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ALERT ALERT

Commercial

Airplane

Group 737

ALERT ALERT

Service Bulletin

Number: 737-57A1294

Date: April 23, 2007

ATA System: 5710

SUBJECT: WINGS - Wing Center Section - Upper and Lower Stringers - Drill Start Inspection and 

Repair

BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET

Copyright © 2007 The Boeing Company

Unpublished Work - All Rights Reserved

Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable 

subject matter. Boeing also claims copyright in this document as a compilation and/or collective work.

This document includes proprietary information owned by The Boeing Company and/or one or more third 

parties. Treatment of the document and the information it contains is governed by contract with Boeing. For 

more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124.

Boeing, 707, 717, 727, 737, 747, 757, 767, 777, BBJ, BOEING BUSINESS JET, DC-8, DC-9, DC-10, MD-10, 

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its subsidiaries. No intellectual property license (express or implied) is granted in connection with this document 

or otherwise.
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 Table of Contents

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Table of Contents

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. Data supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . 16

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Kits/Parts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Parts and Materials Supplied by the Operator: . . . . . . . . . . . . . . . . . . . . . . 17

3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4. Parts Removed and Not Replaced: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . 18

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION . . . . 22

FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION . . . . 26

FIGURE 3: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START HIGH

FREQUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION. . . . . . . . . . 30

FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
 Table of Contents

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BOEING SERVICE BULLETIN 737-57A1294

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ALERT ALERT

Commercial

Airplane

Group 737

ALERT ALERT

Service Bulletin

Number: 737-57A1294 Summary

Date: April 23, 2007

ATA System: 5710

SUBJECT: WINGS - Wing Center Section - Upper and Lower Stringers - Drill Start Inspection and 

Repair

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN 

PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE 

BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE 

BULLETIN TO THE NEW OWNER.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

This service bulletin gives instructions to inspect the free flange of the wing center section upper and lower 

stringers for drill starts and cracks. If the work given in this service bulletin is not accomplished, cracks could 

propagate from drill starts in the free flange of the wing center section upper and lower stringers and may go 

undetected. Undetected cracks could cause a loss of structural integrity of the wing center section and may 

result in a fuel leak.

Drill starts were found on the wing center section upper and lower stringers during a quality assurance 

inspection at the final assembly plant. The drill starts were caused by a manufacturing error during wing 

assembly. 

Airplane line number 1777 through 1842, 1844 through 1847, 1851 and 1852 require inspection. Airplane line 

numbers 1843, 1848, 1849, 1850 and 1853 through 1918 were inspected and/or repaired by Boeing. After line 

number 1918 the manufacturing process was changed to prevent further occurrences of drill starts in the wing 

center section upper and lower stringers.

Boeing Service Related Problem (SRP) 737-SRP-57-0201 is related to this service bulletin.
 

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BOEING SERVICE BULLETIN 737-57A1294

ALERT ALERT

ACTION

Install landing gear downlock pins, defuel and drain the wing center section fuel tank, open the equipment 

cooling system and the fuel tank access panel doors. Do a detailed inspection of the wing center section upper 

and lower stringers for any drill starts. If a drill start is found, do a High Frequency Eddy Current (HFEC) open 

hole inspection for any crack. At each crack location do the zero-timing procedure as given in this service 

bulletin. If the hole is within the service bulletin tolerance limits, install a new fastener. If the hole exceeds the 

tolerance limits, contact Boeing for repair instructions. If no crack is found, increase the diameter of the hole and 

install a new fastener. Close access and put the airplane back into a serviceable condition.

EFFECTIVITY

737-600, -700 and -800 Airplanes. Refer to Paragraph 1.A.1., Airplanes for a list of affected airplanes.

COMPLIANCE

See Service Bulletin Paragraph 1.E. for compliance information.

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service 

bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin 

mandatory.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are available for airplanes in warranty as of July 17, 2006. Please refer to Paragraph 

2.B., Industry Support Information.

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

Operator Supplied Parts/Materials. 

Refer to Paragraph 2.A., Material - Price and Availability.
 

