bolts. 16. Install the post end and the shim on the cargo post end with seven fasteners. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. Apply a layer of sealant (BMS 5-95) to the faying surfaces and to the hex drive bolts. 17. Connect the bottom of the post to the Body Station 520 frame. Make sure to install a Cotter Pin MS24665-132 (operator supplied) through the bolt. 18. Attach the cargo post to the beam angle and to the side and bottom angles that are near the Body Station 520 frame. 19. Make more cuts to the rubber shroud as necessary to give it clearance with the post end. 20. Connect the top end of the cargo post to the attach bracket. Make sure to install a Cotter Pin MS24665-132 through the screw. 21. (Not shown) Use tape (Permacel) to cover the areas on the rubber shroud where material was cut and removed. The tape can be attached to both the rubber shroud and the aluminum structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a 0.247 - 0.250 inch diameter hole to match the hole in the floor beam structure. Install a hex drive bolt BACB30MB8-8 on Group 2,3 Airplanes and BACB30MB8-10 on Group 5,6 Airplanes. Use a collar BACC30X8. Install with the head on the top side of the floor beam flange. B. Drill a 0.247 - 0.250 inch diameter hole. Install a hex drive bolt BACB30MB8-8 on Group 2,3 Airplanes and BACB30MB8-10 on Group 5,6 Airplanes. Use a collar BACC30X8. Install with the head on the top side of the floor beam flange. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam structure. Install a hex drive bolt BACB30MD6-8 on Group 2,3 Airplanes and BACB30MD6-10 on Group 5,6 Airplanes. Use a collar BACC30AC6. Install with the head on the top side of the floor beam flange. D. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30FM6-17 with a collar BACC30M6. E. Install a rivet MS20427M5-7. F. Install a rivet BACR15BA5D7.

FIGURE 21. CARGO POST ATTACHMENT - INSTALLATION AT LEFT OR RIGHT BUTTOCK LINE 24.75, GROUP 2,3,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 122

### BOEING SERVICE BULLETIN 737-53-1120

TOP CHORD ANGLE FWD

6 A

B B 

### TEE

C C C

C C C C



### 7 PLACES 8 7 PLACES 8 WEB 11 

## VIEW B-B

WEB 10
10

5 3 2 1 7

9 6 REPAIR ANGLE 11 5 4 2

4 A

4 A4 A4 A4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A

4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A

4 A 4 A 4 A 4 A 4 A 

### 6

SEE DETAIL I FOR AIRPLANES WITH TEE FWD 

## VIEW A-A 45` X 0.55
45` X 0.26

14 PLACES B B A A

500B BS 520 BS 500B

BS

BS 520

FLOOR BEAM WEB802171

FIGURE 22. INTERCOSTAL CHANGES - GROUP 1,2,3 AIRPLANES (DOES NOT INCLUDE PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 123

### BOEING SERVICE BULLETIN 737-53-1120

B B


### 9 7 RADIUS 4 A4 A4 A4 A4 A



### FWD TEE



## DETAIL I AIRPLANES WITH TEE 520 BS802175The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. Repair of a Cracked Web (An alternative to the web replacement shown below) 1. Do the web repair as shown in the structural repair manual (Refer to the 737-100/200 Structural Repair Manual Subject 51-40-2). Replacement of a Cracked Intercostal Web or a Cracked Intercostal Top Chord 2. Remove and discard the intercostal web or the intercostal top chord if cracks are found in these parts 3. Get the Intercostal Web 65C34688-33 from Boeing or do the steps in Figure 69 to make this part. 4. Get the Intercostal Top Chord 65C34688-34 from Boeing or do the steps in Figure 71 to make this part. 5. Put the new intercostal top chord or the new intercostal web in the installed position. 6. Adjust the location of a new chord in the forward - aft direction to keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D for the hole on both ends. 7. If necessary, cut and remove material from the aft end of a new chord to make sure that there is sufficient clearance with the adjacent structure (the forward repair angle on the floor beam or the radius in the intercostal tee). Keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D. 8. Adjust the location of a new web to keep a minimum edge distance of 1.0D or a minimum edge margin of 1.5D. FIGURE 22. INTERCOSTAL CHANGES - GROUP 1,2,3 AIRPLANES (DOES NOT INCLUDE PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 124

### BOEING SERVICE BULLETIN 737-53-1120
9. If necessary, cut and remove material from the aft end of a new web to make sure that there is sufficient clearance with the adjacent structure (the forward repair angle on the floor beam or the radius in the intercostal tee). Keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D. 10. Cut and remove the material shown from the new chord. 11. Install the intercostal top chord and the intercostal web with the fasteners shown. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Alternative #1: Drill a No. 20 (0.159 - 0.171) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT5D( ). Alternative #2: Drill a No. 10 (0.191 -0.202) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT6D( ). B. Alternative #1: Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6. Alternative #2: Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30KK6-3 with a collar BACC30R6. C. This hole was drilled in the intercostal angle as shown in Figure 28 or 47. Figure 28 or 47 also specifies the fastener type.

FIGURE 22. INTERCOSTAL CHANGES - GROUP 1,2,3 AIRPLANES (DOES NOT INCLUDE PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 125

### BOEING SERVICE BULLETIN 737-53-1120

ANGLE TOP CHORD REPAIR ANGLE

4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 

### TEE 6 A

B

4 A4 A4 A4 A B 

### FWD

7 PLACES 9 7 PLACES 9 1 12 3 6 2 

## VIEW B-B WEB

WEB 

## VIEW C-C

12 5 6 4 2

7 8

10 500D 500 OR BS

4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A 4 A C

C C C C C C 

### 4 11
4 11 0.95 5 11 11 5

7 45` X 0.25 45` X 0.60

AIRPLANES WITH TEE SEE DETAIL I FOR FWD 16 PLACES



## VIEW A-A GROUP 7 AT ALL LOCATIONS AND GROUP 8 AT LEFT OR RIGHT BL 24.75 SHOWN ALL OTHER INTERCOSTALS SIMILAR A A

B B C C 45` X 0.15 45` X 0.22

WEB BS 520 BS 520

FLOOR BEAM WEB802185

FIGURE 23. INTERCOSTAL CHANGES - GROUP 7,8 AIRPLANES (INCLUDES PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 126

### BOEING SERVICE BULLETIN 737-53-1120

4 A4 A4 A4 A4 A 

### 10 8

B B



### FWD 

## DETAIL I TEE 520 BS

AIRPLANES WITH TEE RADIUS802414The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. Repair of a Cracked Web (An alternative to the web replacement shown below) 1. Do the web repair as shown in the structural repair manual ((Refer to the 737-100/200 Structural Repair Manual Subject 51-40-2 or refer to the 737-300/400/500 Structural Repair Manual Subject 51-70-13). Replacement of a Cracked Intercostal Web or a Cracked Intercostal Top Chord 2. Remove and discard the intercostal web or the intercostal top chord if cracks are found in these parts. 3. Get the Intercostal Web 65C34688-35 from Boeing or do the steps in Figure 70 to make this part. 4. On Group 7 Airplanes and on PA099, PA001-PA015, PA231-PA232, PA016-PA022, PC001-PC005 Airplanes at Left or Right Buttock Line 24.75 or 45.50 and on Group 8 Airplanes at Left or Right Buttock Line 24.75, get the Intercostal Top Chord 65C34688-37. Get it from Boeing or do the steps in Figure 72 to make this part. 5. On Group 8 Airplanes only at Left or Right Buttock Line 45.50, get the Intercostal Top Chord 65C34688-36. Get it from Boeing or do the steps in Figure 73 to make this part. 6. Put the new intercostal top chord or the new intercostal web in the installed position. 7. Adjust the location of a new chord in the forward - aft direction to keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D for the hole on both ends.

FIGURE 23. INTERCOSTAL CHANGES - GROUP 7,8 AIRPLANES (INCLUDES PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 127

### BOEING SERVICE BULLETIN 737-53-1120
8. If necessary, cut and remove material from the aft end of a new chord to make sure that there is sufficient clearance with the adjacent structure (the forward repair angle on the floor beam or the radius in the intercostal tee). Keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D. 9. Adjust the location of a new web to keep a minimum edge distance of 1.0D or a minimum edge margin of 1.5D. 10. If necessary, cut and remove material from the aft end of a new web to make sure that there is sufficient clearance with the adjacent structure (the forward repair angle on the floor beam or the radius in the intercostal tee). Keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D. 11. Cut and remove the material shown from the new chord. 12. Install the intercostal top chord and the intercostal web with the fasteners shown. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Alternative #1: Drill a No. 20 (0.159 - 0.171) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT5D( ). Alternative #2: Drill a No. 10 (0.191 -0.202) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT6D( ). B. Alternative #1: Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6. Alternative #2: Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30KK6-3 with a collar BACC30R6. C. This hole was drilled in the intercostal angle as shown in Figure 28 or 47. Figure 28 or 47 also specifies the fastener type.

FIGURE 23. INTERCOSTAL CHANGES - GROUP 7,8 AIRPLANES (INCLUDES PA099, PA001-PA015, PA231-PA232, PA016-PA022 AND PC001-PC005 Jul 6/89 737-53-1120 REV 1: May 13/93 128

### BOEING SERVICE BULLETIN 737-53-1120

FWD

A7

B B 

### CHANNEL CHANNEL TOP CHORD

7 PLACES 6 7 PLACES 6 8 C C A6

A6 A6 A6 A6 A5

A5 5 A 5 A 5 A 5 A 5 A 5 A 5 A 5 A 5 A 5 A 5 A A5 A5 A5 A5 A5 A5 A5 A5 A5 A5 A5 A5 A5

A5 A5 C C C C C 

### 3

4

1 3 2 3 8

4 5

7 14 PLACES



## VIEW A-A FWD REPAIR ANGLE

WEB A

A FLOOR BEAM WEB 500B

BS

BS 520

500B

BS BS 520801010

FIGURE 24. INTERCOSTAL - REPAIR, REPLACEMENT OR INSTALLATION, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 129

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. NOTE: Only do the last circle note step if no cracks are found in both the existing intercostal web and the existing intercostal top chord. 1. Do one of these steps if the existing intercostal web is cracked: - Do the web repair shown in the structural repair manual (Refer to the 737-100/200 Structural

Repair Manual Subject 51-40-2). - Get the Intercostal Web 69-51452-7 from Boeing or do the steps in Figure 74 to make this part.

Discard the cracked intercostal web after the new one is made. 2. Get the Intercostal Top Chord "A" if the existing intercostal top chord is cracked. Refer to the steps in Figure 75 to make this part. 3. Put the new intercostal top chord, the new intercostal web and the new intercostal channel in the installed position. 4. Adjust the location of a new chord in the forward - aft direction to keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D for the hole on both ends. 5. If necessary, cut and remove material from the aft end of a new chord to make sure that there is sufficient clearance with the radius in the adjacent intercostal channel. Keep a minimum edge distance of 1.0 X the Diameter (1.0 D) or a minimum edge margin of 1.5D. 6. Adjust the location of a new web to keep a minimum edge distance of 1.0D or a minimum edge margin of 1.5D. 7. If necessary, cut and remove material from the aft end of a new web to make sure that there is sufficient clearance with the radius in the adjacent intercostal channel. Keep a minimum edge distance of 1.0D or a minimum edge margin of 1.5D. 8. Install the intercostal top chord and the intercostal web with the fasteners shown. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Alternative #1: Drill a No. 20 (0.159 - 0.171) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT5D( ). Alternative #2: Drill a No. 10 (0.191 -0.202) inch diameter hole. Drill to match the holes in the existing structure. Install a rivet BACR15FT6D( ).

FIGURE 24. INTERCOSTAL - REPAIR, REPLACEMENT OR INSTALLATION, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 130

### BOEING SERVICE BULLETIN 737-53-1120

B. Alternative #1: Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6. Alternative #2: Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30KK6-3 with a collar BACC30R6. C. This hole was drilled in the intercostal channel as shown in Figure 41 or 48. Figure 41 or 48 also specifies the fastener type.

FIGURE 24. INTERCOSTAL - REPAIR, REPLACEMENT OR INSTALLATION, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 131

### BOEING SERVICE BULLETIN 737-53-1120

RADIUS FILLERS

B

A A B AND FASTENERS

AT RBL 45.50 BETWEEN BS 520 AND WING BOX ON GROUP 1, GROUP 2 AND GROUP 3 AIRPLANES ONLY 22 26 INSTALL ELECTRICAL BRACKET 30 9

LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR INBD FWD FLOOR BEAM

PIVOT LINK BUSHING PLAIN 19 29 13 3 31 PIN 27 14 7 PIN 32

BUSHING PLAIN 31 PIN

CHANNEL

WING BOX LINK INTERCOSTAL 6 BS 520

28 8 15 STRAP 12 4 5

2 1 NO SEAT TRACK AT BL 0A97117

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 132

### BOEING SERVICE BULLETIN 737-53-1120

LINK INTERCOSTAL

BUSHING FLANGED



## VIEW B-B 90` L C 2

FWD520 STA 20

11 11 10 10 10

0.18
C C

PIVOT BOLT

PIVOT JOINT

CHANNEL



## VIEW A-A SEAT TRACK ENDS

INTERCOSTAL LINK FASTENER HEAD CHANNEL RADIUS FILLER AND

PIVOT LINK FLOOR BEAM 0.19 0.06A92427

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 133

### BOEING SERVICE BULLETIN 737-53-1120

12

16 18

0.18 25 25 17 (2 PLACES)

21 23 25

FILLER CHANNEL RADIUS

CHANNEL23 INTERCOSTAL C L LINK

A A A A

B

B

B B

B

B

B B 

### 8 PLACES 12 PLACES



## VIEW C-C LOOKING FORWARD FLOOR BEAM WEB

D D

SEE DETAIL I IF THE CONDITION IN CIRCLE NOTE 17 OCCURS SEE DETAIL II IF THE CONDITION IN CIRCLE NOTE 18 OCCURSA97702

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 134

### BOEING SERVICE BULLETIN 737-53-1120

C C C C C C C C 

### INTERCOSTAL C L LINK

CHANNEL INTERCOSTAL C L LINK 23 25

24 25 23 25

23 25

LOOKING FORWARD 

## DETAIL II INSTALLATION WITH CHANNEL ASSEMBLY "A", "B" OR "C" CHANNEL RADIUS FILLER "A" INSTALLATION WITH

LOOKING FORWARD 

## DETAIL I "A", "B", OR "C" CHANNEL ASSEMBLY

PLATE "A" RADIUS FILLER "A" (2 PLACES) FILLER CHANNEL RADIUSA92419

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 135

### BOEING SERVICE BULLETIN 737-53-1120

18

CHANNEL CHANNEL

HEAD INSTALLATIONS INCORRECT FASTENER HEAD INSTALLATIONS INCORRECT FASTENER

CHANNEL CHANNEL

17

RADIUS

SIDE OF CHANNEL



## VIEW D-D VIEW D-D FWD

FWDA98222

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 136

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Radius Filler 66-13222-1, the Washer AN960-D516, the Bolt BACB30FL5-6 and the Nut NAS679-A5 that were kept. Install these parts below the forward and aft floor beam flange. 2. Locate the Channel 69-77845-3 of the Channel-Pivot Link Assembly 65C34688-5 or -6 on the floor beam: - Locate the channel for the 65C34688-5 Channel-Pivot Link Assembly at Left Buttock Line 24.75,

45.50 or at Right Buttock Line 24.75, 45.50 - Locate the channel for the 65C34688-6 Assembly at Buttock Line 0.00. NOTE: The Pivot Link Assembly is made of the Pivot Link 65C34622-3 and the channel. 3. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-170, the Pivot Bolt BACB30NR5DK28, the Washer AN960C516 and the Nut BACN10JD5CD. 4. Get the intercostal link that was kept. Remove and discard the flanged bushings (two places) from the forward end. 5. Ream the holes in the forward end of the intercostal link to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. Install a Flanged Bushing BACB28AT07B010C (two places) with sealant (BMS 5-95). Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. NOTE: Make sure that there is no sealant on the reamed surface of the flanged bushing. 6. Rubber stamp the new part number 65C34688-30 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 8. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 9. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-128, the Pivot Bolt BACB30NR5DK21, the Washer AN960C516 and the Nut BACN10JD5CD. 10. At Left or Right Buttock Line 24.75 or 45.50, make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends. Make sure that the clearances at the following locations are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads, when they are installed,

on the channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient.

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 137

### BOEING SERVICE BULLETIN 737-53-1120
11. At Buttock Line 0.00, make sure that there is a minimum horizontal clearance of 0.20 inch between the following: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads when they are installed

on the channel radius filler. Make a mark at the location where material will be removed if the clearance is not sufficient. 12. Adjust the location of the channel on the floor beam in the inboard or the outboard directions until it is centered with the intercostal link. This prevents an inboard-outboard force (preload) on the pivot link and the intercostal link. Clamp the channel to the floor beam. 13. Remove and keep the pivot link and the fasteners at both pivot joints. 14. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 15. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 16. Backdrill the holes in the channel through the holes in the floor beam. 17. Check the location of the fastener holes in the center of the channel. An incorrect installation occurs if any of the eight hex drive bolt heads shown make contact with the radius of the channel. Make a Channel Radius Filler "A" if this condition occurs at any of the following location on the floor beam: - At Left Buttock Line 24.75, or 45.50, or Right Buttock Line 24.75 - Group 1,2,3,7,8 Airplanes - At Right Buttock Line 45.50 - Group 3,7,8 Airplanes. This condition is caused when the intercostal link and the holes in the floor beam are not aligned in the inboard or in the outboard direction. Refer to the instructions in Figure 64 to make a Radius Filler "A". NOTE: An electrical bracket is installed on the outboard side of the channel on Group 1, 2 and 3 Airplanes at Right Buttock Line 45.50. Sufficient clearance is necessary between the forward end of the electrical bracket and the inside surface of the channel. This clearance is necessary because of the relative movement between the floor beam and the wing box structure. Do not use the Channel Radius Filler "A" on Group 1 and 2 Airplanes at Right Buttock Line 45.50. Make another channel as shown in a subsequent Circle Note step.

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 138

### BOEING SERVICE BULLETIN 737-53-1120
18. Do the steps In Figure 76 to make a Channel Assembly "A", "B", or "C" if any of the hex drive bolt heads shown make contact with a side of the channel. This condition is caused when the intercostal link and the holes in the floor beam are not aligned in the inboard or in the outboard direction. Figure 76 gives steps to locate Plate "A" on Channel "A" on the same side (inboard or outboard) where the fastener heads make contact with the channel. Do the steps in Figure 65 to make the Channel Radius Filler "B". Use the table below to choose the channel assembly:

Buttock Line (BL) Location Airplane Group Side of Channel Assembly With Plate "A" Channel Assembly Channel Radius Fillers Left or Right BL 24.75, 1,2,3,7,8 Inboard or Outboard "A" "B"
Left BL 45.50 1,2,3,7,8 Inboard or Outboard "A" "B"
Right BL 45.50 7,8 Inboard or Outboard "A" "B" 1,2,3 Outboard "B" "B" BL 0.00 1,2,3,7,8 Inboard or Outboard "C" "B" 19. If Channel Assemblies "A", "B", or "C" were made, temporarily connect the pivot link to the channel. Use the Bolt BACB30NR5DK32 and the Bushing BACB28AK05-190. Do the steps given in Circle Notes 7 through 16 again. 20. If necessary, cut and remove material from the seat track end, or the channel, or the intercostal link where the marks were made. For the channel, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. For the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 21. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts. 22. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket on the channel : - On Group 1 and 2 Airplanes with Channel 69-77845-3, refer to Figure 53 - On Group 1 and 2 Airplanes with Channel Assembly "B", refer to Figure 54 - On Group 3 Airplanes with Channel 69-77845-3, refer to Figure 55 - On Group 3 Airplanes with Channel Assembly "B", refer to Figure 56 23. On Channel 69-77845-3, make sure that the pivot link is not connected to the channel. Get the two Channel Radius Fillers 65-46803-9 that were kept. Install the channel and the channel radius fillers on the floor beam web. Also install the Channel Radius Filler "A" if necessary. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95).

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 139

### BOEING SERVICE BULLETIN 737-53-1120
24. On Channel Assembly "A", "B", or "C", make sure that the pivot link is not connected to the channel. Install the channel and two Channel Radius Fillers "B" on the floor beam web. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 25. Apply a layer of water-displacing corrosion-inhibiting compound to the channel, the channel radius fillers, and to the areas of the floor beam where it was removed. (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 26. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 1 and 2 Airplanes with Channel 69-77845-3, refer to Figure 59 - On Group 1 and 2 Airplanes with Channel Assembly "B", refer to Figure 60 - On Group 3 Airplanes, refer to Figure 61. 27. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 28. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 29. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 30. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 31. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 32. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30NX6K8X with a collar BACC30X6. Install with the head on the surface of the channel radius filler. B. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K5Y with a collar BACC30R6. Install with the head on the channel surface. C. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30KK6-8 with a collar BACC30R6. Install with the head on the surface of the channel radius filler.

