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 0

B54180

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.

Jul 6/89 737-53-1120

REV 1: May 13/93 14
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 15
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 16
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).

Jul 6/89 737-53-1120

REV 1: May 13/93 17
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 18
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

Jul 6/89 737-53-1120

REV 1: May 13/93 19
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

Jul 6/89 737-53-1120

REV 1: May 13/93 20
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 21
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 22
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 23
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

Jul 6/89 737-53-1120

REV 1: May 13/93 24
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 SubkitName

Buttock Line (BL) Location On The Floor Beam

Left BL

45.50

Left BL

24.75 BL 0.00 Right BL24.75

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 -

Jul 6/89 737-53-1120

REV 1: May 13/93 25
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

65C34688-9 65C27712-2

65C35994-3

2

3

4

65C34978-25

65C34978-6

65C35994-2

65C34978-26

65C34978-7 65C34978-27

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

Jul 6/89 737-53-1120

REV 1: May 13/93 42
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

20 MS20470D5-6 Rivet

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

Jul 6/89 737-53-1120

REV 1: May 13/93 43
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 44
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)

Jul 6/89 737-53-1120

REV 1: May 13/93 45
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

Intercostal 2.a

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

Jul 6/89 737-53-1120

REV 1: May 13/93 46
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

Jul 6/89 737-53-1120

REV 1: May 13/93 47
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

Jul 6/89 737-53-1120

REV 1: May 13/93 48
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 49
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

Jul 6/89 737-53-1120

REV 1: May 13/93 50
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 51
BOEING SERVICE BULLETIN 737-53-1120

BLANK PAGE

Jul 6/89 737-53-1120

REV 1: May 13/93 52
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.

Jul 6/89 737-53-1120

REV 1: May 13/93 53
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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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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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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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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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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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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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

Jul 6/89 737-53-1120

REV 1: May 13/93 65
BOEING SERVICE BULLETIN 737-53-1120

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

Jul 6/89 737-53-1120

REV 1: May 13/93 66
BOEING SERVICE BULLETIN 737-53-1120

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

Jul 6/89 737-53-1120

REV 1: May 13/93 67
BOEING SERVICE BULLETIN 737-53-1120

* 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

YES NO

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 THE

802247

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

PANEL

A98707

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 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

INTERCOSTAL

802098

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

3

2

2

3

4

2

5

0.5

EDDY CURRENT INSPECT

INTERCOSTAL CHANNEL ON

GROUP 4, 5 AND 6 AIRPLANES

LINK

INTERCOSTAL

CL

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

WEB

C19377

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

A

A98762

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

5 9

6

3 4

8

3 4

FWD

STA

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

0.19

B00960

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

6 10

520

BS

7 INTERCOSTAL

LINK

WING BOX

PLAIN

BUSHING

5 9

PIN

11

PIN

PLAIN

BUSHING

CHANNEL

B01603

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

1 2

1 2

8

FWD

520

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

0.06

B01612

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 CHANNEL

1

6 CHANNEL RADIUS FILLER

1 CHANNEL

A

BS

520

A

B02583

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

2 5 10 5 10

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

CL

INTERCOSTAL TEE

RADIUS FILLER

LINK

INTERCOSTAL

CL

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 CRACKS

B03070

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

INTERCOSTAL

801794

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

1 4

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

0.49

801799

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

INTERCOSTAL

801803

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

1 6 1 6

1 4

1 4

3

5

10 11 7 11

8 11

0.165 MINIMUM

0.130 MINIMUM FOR

THE TOP FLANGE

CRACK ENDS NEAR

PROBE 3 FOR THE MARK

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 CRACK

801792

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 CRACKS

802236

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. 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