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BOEING SERVICE BULLETIN 737-57A1294

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DO A DETAILED INSPECTION OF THE

WING CENTER SECTION UPPER AND LOWER

STRINGERS FOR ANY DRILL STARTS.

IF A DRILL START IS FOUND, DO A

HIGH FREQUENCY EDDY CURRENT (HFEC)

INSPECTION FOR ANY CRACK AND

INSTALL NEW FASTENER.

STA

664

STA

540

FWD

1338185
 

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ALERT ALERT

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ALERT ALERT

Commercial

Airplane

Group 737

ALERT ALERT

Service Bulletin

Number: 737-57A1294

Date: April 23, 2007

ATA System: 5710

SUBJECT: WINGS - Wing Center Section - Upper and Lower Stringers - Drill Start Inspection and 

Repair

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN 

PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE 

BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE 

BULLETIN TO THE NEW OWNER.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

This service bulletin is for the airplanes shown below.

Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line 

Number, and Serial Number data.

Airplane models:

737-600 737-700 737-800

IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER

AEROMEXICO (AMX)

1 YB874 YM503–YM506

AIR CHINA (BEJ)

1 YB592

AIR EUROPA (ARE)

1 YK602

GROUP CONFIGURATION DESCRIPTION

1 - 737-600, -700 and -800 Airplanes line number 

1777-1842, 1844-1847 and 1851-1852.
 

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AIR NIPPON (ANK)

1 YN001

AIRTRAN AIRWAYS (CQT)

1 YB382–YB385 YM205–YM206

CHINA EASTERN AIRLINES (CEA)

1 YB578–YB579

CHINA SOUTHERN AIRLINES (GUN)

1 YJ683–YJ685

CHINA XINJIANG AIRLINES (XIJ)

1 YM572

CONTINENTAL AIRLINES (CAL)

1 YJ548–YJ552

HAINAN AIRLINES (HNA)

1 YK702–YK705

INTEGRATED DEFENSE SYSTEMS (BSP)

1 YG202 YG212

NOFA LTD. (NFA)

1 YD413

PEGASUS AVIATION FINANCE (PSF)

1 YB590–YB591

QANTAS (QAN)

1 YJ924–YJ927

RYANAIR (RYR)

1 YJ854–YJ860 YK801–YK807

SHANDONG AIRLINES (SHG)

1 YM552–YM553

SHANGHAI AIRLINES (SHA)

1 YD492

SIVA (SVM)

1 YG094

SKYMARK AIRLINES (SKM)

1 YK611

SOUTHWEST AIRLINES (SWA)

1 YM270–YM276

TURKISH AIRLINES (THY)

1 YK551–YK552
 

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VIRGIN BLUE AIRLINES (VOZ)

1 YM522

VIZAVI (VIZ)

1 YG093

WESTJET (WJI)

1 YB962–YB963 YE372–YE373

IDENTIFICATION BY VARIABLE NUMBER

2. Spares Affected

None.

Variable Group

YB382–YB385 1

YB578–YB579 1

YB590–YB592 1

YB874 1

YB962–YB963 1

YD413 1

YD492 1

YE372–YE373 1

YG093–YG094 1

YG202 1

YG212 1

YJ548–YJ552 1

YJ683–YJ685 1

YJ854–YJ860 1

YJ924–YJ927 1

YK551–YK552 1

YK602 1

YK611 1

YK702–YK705 1

YK801–YK807 1

YM205–YM206 1

YM270–YM276 1

YM503–YM506 1

YM522 1

YM552–YM553 1

YM572 1

YN001 1
 

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B. Concurrent Requirements

None.

C. Reason

This service bulletin gives instructions to inspect the free flange of the wing center section upper and 

lower stringers for drill starts and cracks. If the work given in this service bulletin is not accomplished, 

cracks could propagate from drill starts in the free flange of the wing center section upper and lower 

stringers and may go undetected. Undetected cracks could cause a loss of structural integrity of the 

wing center section and may result in a fuel leak.