FIGURE 25. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 140

### BOEING SERVICE BULLETIN 737-53-1120

2 10 RADIUS FILLERS AND FASTENERS

A

A 24 11

CHANNEL FLOOR BEAM 1

LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR FWD INBD STRAP 13 6 22 520 BS

4 INTERCOSTAL LINK

WING BOX 7 PIN

25

PLAIN BUSHING 26 PIN 5 12 21 PIN 25 3 11 23

PLAIN BUSHING PIVOT LINK

INSTALL ELECTRICAL BRACKET 20 17 AT RBL 45.50 BETWEEN BS 520 AND AND GROUP 3 AIRPLANES ONLY WING BOX ON GROUP 1, GROUP 2 NO SEAT TRACK AT BL 0A98288

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 141

### BOEING SERVICE BULLETIN 737-53-1120

9 8 15 520 STA

FWD 9 8 8 B

B PIVOT BOLT SEAT TRACK ENDS

CHANNEL INTERCOSTAL LINK FASTENER HEAD CHANNEL RADIUS FILLER AND

PIVOT LINK PIVOT JOINT FLOOR BEAM



## VIEW A-A 0.19 0.06A98290

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 142

### BOEING SERVICE BULLETIN 737-53-1120

10 14 10

CHANNEL

10 19 19 18

0.18 16 INTERCOSTAL C L LINK

A A A A

B

B

B B

B

B

B B 

### CHANNEL RADIUS FILLER (2 PLACES) 18 19

12 PLACES

FLOOR BEAM WEB

RADIUS



## VIEW B-B LOOKING FORWARDA98305

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 143

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Radius Filler 66-13222-1, the Washer AN960-D516, the Bolt BACB30FL5-6 and the Nut NAS679-A5 that were kept. Install these parts below the forward and the aft floor beam flange. 2. Make a Channel Assembly "D" or "E" as shown in Figure 77. - Locate Channel Assembly "D" at Left Buttock Line 24.75, 45.50 or at Right Buttock Line 24.75,

45.50 - Locate Channel Assembly "E" at Buttock Line 0.00 3. If it has not been done, temporarily connect the pivot link to the channel. The pivot link that was kept can be used. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-170, the Pivot Bolt BACB30NR5DK28, the Washer AN960C516 and the Nut BACN10JD5CD. The fasteners that were kept can be used. 4. Get the intercostal link that was kept. Rubber stamp the new part number 65C34688-30 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 5. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 6. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 7. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-128, the Pivot Bolt BACB30NR5DK21, the Washer AN960C516 and the Nut BACN10JD5CD. The fasteners that were kept can be used. 8. At Left or Right Buttock Line 24.75 or 45.50, make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends. Make sure that the clearances at the following locations are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads that are installed on the

channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient. 9. At Buttock Line 0.00, make sure that there is a minimum horizontal clearance of 0.20 inch between the following: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads when they are installed

on the channel radius filler. Make a mark at the location where material will be removed if the clearance is not sufficient.

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 144

### BOEING SERVICE BULLETIN 737-53-1120
10. Adjust the location of the channel on the floor beam to get these conditions : - The centerline of the channel is as near as possible to the centerline of the intercostal link in the

inboard-outboard direction. This helps to prevent an inboard-outboard force (preload) on the pivot link or the intercostal link. - The hex-drive bolt heads do not make contact with the radius of the channel. Clamp the channel to the floor beam. 11. Remove and keep the pivot link and the fasteners at both pivot joints. 12. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 13. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 14. Backdrill the holes in the channel through the holes in the floor beam. 15. If necessary, cut and remove material from the seat track end, the channel, or the intercostal link where the marks were made. On the channel, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. On the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 16. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts. 17. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket on the channel : - On Group 1 and 2 Airplanes, refer to Figure 53 - On Group 3 Airplanes, refer to Figure 55. 18. Make sure that the pivot link is not connected to the channel. Get the two Channel Radius Fillers 65-46803-9 that were kept. Install the channel and the radius fillers on the floor beam web. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 19. Apply a layer of water-displacing corrosion-inhibiting compound to the channel and to the areas of the floor beam where it was removed (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01. Obey all warnings and cautions given). Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 20. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 1 and 2 Airplanes, refer to Figure 59 - On Group 3 Airplanes, refer to Figure 61. 21. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 22. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places).

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 145

### BOEING SERVICE BULLETIN 737-53-1120
23. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 24. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 25. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 26. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a 0.216 - 0.219 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30MD6-8 with a collar BACC30AC6. Install with the head on the surface of the channel radius filler. B. Drill a 0.231 - 0.234 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30MA6-5 with a collar BACC30Y6. Install with the head on the channel surface.

FIGURE 26. CHANNEL - REPLACEMENT OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, OR 0.00, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 146

### BOEING SERVICE BULLETIN 737-53-1120

A

A RADIUS FILLERS AND FASTENERS

AT RBL 45.50 BETWEEN BS 520 AND WING BOX INSTALL ELECTRICAL BRACKET 19 22 PIVOT LINK 28 2 12 CHANNEL 3 13 25 13 26

BUSHING PLAIN 24 8 15 PIN STRAP

WING BOX 9

BUSHING PLAIN 23 14 7 520 BS 1

5 4 FLOOR BEAM

FWD INBD LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR 27 PIN
27 PIN

6 LINK INTERCOSTALB13182

FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 147

### BOEING SERVICE BULLETIN 737-53-1120

LINK INTERCOSTAL



## VIEW B-B L C

90` BUSHING FLANGED 10

11

FWD 520 STA

5 4 0.25 MINIMUM 17

2B B

D D

C C 0.20 0.17

0.24



## VIEW A-A PIVOT JOINT PIVOT LINK PIVOT BOLTINTERCOSTAL LINK FLOOR BEAM

FASTENER HEAD CHANNEL RADIUS FILLER AND SEAT TRACK ENDS

CHANNELB13369

FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 148

### BOEING SERVICE BULLETIN 737-53-1120

12

12 12 16

C C

B B

B B B B

A A A A



### 18

0.24



## VIEW D-D LOOKING FORWARD 21 25 3 13 

## SECTION C-C 27

WASHER

20 21

20 21 12 PLACES

FLOOR BEAM WEB LINK INTERCOSTAL C L CHANNEL RADIUS FILLER (2 PLACES)

CHANNEL RADIUSB13387

FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 149

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Radius Filler 66-13222-1, the Washer AN960-D516, the Bolt BACB30FL5-6 and the Nut NAS679-A5 that were kept. Install these parts below the forward and the aft floor beam flange. 2. Locate the Channel 69-77976-1 of the Channel-Pivot Link Assembly 65C34978-4 on the floor beam. 3. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-231, the Pivot Bolt BACB30NF5D37 or BACB30NR5DK37, the Washer AN960C516 (install between the channel and the nut), the Washers AN960C716L (install between the channel and the pivot link) and the Nut BACN10JD5CD. 4. Get the intercostal link that was kept. Remove and discard the flanged bushings (two places) from the forward end. 5. Ream the holes in the forward end of the intercostal link to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. Install a Flanged Bushing BACB28AT07B018C (two places) with sealant (BMS 5-95). Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. See View B-B. NOTE: Make sure that there is no sealant on the reamed surface of the flanged bushing. 6. Rubber stamp the new part number 65C34978-29 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 8. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 9. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-147 the Pivot Bolt BACB30NR5DK25, the Washer AN960C516 and the Nut BACN10JD5CD. 10. Make sure that there is a horizontal clearance of 0.17 to 0.20 inch between the seat track ends. Make a mark at the location where the material will be removed if the clearance is not sufficient. 11. Make sure that there is a minimum horizontal clearance of 0.25 inch between the forward edge of the intercostal link and the fastener heads, when they are installed, on the channel radius filler. Make a mark at the location where the material will be removed if the clearance is not sufficient. NOTE: This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction.

FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 150

### BOEING SERVICE BULLETIN 737-53-1120
12. Locate the channel on the floor beam to get these conditions : - The centerline of the channel is as near as possible to the centerline of the intercostal link in the

inboard-outboard direction. This helps to prevent an inboard-outboard force (preload) on the pivot link and the intercostal link. - The hex-drive bolt heads do not make contact with the radius of the channel. Clamp the channel to the floor beam. 13. Remove and keep the pivot link and the fasteners at both pivot joints. 14. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 15. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 16. Backdrill the holes in the channel through the holes in the floor beam. 17. If necessary, cut and remove material from the seat track end or the intercostal link where the marks were made. For the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.09 inch. 18. At Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts. 19. At Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket on the channel : - On Group 4 and 5 Airplanes, refer to Figure 57 - On Group 6 Airplanes, refer to Figure 58. 20. Make sure that the pivot link is not connected to the channel. Get the two Channel Radius Fillers 65C34978-47. Install the channel and the channel radius fillers on the floor beam web. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 21. Apply a layer of water-displacing corrosion-inhibiting compound to the channel, the channel radius fillers, and to the areas of the floor beam where it was removed. (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 22. At Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 4 and 5 Airplanes, refer to Figure 62 - On Group 6 Airplanes, refer to Figure 63. 23. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 24. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 25. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 26. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 151

### BOEING SERVICE BULLETIN 737-53-1120
27. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 28. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Increase the existing hole diameter to 0.263 - 0.266 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30NX8K8X with a collar BACC30X8. Install with the head on the surface of the channel radius filler. B. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.510 - 0.531 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MY6K6Y with a collar BACC30R6. C. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.600 - 0.625 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface.Install a hex drive bolt BACB30MY8K6Y with a collar BACC30R8.

FIGURE 27. CHANNEL - INSTALLATION OF A CHANNEL WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 152

### BOEING SERVICE BULLETIN 737-53-1120

24 41 23

16
47 40 8 9 7 17 50 3

13 49 19 12 48 18 14 51 17

5 6

5 6 REMOVE

FORWARD REPAIR ANGLE

AFT REPAIR ANGLE E E

A A B

B

FWD INBD
ALL OTHER BL LOCATIONS SIMILAR LBL 24.75 LOCATION SHOWN PLAIN BUSHING

CHANNEL INSTALL AN ELECTRICAL BRACKET AT RBL 45.50 BETWEEN BS 520 AND AND GROUP 3 AIRPLANES ONLY WING BOX ON GROUP 1, GROUP 2 PIVOT LINK INTERCOSTAL LINK STRAP

WING BOX PLAIN BUSHING PIN 52 PIN 52 520 BS FLOOR BEAM SEAT TRACK

PIN 53801659

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 153

### BOEING SERVICE BULLETIN 737-53-1120

J I

K J J J J 

### 33 32 35 44 34

4 2 1 2 28 46

4634 46 31

15

46 31 30 29

29 6 36
520 STA 15

15

FWD 10 11 6

38 TOP INTERCOSTAL CHORD

INSTALL INTERCOSTAL ANGLE REMOVE INTERCOSTAL TEE AND

INTERCOSTAL WEB6 PLACES

0.18 INTERCOSTAL ANGLE

REPAIR ANGLES

7 PLACES FLANGE RADIUS FILLER

REPAIR ANGLE

C C

0.40 0.70 CHANNEL RADIUS FILLER AND FASTENER HEAD

INTERCOSTAL LINK FLOOR BEAM

CHANNEL PIVOT LINK 0.19 0.06



## VIEW A-A PIVOT JOINT INTERCOSTAL LINK SEAT TRACK ENDS

PIVOT BOLT801735

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 154

### BOEING SERVICE BULLETIN 737-53-1120



## VIEW B-B BUSHING FLANGED

90` C L LINK INTERCOSTAL

9 A 10 A 9 A 10 A

6 B 8 B

6 B 8 B

6 B 8 B 6 B 8 B 

### 16

CHANNEL

46 45 46 42

45 CHANNEL RADIUS FILLER 46 46
21 FLANGE RADIUS FILLER

20 22 42 46 25

42 46

39

L L L D 

### 37 46 LINK L INTERCOSTAL CHANNEL RADIUS FILLER 1 42 C 9 8

D
D D D
D D
D 

### 22 20
42 24 41 46 12 PLACES

D D

BRACKET SHIM FLOOR BEAM WEB 8 PLACES FORWARD REPAIR ANGLE

AFT REPAIR ANGLE

LOOKING FORWARD 

## VIEW C-C SEE DETAIL I IF THE CONDITION SHOWN IN CIRCLE NOTE 21 OCCURS SEE DETAIL II IF THE CONDITION SHOWN IN CIRCLE NOTE 22 OCCURS 0.18801756

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 155

### BOEING SERVICE BULLETIN 737-53-1120

9 C

9 C

9 C9 C 10 C

10 C

10 C

10 C 

### LINK L C INTERCOSTAL

CHANNEL INTERCOSTAL C L LINK

46 42

FILLER RADIUS CHANNEL 43 46

43 46 43 46FILLER RADIUS CHANNEL



## DETAIL I LOOKING FORWARD INSTALLATION WITH CHANNEL RADIUS FILLER "A" CHANNEL ASSEMBLY "A", "B" OR "C" INSTALLATION WITH 

## DETAIL II LOOKING FORWARD PLATE "A" RADIUS FILLER "A"

CHANNEL ASSEMBLY "A", "B" OR "C"801760

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 156

### BOEING SERVICE BULLETIN 737-53-1120



## VIEW D-D RADIUS 21 CHANNEL



## VIEW D-D SIDE OF CHANNEL CHANNEL

22 INCORRECT FASTENER HEAD INSTALLATIONS INCORRECT FASTENER HEAD INSTALLATIONS

26 27 27

46 42 H M H M H H

H H H G

G H G G F

E



### 26 46 42

26 26 FWD FWD

FWD L SEAT TRACK

AFT REPAIR ANGLE SEAT TRACK 4 PLACES AT THE FORWARD ANGLE REPAIR



## VIEW E-E CB29128

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 157

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Apply a layer of enamel (BMS 10-11 Type II) to the Channel Radius Filler 66-13222-10 (View C-C) and to the Flange Radius Filler 66-13222-9 (View A-A). 2. Discard the radius filler, the bolt, the nut, and the washer that was removed from below the forward and the aft floor beam flange. 3. Remove and discard the these four fasteners that attach the seat track to the floor beam flange. 4. Remove and discard the intercostal "Tee" stiffener from the intercostal web. 5. Get the Channel 69-77845-3 of the Channel-Pivot Link Assembly 65C34688-5 and the Aft Repair Angle 69-77942-1. 6. Locate the channel and the aft repair angle on the floor beam. Cut and remove material from the top of the channel. This is done to give sufficient clearance between the top of the channel and the flange radius filler. The maximum distance that the cut edge can be made from the original edge is 0.25 inch. 7. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-170, the Pivot Bolt BACB30NR5DK28, the Washer AN960C516 and the Nut BACN10JD5CD. 8. Get the intercostal link that was kept. Remove and discard the flanged bushings (two places) from the forward end. 9. Ream the holes in the forward end of the intercostal link to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. Install a Flanged Bushing BACB28AT07B010C (two places) with sealant (BMS 5-95). Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. NOTE: Make sure that there is no sealant on the reamed surface of the flanged bushing. 10. Cut and remove material from the forward end of the intercostal link. 11. Rubber stamp the new part number 65C34688-29 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 12. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 13. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 14. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-128, the Pivot Bolt BACB30NR5DK21, the Washer AN960C516 and the Nut BACN10JD5CD.

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 158

### BOEING SERVICE BULLETIN 737-53-1120

15. Make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends. Make sure that the clearances at the following locations are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads when they are installed

on the channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient. 16. Adjust the location of the channel on the floor beam in the inboard or the outboard directions until it is centered with the intercostal link. This prevents an inboard-outboard force (preload) on the pivot link and the intercostal link. Clamp the channel to the floor beam. 17. Remove and keep the pivot link and the fasteners at both pivot joints. 18. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 19. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 20. Backdrill the holes in the channel and the aft repair angle through the holes in the floor beam. See View C-C. 21. Check the location of the fastener holes in the center of the channel. An incorrect installation occurs if any of the eight hex drive bolt heads shown make contact with the radius of the channel. Make a Channel Radius Filler "A" if this condition occurs at any of the following location on the floor beam: - At Left Buttock Line 24.75, or 45.50, or Right Buttock Line 24.75 - Group 1,2,3,7,8 Airplanes - At Right Buttock Line 45.50 - Group 3,7,8 Airplanes. This condition is caused when the intercostal link and the holes in the floor beam are not aligned in the inboard or in the outboard direction. Refer to the instructions in Figure 64 to make a Radius Filler "A". NOTE: An electrical bracket is installed on the outboard side of the channel on Group 1, 2 and 3 Airplanes at Right Buttock Line 45.50. Sufficient clearance is necessary between the forward end of the electrical bracket and the inside surface of the channel. This clearance is necessary because of the relative movement between the floor beam and the wing box structure. Do not use the Channel Radius Filler "A" on Group 1 and 2 Airplanes at Right Buttock Line 45.50. Make another channel as shown in a subsequent Circle Note step.

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 159

### BOEING SERVICE BULLETIN 737-53-1120
22. Do the steps In Figure 76 to make a Channel Assembly "A" or "B" if any of the hex drive bolt heads shown make contact with a side of the channel. This condition can occur if the intercostal link and the holes in the floor beam are not aligned in the inboard or in the outboard direction. Figure 76 gives steps to locate Plate "A" on Channel "A" on the same side (inboard or outboard) where the fastener heads make contact with the channel. Do the steps in Figure 65 and Figure 66 to make the Channel Radius Filler "B" and "C". Use the table below to choose the channel assembly : Buttock Line (BL) Location Airplane Group Side of Channel Assembly With Plate "A" Channel Assembly Channel Radius Fillers Left or Right BL 24.75 1,2,3,7,8 Inboard or Outboard "A" "B" and "C" Left BL 45.50 1,2,3,7,8 Inboard or Outboard "A" "B" and "C" Right BL 45.50 7,8 Inboard or Outboard "A" "B" and "C" 1,2,3 Outboard "B" "B" and "C" 23. If Channel Assemblies "A" or "B" were made, temporarily connect the pivot link to the channel. Use the Bolt BACB30NR5DK32 and the Bushing BACB28AK05-190. Do the steps in Circle Notes 12 through 20 again. 24. Refer to the correct figure in the table below. Use the figure to locate the fastener holes for the forward repair angle 69-77942-2 : NOTE: The referenced figures are shown looking aft. Airplane Group Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 1, 2, 3 29 30 31 32 7 33 34 35 36 8 37 38 39 40 25. Locate and drill the holes for the fasteners that attach the aft repair angle to the floor beam and the forward repair angle. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 26. Backdrill the holes shown in both the forward and aft repair angles through the holes in the seat track and the floor beam flange. 27. Locate and drill the holes for the fasteners that attach the repair angles to the floor beam flange. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 160

### BOEING SERVICE BULLETIN 737-53-1120
28. Install the Flange Radius Fillers 66-13222-9 below top end of the forward and the aft repair angles. These locations are below the forward and aft floor beam flanges. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 29. Locate the Intercostal Angle 65C34688-28 on the forward repair angle. If necessary, cut and remove material from top end. This is done to give sufficient clearance between the intercostal angle and the collar for the 1/4 inch hex drive bolt in the seat track. Keep a minimum edge margin of 0.33 inch on the hole that will be backdrilled near the top edge. 30. Backdrill the holes in the intercostal angle through the holes in the floor beam web. 31. In the next four Circle Note Steps, refer to one of the figures below if cracks are found in the intercostal web or in the intercostal top chord. These figures give the steps to repair or replace the intercostal web. These figures also gives the steps to replace the top intercostal chord. - On Group 1, 2, 3 Airplanes (does not include PA099, PA001-PA015, PA231-PA232,

PA016-PA022 and PC001-PC005), do the steps in Figure 22. - On Group 7, 8 Airplanes (also includes PA099, PA001-PA015, PA231-PA232, PA016-PA022,

PC001-PC005), do the steps in Figure 23. 32. If no cracks are found in both the intercostal web and the top intercostal chord, backdrill these holes in the intercostal angle. Backdrill through the holes in the intercostal top chord and the intercostal web. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on these existing holes. Also do this step if a cracked intercostal web was repaired and no cracks were found in the top intercostal chord. Install the fasteners shown. 33. Backdrill the holes in the intercostal angle if cracks are found in the intercostal top chord only. Backdrill through the holes in the intercostal web. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on the existing holes at the end of the intercostal web. Refer to the correct figure to replace the intercostal top chord. 34. Backdrill one hole in the intercostal angle if cracks are found in the intercostal web only. Backdrill through the hole at the aft end of intercostal top chord. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on the existing hole at the end of the top chord. Drill new holes in the intercostal angle 0.33 - 0.39 inch from the forward edge of the intercostal angle. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. Refer to the correct figure to replace the intercostal web. 35. If cracks are found in both the intercostal web and in the top chord, drill new holes in the intercostal angle 0.33 - 0.39 inch from the forward edge of the intercostal angle. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. Refer to the correct figure to replace the intercostal web and the intercostal top chord. 36. Make sure that there is sufficient clearance between the channel and the collar for the 5/16 inch hex drive bolt that is installed in the center of the seat track below the flange filler. 37. If the clearance is not sufficient, use the Channel Radius Filler 66-13222-10 as a template to cut and remove material from the top end of the channel. See View C-C. 38. If necessary, cut and remove material from the seat track ends, or the channel, or the intercostal link where the marks were made. On the channel, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. On the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 39. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts.
FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 161

### BOEING SERVICE BULLETIN 737-53-1120
40. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket on the channel : - On Group 1 and 2 Airplanes with Channel 69-77845-3, refer to Figure 53 - On Group 1 and 2 Airplanes with Channel Assembly "B", refer to Figure 54 - On Group 3 Airplanes with Channel 69-77845-3, refer to Figure 55 - On Group 3 Airplanes with Channel Assembly "B", refer to Figure 56. 41. Refer to the correct figure in the table below. Use the figure to install some of the fasteners that attach the forward repair angle 69-77942-2 to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95) : NOTE: The referenced figures are shown looking aft. Airplane Group Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 1, 2, 3 29 30 31 32 7 33 34 35 36 8 37 38 39 40 42. On Channel 69-77845-3, make sure that the pivot link is not connected to the channel. Install all of the fasteners that attach the intercostal angle, the repair angles, the channel and the channel radius fillers to the floor beam. Install one of the Channel Radius Fillers 65-46803-9 that were kept. Install it on the bottom end of the channel. Install the Channel Radius Filler 66-13222-10 on the top end of the channel. Also install the Channel Radius Filler "A" if necessary. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 43. On Channel Assembly "A" or "B", make sure that the pivot link is not connected to the channel. Install all of the fasteners that attach the repair angles, the channel and the channel radius fillers to the floor beam. Install the Channel Radius Filler "B" on the bottom end of the channel. Install the Channel Radius Filler "C" on the top end of the channel. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 44. Install the fasteners that attach the intercostal angle to the intercostal web and Intercostal top chord. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 45. On Group 7,8 Airplanes, at Left Buttock Line 24.75, get the Bracket 65-49717, if it was removed. Apply a layer of primer (BMS 10-11 Type I) to the Shim BACS40R007D030F and install the shim on the floor beam web with the bracket. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95).