FWD INBD

B09550

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-A

801094

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 INBD

B08818

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

CHANNEL

B11061

The 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

1

B11059

The 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 6

1

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 AIRPLANES

802166

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 0

LINK

PIVOT

1

CHANNEL 5 6

7

2

3

7

STRAP

LINK

INTERCOSTAL 4

BEAM

FLOOR BS

520

FWD INBD

ALL OTHER BL LOCATIONS SIMILAR

LBL 24.75 LOCATION SHOWN

B03190

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 0

LINK

PIVOT

1

2

3 STRAP

LINK

INTERCOSTAL 4

BEAM

FLOOR

WING BOX

BS

520

REPAIR ANGLE

5

CHANNEL

CHANNEL

RADIUS

FILLER

FWD INBD

ALL OTHER BL LOCATIONS SIMILAR

LBL 24.75 LOCATION SHOWN

B03270

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

3 STRAP

B12134

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 24.75

802165

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

CEILING

1

STABILIZER STRAP

CLOSURE PANEL

RUBBER SHROUD

RUBBER TAPE

A

A

FWD INBD

802164

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

6 3 4

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

CUT

802170

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

FWD

B08538

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

BOTTOM 2

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 SEAL

802226

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

11 WASHER

WASHER

11

11

PIN

SPACER 11

11 SPACER

11 WASHER

ATTACH BRACKET

(SEE DETAIL I)

(RBL ONLY)

ELECTRICAL BRACKET

8 CARGO POST

7

9 15

POST END

ASSEMBLY

BS 520 FRAME

SIDE ANGLE

16

16

BEAM TEE 10

BS 520

FLOOR BEAM

RBL 24.75 LOCATION SIMILAR

LBL 24.75 LOCATION SHOWN

A

A

FWD INBD

800978

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

D

D

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

STIFFENER

801096

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

6 13

13

NARROW STABILIZER

5 13

4 13

24.75

LBL/RBL

WIDE STABILIZER

DETAIL I

6 13

3 13

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

FLANGE

801098

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

13 WASHER

13 SPACER

10

11 17

9

SHIM 8 9 16

SPACER 13

PIN

13

13

WASHER

13 WASHER

20 COTTER PIN

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 INBD

802209

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 D

D D

D D

16

1

14 3

19

14

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

POST

800049

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

7 15

4 15

15

5 15

24.75

LBL/RBL

DETAIL I

7 15

15

NARROW STABILIZER

6 15

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

FILLER

800996

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 8 7 PLACES 11 WEB

VIEW B-B

WEB

10

10

1 2 3 5

7

9

6

REPAIR ANGLE

2 4 5 11

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

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

A B B

A

500B

BS

520

BS

500B

BS

BS

520

FLOOR BEAM WEB

802171

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

4 7 9 RADIUS

A

4

A

4

A

4

A

4

A

FWD

TEE

DETAIL I

AIRPLANES WITH TEE

520

BS

802175

The 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

TOP CHORD ANGLE

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

A

4

A

4

A

4

A

B

FWD

7 PLACES

9 9 7 PLACES 1 2 3 6 12

VIEW B-B

WEB

WEB

VIEW C-C

2 4 5 6 12

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

5 11

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 WEB

802185

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

A

4

A

4

A

4

A

4

A

8 10

B

B

FWD

DETAIL I

TEE

520

BS

AIRPLANES WITH TEE

RADIUS

802414

The 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

A

7

B

B

CHANNEL

CHANNEL

TOP CHORD

7 PLACES

6 6 7 PLACES 8

C

C

A

6

A

6

A

6

A

6

A

6

A

5

A

5 5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

A

5

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

520

801010

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

INSTALL ELECTRICAL BRACKET 22 26

9 30

LBL 24.75 LOCATION SHOWN

ALL OTHER BL LOCATIONS SIMILAR

FWD INBD

FLOOR BEAM

PIVOT LINK

BUSHING

PLAIN

3 13 19 29

31 PIN

7 14 27

32 PIN

BUSHING

PLAIN

31 PIN

CHANNEL

WING BOX

LINK

INTERCOSTAL 6

BS

520

8 15 28

STRAP

12

4 5

2

1

NO SEAT TRACK AT BL 0

A97117

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`

CL

2

FWD

520

STA 20

11

10 11

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

0.06

A92427

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

FILLER 23 25

CHANNEL

RADIUS

CHANNEL 23

INTERCOSTAL

CL

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 OCCURS

A97702

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

CL

LINK

CHANNEL

INTERCOSTAL

CL

LINK

23 25

24 25

23 25

23 25

LOOKING FORWARD

DETAIL II

INSTALLATION WITH

CHANNEL RADIUS FILLER "A" CHANNEL ASSEMBLY "A", "B" OR "C"

INSTALLATION WITH

LOOKING FORWARD

DETAIL I

"A", "B", OR "C"

CHANNEL ASSEMBLY

PLATE "A"

RADIUS FILLER "A"