Drill starts were found on the wing center section upper and lower stringers during a quality assurance 

inspection at the final assembly plant. The drill starts were caused by a manufacturing error during 

wing assembly. 

Airplane line number 1777 through 1842, 1844 through 1847, 1851 and 1852 require inspection. 

Airplane line numbers 1843, 1848, 1849, 1850 and 1853 through 1918 were inspected and/or repaired 

by Boeing. After line number 1918 the manufacturing process was changed to prevent further 

occurrences of drill starts in the wing center section upper and lower stringers.

Boeing Service Related Problem (SRP) 737-SRP-57-0201 is related to this service bulletin.

D. Description

Install landing gear downlock pins, defuel and drain the wing center section fuel tank, open the 

equipment cooling system and the fuel tank access panel doors. Do a detailed inspection of the wing 

center section upper and lower stringers for any drill starts. If a drill start is found, do a High Frequency 

Eddy Current (HFEC) open hole inspection for any crack. At each crack location do the zero-timing 

procedure as given in this service bulletin. If the hole is within the service bulletin tolerance limits, 

install a new fastener. If the hole exceeds the tolerance limits, contact Boeing for repair instructions. 

If no crack is found, increase the diameter of the hole and install a new fastener. Close access and 

put the airplane back into a serviceable condition.
 

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BOEING SERVICE BULLETIN 737-57A1294

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E. Compliance

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to 

this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in 

this service bulletin mandatory.

Table 1: Inspection of the wing center section upper and lower stringers to minimize crack size

Condition Action Compliance Time

All airplanes. Do a detailed inspection of the wing 

center section lower stringers for any drill 

starts as given in the Accomplishment 

Instructions Paragraph 3.B.2. Part 2.

Before 9,000 total 

flight cycles. 

All airplanes. Do detailed inspection of the wing center 

section upper stringers for any drill starts 

as given in the Accomplishment 

Instructions Paragraph 3.B.3. Part 3.

Before 9,000 total 

flight cycles. 

Any drill start found. Do the High Frequency Eddy Current 

(HFEC) inspection for any crack as given 

in Accomplishment Instructions 

Paragraph 3.B.4. Part 4.

Before further flight.

Crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are not within the limits 

given in this service bulletin.

Contact Boeing for repair instructions 

and repair.

Before further flight.

Crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are within the limits given in 

this service bulletin.

Install fastener as given in 

Accomplishment Instructions Paragraph 

3.B.4. Part 4.

Before further flight.

No crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are within the limits given in 

this service bulletin.

Install fastener as given in 

Accomplishment Instructions Paragraph 

3.B.4. Part 4.

Before further flight.

Table 2: Inspection of the wing center section lower stringers for safety

Condition Action Compliance Time

All airplanes. Do a detailed inspection of the wing 

center section lower stringers for any drill 

starts as given in the Accomplishment 

Instructions Paragraph 3.B.2. Part 2.

Before 18,000 total 

flight cycles. 

Any drill start found. Do the High Frequency Eddy Current 

(HFEC) inspection for any crack as given 

in Accomplishment Instructions 

Paragraph 3.B.4. Part 4.

Before further flight.
 

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ALERT ALERT

F. Approval

This service bulletin was examined by the Federal Aviation Administration (FAA). The changes 

specified in this service bulletin comply with the applicable regulations and are FAA approved, as well 

as European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/

JAA approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval 

were based on the airplane in its original Boeing delivery configuration or as modified by other 

approved Boeing changes.

If an airplane has a non-Boeing modification or repair that affects a component or system also affected 

by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency 

approval before incorporating this service bulletin.

G. Manpower

The table below shows an estimate of the task-hours necessary to do this inspection for each airplane. 

This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator 

task-hour data if necessary. The estimate does not include lost time. These are some examples of lost 

time:

— Time to adjust to the workplace

— Time to schedule the work

— Time to examine the work

— Time to cure the materials

— Time to make the parts

— Time to find the tools.

Crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are not within the limits 

given in this service bulletin.

Contact Boeing for repair instructions 

and repair.

Before further flight.

Crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are within limits the given in 

this service bulletin.