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 162

### BOEING SERVICE BULLETIN 737-53-1120
46. Apply a layer of water-displacing corrosion-inhibiting compound to the intercostal web, the intercostal top chord, the intercostal angle, the channel, the repair angles, the channel radius fillers and flange radius fillers, the bracket and to the areas of the floor beam where it was removed. (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 47. On Group 1,2,3 Airplanes at Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 1 and 2 Airplanes with Channel 69-77845-3, refer to Figure 59 - On Group 1 and 2 Airplanes with Channel Assembly "B", refer to Figure 60 - On Group 3 Airplanes, refer to Figure 61. 48. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 49. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 50. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 51. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 52. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 53. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30NX6K( )X with a collar BACC30X6. Install with the head on the surface of the channel radius filler. B. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K( )X with a collar BACC30M6. Install with the head on the channel surface. C. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30FP6-( ) with a collar BACC30M6. Install with the head on the surface of the channel radius filler. D. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VT6K5 with a collar BACC30BL6. E. Install a hex drive bolt BACB30NY10K11 with a collar BACC30X10. Install with the head on the seat track surface. F. Install a hex drive bolt BACB30NY8K11 with a collar BACC30X8. Install with the head on the seat track surface. G. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the seat track. Install a hex drive bolt BACB30NY6K8X with a collar BACC30X6. Install with the head in the seat track. FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 163

### BOEING SERVICE BULLETIN 737-53-1120
H. Drill a 0.187 - 0.190 inch diameter hole with a 100 degree countersink in the floor beam. Install a hex drive bolt BACB30NY6K4 with a collar BACC30BH6. Install with the head in the floor beam. I. See the table below. J. See the table below. Fasteners for the Intercostal Angle Changes Fastener Symbol "I" Fastener Symbol "J" Name Fastener Hole Size (inch) Name Fastener Hole Size (inch) The Intercostal Web is Repaired Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FP6-3 and BACC30M6 0.216 -0.219

0.200 -0.203 Rivet

or Hex Drive Bolt BACR15FT5D4

or BACB30VT6K2 and BACC30BL6 0.159 -0.171

0.187 -0.190 The Intercostal Web is Replaced The Intercostal

Top Chord is

Replaced

Both the Intercostal Web and the Intercostal Top Chord are Replaced Hex Drive Bolt BACB30FM6-3 and BACC30M6 or BACB30MY6K3Y and BACC30R6 0.187 -0.190

0.216 -0.219 Rivet

or Hex Drive Bolt BACR15FT5D4

or BACB30VT6K2 and BACC30BL6 0.159 -0.171

0.187 -0.190

K. Alternative #1: Increase the existing hole diameter to 0.216 - 0.219 inch. Install a hex drive bolt BACB30MY6K3Y with a collar BACC30R6. Alternative #2: Increase the existing hole diameter to 0.200 - 0.203 inch. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6. L. Drill a 0.187 - 0.190 inch diameter hole in the shim to match the holes in the floor bream. Install a hex drive bolt BACB30NX6K4 with a collar BACC30X6.

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 164

### BOEING SERVICE BULLETIN 737-53-1120
M. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. Install the Nut BACN10YD6 at this location. NOTE: This nut will be used with the Screw BACS12GM3-15 to attach the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions.

FIGURE 28. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75, 45.50, GROUP 1,2,3,7,8 Jul 6/89 737-53-1120 REV 1: May 13/93 165

### BOEING SERVICE BULLETIN 737-53-1120

B B

B B B B C C B

B B A

A A A A A A

A A A A A 

### 2

4 1 3 2 AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB SEAT TRACK INTERCOSTAL LINK801059The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley brackets to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 29. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 166

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K4 with a collar BACC30BL6 is installed.

FIGURE 29. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 167

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A B B BB B B B B C 

### 3

4 1 5 2 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES FORWARD REPAIR ANGLE AFT REPAIR ANGLE801104The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Cut and remove material from the forward repair angle at the location shown to give sufficient clearance with the existing fastener on the web. 3. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam. Backdrill a hole in the forward repair angle through this hole. 4. Backdrill the holes in the forward repair angle through the holes in the floor beam. 5. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 30. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 168

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K4 with a collar BACC30BL6 is installed.

FIGURE 30. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 169

### BOEING SERVICE BULLETIN 737-53-1120

B

B BB B B B

B C

A

A

A

A

A A

A

A

A

A

A A 

### 2 3

4 1 5 AFT REPAIR ANGLE INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES FORWARD REPAIR ANGLE801106The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Cut and remove material from the forward repair angle at the location shown to give sufficient clearance with the existing fasteners on the web. 3. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 4. Backdrill the holes in the forward repair angle through the holes in the floor beam. 5. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 31. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 170

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K4 with a collar BACC30BL6 is installed.

FIGURE 31. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 171

### BOEING SERVICE BULLETIN 737-53-1120

B

B B B BB B B B C A

A A A A A A

A A A A A 

### 2

4 1 3 FORWARD REPAIR ANGLE AFT REPAIR ANGLE

12 PLACES FLOOR BEAM WEB SEAT TRACK INTERCOSTAL LINK801110The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 32. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 172

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K4 with a collar BACC30BL6 is installed.

FIGURE 32. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 1,2,3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 173

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A C B

B B
B C
B B B B



### 3

1 4 2

2 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES FORWARD REPAIR ANGLE AFT REPAIR ANGLE801111The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley brackets to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 33. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 174

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.200 - 0.203 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30NX6K5X with a collar BACC30X6 is installed.

FIGURE 33. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 175

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A B C B BB B B

B B B B B


### 4

6 1 5 2 3 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES BRACKET801225The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Make sure that there is sufficient clearance between the bracket on the floor beam web and the forward repair angle. 3. Remove and keep the bracket if the clearance is not sufficient. Discard the fasteners. The operator will get sufficient clearance when a shim is installed in the repair installation figure. 4. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 5. Backdrill the holes in the forward repair angle through the holes in the floor beam. 6. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 34. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 176

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.200 - 0.203 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30NX6K5X with a collar BACC30X6 is installed.

FIGURE 34. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 177

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A B

B BB B B B C B B

B B



### 3 1 4 2 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES FORWARD REPAIR ANGLE AFT REPAIR ANGLE801596The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 35. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75 GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 178

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.200 - 0.203 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30NX6K5X with a collar BACC30X6 is installed.

FIGURE 35. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75 GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 179

### BOEING SERVICE BULLETIN 737-53-1120

B

B B B BB B B B A

A A A A A A

A A A A A C



### 4 1 3 2

FORWARD REPAIR ANGLE AFT REPAIR ANGLE

12 PLACES FLOOR BEAM WEB SEAT TRACK INTERCOSTAL LINK801227The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 36. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 180

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.200 - 0.203 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30NX6K5X with a collar BACC30X6 is installed.

FIGURE 36. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 7 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 181

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A B C C B

B B B B B B



### 2

3 1 4 2 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES FORWARD REPAIR ANGLE AFT REPAIR ANGLE801364The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley brackets to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 37. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 182

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K5 with a collar BACC30BL6 is installed.

FIGURE 37. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 183

### BOEING SERVICE BULLETIN 737-53-1120

B B

B B B

A

A

A

A

A A

A

A

A

A

A A B B B B B



### 2

6 1 5 3 4 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES BRACKET PULLEY BRACKET801642The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Cut and remove material from the forward repair angle at the location shown to give sufficient clearance with the existing fasteners on the web. 3. Make sure that there is sufficient clearance between the bracket on the floor beam web and the forward repair angle. 4. Remove and keep the bracket if the clearance is not sufficient. Discard the fasteners. The operator will get sufficient clearance when a shim is installed in the repair installation figure. 5. Backdrill the holes in the forward repair angle through the holes in the floor beam. 6. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 38. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 184

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed.

FIGURE 38. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - LEFT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 185

### BOEING SERVICE BULLETIN 737-53-1120

B B B

B A

A A A A A A

A A A A A B B B B B B 

### 2

4 1 3 FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB SEAT TRACK INTERCOSTAL LINK AFT REPAIR ANGLE801446The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Cut and remove material from the forward repair angle at the location shown to give sufficient clearance with the existing fasteners on the web. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 39. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 186

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed.

FIGURE 39. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 24.75, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 187

### BOEING SERVICE BULLETIN 737-53-1120

A

A

A

A

A A

A

A

A

A

A A C B BB B B B B B B



### 3 1 4 2 INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB 12 PLACES AFT REPAIR ANGLE

FORWARD REPAIR ANGLE801657The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Locate the Forward Repair Angle 69-77942-2 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and aft repair angle are the same. 2. Remove and discard the rivet that attaches the top of the pulley bracket to the floor beam web. Backdrill a hole in the forward repair angle through this hole. 3. Backdrill the holes in the forward repair angle through the holes in the floor beam. 4. Locate and drill the holes for the fasteners that attach the forward repair angle to the floor beam web. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 40. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 188

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Backdrill to match the hole in the floor beam. B. Drill a 0.187 - 0.190 inch diameter hole. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K3 with a collar BACC30BL6 is installed. C. Drill a 0.187 - 0.190 inch diameter hole to match the hole in the floor beam. Do more steps, as shown in the repair installation figure, before the hex drive bolt BACB30VT6K5 with a collar BACC30BL6 is installed.

FIGURE 40. FASTENER LOCATIONS FOR THE FORWARD REPAIR ANGLE - RIGHT BUTTOCK LINE 45.50, GROUP 8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 189

### BOEING SERVICE BULLETIN 737-53-1120

12 11 SEAT TRACK

A

A TOP CHORD

23 15 40 45

41 38 2 29 32 INTERCOSTAL INTERCOSTAL WEB 38 32 2 29 38 31 25 FORWARD REPAIR ANGLE

WING BOX FWD INBD LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR INSTALL ELECTRICAL BRACKET 35 AT RBL 45.50 BETWEEN BS 520 AND WING BOX 39 BUSHING PLAIN 6 20 8 CHANNEL PIVOT LINK BUSHING PLAIN STRAP 22 10 42

24 16 INTERCOSTAL LINK PIN 44
44 22 17 43 PIN 520 BS BEAM FLOOR

45 PIN

ANGLE AFT REPAIR 7 8 31 38 21 25B20737

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 190

### BOEING SERVICE BULLETIN 737-53-1120

F F F F F

G E



### 29 37

29

27 8 3 27 29 36 38 14 19

13

FWD STA 520 18 33

38 36 28 9

32 38

32 38 31 38 1 31 38 1

30 7 PLACES

0.24 AND INSTALL NEW ONE INTERCOSTAL CHANNEL REMOVE EXISTING INTERCOSTAL TOP CHORD

C 0.70 1.01 B

D D

C 0.20 0.17

B FLANGE FILLER

INTERCOSTAL WEB FORWARD

12 PLACES

CHANNEL RADIUS FILLER CHANNEL INTERCOSTAL LINK PIVOT BOLT
PIVOT LINK

PIVOT JOINT



## VIEW A-A SEAT TRACK ENDS

INTERCOSTAL LINK FLOOR BEAM AFT FLANGE FILLERB19802

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 191

### BOEING SERVICE BULLETIN 737-53-1120

LINK INTERCOSTAL L C

90` BUSHING FLANGED



## SECTION B-B

22 42 10 44



## SECTION C-C 12 11

WASHERB19835

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 192

### BOEING SERVICE BULLETIN 737-53-1120

20 20

20
38 26 30 21 25 31

0.24 38 31

38 36 D D 

### 36 38 31 38 25

54

34 B

B
B B

B A
C

B A
C 

### 38

INBD RADIUS

BEAM WEB FLOOR 12 PLACES

ALL OTHER LOCATIONS SIMILIAR LBL 24.75 SHOWN LOOKING FORWARD 

## VIEW D-D FILLER AFT FLANGE

FILLER RADIUS CHANNEL CHANNEL ANGLE REPAIR FORWARD C LINK INTERCOSTAL L

BRACKET PULLEY BRACKET PULLEY
ANGLE AFT REPAIRB19823

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 193

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Discard the radius filler, the bolt, the nut, and the washer that was removed from below the forward and the aft floor beam flange. 2. Mark and identify the forward edge of the intercostal web and the intercostal top chord. Remove and keep them. 3. Remove and discard the intercostal channel. 4. Remove and discard the fasteners that attach the pulley brackets to the floor beam where the repair angle will be installed. 5. Move the pulley bracket away from the floor beam. 6. Get the Channel 69-77976-1 of the Channel-Pivot Link Assembly 65C34978-4. 7. Get the aft repair angle (Refer to Circle Note Step 25 to get the part number for the aft repair angle). 8. Locate the channel and the aft repair angle on the floor beam. 9. Cut and remove material from the top of the channel. This is done to give sufficient clearance between the top of the channel and the flange filler that is installed in a later step. The maximum distance that the cut edge can be made from the original edge is 0.10 inch. 10. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-231, the Pivot Bolt BACB30NF5D37 or BACB30NR5DK37, the Washer AN960C516 (install between the channel and the nut), the Washers AN960C716L (install between the channel and the pivot link) and the Nut BACN10JD5CD. 11. Get the intercostal link that was kept. Remove and discard the flanged bushings (two places) from the forward end. 12. Ream the holes in the forward end of the intercostal link to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. Install a Flanged Bushing BACB28AT07B018C (two places) with sealant (BMS 5-95). Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. NOTE: Make sure that there is no sealant on the reamed surface of the flanged bushing. 13. Cut and remove material from the forward end of the intercostal link. 14. Rubber stamp the new part number 65C34978-30 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 15. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 16. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed.

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 194

### BOEING SERVICE BULLETIN 737-53-1120
17. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-147 the Pivot Bolt BACB30NR5DK25, the Washer AN960C516 and the Nut BACN10JD5CD. 18. Make sure that there is a horizontal clearance of 0.17 to 0.20 inch between the seat track ends. Make a mark at the location where the material will be removed if the clearance is not sufficient. 19. Make sure that there is a minimum horizontal clearance of 0.25 inch between the forward edge of the intercostal link and the structure below the seat track ends. This structure includes the aft flange filler and the inside surface of the channel. NOTE: This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. 20. Locate the channel on the floor beam to get these conditions : - The centerline of the channel is as near as possible to the centerline of the intercostal link in the

inboard-outboard direction. This helps to prevent an inboard-outboard force (preload) on the pivot link and the intercostal link. - The hex-drive bolt heads do not make contact with the radius of the channel. Clamp the channel to the floor beam. 21. (not shown) Make marks to identify the installed position of the channel and the aft repair angle on the floor beam. 22. Remove and keep the pivot link and the fasteners at both pivot joints. 23. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 24. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 25. Refer to the correct figure in the table below : NOTE: The referenced figures are shown looking forward. Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 Do Circle Note Steps 1 through 12 in Figure 42 Do Circle Note Steps 1 through 13 in Figure 43 Do Circle Note Steps 1 through 13 in Figure 44 Do Circle Note Steps 1 through 10 in Figure 45 26. Backdrill the repair angles and the channel through the holes in the floor beam. 27. Locate the new intercostal channel on the floor beam. Use the Intercostal Channel 65C34978-49 at Left or Right Buttock Line 45.50. Use the Intercostal Channel 65C34978-50 at Left or Right Buttock Line 24.75. 28. Cut and remove material from the top of the intercostal channel. This is done to give sufficient clearance between the top of the intercostal channel and the forward flange filler. The maximum distance that the cut edge can be made from the original edge on the Intercostal Channel 65C34978-49 is 0.22 inch. The maximum distance that the cut edge can be made from the original edge on the Intercostal Channel 65C34978-50 is 0.10 inch. FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 195

### BOEING SERVICE BULLETIN 737-53-1120
29. Locate the new intercostal channel, the existing intercostal web without cracks and/or the existing intercostal top chord without cracks on the floor beam. Make sure that there is sufficient clearance between the aft end of the intercostal web/top chord and the radius in the intercostal channel. If necessary, cut and remove material from the aft end of the intercostal web and the intercostal top chord. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on these existing holes. Backdrill the new holes in the intercostal channel through the existing holes. If the intercostal web or the intercostal top chord are cracked, drill new holes on the intercostal channel 0.33 - 0.39 inch from the forward edge of the intercostal channel. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. 30. Backdrill the holes in the intercostal channel through the holes in the floor beam. 31. Refer to the correct figure in the table below. Use the figure to install the repair angles, the flange fillers, and the other repair parts. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95) : NOTE: The referenced figures are shown looking forward. Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 Do the steps that remain in Figure 42 Do the steps that remain in in Figure 43 Do the steps that remain in Figure 44 Do the steps that remain in Figure 45 32. Refer to Figure 24 to install the intercostal web and the intercostal top chord that were removed for access. 33. If necessary, cut and remove material from the seat track end where the mark was made. 34. At Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts. 35. At Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket on the channel : - On Group 4 and 5 Airplanes, refer to Figure 57 - On Group 6 Airplanes, refer to Figure 58. 36. Make sure that the pivot link is not connected to the channel. Get the Channel Radius Filler 65C34978-47. Install the intercostal channel, the channel, and the channel radius filler on the repair angles. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 37. Install the fasteners that attach the intercostal channel to the intercostal web and to the intercostal top chord. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 38. Apply a layer of water-displacing corrosion-inhibiting compound to the intercostal web, the intercostal top chord, the intercostal channel, the channel, the repair angles, the channel radius fillers, the flange fillers and to the areas of the floor beam where it was removed (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed.

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 196

### BOEING SERVICE BULLETIN 737-53-1120
39. At Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 4 and 5 Airplanes, refer to Figure 62 - On Group 6 Airplanes, refer to Figure 63. 40. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 41. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 42. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 43. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 44. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 45. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Increase the existing hole diameter to 0.263 - 0.266 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.630 - 0.656 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30NX8K8X at Right Buttock Line 45.50. Install a hex drive bolt BACB30NX8K9X at the other locations. Install with a collar BACC30X8. B. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.510 - 0.531 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MY6K8Y at Right Buttock Line 45.50. Install a hex drive bolt BACB30MY6K9Y at the other locations. Install with a collar BACC30R6. C. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.600 - 0.625 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MY8K8Y at Right Buttock Line 45.50. Install a hex drive bolt BACB30MY8K9Y at the other locations. Install with a collar BACC30R8. D. Increase the existing hole diameter to 0.263 - 0.266 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30NX8K10X at Right Buttock Line 45.50. Install a hex drive bolt BACB30NX8K11X at the other locations. Install with a collar BACC30X8. Install with the head on the surface of the channel radius filler.