(2 PLACES)

FILLER

CHANNEL

RADIUS

A92419

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

FWD

A98222

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

11 24

CHANNEL

FLOOR BEAM

1

LBL 24.75 LOCATION SHOWN

ALL OTHER BL LOCATIONS SIMILAR

FWD INBD

STRAP

6 13 22

520

BS

4 INTERCOSTAL

LINK

WING BOX

7

25 PIN

PLAIN

BUSHING

26 PIN

5 12 21

25 PIN

3 11 23

PLAIN

BUSHING

PIVOT LINK

INSTALL ELECTRICAL BRACKET 17 20

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 0

A98288

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

8 9

15

520

STA

FWD

8 9

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

0.06

A98290

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

18 19

0.18

16

INTERCOSTAL

CL

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 FORWARD

A98305

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

CHANNEL 2 12

3 13 25

13 26

BUSHING

PLAIN

8 15 24

PIN

STRAP

WING BOX

9

BUSHING

PLAIN

7 14 23

520

BS

1

4 5

FLOOR BEAM

FWD INBD

LBL 24.75 LOCATION SHOWN

ALL OTHER BL LOCATIONS SIMILAR

27 PIN

27 PIN

6

LINK

INTERCOSTAL

B13182

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

CL

90`

BUSHING

FLANGED

10

11

FWD

520

STA

5

4

0.25

MINIMUM

17

2

B B

D

D

C C

0.20

0.17

0.24

VIEW A-A

PIVOT JOINT

PIVOT LINK

PIVOT BOLT

INTERCOSTAL

LINK

FLOOR

BEAM

FASTENER HEAD

CHANNEL RADIUS

FILLER AND

SEAT TRACK ENDS

CHANNEL

B13369

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

3 13 25

SECTION C-C

27

WASHER

20 21

20 21

12 PLACES

FLOOR BEAM WEB

LINK

INTERCOSTAL

CL CHANNEL

RADIUS

FILLER

(2 PLACES)

CHANNEL

RADIUS

B13387

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

40 47

8 9

7 17 50

3

13 19 49

12 18 48

14 17 51

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

52 PIN

52 PIN

520

BS

FLOOR BEAM

SEAT TRACK

53 PIN

801659

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

32 33 34 35 44

4

2

1 2 28 46

46

34

31 46

15

31 46

30

29

6 29

36

520

STA

15

15

FWD

10

11

6

38

TOP INTERCOSTAL

CHORD

INSTALL INTERCOSTAL ANGLE

REMOVE INTERCOSTAL TEE AND

INTERCOSTAL WEB

6 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 BOLT

801735

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`

CL

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

45 46

42 46

45

CHANNEL

RADIUS FILLER

46

46

21

FLANGE

RADIUS FILLER

20 22

25 42 46

42 46

39

L L L

D

46 37

LINK

L

INTERCOSTAL

CHANNEL

RADIUS FILLER 1 42

C

9

8

D

D

D

D

D

D

D

20 22

24 41 42 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

0.18

801756

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

C

9

C

10

C

10

C

10

C

10

C

LINK

LC

INTERCOSTAL

CHANNEL

INTERCOSTAL

CL

LINK

42 46

FILLER

RADIUS

CHANNEL

43 46

43 46

43 46

FILLER

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

42 46

H M H H M H

H

H G H

H G G

F G

E

26

42 46

26 26

FWD FWD

FWD

L SEAT TRACK

AFT REPAIR ANGLE

SEAT TRACK

4 PLACES AT THE

FORWARD

ANGLE

REPAIR

VIEW E-E

C

B29128

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 Inboardor 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