Install fastener as given in 

Accomplishment Instructions Paragraph 

3.B.4. Part 4.

Before further flight.

No crack found and High Frequency 

Eddy Current (HFEC) inspected drill 

start holes are within the limits given in 

this service bulletin.

Install fastener as given in 

Accomplishment Instructions Paragraph 

3.B.4. Part 4.

Before further flight.

Wing Center Section Upper and Lower Stringer Drill Start Inspection

Task Number of Persons Task-Hours Elapsed Hours

Open Access 4 12.00 3.00

Figure 1 2 7.00 3.50

Figure 2 2 11.00 5.50

Figure 3 1 0.10(a) 0.10(a)

Figure 4 1 0.15(a) 0.15(a)

Close Access 4 5.00 1.25

Table 2: Inspection of the wing center section lower stringers for safety

Condition Action Compliance Time
 

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H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data:

a. 737-600 Structural Repair Manual (SRM) 51-20-01, 51-40-02, 51-40-05.

b. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 06-41-00, 12-11-00, 28-11-00, 

28-11-31, 28-26-00, 32-00-01.

c. 737-700 Structural Repair Manual (SRM) 51-20-01, 51-40-02, 51-40-05.

d. 737-700CONV Structural Repair Manual (SRM) 51-20-01, 51-40-02, 51-40-05.

e. 737-700IGW (BBJ) Structural Repair Manual (SRM) 51-20-01, 51-40-02, 51-40-05.

f. 737-800 Structural Repair Manual (SRM) 51-20-01, 51-40-02, 51-40-05.

g. 737 Non-Destructive Testing (NDT) Manual, Part 6, 51-00-00 Figure 11, Part 6, 51-00-00 

Figure 16.

h. Boeing Drawing 65-88700. 

i. Boeing Parts Standards Document D-590.

j. Service Related Problem (SRP) 737-SRP-57-0201.

k. Standard Overhaul Practices Manual (SOPM) 20-43-03.

2. Data supplied with this Service Bulletin:

None.

Fuel leak test 1 0.25 0.25

TOTAL FOR EACH AIRPLANE 35.25(b) 13.50(b)

(a) Time is for one hole location only.

(b) Total time does not include time in figures 3 or 4. 

Wing Center Section Upper and Lower Stringer Drill Start Inspection

Task Number of Persons Task-Hours Elapsed Hours
 

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3. Installation Drawings Used in the Preparation of this Service Bulletin:

These drawings were used to prepare this service bulletin. These drawings are not necessary to 

make the specified changes, and are not supplied with this service bulletin. These drawings may 

not be applicable to all airplane configurations or operators.

K. Publications Affected

None.

L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

Drawing Number Title

111A3000 Upper Panel Instl - Wing Center Section

111A4000 Lower Panel Instl - Wing Center Section
 

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2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

Boeing warranty remedies are available for 737 airplanes in warranty as of July 17, 2006. For 

inspection task hour reimbursement for airplanes in warranty as of that date, send a warranty claim to 

Boeing Commercial Airplanes Group - Warranties. If the condition described in this service bulletin is 

found during the inspection for airplanes in warranty as of that date and additional task hours and kits, 

parts, and/or special tools are required, send a warranty claim to Boeing Commercial Airplanes Group 

- Warranties. Please refer to this service bulletin number and reference the airplane variable numbers 

in your purchase order.

C. Parts Necessary For Each Airplane

1. Kits/Parts:

None.

2. Parts and Materials Supplied by the Operator:

NOTE: The quantity of rivets given below is an estimate based on the number of drill starts

found by Boeing.

