April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 1 of 34 ALERT ALERT 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## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2007 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter.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, MD-11, MD-80, MD-90, the Boeing logo and the Boeing livery are among the trademarks owned by Boeing or its subsidiaries. No intellectual property license (express or implied) is granted in connection with this document or otherwise.**BLANK PAGE** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 2 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

BLANK PAGE**Table of Contents** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 3 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT 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 STRING ERS - 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2**Table of Contents** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 4 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

BLANK PAGEApril 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 5 of 34 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 6 of 34 

### 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 7 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

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

FWD1338185April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 8 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

BLANK PAGEApril 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 9 of 34 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 10 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT** 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–YK552April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 11 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT** 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 1April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 12 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 13 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 14 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **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**April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 15 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

**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** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 16 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

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 SectionApril 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 17 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT 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)April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 18 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

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**April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 19 of 34 

### 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 20 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT** 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.April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 21 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT** 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** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 22 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION** 



### STA 664

STA 540

FWD A SEE

B SEE



### A1338089

**(SHEET 1 OF 4) FIGURE 1: WING CENTER SECTION -**  **LOWER STRINGERS - DRILL START INSPECTION** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 23 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

FWD



### B STA 545.8 STA 654.4 10 2 7 1 8 6 5 4 3 9 11 12 S-14L S-13L S-12L S-10L S-9L S-8L S-7L S-5L S-4L S-3L S-2L S-1L

C SEE

LBL 45.5

LBL 69.95

RBL 69.95

BL 0.0 RBL 45.5

WING CENTER SECTION LOWER SKIN STRINGER LOCATION - VIEW LOOKING DOWN1338094

**(SHEET 2 OF 4) FIGURE 1: WING CENTER SECTION - LOWER STRINGERS - DRILL START INSPECTION**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 24 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

LOWER WING PANEL

LOWER STRINGER

FREE FLANGE MIRROR DRILL START

(TYPICAL)



### C1338127

**(SHEET 3 OF 4) FIGURE 1: WING CENTER SECTION -**  **LOWER STRINGERS - DRILL START INSPECTION** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 25 of 34 

### 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 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**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 26 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION** 



### STA 664

STA 540

FWD A SEE

B SEE



### A1338072

**(SHEET 1 OF 4) FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 27 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

FWD

RBL 45.5

BL 0.0 LBL 45.5

C SEE

2 7 1 8 6 5 4 3 9 10 15 17 11 12 13 14 16 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 69.451338071

**(SHEET 2 OF 4) FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 28 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT**

UPPER WING PANEL

UPPER STRINGER

FREE FLANGE MIRROR DRILL START

(TYPICAL)



### C1338075

**(SHEET 3 OF 4) FIGURE 2: WING CENTER SECTION - UPPER STRINGERS - DRILL START INSPECTION**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 29 of 34 

### 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 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 FRE**  **QUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 30 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT FIGURE 3: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START HIGH**  **FREQUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION**

FWD A SEE

B SEE


### A

B FREE FLANGE

VERTICAL WEB

SKIN

SKIN ATTACHMENT FLANGE 2 1



### TYPICAL STRINGER1338136

**(SHEET 1 OF 2) FIGURE 3: WING CENTER SECTION - UPPE**  **R AND LOWER STRINGERS - DRILL START HIGH FRE QUENCY EDDY CURRENT (HFEC) OPEN HOLE INSPECTION**  April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 31 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **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** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 32 of 34 

### BOEING SERVICE BULLETIN 737-57A1294 **ALERT ALERT FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER**  **INSTALLATION**

FWD A SEE

B SEE


### A

B FREE FLANGE

VERTICAL WEB

SKIN

SKIN ATTACHMENT FLANGE 2 1



### TYPICAL STRINGER 3 4 5 A N C1338164

**(SHEET 1 OF 3) FIGURE 4: WING CENTER SECTION - UPPER AND LOWER STRINGERS - DRILL START FASTENER**  **INSTALLATION** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 33 of 34 

### 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** April 23, 2007 737-57A1294 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 34 of 34 

### 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)**