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 197

### BOEING SERVICE BULLETIN 737-53-1120

E. See the table below. F. See the table below. Fasteners for the Intercostal Channel Changes Fastener Symbol "E" Fastener Symbol "F" Name Fastener Hole Size (inch) Name Fastener Hole Size (inch) The Intercostal Web is Repaired Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FP6-3 and BACC30M6 0.216 -0.219

0.200 -0.203 Rivet BACR15BB6D6

or MS20470D5-6 0.191 -0.202

0.159 -0.171 The Intercostal Web is Replaced The Intercostal

Top Chord is

Replaced

Both the Intercostal Web and the Intercostal Top Chord are Replaced Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FM6-3 and BACC30M6 216 - 0.219

0.187 -0.190 Rivet BACR15BB6D6

or MS20470D5-6 0.191 -0.202

0.159 -0.171

G. Alternative #1: Increase the existing hole diameter to 0.216 - 0.219 inch. Install a hex drive bolt BACB30MY6K3Y with a collar BACC30R6. Alternative #2: Increase the existing hole diameter to 0.200 - 0.203 inch. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6.

FIGURE 41. REPAIR - INSTALLATION WITH TWO REPAIR ANGLES AT LEFT OR RIGHT BUTTOCK LINE 24.75 AND 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 198

### BOEING SERVICE BULLETIN 737-53-1120

6 13 6 13

6 13

7 8 6

6 3

F6 J J
J J J J J

4 F 5 F F6

J J J J J

J B E

E E


### 14

4 5 4 H 4 H 5 I

4 H 8 H 8 H 5 H 5 H 5 H 5 H 15 H 5 H 12 I 5 I D

D



### 15 15 15 15 11 14 10 8 13 11

3 14 6 14 5

5 9

9

SHIM

10 PLACES FWD

WEB FILLER (FORWARD SIDE ONLY) SHEAR WEB

INBD A A AFT REPAIR ANGLE SEE DETAIL I SEAT TRACK



## VIEW A-A
LBL 45.50

LBL 45.50

DOUBLER FILLER PULLEY BRACKET PULLEY FLOOR BEAM FILLER PULLEY BRACKET PULLEY AFT FLANGE FILLER FORWARD FLANGE FILLER

SEAT TRACK FILLER 11 PLACES FORWARD REPAIR ANGLE
SEE DETAIL IB24530

FIGURE 42. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 199

### BOEING SERVICE BULLETIN 737-53-1120

G A K

C 

### 12

12 1

12 2
6 NUTPLATE EXISTING REMOVE SHEAR WEB

REPAIR ANGLE NUTPLATE

OUTBOARD NUTPLATE SIMILAR INBOARD NUTPLATE SHOWN 

## DETAIL I FWD (OUTBOARD NUTPLATE ONLY)

FLANGEB24552

FIGURE 42. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 200

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplate or nutclip. An airplane with a nutplate is shown in this figure. 2. Plug the rivet hole shown if a nutplate was attached to the floor beam structure with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface 3. Remove and discard these existing rivets from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-44. 5. Locate the Forward Repair Angle 69-77969-9 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-10 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. 7. Remove the laminations from the Shim BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 8. Put the Seat Track Filler 65C34978-48 and the shim in the installed position. 9. Put the Forward Flange Filler 65C34978-42 and the Aft Flange Filler 65C34978-41 in the installed position. 10. Locate and drill the holes for the new fasteners at any of these locations if it is possible to keep all of these dimensions : - A minimum distance of 0.22 between the center of a new fastener hole and the edge of a

stop-drill hole (Repaired cracks have stop-drill holes at the crack ends) - A minimum distance of 0.65 between the center of each fastener hole - A minimum edge margin of 0.33. 11. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 12. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle, the flange and the shear web. Microshave the rivet surface that is adjacent to the top surface of the shear web or the flange. Give the surface of a microshaved head the same finish as the adjacent surface.

FIGURE 42. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 201

### BOEING SERVICE BULLETIN 737-53-1120
NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 13. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 14. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 15. Install the pulley brackets with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Where the outboard nutplate was installed, make a 100 degree countersink on the top side of the shear web. Where the inboard nutplate was installed, make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange at both locations. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on the repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam structure. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K12X with a collar BACC30X8. Install with the head on the seat track. E. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K5Y with a collar BACC30R6. F. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. G. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. H. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the top surface of the flange or the seat track. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. I. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam structure. Make a 100 degree countersink on the top surface of the seat track or the shear web. Install a hex drive bolt BACB30NW6K( )Y with a collar BACC30R6. J. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K5 with a collar BACC30M6. K. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions.

FIGURE 42. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 202

### BOEING SERVICE BULLETIN 737-53-1120

10 6 14 D

D 5 K

5 K 5 K 5 K K9 5 K 5 K K9 5 K 5 K K16 5 K K16 

### 10 5

5 14 12

G 5 G6 L B

L L E L L F E L L L

L L L L L L



### 5 4 3 6

16

16 15 12 15 11

6 15 3 15 9 9 8 FWD

INBD A A SHIM (2 PLACES) AFT FLANGE FILLER LBL 24.75 SEAT TRACK FORWARD FLANGE FILLER SEE DETAIL II SEE DETAIL I FORWARD REPAIR ANGLE

AFT REPAIR ANGLE 13 PLACES


## VIEW A-A
24.75

LBL

WEB FILLER (FORWARD SIDE ONLY) DOUBLER SEAT TRACK FILLER (2 PLACES)

FILLER PULLEY PULLEY BRACKET 11 PLACES

FLOOR BEAMB21734

FIGURE 43. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 203

### BOEING SERVICE BULLETIN 737-53-1120

A
J I H N

C M

A 

### 13

13

2

13 1 1 6

7 2

NUTPLATE EXISTING REMOVE NUTPLATE EXISTING REMOVE

NUTPLATE NUTPLATE REPAIR ANGLE

FWD 

## DETAIL II FWD 

## DETAIL I FLANGE FLANGEB24449

FIGURE 43. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 204

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplate. An airplane with a nutplate is shown in this figure. 2. Plug the rivet hole shown if a nutplate was attached to the floor beam with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Remove and discard these existing rivets from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-45. 5. Locate the Forward Repair Angle 69-77969-7 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-8 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. 7. Install the Nutplate BACN10KE3D below the forward side of the floor beam flange. Microshave the top end of the rivets that attach the nutplate to the floor beam. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent floor beam. 8. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 9. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 10. Put the Forward Flange Filler 65C34978-38 and the Aft Flange Filler 65C34978-37 in the installed position. 11. Locate and drill the holes for the new fasteners at any of these locations if it is possible to keep all of these dimensions : - A minimum distance of 0.22 between the center of a new fastener hole and the edge of a

stop-drill hole (Repaired cracks have stop-drill holes at the crack ends) - A minimum distance of 0.65 between the center of each fastener hole - A minimum edge margin of 0.33. 12. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 13. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface. FIGURE 43. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 205

### BOEING SERVICE BULLETIN 737-53-1120
NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 14. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 15. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 16. Install the pulley bracket with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on both repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K13X with a collar BACC30X8. Install with the head on the seat track. E. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K6Y with a collar BACC30R6. F. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY8K6Y with a collar BACC30R8. G. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. H. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange on the floor beam. Install a rivet BACR15BA3D6. I. Install a rivet BACR15BA3D6. J. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. K. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. Make a 100 degree countersink on the top surface of the flange or the seat track. L. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K6 with a collar BACC30M6. NOTE: The screws below attach the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. M. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. N. Install the screw BACS12GP3K12 in the nutplate. Install with a 15 to 20 inch - pound torque.
FIGURE 43. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 206

### BOEING SERVICE BULLETIN 737-53-1120

L L L L L L L L L

L L

L L

E B

E F G6

G 5 

### 14 12 5 5

K16
K9 5 K 5 K 5 K 5 K 

### 10

15 11 5 K 5 K

5 K 5 K 5 K



### 6

3 6 15 16

16

5 4 12 15 10 6 14 D

D K9 K16



### 3 15 9 8 9 FWD

INBD SHIM (2 PLACES)
A A

10 PLACES SEAT TRACK
SEE DETAIL I SEE DETAIL II

13 PLACES AFT REPAIR ANGLE FORWARD REPAIR ANGLE FORWARD FLANGE FILLER

PULLEY BRACKET

FILLER PULLEY

(FORWARD SIDE ONLY) WEB FILLER DOUBLER (2 PLACES) RBL 24.75

RBL 24.75

FLOOR BEAM AFT FLANGE FILLER


## VIEW A-A SEAT TRACK FILLERB24586

FIGURE 44. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 207

### BOEING SERVICE BULLETIN 737-53-1120

J A

C M

A H I N 

### 13

13

13 2

7 1 1 6 2

NUTPLATE NUTPLATE EXISTING REMOVE

NUTPLATE NUTPLATE EXISTING REMOVE

REPAIR ANGLE

FWD 

## DETAIL II FWD 

## DETAIL I FLANGE FLANGEB24587

FIGURE 44. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 208

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplates. An airplane with a nutplate is shown in this figure. 2. Plug the rivet hole shown if a nutplate was attached to the floor beam with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Remove and discard these existing rivets from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-46. 5. Locate the Forward Repair Angle 69-77969-5 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-6 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. 7. Install the Nutplate BACN10KE3D below the forward side of the floor beam flange. Microshave the top end of the rivets that attach the nutplate to the floor beam. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent floor beam. 8. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 9. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 10. Put the Forward Flange Filler 65C34978-38 and the Aft Flange Filler 65C34978-37 in the installed position. 11. Locate and drill the holes for the new fasteners at any of these locations if it is possible to keep all of these dimensions : - A minimum distance of 0.22 between the center of a new fastener hole and the edge of a

stop-drill hole (Repaired cracks have stop-drill holes at the crack ends) - A minimum distance of 0.65 between the center of each fastener hole - A minimum edge margin of 0.33. 12. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 13. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface. FIGURE 44. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 209

### BOEING SERVICE BULLETIN 737-53-1120

NOTE: Do more steps, as shown in the repair figure before you do the subsequent circle note steps. 14. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 15. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 16. Install the pulley bracket with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on the repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K13X with a collar BACC30X8. Install with the head on the seat track. E. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K6Y with a collar BACC30R6. F. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY8K6Y with a collar BACC30R8. G. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. H. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange on the floor beam. Install a rivet BACR15BA3D6. I. Install a rivet BACR15BA3D6. J. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. K. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. Make a 100 degree countersink on the top surface of the flange or the seat track. L. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K6 with a collar BACC30M6. M. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw and the screw below attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. N. Install the screw BACS12GP3K12 in the nutplate. Install with a 15 to 20 inch - pound torque. FIGURE 44. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 210

### BOEING SERVICE BULLETIN 737-53-1120

3

3 9 11

9 12 4 6 7 7

4 11

5 6 C

C



### 13

D4

5 D G

G G G G G G G

G G G G G G G

G 4 F 4 F

4 F 4 F

8 F 8 F 4 F 5 F 5 F 5 F 5 F 5 F 15 F 15 F



### 13 8 12 8 12

INBD 12 PLACES SHIM FWD

A A FORWARD REPAIR ANGLE

14 PLACES AFT REPAIR ANGLE 

## VIEW A-A
45.50 45.50

BRACKET PULLEY AFT FLANGE FILLER FORWARD FLANGE FILLER

SEAT TRACK FILLER RBL RBL

FILLER PULLEY BEAM FLOOR SEE DETAIL I SEE DETAIL I SEAT TRACKB24608

FIGURE 45. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 211

### BOEING SERVICE BULLETIN 737-53-1120

E A

B H 

### 10

10 1 2

10 4 REMOVE EXISTING NUTPLATE

FWD 

## DETAIL I NUTPLATE REPAIR ANGLE FLANGEB24651

FIGURE 45. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 212

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplates. An airplane with a nutplate is shown in this figure. 2. Plug the hole shown if a nutplate was attached to the flange with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Locate the Forward Repair Angle 69-77969-3 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-4 are the same. 4. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. 5. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 6. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 7. Put the Forward Flange Filler 65C34978-36 and the Aft Flange Filler 65C34978-35 in the installed position. 8. Locate and drill the holes for the new fasteners at any of these locations if it is possible to keep all of these dimensions : - A minimum distance of 0.22 between the center of a new fastener hole and the edge of a

stop-drill hole (Repaired cracks have stop-drill holes at the crack ends) - A minimum distance of 0.65 between the center of each fastener hole - A minimum edge margin of 0.33. 9. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 10. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface.

FIGURE 45. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 213

### BOEING SERVICE BULLETIN 737-53-1120
NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 11. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 12. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 13. Install the pulley bracket with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam flange. Give the hole surface the same finish as the adjacent structure. C. Install a hex drive bolt BACB30NY8K12X with a collar BACC30X8. Install with the head on the seat track. D. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. E. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. F. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. Make a 100 degree countersink on the top surface of the flange or the seat track. G. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K5 with a collar BACC30M6. H. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions.

FIGURE 45. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 214

### BOEING SERVICE BULLETIN 737-53-1120

B A


### 2

26 30 20 34 17

20 33 12 21 31 15

22 32 16 7 19 11 3 6 2

BOLT AND INSTALL REMOVE HEX-DRIVE REMOVE BOLT AND INSTALL

REPAIR ANGLE

A A SEAT TRACK

WING BOX ON GROUP 1, GROUP 2 AND GROUP 3 AIRPLANES ONLY AT RBL 45.50 BETWEEN BS 520 AND ELECTRICAL BRACKET

LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR INBD FWD FLOOR BEAM BS 520

35 PIN

35 PIN
LINK INTERCOSTAL

PLAIN BUSHING PLAIN BUSHING

WING BOX PIVOT LINK STRAP 36 PIN
CHANNEL802045

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 215

### BOEING SERVICE BULLETIN 737-53-1120

1 10

8 49 8

18

18 18 24

FWD520 STA

13 14
0.18 NUT FLANGE RADIUS FILLER

REPAIR ANGLE COLLAR

B

B 0.40 0.70

CHANNEL PIVOT LINK 0.19 0.06



## VIEW A-A PIVOT JOINT INTERCOSTAL LINK SEAT TRACK ENDS FLOOR BEAM

FASTENER HEAD CHANNEL RADIUS FILLER AND

PIVOT BOLT

INTERCOSTAL LINK802069

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 216

### BOEING SERVICE BULLETIN 737-53-1120

29 CHANNEL 1 27 RADIUS FILLER CHANNEL INTERCOSTAL L LINK

29

RADIUS FILLER FLANGE 29

29 RADIUS FILLER CHANNEL 29 9 C

C C



### FLOOR BEAM WEB REPAIR ANGLE



## VIEW B-B LOOKING FORWARD IF THE ORIGINAL CHANNEL IS NOT REMOVED802057

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 217

### BOEING SERVICE BULLETIN 737-53-1120

19 19

19 29 28 19 23 29 CHANNEL RADIUS FILLER 1 9 29 FLANGE RADIUS FILLER

25

CHANNEL 29 28 LINK L INTERCOSTAL C

29 28 3 6 CHANNEL RADIUS FILLER 3 6 E E

D D E E E E E E C C



### RADIUS 12 PLACES ANGLE REPAIR

0.18 

## VIEW B-B LOOKING FORWARD FLOOR BEAM WEB

IF THE ORIGINAL CHANNEL IS CRACKED OR REMOVED802072

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 218

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Apply a layer of enamel (BMS 10-11 Type II) to the Channel Radius Filler 66-13222-10 and to the Flange Radius Filler 66-13222-9. Refer to View A-A and View B-B. 2. Remove and discard the three fasteners that attach the end of the seat track to the floor beam flange. 3. On airplanes with cracked channels, remove and discard the cracked channel and the hex drive bolts that attach it to the floor beam. Keep the channel radius filler that was installed on the bottom end of the channel. 4. Before the Flange Radius Filler 66-13222-9 is installed, make sure that there is sufficient clearance between an installed channel and the collar nut for the 5/16 inch hex drive bolt. 5. (Not shown) If the clearance is not sufficient on Group 1, 2, 3 Airplanes at Left or Right Buttock Line 24.75, remove and keep the cargo posts. 6. If the clearance is not sufficient, remove and keep the channel. Remove and discard the hex drive bolts that attach the channel to the floor beam. Keep the channel radius filler that was installed on the bottom end of the channel. 7. On Airplanes with cracked channels, make a Channel Assembly "D" as shown in Figure 77. 8. Locate Channel Assembly "D" on the repair angle. Cut and remove material from the top of the channel. This is done to give sufficient clearance between the top of the channel and the flange radius filler. The maximum distance that the cut edge can be made from the original edge is 0.25 inch. 9. If more clearance is necessary between the channel and the collar, use the Channel Radius Filler 66-13222-10 as a template to cut and remove material from the top end of the channel. 10. Install the Flange Radius Filler 66-13222-9 below the top end of the repair angle. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 11. Put the channel in the installed position. 12. If it has not been done, temporarily connect the pivot link to the channel. The pivot link that was kept can be used. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-170, the Pivot Bolt BACB30NR5DK28, the Washer AN960C516 and the Nut BACN10JD5CD. The fasteners that were kept can be used. 13. Get the intercostal link that was kept. Cut and remove material from the forward end of the intercostal link. 14. Rubber stamp the new part number 65C34688-29 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10).

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 219

### BOEING SERVICE BULLETIN 737-53-1120
15. Temporarily connect the intercostal link to the wing box structure. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416, the Nut AN320-4 and the Pin MS24665-134. Use the fasteners that were kept. 16. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 17. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-128, the Pivot Bolt BACB30NR5DK21, the Washer AN960C516 and the Nut BACN10JD5CD. The fasteners that were kept can be used. 18. Make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends. Make sure that the clearances at the following locations are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads when they are installed

on the channel radius filler. This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient. 19. Adjust the location of Channel Assembly "D" on the floor beam to get these conditions : - The centerline of the channel is as near as possible to the centerline of the intercostal link in the

inboard-outboard direction. This helps to prevent an inboard-outboard force (preload) on the pivot link or the intercostal link. - The hex-drive bolt heads do not make contact with the radius of the channel. Clamp the channel to the floor beam. 20. Remove and keep the pivot link and the fasteners at both pivot joints. 21. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 22. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 23. On airplanes with channels that were cracked, backdrill the holes in the new channel through the holes in the floor beam. 24. If necessary, cut and remove material from the seat track end, or the channel, or the intercostal link where the marks were made. On the channel, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. On the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 25. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, put these fasteners in the channel. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts.

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 220

### BOEING SERVICE BULLETIN 737-53-1120
26. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket : - On Group 1 and 2 Airplanes, refer to Figure 53 - On Group 3 Airplane, refer to Figure 55 27. Install Channel Radius Filler 66-13222-10 the on the top end of the channel. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 28. On Airplanes with channels that were cracked or removed, install the new channel or the channel that was removed on the floor beam. Make sure that the pivot link is not connected to the channel. Install the Channel Radius Filler 65-46803-9 that was kept. Install it on the bottom end of the channel. Also install Channel Radius Filler 66-13222-10 the on the top end of the channel. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 29. Apply a layer of water-displacing corrosion-inhibiting compound to the channel, the repair angle, the channel radius fillers and to the flange radius filler. (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 30. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 1 and 2 Airplane, refer to Figure 59 - On Group 3 Airplanes, refer to Figure 61. 31. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 32. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 33. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 34. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 35. Install the Pin MS24665-134 through the nut and the pivot bolt at both pivot joints. 36. Install a new Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. 37. (Not shown) Install the cargo posts if removed.

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 221

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Install a hex drive bolt BACB30NY10K11 with a collar BACC30X10. Install with the head on the seat track surface. B. Drill a 0.216 - 0.219 inch diameter hole to match the hole in the seat track. Install a hex drive bolt BACB30NY6K8Y with a collar BACC30AC6. Install with the head on the seat track surface. C. Drill a 0.216 - 0.219 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30NX6K9Y or BACB30MD6-9 with a collar BACC30AC6. Install with the head on the surface of the radius filler. D. Drill a 0.0.216 - 0.219 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30MD6-9 with a collar BACC30AC6. Install with the head on the surface of the radius filler. E. Drill a 0.231 - 0.234 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30MA6-6 with a collar BACC30Y6. Install with the head on the channel surface.