Part Number / Specification QTY Name Notes

BACR15FT5AD4C OR BACR15FT5D4C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT5AD5C OR BACR15FT5D5C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT5AD6C OR BACR15FT5D6C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT5AD7C OR BACR15FT5D7C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT5AD8C OR BACR15FT5D8C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT6AD4C OR BACR15FT6D4C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT6AD5C OR BACR15FT6D5C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT6AD6C OR BACR15FT6D6C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT6AD7C OR BACR15FT6D7C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT6AD8C OR BACR15FT6D8C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT7AD5C OR BACR15FT7D5C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT7AD6C OR BACR15FT7D6C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT7AD7C OR BACR15FT7D7C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT7AD8C OR BACR15FT7D8C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT7AD9C OR BACR15FT7D9C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT8AD5C OR BACR15FT8D5C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT8AD6C OR BACR15FT8D6C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT8AD7C OR BACR15FT8D7C 36 Rivet, Modified Universal Head (a)(b)(c)
 

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3. Parts Modified and Reidentified:

None.

4. Parts Removed and Not Replaced:

None.

D. Parts Necessary to Change Spares

None.

E. Special Tooling - Price and Availability

None.

F. Special Tooling Necessary to do this Service Bulletin

No special tools or equipment are necessary to do the change in this service bulletin. But, 

maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be 

necessary. Examine operator tool supply to make sure all necessary tools are available.

BACR15FT8AD8C OR BACR15FT8D8C 36 Rivet, Modified Universal Head (a)(b)(c)

BACR15FT8AD9C OR BACR15FT8D9C 36 Rivet, Modified Universal Head (a)(b)(c)

Type 2, Class A 4 Ounces Chemical Conversion Coating (d)

BMS 10-20, Type II 4 Ounces Primer (e)

(a) Refer to 737 Structural Repair Manual Chapter 51 for alternative fasteners.

(b) There are more parts than are necessary.

(c) This part is necessary if the hole diameter is increased.

(d) Refer to SOPM 20-43-03 or 737 Structural Repair Manual (SRM) Chapter 51 for material sources.

(e) See the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data.

Part Number / Specification QTY Name Notes
 

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BOEING SERVICE BULLETIN 737-57A1294

ALERT ALERT

3. ACCOMPLISHMENT INSTRUCTIONS

A. GENERAL INFORMATION

CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL

PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED

MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES

CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE

SPARKS OR OTHER ELECTRICAL DAMAGE.

NOTE:

1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for 

definition of the acronyms.

2. Obey all of the warnings and cautions given in the specified manual sections.

3. Unless shown differently, these dimensions and tolerances are used:

— Linear dimensions are in inches.

— Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch.

— Hole dimensions for standard solid rivets are given in 737 Structural Repair 

Manual, Chapter 51.

4. For approved fastener and process material substitutions, refer to 737 Structural Repair 

Manual, Chapter 51, Alternate fasteners are given in 737 Structural Repair Manual 

Chapter 51 and Boeing Drawing 65-88700.

5. If the length of fasteners specified in this service bulletin do not meet the installation 

standards, fasteners of the same specification, or an approved substitute, one grip 

length longer or shorter may be used.

6. A Detailed Inspection is defined as: An intensive examination of a specific item, 

installation, or assembly to detect damage, failure, or irregularity. Available lighting is 

normally supplemented with a direct source of good lighting at an intensity deemed 

appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be necessary. 

Surface cleaning and elaborate procedures may be required.

7. These work instructions refer to procedures included on other Boeing documents. When 

the words "refer to" are used and the operator has an accepted alternative procedure, 

the accepted alternative procedure can be used. When the words "as given in" are 

included in the instruction, the procedure in the Boeing document must be used.

B. WORK INSTRUCTIONS

1. PART 1 - ACCESS

a. Install landing gear downlock pins. Refer to 737-600/700/800/900 AMM 32-00-01 as an 

accepted procedure.

b. Defuel the wing center section fuel tank. Refer to 737-600/700/800/900 AMM 28-26-00 as 

accepted procedure.
 

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c. Drain fuel from the sump of the wing center section fuel tank. Refer to 737-600/700/800/900 

AMM 12-11-00 as accepted procedure.

d. Purge the wing center section fuel tank and prepare it for entry. Refer to 737-600/700/800/

900 AMM 28-11-00 as an accepted procedure.

e. Open access door 192CL of the Equipment Cooling System (ECS). Refer to 737-600/700/

800/900 AMM 06-41-00 as an accepted procedure.

f. Remove keep wing center section fuel tank access panel door 131AB. Refer to 737-600/

700/800/900 AMM 28-11-31 as an accepted procedure.