1 4 3

2

AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

SEAT TRACK INTERCOSTAL LINK

801059

The 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

B

B B

B

B

B

C

3

1 5 4

2

INTERCOSTAL LINK SEAT TRACK

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

AFT REPAIR ANGLE

801104

The 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 B

B B

B B

B

C

A

A

A

A

A

A

A

A

A

A

A

A

2

3

1 5 4

AFT REPAIR ANGLE

INTERCOSTAL LINK SEAT TRACK

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

801106

The 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

B

B B

B

B

C

A

A

A

A

A

A

A

A

A

A

A

A 2

1 4 FORWARD REPAIR ANGLE 3

AFT REPAIR ANGLE

12 PLACES FLOOR BEAM WEB

SEAT TRACK INTERCOSTAL LINK

801110

The 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

1 4 3

2

2

INTERCOSTAL LINK SEAT TRACK

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

AFT REPAIR ANGLE

801111

The 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

B

B B

B

B B

B

B

B

4

1 6 5 2 3

INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB

AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES BRACKET

801225

The 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 B

B B

B

B

C

B B

B

B

1 4 3

2

INTERCOSTAL LINK SEAT TRACK

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

AFT REPAIR ANGLE

801596

The 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

B

B B

B

B

A

A

A

A

A

A

A

A

A

A

A

A

C

1 4 3

2

FORWARD REPAIR ANGLE

AFT REPAIR ANGLE

12 PLACES FLOOR BEAM WEB

SEAT TRACK INTERCOSTAL LINK

801227

The 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

1 4 3

2

INTERCOSTAL LINK SEAT TRACK

FORWARD REPAIR ANGLE 12 PLACES FLOOR BEAM WEB

AFT REPAIR ANGLE

801364

The 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

1 6 5 3 4

INTERCOSTAL LINK SEAT TRACK

FLOOR BEAM WEB

AFT REPAIR ANGLE

FORWARD REPAIR ANGLE 12 PLACES BRACKET

PULLEY BRACKET

801642

The 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

1 4 FORWARD REPAIR ANGLE 3 12 PLACES FLOOR BEAM WEB

SEAT TRACK INTERCOSTAL LINK

AFT REPAIR ANGLE

801446

The 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

B

B B

B

B

B

B

B

1 4 3

2

INTERCOSTAL LINK SEAT TRACK

12 PLACES FLOOR BEAM WEB

AFT REPAIR ANGLE

FORWARD REPAIR ANGLE

801657

The 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

11 12

SEAT TRACK

A

A

TOP CHORD

15 23 40 45

41

2 29 32 38

INTERCOSTAL

INTERCOSTAL WEB

2 29 32 38

25 31 38

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 8 20

CHANNEL

PIVOT

LINK

BUSHING

PLAIN

STRAP

10 22 42

16 24

INTERCOSTAL

LINK

PIN

44

44

17 22 43

PIN

520

BS

BEAM

FLOOR

45 PIN

ANGLE

AFT REPAIR

7 8 21 25 31 38

B20737

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

8 27

3 27 29 36 38

14

19

13

FWD

STA

520 18

33

36 38

28 9

32 38

32 38

1 31 38

1 31 38

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

FILLER

B19802

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

CL

90`

BUSHING

FLANGED

SECTION B-B

10 22 42

44

SECTION C-C

12

11

WASHER

B19835

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

31 38

36 38

D D 36 38

25 31 38

5

4

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 REPAIR

B19823

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

F

6

J

J

J

J

J

J

J

4

F

5

F

F

6

J

J

J

J J

J

E B

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

10 14

8

11 13

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 I

B24530

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

NUTPLATE 6

EXISTING

REMOVE

SHEAR WEB

REPAIR ANGLE

NUTPLATE

OUTBOARD NUTPLATE SIMILAR

INBOARD NUTPLATE SHOWN

DETAIL I

FWD

(OUTBOARD NUTPLATE ONLY)

FLANGE

B24552

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

6 14 10

D

D

5

K

5

K

5

K

5

K K

9 5

K

5

K K

9

5

K

5

K K

16 5

K K

16

5 10

5

12 14

G

5

G

6 L B

L

L

E

L L

F E

L L

L

L

L

L

L

L

L

4 5

3

6

16

16

12 15

11 15

6 15

3 15

9

8 9

FWD

INBD

A A

SHIM

(2 PLACES)

AFT FLANGE FILLER

LBL

24.75 SEAT TRACK

FORWARD FLANGE FILLER

SEE DETAIL I SEE DETAIL II

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

BEAM

B21734

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

FLANGE

B24449

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 G

6

G

5

12 14

5

5

K

16

K

5 9

K

5

K

5

K

5

K

10

11 15

5

K

5

K

5

K

5

K

5

K

6

3 6 15

16

16

4 5

12 15

6 14 10

D

D K

9

K

16

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)

DOUBLER WEB FILLER

(2 PLACES)