FIGURE 46. REPAIR - CHANGES TO THE AFT REPAIR ANGLE WITH A PIVOT LINK AT LEFT OR RIGHT BUTTOCK LINE 24.75 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 222

### BOEING SERVICE BULLETIN 737-53-1120

18 48 14

20 46 13 3

18 9

38 44 47 39 22

7 17 6 19 45 12

5 8 16 7 REPAIR ANGLE FORWARD REMOVE

AFT REPAIR ANGLE C

C A

A 50 PIN SEAT TRACK FLOOR BEAM BS 520

49 PIN

49 PIN

PLAIN BUSHING

WING BOX STRAP LINK INTERCOSTAL

PLAIN BUSHING

LBL 24.75 LOCATION SHOWN ALL OTHER BL LOCATIONS SIMILAR INBD FWD PIVOT LINK CHANNEL

GROUP 2 AND GROUP 3 AIRPLANES ONLY BS 520 AND WING BOX ON GROUP 1, ELECTRICAL BRACKET AT RBL 45.50 BETWEENA98127

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 223

### BOEING SERVICE BULLETIN 737-53-1120

J
J
J
J

K I

J 

### 31 30 33 41 32

43 4 2 2 1 43 26

36 8

11 10

FWD 15 15 STA 520 34

7 27 27

28 40

29 15 32 29

7 PLACES REPAIR ANGLES INTERCOSTAL ANGLE

0.18 6 PLACES

INTERCOSTAL WEB

REMOVE INTERCOSTAL TEE AND INSTALL INTERCOSTAL ANGLE CHORD TOP INTERCOSTAL FLANGE RADIUS FILLER

0.70

0.40
REPAIR ANGLE B

B PIVOT BOLT SEAT TRACK ENDS

INTERCOSTAL LINK

PIVOT JOINT



## VIEW A-A 0.06 0.19

PIVOT LINK
CHANNEL INTERCOSTAL LINK AND FASTENER HEAD CHANNEL RADIUS FILLER

FLOOR BEAMB08701

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 224

### BOEING SERVICE BULLETIN 737-53-1120

B8 B6

B8 B6 B8 B6 B8 B6 A 10 A9

A 10 A9 

### 16 16

23 43 40 16 21 C INTERCOSTAL L LINK
43 39 22 40

C C
C C C
C C 

### 40 1 RADIUS FILLER CHANNEL 43 35

C

N N N 

### 37
43 40
21 RADIUS FILLER FLANGE 43

43

42

42 43 CHANNEL 40 CHANNEL RADIUS FILLER 12 PLACES

RADIUS AFT REPAIR ANGLE

SEE DETAIL I FOR ARPLANES WHERE AN AFT REPAIR ANGLE WAS INSTALLED WITH THE CHANNEL 0.18 FORWARD REPAIR ANGLE

FLOOR BEAM WEB

SHIM

BRACKET

LOOKING FORWARD FOR AIRPLANES WHERE ONLY A CHANNEL WITH A PIVOT LINK WAS INSTALLED 

## VIEW B-BB09547

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 225

### BOEING SERVICE BULLETIN 737-53-1120

D D D D D D D D

D 

### LINK L INTERCOSTAL C

D D D D D 

### 21 43 40



## DETAIL I LOOKING FORWARD AFT REPAIR ANGLE

FOR AIRPLANES WHERE AN AFT REPAIR ANGLE WAS INSTALLED WITH THE CHANNELB19431

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 226

### BOEING SERVICE BULLETIN 737-53-1120

24 24 24

M L M L 

### 40 43

24 24 E F G

G H G G H H

H H H O H O H



### 40 43 25 25 24

40 43 FWD

FLOOR BEAM
FOR AIRPLANES WHERE AN AFT REPAIR ANGLE WAS INSTALLED WITH THE CHANNEL 

## DETAIL II REPAIR ANGLE FORWARD

4 PLACES AT THE SEAT TRACK AFT REPAIR ANGLE SEE DETAIL II L SEAT TRACK C

FOR AIRPLANES WHERE ONLY A CHANNEL WITH A PIVOT LINK WAS INSTALLED 

## VIEW C-C

AFT REPAIR ANGLE801739

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 227

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Apply a layer of enamel (BMS 10-11 Type II) to the Channel Radius Filler 66-13222-10 (View B-B) and to the Flange Radius Fillers 66-13222-9 (View A-A). 2. Discard the radius filler, the bolt, the nut, and the washer that was removed from below the forward or the aft floor beam flange. 3. If it has not been done, remove and discard the four fasteners that attach the end of the seat track to the floor beam flange. 4. Remove and discard the intercostal "Tee" stiffener from the intercostal web. 5. On Airplanes with cracked channels, make a Channel Assembly "D" as shown in Figure 77. 6. Get an Aft Repair Angle 69-77942-1. If an aft repair angle was installed with the steps given in the initial release of this service bulletin, get another repair angle with the same part number as the original one. 7. Locate the repair angle and the channel on the floor beam. 8. Cut and remove material from the top of Channel Assembly "D" or from a channel that was installed without a repair angle (Installed with the steps given in the initial release of this service bulletin). This is done to give sufficient clearance between the top of the channel and the flange radius filler. The maximum distance that the cut edge can be made from the original edge is 0.25 inch. 9. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-170, the Pivot Bolt BACB30NR5DK28, the Washer AN960C516, the Nut BACN10JD5CD. 10. Get the intercostal link that was kept. Cut and remove material from the forward end of the intercostal link as shown. 11. Rubber stamp the new part number 65C34688-29 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 12. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416, the Nut AN320-4. 13. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 14. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-128, the Pivot Bolt BACB30NR5DK21, the Washer AN960C516 and the Nut BACN10JD5CD. You can use the fasteners that were kept.

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 228

### BOEING SERVICE BULLETIN 737-53-1120

15. Make sure that there is a horizontal clearance of 0.06 to 0.19 inch between the seat track ends. Make sure that the clearances at the following locations are more than the clearance between the seat tracks: - Between the edge of the pivot bolt and the edge of the channel - Between the forward edge of the intercostal link and the fastener heads when they are installed

on the channel radius filler This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. Make a mark at the location where material will be removed if the clearance is not sufficient. 16. Adjust the location of Channel Assembly "D" on the floor beam to get these conditions : - The centerline of the channel assembly is as near as possible to the centerline of the intercostal

link in the inboard-outboard direction. This helps to prevent an inboard-outboard force (preload) on the pivot link or the intercostal link. - The hex-drive bolt heads do not make contact with the radius of the channel assembly. Clamp the channel assembly to the floor beam. 17. Make sure that the aft repair angle is in the correct location. 18. Remove and keep the pivot link and the fasteners at both pivot joints. 19. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 20. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 21. Backdrill these holes in the aft repair angle and the Channel Assembly "D" if it is used. Backdrill through the holes in the floor beam. See View B-B. 22. Refer to the correct figure in the table below. Use the figure to locate the fastener holes for the forward repair angle 69-77942-2 : NOTE: The referenced figures are shown looking aft. Airplane Group Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 1, 2, 3 29 30 31 32 7 33 34 35 36 8 37 38 39 40 23. On a floor beam where only a channel with a pivot link was installed, locate and drill the holes for the fasteners that attach the aft repair angle to the floor beam and the forward repair angle. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes.

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 229

### BOEING SERVICE BULLETIN 737-53-1120
24. Backdrill the holes shown in both the forward and aft repair angles through the holes in the seat track and the floor beam flange. 25. Locate and drill the holes for the fasteners that attach the repair angles to the floor beam flange. Keep a minimum distance of 0.65 between the center of each fastener hole. Also keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 26. Install the Flange Radius Fillers 66-13222-9. Install it below top end of the forward and the aft repair angles. These locations are below the forward and aft floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 27. Locate the Intercostal Angle 65C34688-28 on the forward repair angle. If necessary, cut and remove material from top end. This is done to give sufficient clearance between the intercostal angle and the collar for the 1/4 inch hex drive bolt in the seat track. Keep a minimum edge margin of 0.33 inch on the hole that will be backdrilled near the top edge. 28. Backdrill the holes in the intercostal angle through the holes in the floor beam. 29. In the next four Circle Note Steps, refer to one of the figures below if cracks are found in the intercostal web or in the intercostal top chord. These figures give the steps to repair or replace the intercostal web. These figures also gives the steps to replace the top intercostal chord. - On Group 1, 2, 3 Airplanes (does not include PA099, PA001-PA015, PA231-PA232,

PA016-PA022 and PC001-PC005), do the steps in Figure 22. - On Group 7, 8 Airplanes (also includes PA099, PA001-PA015, PA231-PA232, PA016-PA022,

PC001-PC005), do the steps in Figure 23. 30. If no cracks are found in both the intercostal web and the top intercostal chord, backdrill these holes in the intercostal angle. Backdrill through the holes in the intercostal top chord and the intercostal web. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on these existing holes. Also do this step if a cracked intercostal web was repaired and no cracks were found in the top intercostal chord. Install the fasteners shown. 31. Backdrill the holes in the intercostal angle if cracks are found in the intercostal top chord only. Backdrill through the holes in the intercostal web. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on the existing holes at the end of the intercostal web. Refer to the correct figure to replace the intercostal top chord. 32. Backdrill one hole in the intercostal angle if cracks are found in the intercostal web only. Backdrill through the hole at the aft end of intercostal top chord. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on the existing hole at the end of the top chord. Drill new holes in the intercostal angle 0.33 - 0.39 inch from the forward edge of the intercostal angle. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. Refer to the correct figure to replace the intercostal web. 33. If cracks are found in both the intercostal web and in the top chord, drill new holes in the intercostal angle 0.33 - 0.39 inch from the forward edge of the intercostal angle. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. Refer to the correct figure to replace the intercostal web and the intercostal top chord. 34. Make sure that there is sufficient clearance between the channel or channel assembly and the collar for the 5/16 inch hex drive bolt that is installed in the center of the seat track below the flange filler. 35. If the clearance is not sufficient, use the Channel Radius Filler 66-13222-10 as a template to cut and remove material from the top end of the channel or channel assembly. See View B-B.
FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 230

### BOEING SERVICE BULLETIN 737-53-1120
36. If necessary, cut and remove material from the seat track end, the channel or channel assembly, or the intercostal link where the marks were made. On the channel or channel assembly, the maximum distance that the cut edge can be made from the original edge is 0.20 inch. On the intercostal link, the maximum distance that the cut edge can be made from the original edge is 0.10 inch. 37. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, put these fasteners in the channel or channel assembly. It is possible that these fasteners cannot be installed after the support clip is installed in the next circle note step. Apply a layer of sealant to the hex drive bolts. 38. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, refer to the figures below to change the electrical bracket that was kept and to install a support clip for the electrical bracket : - On Group 1 and 2 Airplanes, refer to Figure 53 - On Group 3 Airplanes, refer to Figure 55 39. Refer to the correct figure in the table below. Use the figure to install some of the fasteners that attach the forward repair angle 69-77942-2 to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95) : NOTE: The referenced figures are shown looking aft. Airplane Group Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 1, 2, 3 29 30 31 32 7 33 34 35 36 8 37 38 39 40 40. Make sure that the pivot link is not connected to the channel or channel assembly. Install all of the fasteners that attach the intercostal angle, the repair angles, the channel and the channel radius fillers to the floor beam. Install one of the Channel Radius Fillers 65-46803-9 that were kept. Install it on the bottom end of the channel or channel assembly. Install the Channel Radius Filler 66-13222-10 on the top end of the channel or channel assembly. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 41. Install the fasteners that attach the intercostal angle to the intercostal web and the intercostal top chord. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 42. On Group 7,8 Airplanes, at Left Buttock Line 24.75, get the Bracket 65-49717, if it was removed. Apply a layer of primer (BMS 10-11 type I) to the Shim BACS40R007D030F and install the shim on the floor beam web with the bracket. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 43. Apply a layer of water-displacing corrosion-inhibiting compound to the intercostal web, the intercostal top chord, the intercostal angle, channel, the repair angles, the channel radius fillers and flange radius fillers, the bracket and to the areas of the floor beam where it was removed. (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2 or to the 737-300/400 Structural Repair Manual Subject 51-20-01). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed.
FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 231

### BOEING SERVICE BULLETIN 737-53-1120
44. On Group 1,2,3 Airplanes with channels that were cracked at Right Buttock Line 45.50, refer to the figures below to install the electrical bracket that was kept : - On Group 1 and 2 Airplanes, refer to Figure 59 - On Group 3 Airplanes, refer to Figure 61. 45. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 46. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 47. Connect the pivot link to the channel or channel assembly. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 48. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 49. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 50. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. A. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MD6-( ) with a collar BACC30AC6. Install with the head on the surface of the channel radius filler. B. Drill a 0.231 - 0.234 inch diameter hole to match the hole in the floor beam. Install a hex drive bolt BACB30MA6-( ) with a collar BACC30Y6. Install with the head on the channel surface. C. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VT6K5 with a collar BACC30BL6. D. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30FP6-5 with a collar BACC30M6. E. Install a hex drive bolt BACB30NY10K11 with a collar BACC30X10. Install with the head on the seat track surface. F. Install a hex drive bolt BACB30NY8K11 with a collar BACC30X8. Install with the head on the seat track surface. G. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the seat track. Install a hex drive bolt BACB30NY6K8X with a collar BACC30X6. Install with the head in the seat track. H. Drill a 0.187 - 0.190 inch diameter hole with a 100 degree countersink. Install a hex drive bolt BACB30NY6K4 with a collar BACC30BH6. Install with the head in the floor beam.

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 232

### BOEING SERVICE BULLETIN 737-53-1120

I. See the table below. J. See the table below. Fasteners for the Intercostal Angle Changes Fastener Symbol "I" Fastener Symbol "J" Name Fastener Hole Size (inch) Name Fastener Hole Size (inch) The Intercostal Web is Repaired Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FP6-3 and BACC30M6 0.216 -0.219

0.200 -0.203 Rivet

or Hex Drive Bolt BACR15FT5D4

or BACB30VT6K2 and BACC30BL6 0.159 -0.171

0.187 -0.190 The Intercostal Web is Replaced The Intercostal

Top Chord is

Replaced

Both the Intercostal Web and the Intercostal Top Chord are Replaced Hex Drive Bolt BACB30FM6-3 and BACC30M6 or BACB30MY6K3Y and BACC30R6 0.187 -0.190

0.216 -0.219 Rivet

or Hex Drive Bolt BACR15FT5D4

or BACB30VT6K2 and BACC30BL6 0.159 -0.171

0.187 -0.190

K. Alternative #1: Increase the existing hole diameter to 0.216 - 0.219 inch. Install a hex drive bolt BACB30MY6K3Y with a collar BACC30R6. Alternative #2: Increase the existing hole diameter to 0.200 - 0.203 inch. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6. L. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the seat track. Install a hex drive bolt BACB30LY6-8 with a collar BACC30AC6. M. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30LX6-4 with a collar BACC30X6.

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 233

### BOEING SERVICE BULLETIN 737-53-1120

N. Drill a 0.187 - 0.190 inch diameter hole in the shim to match the holes in the floor bream. Install a hex drive bolt BACB30NX6K4 with a collar BACC30X6. O. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. Install the Nut BACN10YD6 at this location. NOTE: This nut will be used with the Screw BACS12GM3-15 to attach the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions.

FIGURE 47. REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE A PIVOT LINK WAS

INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.7, 45.50, GROUP 1,2,3,7,8 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 234

### BOEING SERVICE BULLETIN 737-53-1120

2.00 TYPICAL

7



## INSPECTION 3 3

6

5 4 3

0.50 CRACKS CHECK FOR C L LINK INTERCOSTAL

ALL OTHER LOCATIONS SIMILIAR LBL 24.75 SHOWN LOOKING FORWARD FOR REPAIR SEE DETAIL I WEB-TO-FLANGE RADIUS

PULLEY BRACKET DOUBLER WEB

EDDY CURRENT INSPECT CRACK WITH STOP DRILL TOP FLANGE SEAT TRACKB21951

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 235

### BOEING SERVICE BULLETIN 737-53-1120

25 39 18

26 40 19 24 41 13 24 42 20

12 11 10 12 28 14 15 SEAT TRACK

A

A FORWARD REPAIR ANGLE 28 TOP CHORD INTERCOSTAL 1

CHANNEL



## DETAIL I AT RBL 45.50 BETWEEN BS 520 AND WING BOX ELECTRICAL BRACKET ANGLE AFT REPAIR INTERCOSTAL WEB 1

WING BOX FWD INBD BUSHING PLAIN PIVOT LINK BUSHING PLAIN STRAP INTERCOSTAL LINK PIN 43 43 PIN 520 BS

44 PIN FLOOR BEAMB22312

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 236

### BOEING SERVICE BULLETIN 737-53-1120

F F F F F

G E



### 32 37
32 35 38 32 35

38

17 22

FWD STA 520 21 27 38 34

34 38

3016 31

2 30 32 36 38 33 32 12 PLACES 7 PLACES FORWARD

INTERCOSTAL WEB
C 0.70 1.01 B

D D

C 0.20 0.17

B FLANGE FILLER

INTERCOSTAL TOP CHORD

0.24 AND INSTALL NEW ONE INTERCOSTAL CHANNEL REMOVE EXISTING

CHANNEL RADIUS FILLER INTERCOSTAL LINK PIVOT BOLT
PIVOT LINK

PIVOT JOINT



## VIEW A-A SEAT TRACK ENDS AFT FLANGE FILLER

INTERCOSTAL LINK

CHANNEL FLOOR BEAMB22703

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 237

### BOEING SERVICE BULLETIN 737-53-1120

LINK INTERCOSTAL L C

90` BUSHING FLANGED 14

WASHER 15

43

24 41 13 

## SECTION C-C SECTION B-BB22789

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 238

### BOEING SERVICE BULLETIN 737-53-1120

34 28

33

29 34 38 28

36 38 38 34

38 36 D D B

B
B B

B A
C

B A
C 

### 38

38 98

12 PLACES ANGLE REPAIR FORWARD

CHANNEL FILLER AFT FLANGE C LINK INTERCOSTAL L

BRACKET PULLEY

CHANNEL RADIUS FILLER ANGLE AFT REPAIR

BEAM WEB FLOOR

ALL OTHER LOCATIONS SIMILIAR LBL 24.75 SHOWN LOOKING FORWARD 

## VIEW D-D BRACKET PULLEYB23181

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 239

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. Removal Steps 1. Mark and identify the forward edge of the intercostal web and the intercostal top chord. Remove and keep them. 2. Remove and discard the intercostal channel. Inspection Steps 3. Make a close visual inspection for cracks on both sides of the floor beam. Look for more cracks that started after the repair steps in the initial release of this service bulletin were done. Also look for more cracks in the top flange and in the web-to-flange radius below it. NOTE: Most floor beam cracks start at the centerline of the intercostal link. 4. It is not necessary to do more work on floor beam cracks that were stop-drilled with steps in the initial release of this service bulletin. 5. Make an eddy current inspection of the aft side of the floor beam surface to find cracks that cannot be seen visually. Inspect the surface of the web and the web-to-flange radius inside the area shown (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 4). 6. Make an eddy current inspection of these two existing fastener holes for small cracks (Refer to the 737 Nondestructive Test Manual Part 6, Subject 51-00-00, Figure 1 or Figure 11). NOTE: As shown in Figure 9, a minimum distance of 0.125 inch is permitted between the edge of a new stop-drill hole and the edge of one of the existing fastener holes shown. The floor beam cannot be repaired with the instructions given in this service bulletin if this minimum distance cannot be kept. Refer to Figure 9 for the stop-drill instructions. 7. If more cracks are found in the floor beam, stop-drill the crack ends as shown in Figure 9. The steps in this service bulletin can only be done if the cracks are in the limits shown in Figure 9. Repair Steps 8. Remove and discard the fasteners that attach the pulley brackets to the floor beam where the repair angle will be installed. 9. Move the pulley bracket away from the floor beam. 10. Get the Channel 69-77976-1 that was kept. This channel is part of the Channel-Pivot Link Assembly 65C34978-4. 11. Get the aft repair angle (Refer to Circle Note Step 28 to get the part number for the aft repair angle). 12. Locate the channel and the aft repair angle on the floor beam. 13. If it has not been done, temporarily connect the pivot link to the channel. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-231, the Pivot Bolt BACB30NF5D37 or BACB30NR5DK37, the Washer AN960C516 (install between the channel and the nut), the Washers AN960C716L (install between the channel and the pivot link) and the Nut BACN10JD5CD.

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 240

### BOEING SERVICE BULLETIN 737-53-1120
14. Get the intercostal link that was kept. If the Flanged Bushing BACB28AT07B018C are not installed, remove and discard the existing flanged bushings (two places) from the forward end. NOTE: The length of the flanged bushings in the kits referenced with the initial release of this service bulletin were not correct. 15. Install the new Flanged Bushing BACB28AT07B018C (two places) with sealant (BMS 5-95). Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. 16. Cut and remove material from the forward end of the intercostal link. 17. Rubber stamp the new part number 65C34978-30 on the intercostal link (Refer to the Standard Overhaul Practices Manual 20-50-10). 18. Temporarily connect the intercostal link to the wing box structure. Use the fasteners that were kept at the connection. These fasteners include the Plain Bushing NAS75-4-112, the Bolt NAS1104-23D, the Washer AN960-PD416 and the Nut AN320-4. 19. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, temporarily install the fasteners that attach the aft end of the intercostal link to the strap (two places). These fasteners were kept when the intercostal link was removed. 20. Temporarily connect the pivot link to the intercostal link. The fasteners at this pivot joint include the Plain Bushing BACB28AK05-147 the Pivot Bolt BACB30NR5DK25, the Washer AN960C516 and the Nut BACN10JD5CD. NOTE: The length of the plain bushing and the pivot bolt in the kits referenced with the initial release of this service bulletin was not correct. 21. Make sure that there is a horizontal clearance of 0.17 to 0.20 inch between the seat track ends. Make a mark at the location where the material will be removed if the clearance is not sufficient. 22. Make sure that there is a minimum horizontal clearance of 0.25 inch between the forward edge of the intercostal link and the structure below the seat track ends. This structure includes the aft flange filler and the inside surface of the channel. NOTE: This is done to make sure that only the seat track ends touch each other when relative movement occurs between the floor beam and the wing box structure in the forward-aft direction. 23. (Not shown) Make marks to identify the installed position of the aft repair angle on the floor beam. 24. Remove and keep the pivot link and the fasteners at both pivot joints. 25. Remove and keep the fasteners that attach the aft end of the intercostal link to the wing box structure. 26. Remove and keep the fasteners that attach the aft end of the intercostal link to the strap (two places). 27. If necessary, cut and remove material from the seat track end where the mark was made.