NOTE: Operator may get additional access as required.

2. PART 2 - WING CENTER SECTION - LOWER STRINGER INSPECTION

a. Do a detailed inspection of the lower stringers for any drill start as given in Figure 1.

(1) If any drill start is found. Do the PART 4 - STRINGER REPAIR.

3. PART 3 - WING CENTER SECTION - UPPER STRINGER INSPECTION

a. Do a detailed inspection of the upper stringers for any drill start as given in Figure 2.

(1) If any drill start is found. Do the PART 4 - STRINGER REPAIR.

4. PART 4 - STRINGER REPAIR

a. At each drill start location, drill the drill start and do a High Frequency Eddy Current (HFEC) 

open hole inspection for any crack as given in Figure 3.

(1) If any crack is found, remove the crack as given in 737 NDT, Part 6, 51-00-00 Figure 

16 or 737 NDT, Part 6, 51-00-00 Figure 11.

(a) If final hole exceeds the diameter required for a 0.250 inch rivet or a 4D spacing 

to any adjacent fasteners or other drill plug holes can not be maintained or a 2D 

edge margin can not be maintained or the tail or head of fastener will be closer 

than 0.02 inch to the stringer fillet radius, contact Boeing for repair instructions.

(2) If no crack is found, increase the hole diameter by 0.0625 inch to make sure that any 

fatigue damage is removed.

(a) If final hole exceeds the diameter required for a 0.250 inch rivet or a 4D spacing 

to any adjacent fasteners or other drill plug holes can not be maintained or a 2D 

edge margin can not be maintained or the tail or head of fastener will be closer 

than 0.02 inch to the stringer fillet radius, contact Boeing for repair instructions.

b. At each drill start location, install a fastener as given in Figure 4.

5. PART 5 - CLOSE ACCESS

a. Install kept access panel door 131AB. Refer to 737-600/700/800/900 AMM 28-11-31 as an 

accepted procedure.
 

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b. Refuel the wing center section fuel tank. Refer to 737-600/700/800/900 AMM 12-11-00 as 

accepted procedure.

c. Do a fuel leak inspection of the wing center section fuel tank access panel door 131AB. 

Refer to 737-600/700/800/900 AMM 28-11-00 as an accepted procedure.

d. Close access doors 192CL. Refer to 737-600/700/800/900 AMM 06-41-00 as an accepted 

procedure.

e. Remove landing gear downlock pins. Refer to 737-600/700/800/900 AMM 32-00-01 as an 

accepted procedure.

f. Put the airplane back to a serviceable condition.
 FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION

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FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION

STA

664

STA

540

FWD

SEE A

SEE B

A

1338089

(SHEET 1 OF 4)
 FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION

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BOEING SERVICE BULLETIN 737-57A1294

ALERT ALERT

FWD

B

STA

545.8

STA

654.4

12 11 10 9 8 7 6 5 4 3 2 1

S-14L

S-13L

S-12L S-10L

S-9L

S-8L

S-7L

S-5L

S-4L

S-3L

S-2L

S-1L

SEE C

LBL

45.5

LBL

69.95

RBL

69.95

BL

0.0

RBL

45.5

WING CENTER SECTION LOWER SKIN STRINGER LOCATION - VIEW LOOKING DOWN

1338094

(SHEET 2 OF 4)
 FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION

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ALERT ALERT

LOWER WING PANEL

LOWER STRINGER

FREE FLANGE

MIRROR

DRILL START

(TYPICAL)

C

1338127

(SHEET 3 OF 4)
 FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION

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ALERT ALERT

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

numbers shown below are the number of parts necessary to inspect

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Inspect Stringer-1L - 1 (a)

2 Inspect Stringer-2L - 1 (a)

3 Inspect Stringer-3L - 1 (a)

4 Inspect Stringer-4L - 1 (a)

5 Inspect Stringer-5L - 1 (a)

6 Inspect Stringer-7L - 1 (a)

7 Inspect Stringer-8L - 1 (a)

8 Inspect Stringer-9L - 1 (a)

9 Inspect Stringer-10L - 1 (a)

10 Inspect Stringer-12L - 1 (a)

11 Inspect Stringer-13L - 1 (a)

12 Inspect Stringer-14L - 1 (a)

(a) Do a detailed inspection for drill starts on the entire length of the underside of the lower 

stringer free flange, stringer vertical web and the fillet radius between the free flange and 

vertical web.