RBL

24.75

RBL

24.75

FLOOR

BEAM

AFT FLANGE FILLER

VIEW A-A

SEAT TRACK FILLER

B24586

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

FLANGE

B24587

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

D

4

5

G D

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 TRACK

B24608

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

FLANGE

B24651

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

17 20 34

12 20 33 15 21 31

16 22 32

3 6 7 11 19

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

FWD INBD

FLOOR BEAM

BS

520

35 PIN

35 PIN

LINK

INTERCOSTAL

PLAIN BUSHING

PLAIN BUSHING

WING BOX

PIVOT LINK

STRAP

36 PIN

CHANNEL

802045

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

4

9

8

18

18

18

24

FWD

520

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 LINK

802069

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

CHANNEL 29

RADIUS FILLER 1 27

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 REMOVED

802057

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

28 29

19 23

29

CHANNEL

RADIUS FILLER 1

9

FLANGE 29

RADIUS FILLER

25

CHANNEL

28 29

LINK

L

INTERCOSTAL

C

3 6 28 29

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 REMOVED

802072

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

14 18 48

13 20 46

3

9 18

38 44

47

22 39

6 7 17

12 19 45

5 7 8 16

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

FWD INBD

PIVOT LINK

CHANNEL

GROUP 2 AND GROUP 3 AIRPLANES ONLY

BS 520 AND WING BOX ON GROUP 1,

ELECTRICAL BRACKET AT RBL 45.50 BETWEEN

A98127

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 30 31 32 33 41

4 43

2

1 2 26 43

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 BEAM

B08701

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

B

8

B

6

B

8

B

6

B

8

B

6

B

8

B

6

A

10

A

9

A

10

A

9

16

16

23 40 43

16 21

C

INTERCOSTAL

L

LINK

22 39 40 43

C

C

C

C

C

C

C

RADIUS FILLER 1 40

CHANNEL

43 35

C

N N N

37

40 43

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-B

B09547

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 40 43

DETAIL I

LOOKING FORWARD

AFT REPAIR ANGLE

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

B19431

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 L M

40 43

24

24

E

F G

H G G

H G H

H

H O H 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 ANGLE

801739

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

CL

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 TRACK

B21951

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

18 25 39

19 26 40

13 24 41

20 24 42

11 12 10 12 28

14 15

SEAT TRACK

A

A

28 FORWARD REPAIR ANGLE

TOP CHORD

INTERCOSTAL

1

CHANNEL

DETAIL I

AT RBL 45.50 BETWEEN

BS 520 AND WING BOX

ELECTRICAL BRACKET

ANGLE

AFT REPAIR

1 INTERCOSTAL WEB

WING BOX

FWD INBD

BUSHING

PLAIN

PIVOT

LINK

BUSHING

PLAIN

STRAP

INTERCOSTAL

LINK

PIN

43

43

PIN

520

BS

44 PIN

FLOOR BEAM

B22312

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

32 35 38

38

17

22

FWD

STA

520 21

27

34 38

34 38

30

16

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 BEAM

B22703

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

CL

90`

BUSHING

FLANGED 14

WASHER

15

43

13 24 41

SECTION C-C

SECTION B-B

B22789

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

28 34

29 33

28 34 38

36 38

34 38

36 38

D D

B

B

B

B

B

A

C

B

A

C

38

38

9

8

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

PULLEY

B23181

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

F

6

J

J

4

F

5

F

F

6

E

13

4 5

4

H

4

H

5

I

N

4 5

H

5

N H

5

5

H

15

H

5

H

12

I

5

I D

D

14

14

14

10

8

10 12

5

N

8

N

8

6 12 6 12

6 12

M

3

J

M B

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 FILLER

B26231

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

FLANGE

B26232

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

8 9

6 14

D

D

5

K

P

5 5

K

5

K

5

P K

5

5

K

5

K K

16 5

K K

16

5 10

5

11 13

G

5

G

6 L B

O

E

F L E

L

4 5

6

15

15

P

9

P

9

10 6 13 6 13

L

3

Q 11 14

11 14

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 I SEE DETAIL II

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 PLACES

B26744

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 I

B26742

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

E B

O

L L

6 14 6 14

11 14

3

6 14

O

O

O

O

O

6 13

11 14

6 13

5

9

P

9

P

16

K

D

D

10

4 5

15

15

6

K

5 5

P K

5

K

5

K

5

K

5

K

5

K

5 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 I SEE DETAIL II

SEAT TRACK

SEAT TRACK FILLER

(2 PLACES)