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 241

### BOEING SERVICE BULLETIN 737-53-1120
28. Refer to the correct figure in the table below : NOTE: The referenced figures are shown looking forward. Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 Do Circle Note Steps 1 through 11 in Figure 49 Do Circle Note Steps 1 through 12 in Figure 50 Do Circle Note Steps 1 through 12 in Figure 51 Do Circle Note Steps 1 through 9 in Figure 52 29. Backdrill the repair angles and the channel through the holes in the floor beam. 30. Locate the new intercostal channel on the floor beam. Use the Intercostal Channel 65C34978-49 at Left or Right Buttock Line 45.50. Use the Intercostal Channel 65C34978-50 at Left or Right Buttock Line 24.75. 31. Cut and remove material from the top of the intercostal channel. This is done to give sufficient clearance between the top of the intercostal channel and the forward flange filler. The maximum distance that the cut edge can be made from the original edge on the Intercostal Channel 65C34978-49 is 0.22 inch. The maximum distance that the cut edge can be made from the original edge on the Intercostal Channel 65C34978-50 is 0.10 inch. 32. Locate the new intercostal channel, the existing intercostal web without cracks and/or the existing intercostal top chord without cracks on the floor beam. Make sure that there is sufficient clearance between the aft end of the intercostal web/top chord and the radius in the intercostal channel. If necessary, cut and remove material from the aft end of the intercostal web and the intercostal top chord. Make sure to keep a minimum edge distance of 1.0 X the diameter (1.0 D) on these existing holes. Backdrill the new holes in the intercostal channel through the existing holes. If the intercostal web or the intercostal top chord are cracked, drill new holes on the intercostal channel 0.33 - 0.39 inch from the forward edge of the intercostal channel. This figure shows, without dimensions, the recommended vertical locations for the new fastener holes. 33. Backdrill the holes in the intercostal channel through the holes in the floor beam. 34. Refer to the correct figure in the table below. Use the figure to install the repair angles, the flange fillers, and the other repair parts. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95): NOTE: The referenced figures are shown looking forward. Buttock Line (BL) Location of Repair Left BL 45.50 Left BL 24.75 Right BL 24.75 Right BL 45.50 Do the steps that remain in Figure 49 Do the steps that remain in Figure 50 Do the steps that remain in Figure 51 Do the steps that remain in Figure 52 35. Refer to Figure 24 to install the intercostal web and the intercostal top chord that were removed. 36. Get the Channel Radius Filler 65C34978-47. Install the intercostal channel, the channel, and the channel radius filler on the repair angle. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95).
FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 242

### BOEING SERVICE BULLETIN 737-53-1120

37. Install the fasteners that attach the intercostal channel to the intercostal web and to the intercostal top chord. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 38. Apply a layer of water-displacing corrosion-inhibiting compound to the intercostal web, the intercostal top chord, the intercostal channel, the channel, the repair angles, the channel radius fillers, the flange fillers, and to the areas of the floor beam where it was removed (Refer to the 737-100/200 Structural Repair Manual Subject 51-10-2). Obey all warnings and cautions given. Cover the pulleys, the cables, and the holes in the channel where the pivot bolt will be installed. 39. Connect the intercostal link to the wing box structure. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 40. Some airplanes have a strap at the aft end of intercostal link. If a strap is installed, install the fasteners that attach the aft end of the intercostal link to the strap (two places). 41. Connect the pivot link to the channel. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 42. Connect the pivot link to the intercostal link. Apply a layer of Grease MIL-G-23827 to both the internal and external surfaces of the plain bushing. 43. Install the Pin MS24665-134 through the pivot bolt at both pivot joints. 44. Install a Pin MS24665-134 (operator supplied) at the connection between the intercostal link and the wing box structure. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.630 - 0.656 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MD8-8 at Right Buttock Line 45.50. Install a hex drive bolt BACB30MD8-9 at the other locations. Install with a collar BACC30AC8. B. Increase the existing hole diameter to 0.231 - 0.234 inch. Drill to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.510 - 0.531 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MA6-8 at Right Buttock Line 45.50. Install a hex drive bolt BACB30MA6-9 at the other locations. Install with a collar BACC30Y6. C. Drill a 0.294 - 0.297 inch diameter hole to match the holes in the floor beam. Spotface the channel for the fastener head. Make the spotface 0.600 - 0.625 inch diameter X 0.01 inch deep maximum. Make a 0.062 - 0.090 inch fillet radius in the spotface. Apply a layer of chemical film treatment, a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on the spotfaced surface. Install a hex drive bolt BACB30MA8-8 at Right Buttock Line 45.50. Install a hex drive bolt BACB30MA8-9 at the other locations. Install with a collar BACC30Y8. D. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MD8-10 at Right Buttock Line 45.50. Install a hex drive bolt BACB30MD8-11 at the other locations. Install with a collar BACC30AC8. Install with the head on the surface of the channel radius filler.

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 243

### BOEING SERVICE BULLETIN 737-53-1120

E. See the table below. F. See the table below. Fasteners for the Intercostal Channel Changes Fastener Symbol "E" Fastener Symbol "F" Name Fastener Hole Size (inch) Name Fastener Hole Size (inch) The Intercostal Web is Repaired Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FP6-3 and BACC30M6 0.216 -0.219

0.200 -0.203 Rivet BACR15BB6D6

or MS20470D5-6 0.191 -0.202

0.159 -0.171 The Intercostal Web is Replaced The Intercostal

Top Chord is

Replaced

Both the Intercostal Web and the Intercostal Top Chord are Replaced Hex Drive Bolt BACB30MY6K3Y and BACC30R6 or BACB30FM6-3 and BACC30M6 216 - 0.219

0.187 -0.190 Rivet BACR15BB6D6

or MS20470D5-6 0.191 -0.202

0.159 -0.171

G. Alternative #1: Increase the existing hole diameter to 0.216 - 0.219 inch. Install a hex drive bolt BACB30MY6K3Y with a collar BACC30R6. Alternative #2: Increase the existing hole diameter to 0.200 - 0.203 inch. Install a hex drive bolt BACB30FP6-3 with a collar BACC30M6.

FIGURE 48. INSPECTION AND REPAIR - INSTALLATION OF TWO REPAIR ANGLES WHERE ONE REPAIR ANGLE WAS INSTALLED AT LEFT OR RIGHT BUTTOCK LINE 24.75,45.50, GROUP 4,5,6 Jul 6/89 737-53-1120 REV 1: May 13/93 244

### BOEING SERVICE BULLETIN 737-53-1120

9

9

14 6

6 13 L

L L L L

L L 

### 5

7 8 6

F6 J J

4 F 5 F F6 E


### 13

4 5 4 H 4 H 5 I

N4 5 H 5 H N 5 5 H 15 H 5 H 12 I 5 I D

D



### 14 14 14 10 8 12 10 5

N8 N8 

### 6 12 6 12 6 12

M



### 3 J B M 

### 6 13

INBD ANGLE REPAIR ORIGINAL

TYPICAL SHIM FWD

WEB FILLER (FORWARD SIDE ONLY) SHEAR WEB

3 PLACES TYPICAL

A A

BRACKET PULLEY AFT REPAIR ANGLE SEE DETAIL I SEAT TRACK



## VIEW A-A
LBL 45.50

LBL 45.50

DOUBLER FILLER PULLEY BRACKET PULLEY FLOOR BEAM FILLER PULLEY FORWARD FLANGE FILLER

SEAT TRACK FILLER FORWARD REPAIR ANGLE
SEE DETAIL I

7 PLACES AFT FLANGE FILLERB26231

FIGURE 49. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 245

### BOEING SERVICE BULLETIN 737-53-1120

G A

C K 

### 11

11 2

11 6 1 SHEAR WEB (OUTBOARD NUTPLATE ONLY)

REMOVE

FWD 

## DETAIL I INBOARD NUTPLATE SHOWN OUTBOARD NUTPLATE SIMILAR EXISTING NUTPLATE

NUTPLATE REPAIR ANGLE

FLANGEB26232

FIGURE 49. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 246

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplate or nutclip. An airplane with a nutplate is shown in this figure. 2. Plug the rivet hole shown if a nutplate was attached to the flange with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Remove and discard this existing rivet from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-44. 5. Locate the Forward Repair Angle 69-77969-9 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-10 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. These holes includes those for the fasteners that attached the original repair angle to the floor beam web. NOTE: The approximate location for some of the fastener holes that attached the original repair angle to the floor beam are shown ( Fastener Symbol "L"). No dimensions were given in the initial release of this service bulletin to locate these holes. 7. Remove the laminations from the Shim BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 8. Put the Seat Track Filler 65C34978-48 and the shim in the installed position. 9. Put the Forward Flange Filler 65C34978-42 and the Aft Flange Filler 65C34978-41 in the installed position. 10. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 11. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle, the flange and the shear web. Microshave the rivet surface that is adjacent to the top surface of the flange or the shear web. Give the surface of a microshaved head the same finish as the adjacent surface. NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 12. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). FIGURE 49. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 247

### BOEING SERVICE BULLETIN 737-53-1120
13. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 14. Install the pulley brackets with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Where the outboard nutplate was installed, make a 100 degree countersink on the top side of the shear web. Where the inboard nutplate was installed, make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange at both locations. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on the repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam structure. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K12X with a collar BACC30X8. Install with the head on the seat track. E. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY6K5Y with a collar BACC30R6. F. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. G. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. H. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the top surface of the flange or the seat track. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. I. Increase the existing hole diameter to 0.216 - 0.219 inch. Drill to match the holes in the floor beam structure. Make a 100 degree countersink on the top surface of the shear web or the seat track. Install a hex drive bolt BACB30NW6K( )Y with a collar BACC30R6. J. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K5 with a collar BACC30M6. K. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. L. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-5 with a collar BACC30M6. M. Drill a 0.231 - 0.234 inch diameter hole to match the holes in the floor beam structure. Install a hex drive bolt BACB30MA6-5 with a collar BACC30Y6. N. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FQ6-( ) with a collar BACC30M6.

FIGURE 49. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 248

### BOEING SERVICE BULLETIN 737-53-1120

9 9 8 6 14 D

D 5 K

P5 5 K 5 K 5 K P5 5 K 5 K K16 5 K K16 

### 10 5

5 13 11

G 5 G6 L B

O E F E L L



### 5 4 6

15

15 P9 P9 

### 10 6 13 6 13

L 

### 3

Q 

### 14 11 14 11 6 14 6 14

INBD FWD

O O O O O 

### TYPICAL

ORIGINAL REPAIR ANGLE SHIM (2 PLACES) A A LBL 24.75 SEAT TRACK FORWARD FLANGE FILLER SEE DETAIL II SEE DETAIL I FORWARD REPAIR ANGLE

AFT REPAIR ANGLE 

## VIEW A-A
24.75

LBL

WEB FILLER (FORWARD SIDE ONLY) DOUBLER FILLER PULLEY PULLEY BRACKET FLOOR BEAM AFT FLANGE FILLER 9 PLACES

SEAT TRACK FILLER (2 PLACES)

4 PLACESB26744

FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 249

### BOEING SERVICE BULLETIN 737-53-1120

J A

C M

A H I N 

### 12

12

12 2

7 1 1 6 2 FLANGE

FLANGE

NUTPLATE NUTPLATE EXISTING REMOVE

NUTPLATE NUTPLATE EXISTING REMOVE

REPAIR ANGLE

FWD 

## DETAIL II FWD 

## DETAIL IB26742

FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 250

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplate. An airplane with a nutplate is shown in this figure. 2. Plug the rivet hole shown if nutplates was attached to the flange with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Remove and discard this existing rivet from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-45. 5. Locate the Forward Repair Angle 69-77969-7 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-8 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. These holes includes those for the fasteners that attached the original repair angle to the floor beam web. NOTE: The approximate location for some of the fastener holes that attached the original repair angle to the floor beam are shown ( Fastener Symbol "O"). No dimensions were given in the initial release of this service bulletin to locate these holes. 7. Install the Nutplate BACN10KE3D below the forward side of the floor beam flange. Microshave the top end of the rivets that attach the nutplate to the floor beam. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent floor beam. 8. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 9. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 10. Put the Forward Flange Filler 65C34978-38 and the Aft Flange Filler 65C34978-37 in the installed position. 11. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. NOTE: Keep a minimum distance of 0.75 between the center of fastener "F" and "Q". 12. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface.
FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 251

### BOEING SERVICE BULLETIN 737-53-1120
NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 13. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 14. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 15. Install the pulley bracket with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on both repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K13X with a collar BACC30X8. Install with the head on the seat track. E. Drill a 0.231 - 0.234 inch diameter hole to match the holes in the floor beam structure. Install a hex drive bolt BACB30MA6-6 with a collar BACC30Y6. F. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY8K6Y with a collar BACC30R8. G. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. H. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange on the floor beam. Install a rivet BACR15BA3D6. I. Install a rivet BACR15BA3D6. J. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. K. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the top surface of the flange or the seat track. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. L. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K6 with a collar BACC30M6. NOTE: The screws below attach the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. M. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. N. Install the screw BACS12GP3K12 in the nutplate. Install with a 15 to 20 inch - pound torque.
FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 252

### BOEING SERVICE BULLETIN 737-53-1120
O. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-6 with a collar BACC30M6. P. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FQ6-( ) with a collar BACC30M6. Q. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the aft surface of the floor beam web. Install a hex drive bolt BACB30FN6-6 with a collar BACC30BL6.

FIGURE 50. REPAIR ANGLES - INSTALLATION AT LEFT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 253

### BOEING SERVICE BULLETIN 737-53-1120

Q L

5 G 6 G F
E B E

O L L 

### 14 6 14 6

11 14 3

14 6 O OO O O 

### 13 6

14 11 13 6 5 9 P 9 P 16 K

D D



### 10

4 5 15

15 6 K5 5 P K5 K5 K5 K5 K5
K5 5 P 16 K 

### 5

11 13

8 9 9 10

TYPICAL FWD

ORIGINAL REPAIR ANGLE

INBD A A (2 PLACES) SHIM AFT REPAIR ANGLE 9 PLACES


## VIEW A-A AFT FLANGE FILLER

BEAM FLOOR 24.75

RBL 24.75

RBL

DOUBLER WEB FILLER (FORWARD SIDE ONLY) PULLEY FILLER BRACKET PULLEY FORWARD REPAIR ANGLE SEE DETAIL II SEE DETAIL I SEAT TRACK

SEAT TRACK FILLER (2 PLACES) FORWARD FLANGE FILLERB26741

FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 254

### BOEING SERVICE BULLETIN 737-53-1120

J A I H N

C M

A 

### 12

12

12 2

1 1 6

7 2 FLANGE

FLANGE NUTPLATE EXISTING REMOVE NUTPLATE EXISTING REMOVE

NUTPLATE NUTPLATE REPAIR ANGLE

FWD 

## DETAIL II FWD 

## DETAIL IB26743

FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 255

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplates. An airplane with a nutplate is shown in this figure. 2. Plug the hole shown if a nutplate was attached to the flange with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Remove and discard this existing rivet from the floor beam web. 4. Use the forward repair angle as a template to cut and remove material from the Web Filler 65C34978-46. 5. Locate the Forward Repair Angle 69-77969-5 and the web filler on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-6 are the same. 6. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. These holes includes those for the fasteners that attached the original repair angle to the floor beam web. NOTE: The approximate location for some of the fastener holes that attached the original repair angle to the floor beam are shown ( Fastener Symbol "O"). No dimensions were given in the initial release of this service bulletin to locate these holes. 7. Install the Nutplate BACN10KE3D below the forward side of the floor beam flange. Microshave the top end of the rivets that attach the nutplate to the floor beam. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent floor beam. 8. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 9. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 10. Put the Forward Flange Filler 65C34978-38 and the Aft Flange Filler 65C34978-37 in the installed position. 11. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. NOTE: Keep a minimum distance of 0.75 between the center of fastener "F" and "Q". 12. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface.
FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 256

### BOEING SERVICE BULLETIN 737-53-1120
NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 13. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 14. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 15. Install the pulley bracket with a Pulley Filler 65C34978-43.

The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a No. 0.221 - 0.233 inch diameter hole. Make a 100 degree countersink on the repair angles. Install a rivet BACR15AD7D10. C. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam. Give the hole surface the same finish as the adjacent structure. D. Install a hex drive bolt BACB30NY8K13X with a collar BACC30X8. Install with the head on the seat track. E. Drill a 0.231 - 0.234 inch diameter hole to match the holes in the floor beam structure. Install a hex drive bolt BACB30MA6-6 with a collar BACC30Y6. F. Increase the existing hole diameter to 0.278 - 0.281 inch. Drill to match the holes in the floor beam. Install a hex drive bolt BACB30MY8K6Y with a collar BACC30R8. G. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. H. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange on the floor beam. Install a rivet BACR15BA3D6. I. Install a rivet BACR15BA3D6. J. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. K. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the top surface of the flange or the seat track. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. L. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K6 with a collar BACC30M6. M. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions.

FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 257

### BOEING SERVICE BULLETIN 737-53-1120
N. Install the screw BACS12GP3K12 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. O. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-6 with a collar BACC30M6. P. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FQ6-( ) with a collar BACC30M6. Q. Drill a 0.187 - 0.190 inch diameter hole. Make a 100 degree countersink on the aft surface of the floor beam web. Install a hex drive bolt BACB30FN6-6 with a collar BACC30BL6.

FIGURE 51. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 24.75, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 258

### BOEING SERVICE BULLETIN 737-53-1120

I I



### 12 F 15 F 15 F 5 F 5
J 5 F 5 F 5 J 4 F 4
F 4 F 4

F 4

G D 5

4 D 

### 12 C C 

### 7

4 10 8
3 3

10 4 7

G G G G
G 

### 11 8 6 5 6 J 8 J 8 

### 10 4

I I I

I I I I

I 

### 11 4

ORIGINAL ANGLE REPAIR FWD

6 PLACES SHIM TYPICAL

INBD A A SEAT TRACK
SEE DETAIL I SEE DETAIL I

FLOOR BEAM PULLEY FILLER RBL

RBL FORWARD FLANGE FILLER

PULLEY BRACKET 45.50

45.50 

## VIEW A-A AFT REPAIR ANGLE FORWARD REPAIR ANGLE

10 PLACES AFT FLANGE FILLER

SEAT TRACK FILLERB26068

FIGURE 52. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 259

### BOEING SERVICE BULLETIN 737-53-1120

E A H

B 

### 9

9

9 2 1 4

REPAIR ANGLE NUTPLATE NUTPLATE EXISTING REMOVE



## DETAIL I FWD FLANGEB26070

FIGURE 52. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 260

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Remove and discard the existing nutplates. An airplane with a nutplate is shown in this figure. 2. Plug the hole shown if a nutplate was attached to the flange with rivets. Microshave the top and bottom ends of the rivet. Refer to the 737-100/200 Structural Repair Manual Subject 51-70. Give the surface of the microshaved head the same finish as the adjacent surface. 3. Locate the Forward Repair Angle 69-77969-3 on the forward side of the floor beam. Adjust the forward repair angle in the inboard - outboard direction until the center of the forward and the Aft Repair Angle 69-77969-4 are the same. 4. Backdrill the holes in the repair angles through the existing holes in the floor beam and in the seat track. These holes includes those for the fasteners that attached the original repair angle to the floor beam web. NOTE: The approximate location for the fastener holes that attached the original repair angle to the floor beam are shown ( Fastener Symbol "I"). No dimensions were given in the initial release of this service bulletin to locate these holes. 5. Remove the laminations from the Shims BACS40R009D010F until the clearance, before the fastener pull, is not greater than 0.010 inch. Apply a layer of primer (BMS 10-11 type I) to the shim. 6. Put the Seat Track Fillers 65C34978-48 and the shims in the installed position. 7. Put the Forward Flange Filler 65C34978-36 and the Aft Flange Filler 65C34978-35 in the installed position. 8. Locate and drill these holes for the fasteners that attach the repair angle to the floor beam. Keep a minimum distance of 0.65 between the center of each fastener hole. Keep a minimum edge margin of 0.33. This figure shows, without dimensions, the recommended locations for the fastener holes. 9. Alternative #1 (as shown in this figure) - Plug the rivet hole shown and install the Nutplate BACN10KE3D on the repair angle. Microshave the rivet surface that is adjacent to the top surface of the repair angle. Give the surface of a microshaved head the same finish as the adjacent surface. Alternative #2 (not shown in this service bulletin) - Install the Nutplate BACN10KE3D on the repair angle. Install the rivets through both the repair angle and the flange. Microshave the rivet surface that is adjacent to the top surface of the flange. Give the surface of a microshaved head the same finish as the adjacent surface. NOTE: Do more steps, as shown in the repair figure before the subsequent circle note steps are done. 10. Install the fasteners that attach the repair angles and the flange fillers to the seat track and to the floor beam flange. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 11. Install the remaining fasteners that attach the repair angles to the floor beam. Apply a layer of sealant to the faying surfaces and to the hex drive bolts (BMS 5-95). 12. Install the pulley bracket with a Pulley Filler 65C34978-43. FIGURE 52. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 261

### BOEING SERVICE BULLETIN 737-53-1120
The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A number in the lower right corner gives the grip length of the fastener. A. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top side of the flange. Light countersink the bottom side of the flange. Install a rivet BACR15CE3D6. B. Drill a 0.250 - 0.261 inch diameter hole in the forward repair angle to match the hole in the floor beam flange. Give the hole surface the same finish as the adjacent structure. C. Install a hex drive bolt BACB30NY8K12X with a collar BACC30X8. Install with the head on the seat track. D. Increase the existing hole diameter to 0.187 - 0.190 inch. Install a hex drive bolt BACB30MY6K( ) with a collar BACC30M6. Install with the head on the pulley bracket surface. E. Drill a No. 40 (0.098 - 0.103) inch diameter hole. Make a 100 degree countersink on the top end of the forward repair angle. Install a rivet BACR15BA3D4. F. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30VU6K( ) with a collar BACC30BL6. Make a 100 degree countersink on the top surface of the flange or the seat track. G. Drill a 0.187 - 0.190 inch diameter hole. Install a hex drive bolt BACB30MY6K5 with a collar BACC30M6. H. Install the screw BACS12GP3K14 in the nutplate. Install with a 15 to 20 inch - pound torque. NOTE: This screw attaches the floor panels to the floor beam. Install this screw when the floor panels are installed with the steps given in the general accomplishment instructions. I. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FP6-5 with a collar BACC30M6. J. Increase the existing hole diameter to 0.200 - 0.203 inch. Drill to match the holes in the existing structure. Install a hex drive bolt BACB30FQ6-( ) with a collar BACC30M6.