(SHEET 4 OF 4)
 FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION

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FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION

STA

664

STA

540

FWD

SEE A

SEE B

A

1338072

(SHEET 1 OF 4)
 FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION

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ALERT ALERT

FWD

RBL

45.5

BL

0.0

LBL

45.5

SEE C

7 2

1

17 16 15 14 13 12 11 10 9 8 6 5 4 3

S-21U

S-20U

S-19U

S-18U

S-17U S-15U

S-14U

S-12U

S-10U

S-9U S-7U

S-6U

S-5U

S-4U

S-3U

S-2U

S-1U

STA

541.6

STA

655.4

B

WING CENTER SECTION UPPER SKIN STRINGER LOCATION - VIEW LOOKING UP

LBL

69.45

RBL

69.45

1338071

(SHEET 2 OF 4)
 FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION

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ALERT ALERT

UPPER WING PANEL

UPPER STRINGER

FREE FLANGE

MIRROR

DRILL START

(TYPICAL)

C

1338075

(SHEET 3 OF 4)
 FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION

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ALERT ALERT

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

numbers shown below are the number of parts necessary to inspect.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Inspect Stringer-1U - 1 (a)

2 Inspect Stringer-2U - 1 (a)

3 Inspect Stringer-3U - 1 (a)

4 Inspect Stringer-4U - 1 (a)

5 Inspect Stringer-5U - 1 (a)

6 Inspect Stringer-6U - 1 (a)

7 Inspect Stringer-7U - 1 (a)

8 Inspect Stringer-9U - 1 (a)

9 Inspect Stringer-10U - 1 (a)

10 Inspect Stringer-12U - 1 (a)

11 Inspect Stringer-14U - 1 (a)

12 Inspect Stringer-15U - 1 (a)

13 Inspect Stringer-17U - 1 (a)

14 Inspect Stringer-18U - 1 (a)

15 Inspect Stringer-19U - 1 (a)

16 Inspect Stringer-20U - 1 (a)

17 Inspect Stringer-21U - 1 (a)

(a)

Do a detailed inspection for drill starts on the entire length of the underside of the upper 

stringer free flange, stringer vertical web and the fillet radius between the free flange and 

vertical web.

(SHEET 4 OF 4)
 FIGURE 3: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START HIGH FREQUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION

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ALERT ALERT

FIGURE 3: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START HIGH 

FREQUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION

FWD

SEE A

SEE B

A

B

FREE FLANGE

VERTICAL WEB

SKIN

SKIN

ATTACHMENT

FLANGE

1 2

TYPICAL STRINGER

1338136

(SHEET 1 OF 2)
 FIGURE 3: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START HIGH FREQUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION

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ALERT ALERT

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

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Drill Drill Start - - (a)(b)

2 Inspect Hole - - (b)(c)(d)

(a) Drill out the drill start to 0.098 - 0.103 inch diameter.

(b)

Make sure the hole diameter does not exceed the diameter required for a 0.250 inch rivet. 

Maintain 4D spacing to any adjacent fasteners or other drill plug holes. Maintain a 2D edge 

margin. Make sure fastener tail or head is no closer than 0.02 inch to the stringer fillet radius.

(c) Do a High Frequency Eddy Current (HFEC) open hole inspection for any crack as given in 737 

NDT, Part 6, 51-00-00 Figure 16 or 737 NDT, Part 6, 51-00-00 Figure 11.

(d)

Initial drill start holes without cracks must also be enlarged 0.0625 inch beyond the initial 

diameter. This “insurance cut” is needed to ensure that a crack too small to be detected by High 

Frequency Eddy Current (HFEC) inspection is fully removed.