FORWARD FLANGE FILLER

B26741

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 I

B26743

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

8 10

3

3

4 10 7

G

G

G

G

8 11 G

5 6

6

J

8

J

8

4 10

I I

I

I

I I

I

I

4 11

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 FILLER

B26068

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

FLANGE

B26070

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

2 3 7

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 CLIP

801100

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

0.35

802173

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

FWD

802174

The 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

1 3 7

4

2 4

PLATE "A"

B

A

A

B

PIVOT LINK

CHANNEL,

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN

SUPPORT CLIP "C" STRAP

RBL

45.5 FLOOR BEAM

BS

520

SUPPORT CLIP

ELECTRICAL BRACKET

WING BOX

INBD

FWD

802076

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

0.35

802083

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

4 5 6 8

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

FWD

802104

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

A

A

0.35

0.60

1.50

1.40

0.56 MINIMUM

802101

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 CLIP

802105

The 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

A

A

0.35

0.60

1.50

1.40

0.60 MINIMUM

802187

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

0.40

802389

The 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

2 3 7 SUPPORT CLIP "B"

A

B

B

4

STRAP

SUPPORT CLIP

WING BOX

ELECTRICAL BRACKET

INBD

FWD

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN

802380

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

0.35

799698

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

45.5 FLOOR BEAM

RBL

CHANNEL,

PIVOT LINK 1

STRAP

WING BOX

FWD

INBD

4 5 ELECTRICAL BRACKET

2 3 (SEE DETAIL II)

SUPPORT CLIP

A

A

INSTALLATION WITHOUT A FLOOR BEAM REPAIR SHOWN

802235

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 3 7

6

FWD

VIEW A-A

FWD

SUPPORT CHANNEL

A

A

SUPPORT CLIP

0.35

0.60

1.10

1.20

0.37

EDGE

MARGIN

0.37 EDGE MARGIN

0.40

802392

DETAIL II

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

45.5 FLOOR BEAM

RBL

B13101

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 I

C22085

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.

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

SEE DETAIL I 4

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

FWD

799726

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

45.5 FLOOR BEAM

RBL

FWD

INBD

SUPPORT CLIP

800992

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

B27626

VIEW A-A

The 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

45.5 FLOOR BEAM

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 CLIP

800039

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 SLEEVE

C22092

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.

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 SHOWN

802394

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

C22093

VIEW A-A

The 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)

B08791

The 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

2 3 4

0.22 R

CHANNEL RADIUS FILLER "B"

(2 PLACES)

0.86

1.60

0.74

802205

The 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

2 3 4

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)

802208

The 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

1 4 5 6

3 BEND UP 90` x 0.19 R

FWD

802222

The 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

1 4 5 6

3 BEND UP 90` x 0.19 R

FWD

802220

The 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

1 3 4 5 45` X 0.20

FLANGE

0.12 0.16R

FWD

3.00

LIGHTNING HOLES

2.86

A A A A A A

3.95

8.69

13.43

B25130

The 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 A-A SECTION B-B

45` X 0.10

9.74

14.57

1 3 4 5

2 2

4.96

0.12 0.16R

FLANGE

0.12 0.16R

FLANGE

FWD

LIGHTNING HOLES

2.86

A A B B B B

3.50 3.00

B25105

The 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

1 4 6 8 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

0.50

B25719

The 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

3 BEND 1 4 6 7 8

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

1.12

B25199

The 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

1 6 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 0.40

B25756

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

1 5 6 7 3 4

SECTION A-A

4

FWD

FLANGE

0.12 0.16R

A A A A

3.00

LIGHTENING HOLES

B25848

The 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

2 BEND DOWN 90` X 0.09R 4 14 PLACES 1 3 5 6 7 BEND

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

1.68

B25957

The 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

PLATE "A" 8 9

CHANNEL "A"

FLANGED BUSHING 12

A

A

799616

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

1 3 6 7

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 R

802390

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

4 5 7

(4 PLACES)

0.25 R

0.77

3.22

1.63

PLATE "A"

DETAIL II

802391

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

0.60

799443

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 8 LINE REAM

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

A

B26785

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

1 3 4 5

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 2

B26793

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

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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