FIGURE 52. REPAIR ANGLES - INSTALLATION AT RIGHT BUTTOCK LINE 45.50, GROUP 4,5,6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 262

### BOEING SERVICE BULLETIN 737-53-1120

A



### 4 7 2 3 1 4

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN

B B

A

A PIVOT LINK CHANNEL,

INBD

FWD RBL 45.5 FLOOR BEAM BS 520

ELECTRICAL BRACKET STRAP

SUPPORT CLIP

WING BOX (SEE DETAIL I) SUPPORT CLIP801100

FIGURE 53. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 263

### BOEING SERVICE BULLETIN 737-53-1120

ELECTRICAL BRACKET

0.07 0.12

CHANGES TO THE ELECTRICAL BRACKET PIVOT LINK



## VIEW B-B ELECTRICAL BRACKET

6

5 0.16R 1.23 CHANNEL DISTANCE EDGE 0.27 FLANGED BUSHING

5 0.60

FLANGED BUSHING

FWD FWD INBD SUPPORT CHANNEL SUPPORT CLIP 0.28



## VIEW A-A 0.35802173

FIGURE 53. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 264

### BOEING SERVICE BULLETIN 737-53-1120



## DETAIL I SUPPORT CLIP "A" 2
BOTTOM HOLE

0.23 EDGE DISTANCE FWD802174The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Channel 69-77845-3. Temporarily connect the Pivot Link 65C34622-3 to the channel. 2. Get the Support Clip 65-49714-8 that was kept or make one Support Clip "B". Refer to the instructions in Figure 67 to make the Support Clip "B". If the Support Clip 65-49714-8 was kept, cut and remove material from it. Keep an edge distance of 0.23 inch between the cut edge on the forward side and the edge of the bottom hole. The Support Clip 65-49714-8 with the changes becomes Support Clip "A". 3. Locate the Support Clip "A" or "B" below the electrical bracket with the forward-bottom edge 0.28 inch from the inside surface of the channel. Move the location of the support clip in the vertical direction until the top edge of the support clip makes contact with the bottom edge of the flanged bushings in the channel. 4. Get the Electrical Bracket 65-49714-12 that was kept. Put the channel and the electrical bracket in the installed position. 5. Cut and remove the material shown. 6. Rubber stamp the new part number 65C35994-6 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Backdrill the holes in the side of the channel through the holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 20 (0.159 - 0.171) inch diameter hole to match the holes in the support clip. Install a rivet BACR15BB5D6.

FIGURE 53. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 265

### BOEING SERVICE BULLETIN 737-53-1120

A 

### 3 7 1

4 4 2 PLATE "A" B A

A

B PIVOT LINK CHANNEL,

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN STRAP SUPPORT CLIP "C" RBL 45.5 FLOOR BEAM BS 520

SUPPORT CLIP ELECTRICAL BRACKET

WING BOX INBD

FWD802076

FIGURE 54. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 266

### BOEING SERVICE BULLETIN 737-53-1120

BRACKET ELECTRICAL



## VIEW B-B PIVOT LINK

CHANGES TO THE ELECTRICAL BRACKET 0.12 0.07 BRACKET ELECTRICAL 0.27 EDGE DISTANCE FLANGED BUSHING

CHANNEL

1.23 0.16R 6

5 0.28



## VIEW A-A SUPPORT CHANNEL

INBD FWD SUPPORT CLIP PLATE "A"

FWD FLANGED BUSHING

PLATE"A" 5 0.60

0.35802083

FIGURE 54. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 267

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make one Support Clip "C". Refer to the instructions in Figure 68 to make the support clip. 2. Get the Channel Assembly "B". Temporarily connect the Pivot Link 65C34622-3 to the channel assembly. 3. Locate the Support Clip "C" below the electrical bracket with the forward-bottom edge 0.28 inch from the inside surface of the channel. Move the location of the support clip in the vertical direction until the top edge of the support clip makes contact with the bottom edge of the flanged bushings in the channel. 4. Get the Electrical Bracket 65-49714-12 that was kept. Put the channel and the electrical bracket in the installed position. 5. Cut and remove the material shown. 6. Rubber stamp the new part number 65C35994-6 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Backdrill the holes in the side of the channel through the holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 10 (0.191 - 0.202) inch diameter hole to match the pilot holes in the support clip. Install a rivet BACR15BB6D10.

FIGURE 54. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 268

### BOEING SERVICE BULLETIN 737-53-1120

6 8 4 5 2 3 1 PIVOT LINK CHANNEL,

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN A A

SUPPORT CLIP (SEE DETAIL II) ELECTRICAL BRACKET RBL 45.5 FLOOR BEAM BS 520

STRAP

WING BOX INBD

FWD802104

FIGURE 55. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 269

### BOEING SERVICE BULLETIN 737-53-1120

0.18 ELECTRICAL BRACKET (SEE DETAIL I)

2

2 0.27 EDGE DISTANCE 

## DETAIL I CHANGES TO THE ELECTRICAL BRACKET 7 0.07 MINIMUM

FWD 

## VIEW A-A FWD SUPPORT CLIP SUPPORT CHANNEL

AA



### 0.35 0.60 1.50 1.40
0.56 MINIMUM802101

FIGURE 55. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 270

### BOEING SERVICE BULLETIN 737-53-1120

6

4 0.37 EDGE MARGIN

0.37 EDGE MARGIN 0.40 0.16 RADIUS (2 PLACES) 0.27 EDGE DISTANCE



## DETAIL II CHANGES TO THE SUPPORT CLIP802105The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Channel 69-77845-3 and temporarily connect the Pivot Link 65C34622-3 to it. 2. Get the Electrical Bracket 65-49714-32 or 65-49714-36 that was kept. Cut and remove material from the forward end of the electrical bracket. 3. Rubber stamp the new part number 65C35994-8 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 4. Drill two 0.125 inch diameter pilot holes in the Support Clip 65C35994-5. 5. Locate the support clip on the channel with the center of the pilot holes in the support clip 0.56 inch minimum from the aft surface of the channel. This is done to keep the fasteners heads away from the radius in the channel when the support clip is installed. Locate the bottom end of the support clip 1.40 to 1.50 inch from the bottom end of the channel. Keep a minimum clearance of 0.07 between the edge of the support clip and the pivot link. 6. If necessary, cut and remove material from the support clip to get the clearances above. Limits for removal of this material are shown. 7. Cut and remove material from the forward end of the support clip if it does not have sufficient clearance with the radius in the channel. Make sure to keep a minimum edge distance of 0.23 at the rivet holes in the support clip. 8. Backdrill the holes in the side of the channel through the pilot holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure.

FIGURE 55. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 271

### BOEING SERVICE BULLETIN 737-53-1120 A. Drill a No. 20 (0.159 - 0.171) inch diameter hole to match the holes in the support clip. Install a rivet BACR15BB5D6.

FIGURE 55. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 272

### BOEING SERVICE BULLETIN 737-53-1120

1

2 3

4 5 6 7 PLATE "A"

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN A A PIVOT LINK CHANNEL,

INBD

FWD RBL 45.5 FLOOR BEAM BS 520

STRAP

WING BOX (SEE DETAIL I) ELECTRICAL BRACKET

SUPPORT CLIP (SEE DETAIL II)802211

FIGURE 56. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 273

### BOEING SERVICE BULLETIN 737-53-1120

0.18 ELECTRICAL BRACKET (SEE DETAIL I)

0.27 EDGE DISTANCE 2

2



## DETAIL I CHANGES TO THE ELECTRICAL BRACKET 0.07 MINIMUM

PLATE "A"

FWD 

## VIEW A-A FWD SUPPORT CLIP SUPPORT CHANNEL

AA



### 0.35 0.60 1.50 1.40
0.60 MINIMUM802187

FIGURE 56. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 274

### BOEING SERVICE BULLETIN 737-53-1120

4 6

0.37 EDGE MARGIN

CHANGES TO THE SUPPORT CLIP 

## DETAIL II 0.37 EDGE MARGIN 0.27 EDGE DISTANCE (2 PLACES) 0.16 RADIUS

0.40802389The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get the Channel Assembly "B" and temporarily connect the Pivot Link 65C34622-3 to it. 2. Get the Electrical Bracket 65-49714-32 or 65-49714-36 that was kept. Cut and remove material from the forward end of the electrical bracket. 3. Rubber stamp the new part number 65C35994-8 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 4. Drill two 0.125 inch diameter pilot holes in the Support Clip 65C35994-5. 5. Locate the support clip on the channel with the center of the pilot holes in the support clip 0.60 inch minimum from the aft surface of the channel. This is done to keep the fasteners heads away from the radius in the channel when the support clip is installed. Locate the bottom end of the support clip 1.40 to 1.50 inch from the bottom end of the channel. Keep a minimum clearance of 0.07 between the edge of the support clip and the pivot link. 6. If necessary, cut and remove material from the support clip to get the clearances above. Limits for removal of this material are shown. 7. Backdrill the holes in the side of the channel through the pilot holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 10 (0.191 - 0.202) inch diameter hole to match the pilot holes in the support clip. Install a rivet BACR15BB6D10. FIGURE 56. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 275

### BOEING SERVICE BULLETIN 737-53-1120

A A 1 PIVOT LINK CHANNEL, RBL 45.5 FLOOR BEAM BS 520

SUPPORT CLIP "B" 3 7 2

A



### B B

4 STRAP

SUPPORT CLIP

WING BOX ELECTRICAL BRACKET

INBD FWD

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN802380

FIGURE 57. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 Jul 6/89 737-53-1120 REV 1: May 13/93 276

### BOEING SERVICE BULLETIN 737-53-1120

ELECTRICAL BRACKET

ELECTRICAL BRACKET

0.07 0.12

CHANGES TO THE ELECTRICAL BRACKET PIVOT LINK



## VIEW B-B DISTANCE EDGE 0.27 FLANGED BUSHING

6

5 0.16R 1.23 CHANNEL SUPPORT CLIP

SUPPORT CHANNEL 0.28

FWD INBD 

## VIEW A-A

FLANGED BUSHING

FWD 0.60

5 0.35799698

FIGURE 57. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 Jul 6/89 737-53-1120 REV 1: May 13/93 277

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Temporarily connect the pivot link 65C34622-3 to the channel. 2. Get the Support Clip 65-49714-8 that was kept or make one Support Clip "B". Refer to the instructions in Figure 67 to make the Support Clip "B". 3. Locate the support clip below the electrical bracket with the forward-bottom edge 0.28 inch from the inside surface of the channel. Move the location of the support clip in the vertical direction until the top edge of the support clip makes contact with the bottom edge of the flanged bushings in the channel. 4. Get the Electrical Bracket 65-49714-12 that was kept. Put the channel and the electrical bracket in the installed position. 5. Cut and remove the material shown. 6. Rubber stamp the new part number 65C35994-6 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Backdrill the holes in the side of the channel through the holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 20 (0.159 - 0.171) inch diameter hole to match the holes in the support clip. Install a rivet BACR15BB5D6.

FIGURE 57. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 Jul 6/89 737-53-1120 REV 1: May 13/93 278

### BOEING SERVICE BULLETIN 737-53-1120

520 BS FLOOR BEAM 45.5 RBL

CHANNEL, PIVOT LINK 1 STRAP

WING BOX FWD INBD 5 4 ELECTRICAL BRACKET

3 2 (SEE DETAIL II) SUPPORT CLIP A

A

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN802235

FIGURE 58. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 Jul 6/89 737-53-1120 REV 1: May 13/93 279

### BOEING SERVICE BULLETIN 737-53-1120

0.18

(SEE DETAIL I) ELECTRICAL BRACKET



## DETAIL I CHANGES TO THE ELECTRICAL BRACKET 5

5 0.27 EDGE DISTANCE 5

2 0.07 MINIMUM

0.28 7 3 6

FWD



## VIEW A-A FWD SUPPORT CHANNEL

AA 

### SUPPORT CLIP 0.35 0.60

1.10 1.20

0.37 EDGE MARGIN

0.37 EDGE MARGIN 0.40



## DETAIL II802392

FIGURE 58. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 Jul 6/89 737-53-1120 REV 1: May 13/93 280

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Temporarily connect the pivot link 65C34622-3 to the channel. 2. Drill two 0.125 inch diameter pilot holes in the Support Clip 65C35994-5. 3. Locate the forward end of the support clip 0.28 inch from the inside surface of the channel. Locate the bottom end of the support clip 1.10 to 1.20 inch from the bottom end of the channel. 4. Get the Electrical Bracket 65-49714-32 or 65-49714-36 that was kept. Put the channel and the electrical bracket in the installed position. 5. Cut and remove material from the slot in the forward end of the electrical bracket. Keep a minimum clearance of 0.07 between the forward edge of the electrical bracket and the pivot link. If necessary, cut and remove material from the forward end of the electrical bracket as shown. 6. Rubber stamp the new part number 65C35994-6 on the electrical bracket (Refer to the Standard Overhaul Practices Manual 20-50-10). 7. Backdrill the holes in the side of the channel through the pilot holes in the support clip. Apply a layer of sealant to the faying surfaces (BMS 5-95). Install the support clip. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 20 (0.159 - 0.171) inch diameter hole to match the holes in the support clip. Install a rivet BACR15BB5D6.

FIGURE 58. ELECTRICAL BRACKET CHANGES AND SUPPORT CLIP INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 Jul 6/89 737-53-1120 REV 1: May 13/93 281

### BOEING SERVICE BULLETIN 737-53-1120

3 INSTALLATION FOR NUT-CLIP SEE DETAIL I CHANNEL

2 4
2 AS NECESSARY 0.229 0.218SLOT 1

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN SUPPORT CLIP SUPPORT CLIP

FWD INBD WING BOX STRAP

ELECTRICAL BRACKET 520 BS FLOOR BEAM 45.5 RBLB13101

FIGURE 59. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 Jul 6/89 737-53-1120 REV 1: May 13/93 282

### BOEING SERVICE BULLETIN 737-53-1120

3 3

3 SPACER SLEEVE SUPPORT CLIP CHANNEL ELECTRICAL BRACKET NUT-CLIP

SCREW
NUT-CLIP INSTALLATION 

## DETAIL IC22085The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Put the Electrical Bracket 65C35994-6 in the installed position. 2. Adjust the forward-aft position of the electrical bracket to give it the maximum possible clearance with the inside surface of the channel. NOTE: This clearance is necessary to permit relative movement between the floor beam and the wing box structure in the forward-aft direction without interference. If necessary, increase the length of the slot for the screw on the aft end of the electrical bracket to get more clearance 3. Install the Screw NAS1801-3-7, the Spacer Sleeve NAS43DD3-5FC and the Nut-Clip BACN10YD1 on the forward end of the electrical bracket. 4. Install the Screw NAS1801-3-7 and the Nut-Clip BACN10YD1 on the aft end of the electrical bracket.

FIGURE 59. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3, RIGHT BUTTOCK LINE 45.50, GROUP 1,2 Jul 6/89 737-53-1120 REV 1: May 13/93 283

### BOEING SERVICE BULLETIN 737-53-1120

CHANNEL ASSEMBLY

5 4 SEE DETAIL I FOR NUT-CLIP INSTALLATION 1

SLOT 2 AS NECESSARY 0.229 0.218 PLATE "A"

A

A

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN SUPPORT CLIP SUPPORT CLIP "C" STRAP RBL 45.5 FLOOR BEAM BS 520

WING BOX ELECTRICAL BRACKET

INBD

FWD799726

FIGURE 60. ELECTRICAL BRACKET INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 Jul 6/89 737-53-1120 REV 1: May 13/93 284

### BOEING SERVICE BULLETIN 737-53-1120

ELECTRICAL BRACKET

4 4

4 3 2

0.37 EDGE MARGIN FLANGED BUSHING MARGIN EDGE 0.37

PLATE "A" CHANNEL



## DETAIL I NUT-CLIP INSTALLATION SCREW NUT-CLIP ELECTRICAL BRACKET

SPACER SLEEVE SUPPORT CLIP "C"

FWD INBD PLATE "A"



## VIEW A-A

CHANNEL

SUPPORT CLIP "C"800893

FIGURE 60. ELECTRICAL BRACKET INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 Jul 6/89 737-53-1120 REV 1: May 13/93 285

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Put the Electrical Bracket 65C35994-6 in the installed position. 2. Adjust the forward-aft position of the electrical bracket to give it the maximum possible clearance with the inside surface of the channel assembly. NOTE: This clearance is necessary to permit relative movement between the floor beam and the wing box structure in the forward-aft direction without interference. If necessary, increase the length of the slot for the screw on the aft end of the electrical bracket to get more clearance. 3. Backdrill a 0.218 - 0.229 inch diameter hole in the Support Clip "C" through the slot in the electrical bracket. Keep an edge margin of 0.37 on the Support Clip "C ". 4. Install the Screw NAS1801-3-7, the Spacer Sleeve NAS43DD3-5FC and the Nut-Clip BACN10YD1 on the forward end of the electrical bracket. 5. Install the Screw NAS1801-3-7 and the Nut-Clip BACN10YD1 on the aft end of the electrical bracket.

FIGURE 60. ELECTRICAL BRACKET INSTALLATION - CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 1,2 Jul 6/89 737-53-1120 REV 1: May 13/93 286

### BOEING SERVICE BULLETIN 737-53-1120

2 5 CHANNEL

1

SLOT

0.218 0.229 AS NECESSARY 4 3 3 A A

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN ELECTRICAL BRACKET

WING BOX STRAP 520 BS FLOOR BEAM 45.5 RBL

FWD INBD

SUPPORT CLIP800992

FIGURE 61. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3 OR CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 287

### BOEING SERVICE BULLETIN 737-53-1120

WASHER 2 2 2

2 ELECTRICAL BRACKET SPACER SLEEVE

SCREW SUPPORT CLIP

NUT



## VIEW A-AB27626The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Put the Electrical Bracket 65C35994-8 in the installed position. 2. Insert the Spacer Sleeve NAS43DD3-5FC, the Washer AN960PD10, the Nut BACN10JC3 and the Screw NAS1801-3-7 on the forward end of the electrical bracket. 3. Adjust the forward-aft position of the electrical bracket to give it the maximum possible clearance with the pivot link that will be installed. NOTE: This clearance is necessary to permit relative movement between the floor beam and the wing box structure in the forward-aft direction without interference. If necessary, slot the hole for the screw on the aft end of the electrical bracket. 4. Install the Screw NAS1801-3-7 and nut BACN10JC3 on the aft end of the electrical bracket. 5. Tighten the screw on the forward end of the electrical bracket.