(SHEET 2 OF 2)
 FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER 

INSTALLATION

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ALERT ALERT

FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER 

INSTALLATION 

FWD

SEE A

SEE B

A

B

FREE FLANGE

VERTICAL WEB

SKIN

SKIN

ATTACHMENT

FLANGE

1 2

TYPICAL STRINGER

3 4 5 A N

C

1338164

(SHEET 1 OF 3)
 FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER 

INSTALLATION

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BOEING SERVICE BULLETIN 737-57A1294

ALERT ALERT

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

The codes shown 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. The QTY numbers shown below are the 

number of fasteners necessary for this figure.

STEP TASK NAME IDENTIFICATION QTY MORE DATA

1 Drill Hole - - (a)(b)

2 Deburr Hole - - -

3

Apply Chemical 

Conversion 

Coating

Type 2, Class A - (c)

4 Install Fastener - - (d)(e)

5 Apply Primer BMS 10-20, Type II - (c)

(a) This step is not required if the hole is within the tolerance required for fasteners as given in the 

fastener table.

(b) Make sure the final insurance cut is within the tolerance required for fasteners as given in the 

fastener code table.

(c) Refer to 737-600 SRM 51-20-01, 737-700 SRM 51-20-01, 737-700CONV SRM 51-20-01, 

737-700IGW (BBJ) SRM 51-20-01, 737-800 SRM 51-20-01 as accepted procedures.

(d)

For fastener installation. Refer to 737-600 SRM 51-40-02,737-700 SRM 51-40-02,737-700CONV 

SRM 51-40-02,737-700IGW (BBJ) SRM 51-40-02,737-800 SRM 51-40-02 as an accepted 

procedures except overdrive all rivets to a minimum bucked tail diameter of 1.4d.

(e) as given in fastener code table.

COUNTERSINK FASTENER

C

D

EXAMPLE OF FASTENER SYMBOL

LENGTH/GRIP

FASTENER

6F

7

LETTER CODE

DIAMETER

(OPTIONAL) 

HEAD LOCATION

N = NEAR SIDE

F = FAR SIDE

(OPTIONAL)

(OPTIONAL)

S36173

(SHEET 2 OF 3)
 FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER 

INSTALLATION

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BOEING SERVICE BULLETIN 737-57A1294

ALERT ALERT

If the grip length shown is not available at Boeing, fasteners supplied in kits may be one grip length longer than 

indicated. Also, if any of the fastener part numbers are not available or have been superseded, substitute 

fasteners may be supplied in Boeing kits, Boeing Document D-590 and Boeing drawing 65-88700 are used to 

determine the part numbers used as substitutes. 

CODE NAME IDENTIFICATION QTY HOLE DIA MORE DATA

A Rivet, modified 

universal head.

BACR15FT5AD( )C OR BACR15FT5D( )C - 0.159 - 0.171 (a)(b)(c)

BACR15FT6AD( )C OR BACR15FT6D( )C - 0.191 - 0.202 (a)(b)(c)

BACR15FT7AD( )C OR BACR15FT7D( )C - 0.221 - 0.223 (a)(b)(c)

BACR15FT8AD( )C OR BACR15FT8D( )C - 0.254 - 0.265 (a)(b)(c)

(a) Determine the length of rivet at installation.

(b) For fastener installation. Refer to 737-600 SRM 51-40-02,737-700 SRM 51-40-02,737-700CONV 

SRM 51-40-02,737-700IGW (BBJ) SRM 51-40-02,737-800 SRM 51-40-02 as an accepted procedures 

except overdrive all rivets to a minimum bucked tail diameter of 1.4d.

(c) For hole diameter sizes. Refer to 737-600 SRM 51-40-05, 737-700 SRM 51-40-05, 737-700CONV 

SRM 51-40-05, 737-700IGW (BBJ) SRM 51-40-05, 737-800 SRM 51-40-05 as accepted procedures.

(SHEET 3 OF 3)