FIGURE 61. ELECTRICAL BRACKET INSTALLATION - CHANNEL 69-77845-3 OR CHANNEL ASSEMBLY "B", RIGHT BUTTOCK LINE 45.50, GROUP 3 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 288

### BOEING SERVICE BULLETIN 737-53-1120

INSTALLATION FOR NUT-CLIP SEE DETAIL I 3 CHANNEL 520 BS FLOOR BEAM 45.5 RBL

2 4
2 AS NECESSARY 0.229 0.218SLOT

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN FWD INBD WING BOX ELECTRICAL BRACKET STRAP

1 SUPPORT CLIP

SUPPORT CLIP800039

FIGURE 62. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 289

### BOEING SERVICE BULLETIN 737-53-1120

3 3

3



## DETAIL I NUT-CLIP INSTALLATION SCREW NUT-CLIP ELECTRICAL BRACKET CHANNEL

SUPPORT CLIP SPACER SLEEVEC22092The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Put the Electrical Bracket 65C35994-6 in the installed position. 2. Adjust the forward-aft position of the electrical bracket to give it the maximum possible clearance with the inside surface of the channel. NOTE: This clearance is necessary to permit relative movement between the floor beam and the wing box structure in the forward-aft direction without interference. If necessary, increase the length of the slot for the screw to get more clearance 3. Install the Screw NAS1801-3-7, the Spacer Sleeve NAS43DD3-5FC and the Nut-Clip BACN10YD1 on the forward end of the electrical bracket. 4. Install the Screw NAS1801-3-7 and the Nut-Clip BACN10YD1 on the aft end of the electrical bracket.

FIGURE 62. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 4,5 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 290

### BOEING SERVICE BULLETIN 737-53-1120

CHANNEL

3 4 1 2

SUPPORT CLIP

INBD FWD WING BOX STRAP RBL 45.5 FLOOR BEAM BS 520

ELECTRICAL BRACKET

A A

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN802394

FIGURE 63. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 291

### BOEING SERVICE BULLETIN 737-53-1120

WASHER 2 2 2

2 ELECTRICAL BRACKET SPACER SLEEVE

SCREW SUPPORT CLIP

NUT



## VIEW A-AC22093The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Put the Electrical Bracket 65C35994-8 in the installed position. 2. Insert the Spacer Sleeve NAS43DD3-5FC, the Washer AN960PD10, the Nut BACN10JC3 and the Screw NAS1801-3-7 on the forward end of the electrical bracket. 3. Insert the Screw NAS1801-3-7 and nut BACN10JC3 on the aft end of the electrical bracket. 4. Before the screws are tightened, adjust the forward-aft position of the electrical bracket to give it the maximum possible clearance with the pivot link that will be installed. NOTE: This clearance is necessary to permit relative movement between the floor beam and the wing box structure in the forward-aft direction without interference.

FIGURE 63. ELECTRICAL BRACKET INSTALLATION - RIGHT BUTTOCK LINE 45.50, GROUP 6 AIRPLANES Jul 6/89 737-53-1120 REV 1: May 13/93 292

### BOEING SERVICE BULLETIN 737-53-1120

2 4 5 6

3 1

0.22 R 1.40

4.44 4.56



## CHANNEL RADIUS FILLER "A" (2 PLACES)B08791The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. For radius fillers that are made from an extrusion, use a BAC1511-1550 X 4.60 inch extrusion made from 2024-T3511 aluminum (QQ-A-200/3). 2. For radius fillers that are made from a sheet, use a 0.16 X 4.60 X 1.50 inch sheet made from bare 2024-T3 aluminum (QQ-A-250/4) or clad 2024-T3 aluminum (QQ-A-250/5). 3. For radius fillers that are made from a sheet, cut and remove the material from the sheet to get the dimensions shown. 4. Apply a layer of chemical film treatment or chromic acid anodize the surface. 5. Apply a layer of primer (BMS 10-11 type I). 6. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 64. OPERATOR MADE PART - CHANNEL RADIUS FILLER "A" Jul 6/89 737-53-1120 REV 1: May 13/93 293

### BOEING SERVICE BULLETIN 737-53-1120

1 4 2 3

0.22 R 

## CHANNEL RADIUS FILLER "B" (2 PLACES) 0.86 1.60

0.74802205The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Cut and remove material from a 0.16 X 0.90 X 1.75 inch sheet of bare 2024-T3 aluminum (QQ-A-250/4) or clad 2024-T3 aluminum (QQ-A-250/5) to get the dimensions shown. 2. Apply a layer of chemical film treatment or chromic acid anodize the surface. 3. Apply a layer of primer (BMS 10-11 type I). 4. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 65. OPERATOR MADE PART - CHANNEL RADIUS FILLER "B" Jul 6/89 737-53-1120 REV 1: May 13/93 294

### BOEING SERVICE BULLETIN 737-53-1120

1 4 2 3

1 0.22 R (2 PLACES) (2 PLACES) 0.09 R 0.86 0.20 1.60



## CHANNEL RADIUS FILLER "C" 0.74 0.40 (2 PLACES)802208The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Cut and remove material from a 0.16 X 0.90 X 1.75 inch sheet of bare 2024-T3 aluminum (QQ-A-250/4) or clad 2024-T3 aluminum (QQ-A-250/5) to get the dimensions shown. 2. Apply a layer of chemical film treatment or chromic acid anodize the surface. 3. Apply a layer of primer (BMS 10-11 type I). 4. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 66. OPERATOR MADE PART - CHANNEL RADIUS FILLER "C" Jul 6/89 737-53-1120 REV 1: May 13/93 295

### BOEING SERVICE BULLETIN 737-53-1120

BEND

0.32 EDGE MARGIN 0.37 EDGE MARGIN 0.84



## SUPPORT CLIP "B" 0.73 0.85

2.34 2.46

1.19

2 6 4 5 1
3 BEND UP 90` x 0.19 R

FWD802222The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.04 X 2.50 X 0.90 inch sheet of clad 7075-T6 aluminum (QQ-A-250/13). 2. Drill two 0.125 inch diameter pilot holes at the locations shown. 3. Bend the sheet to the dimensions shown. 4. Apply a layer of chemical film treatment or chromic acid anodize the surface. 5. Apply a layer of primer (BMS 10-11 type I). 6. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 67. OPERATOR MADE PART - SUPPORT CLIP "B" Jul 6/89 737-53-1120 REV 1: May 13/93 296

### BOEING SERVICE BULLETIN 737-53-1120

0.37 EDGE MARGIN 0.37 EDGE MARGIN 0.84

BEND



## SUPPORT CLIP "C" 2.34 2.46 0.78 0.90

1.19

2 6 4 5 1 3 BEND UP 90` x 0.19 R

FWD802220The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.04 X 2.50 X 0.90 inch sheet of 7075-T6 clad aluminum (QQ-A-250/13). 2. Drill two 0.125 inch diameter pilot holes at the locations shown. 3. Bend the sheet to the dimensions shown. 4. Apply a layer of chemical film treatment or chromic acid anodize. 5. Apply a layer of primer (BMS 10-11 type I). 6. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 68. OPERATOR MADE PART - SUPPORT CLIP "C" Jul 6/89 737-53-1120 REV 1: May 13/93 297

### BOEING SERVICE BULLETIN 737-53-1120

2



## SECTION A-A 2 3 1 5 4 45` X 0.20

FLANGE 0.16R 0.12 FWD

3.00 LIGHTNING HOLES

2.86 A A A A A A

3.95 8.69 13.43B25130The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.025 X 5.75 X 17.75 inch sheet of clad 2024-T3 aluminum (QQ-A-250/5). 2. Make the lightening holes shown. Make with a flange on the hole edge. 3. Apply a layer of chemical film treatment or chromic acid anodize the surface. 4. Apply a layer of primer (BMS 10-11 type I). 5. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 69. OPERATOR MADE PART - INTERCOSTAL WEB 65C34688-33 Jul 6/89 737-53-1120 REV 1: May 13/93 298

### BOEING SERVICE BULLETIN 737-53-1120

2



## SECTION B-B SECTION A-A 45` X 0.10

9.74 14.57 3 1 5 4

2 2 4.96

0.12 0.16R FLANGE 0.16R 0.12 FLANGE FWD LIGHTNING HOLES

2.86 A A B B B B

3.00 3.50B25105The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.025 X 5.75 X 19.63 inch sheet of clad 2024-T3 aluminum (QQ-A-250/5). 2. Make the lightening holes shown. Make with a flange on the hole edge. 3. Apply a layer of chemical film treatment or chromic acid anodize the surface. 4. Apply a layer of primer (BMS 10-11 type I). 5. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 70. OPERATOR MADE PART - INTERCOSTAL WEB 65C34688-35 Jul 6/89 737-53-1120 REV 1: May 13/93 299

### BOEING SERVICE BULLETIN 737-53-1120

2

BEND 8 4 1 6 3 5 7 BEND UP 90` X 0.09R 14 PLACES

FWD 45` X 0.55 0.95

1.49 2.60 3.72 4.83 5.94

7.06 8.17 9.28

10.39 11.51 12.62 13.73 14.84 15.95 0.50B25719The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.05 X 1.80 X 17.75 inch sheet of 7075-O clad aluminum (QQ-A-250/13). 2. Bend the sheet to the dimensions shown. 3. Cut and remove the material shown. 4. Heat treat to the T62 condition. 5. Drill these 0.125 inch diameter pilot holes in the chord if the intercostal web does not have holes (this occurs if the existing web was also replaced) that can be backdrilled from. 6. Apply a layer of chemical film treatment or chromic acid anodize the surface. 7. Apply a layer of primer (BMS 10-11 type I). 8. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 71. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-34 Jul 6/89 737-53-1120 REV 1: May 13/93 300

### BOEING SERVICE BULLETIN 737-53-1120

2 BEND 3 4 8 1 6 7 5 BEND UP 90` X 0.09R 16 PLACES

FWD 0.

0.95 45` X 0.60

46

18.30 17.15 16.00 14.86 13.72 12.57 11.43 10.28 9.14 7.99 6.85 5.70 4.56 3.41 2.27 1.12B25199The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.05 X 1.80 X 19.63 inch sheet of 7075-O clad aluminum (QQ-A-250/13). 2. Bend the sheet to the dimensions shown. 3. Cut and remove the material shown. 4. Heat treat to the T62 condition. 5. Drill these 0.125 inch diameter pilot holes in the chord if the intercostal web does not have holes (this occurs if the existing web was also replaced) that can be backdrilled from. 6. Apply a layer of chemical film treatment or chromic acid anodize the surface. 7. Apply a layer of primer (BMS 10-11 type I). 8. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 72. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-37 Jul 6/89 737-53-1120 REV 1: May 13/93 301

### BOEING SERVICE BULLETIN 737-53-1120

0.13R

6 1 7 8 5 2 0.90 3
0.15 3



## SECTION A-A

BEND BEND DOWN 90` X 0.09R AFTER BEND

. 0

. 0

FWD 16 PLACES 95

46

18.30 17.15 16.00 14.86 13.72 12.57 11.43 10.28 9.14 7.99 6.85 5.70 4.56 3.41 2.27 1.12 A A 45` X 0.40B25756

FIGURE 73. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-36 Jul 6/89 737-53-1120 REV 1: May 13/93 302

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.05 X 2.00 X 19.63 inch sheet of 7075-O clad aluminum (QQ-A-250/13). 2. Bend the sheet to the dimensions shown. 3. Cut and remove the material shown. 4. Heat treat to the T62 condition. 5. Drill these 0.125 inch diameter pilot holes in the chord if the intercostal web does not have holes (this occurs if the existing web was also replaced) that can be backdrilled from. 6. Apply a layer of chemical film treatment or chromic acid anodize the surface. 7. Apply a layer of primer (BMS 10-11 type I). 8. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 73. OPERATOR MADE PART - INTERCOSTAL TOP CHORD 65C34688-36 Jul 6/89 737-53-1120 REV 1: May 13/93 303

### BOEING SERVICE BULLETIN 737-53-1120

3 3 2 3 6 5 7 1 4



## SECTION A-A 4 FWD FLANGE
0.12 0.16R A A A A

3.00 LIGHTENING HOLESB25848The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.025 X 6.13 X 17.50 inch sheet of clad 2024-T3 aluminum (QQ-A-250/5). 2. Get the existing intercostal web that was kept. Use it as a template to cut and remove material from the bottom edge of the sheet. NOTE: Do not use the template to cut and remove material from the vertical edges of the sheet. 3. Use the existing intercostal web that was saved as a template to locate the two lightening holes on the sheet. 4. Make the lightening holes shown. Make with a flange on the hole edge. 5. Apply a layer of chemical film treatment or chromic acid anodize the surface. 6. Apply a layer of primer (BMS 10-11 type I). 7. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 74. OPERATOR MADE PART - INTERCOSTAL WEB 69-51452-7 Jul 6/89 737-53-1120 REV 1: May 13/93 304

### BOEING SERVICE BULLETIN 737-53-1120

3 1 5 6 7 BEND 4 2 14 PLACES BEND DOWN 90` X 0.09R

. 0 . 0

FWD

49 85

15.95 14.84 13.77 12.66 11.55 10.46 9.37 8.28 7.19 6.09 5.01 3.91 2.81 1.68B25957The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Get a 0.05 X 1.71 X 17.50 inch sheet of 7075-O clad aluminum (QQ-A-250/13) for the chord. 2. Bend the sheet to the dimensions shown. 3. Heat treat to the T62 condition. 4. Drill these 0.125 inch diameter pilot holes in the chord if the intercostal web does not have holes (this occurs if the existing web was also replaced) that can be backdrilled from. 5. Apply a layer of chemical film treatment or chromic acid anodize the surface. 6. Apply a layer of primer (BMS 10-11 type I). 7. Apply a layer of enamel (BMS 10-11 type II).

FIGURE 75. OPERATOR MADE PART - INTERCOSTAL TOP CHORD "A" Jul 6/89 737-53-1120 REV 1: May 13/93 305

### BOEING SERVICE BULLETIN 737-53-1120

LINK

L INTERCOSTAL C

90` PIVOT BOLT SEE DETAIL II TO MAKE PLATE "A" SEE DETAIL I TO MAKE CHANNEL "A"

11 FLANGED BUSHING 10 13 LINE REAM

9 PLATE "A" 8

CHANNEL "A" FLANGED BUSHING 12 A

A799616

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 306

### BOEING SERVICE BULLETIN 737-53-1120

1.24

71`

4.60 6.60

1.76 75` 0.40
7 6 3 1

2 B UP 90` x 0.25 R (2 PLACES) 2



## DETAIL I CHANNEL "A" 0.81

95` 85` (2 PLACES) B DN x 0.25 R BEND

BEND

BEND BEND 1.50 R802390

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 307

### BOEING SERVICE BULLETIN 737-53-1120

7 4 5 (4 PLACES) 0.25 R

0.77 3.22 1.63

PLATE "A" 

## DETAIL II802391

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 308

### BOEING SERVICE BULLETIN 737-53-1120

MARGIN EDGE 0.29 0.29 EDGE MARGIN

THE OUTBOARD SIDE) (SHOWN INSTALLED ON PLATE "A"



## VIEW A-A CHANNEL ASSEMBLY "A" A

A A A 

### 0.48

0.28 3.31

0.67

1.20 0.98

CHANNEL "A"

FLANGED BUSHING

0.60799443

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 309

### BOEING SERVICE BULLETIN 737-53-1120

0.29 EDGE MARGIN 0.29 EDGE MARGIN

CHANNEL ASSEMBLY "B" 

## VIEW A-A A A 

### 0.48

0.28 3.31

1.20 0.98

FLANGED BUSHING
PLATE "A" 0.60

CHANNEL "A"

(LOOKING OUTBOARD WHEN INSTALLED ON THE FLOOR BEAM)799515

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 310

### BOEING SERVICE BULLETIN 737-53-1120

MARGIN EDGE 0.29 0.29 EDGE MARGIN

THE OUTBOARD SIDE) (SHOWN INSTALLED ON PLATE "A"



## VIEW A-A A

A A A 

### 0.48

0.28

0.67

1.20 0.98

CHANNEL "A"

FLANGED BUSHING

0.60 3.27

CHANNEL ASSEMBLY "C"800047

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 311

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. See Detail I to make the Channel "A". Cut and remove material from the clad 7075-O aluminum sheet (QQ-A-250/13) to get the dimensions shown. Use a 0.10 x 6.70 x 6.10 inch sheet. 2. Bend Channel "A" as shown. 3. Heat treat Channel "A" to the T62 condition. 4. See Detail II to make Plate "A". Cut and remove material from clad 7075-T6 aluminum sheet (QQ-A-250/13) to get the dimensions shown. Use a 0.19 x 3.40 x 1.80 inch sheet. 5. Apply a layer of chemical film treatment or chromic acid anodize Plate "A" . 6. Apply a layer of chemical film treatment or chromic acid anodize Channel "A". 7. Apply a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II) on Channel "A" and Plate "A". 8. Locate Plate "A" on the inboard side of Channel "A" if the hex drive bolt heads make contact with the inboard side of the Channel 69-77845-3 (Refer to the preventive change or repair instructions ). Apply a layer of sealant to the faying surfaces (BMS 5-95). Install Plate "A" on Channel "A". Install the fasteners as shown in the View A-A for the Channel Assemblies "A" or "C". 9. Locate and install Plate "A" on the outboard side of Channel "A" if the hex drive bolt heads make contact with the outboard side of the Channel 69-77845-3 (Refer to the preventive change or repair instructions). Apply a layer of sealant to the faying surfaces (BMS 5-95). Install Plate "A" on Channel "A". Install the fasteners as shown in the View A-A for the Channel Assemblies "A" or "B" or "C". 10. Drill and ream the holes on each side of the channel assembly to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. See View A-A for the location of this hole on each side of the Channel Assembly "A" ,"B" and "C". 11. Install a Flanged Bushing BACB28AT07B028C in the side of the channel assembly that has the plate. Install the bushing with a layer of sealant (BMS 5-95). 12. Install a Flanged Bushing BACB28AT07B009C in the other side. Install the bushing with a layer of sealant (BMS 5-95). 13. Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline. The instructions given below agree with the letter shown in the upper left corner of the fastener symbols in the figure. A. Drill a No. 10 (0.191 - 0.202) inch diameter hole. Install a rivet BACR15BB6D9.

FIGURE 76. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "A", "B", AND "C" Jul 6/89 737-53-1120 REV 1: May 13/93 312

### BOEING SERVICE BULLETIN 737-53-1120

0.98
TO MAKE CHANNEL "B" SEE DETAIL I

(2 PLACES) FLANGED BUSHING 7

6 LINE REAM 8

CHANNEL "B" PIVOT BOLT 90` LINK

L INTERCOSTAL C

CHANNEL "B"

FLANGED BUSHING 3.31 3.27 ASSEMBLY "E" ASSNMBLY "D"



## VIEW A-A A

AB26785

FIGURE 77. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "D" AND "E" Jul 6/89 737-53-1120 REV 1: May 13/93 313

### BOEING SERVICE BULLETIN 737-53-1120

BEND

BEND BEND

BEND 1.50 R 1.24

71`

4.60 6.60

1.76 75` 0.40
5 4 3 1 0.71

BEND DOWN x 0.25 R 85` (2 PLACES) 95` 2



## DETAIL I CHANNEL "B" (2 PLACES) BEND UP 90` x 0.25 R 2B26793

FIGURE 77. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "D" AND "E" Jul 6/89 737-53-1120 REV 1: May 13/93 314

### BOEING SERVICE BULLETIN 737-53-1120
The instruction numbers shown below agree with the numbers shown inside the circle symbols in the figure. 1. Make the Channel "B". Cut and remove material from the clad 7075-O aluminum sheet (QQ-A-250/13) to get the dimensions shown. Use a 0.10 x 6.70 x 6.10 inch sheet. 2. Bend Channel "B" as shown. 3. Heat treat Channel "B" to the T62 condition. 4. Apply a layer of chemical film treatment or chromic acid anodize. 5. Apply a layer of primer (BMS 10-11 type I) and a layer of enamel (BMS 10-11 type II). 6. Drill and ream the holes on each side of the channel assembly to a diameter of 0.5625 - 0.5631 inch. Line ream the two holes to make sure that they have the same centerline. 7. Install a Flanged Bushing BACB28AT07B009C on both sides of Channel "B". Install the bushing with a layer of sealant (BMS 5-95). 8. Ream the holes in the flanged bushings to a diameter of 0.4375 - 0.4385 inch. Line ream the two holes to make sure that they have the same centerline.

FIGURE 77. OPERATOR MADE PARTS - CHANNEL ASSEMBLY "D" AND "E" Jul 6/89 737-53-1120 REV 1: May 13/93 315

### Commercial Airplane Group 

# 737 Service Bulletin

Number: 737-53-1120 

## Evaluation Form Date: July 6, 1989 Revision 1: May 13, 1993 ATA System: 5321 Prepared By: Manuel Hernandez

SUBJECT: FUSELAGE - BODY STATION 520 FLOOR BEAM INSPECTION, REPAIR AND PREVENTIVE CHANGE 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: R.G. Kelsey, Manager Service Bulletin Engineering Boeing Commercial Airplane Group P.O. Box 3707, Mail Stop 2L-02 Seattle, WA 98124-2207

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