### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-53A1301**  Original Issue: September 03, 2009 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Cracks at Chem-milled Steps in Crown Skins at Specified Locations - Inspection Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2009 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter.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, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 1 of 24 5.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 2 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**

BLANK PAGE**Table of Contents** Summary...................................................... 5 1. PLANNING INFORMATION ........................................ 9 A. Effectivity................................................ 9 1. Airplanes............................................. 9 2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 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. . . . . . . . . . . . 15 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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 17 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 FIGURE 1: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION [Group 2]. . . . . . . . . . . . . . . . . . 21 FIGURE 2: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION [Group 1]. . . . . . . . . . . . . . . . . . 23

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 3 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 4 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Summary**  **Number: 737-53A1301** Original Issue: September 03, 2009 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Cracks at Chem-milled Steps in Crown Skins at Specified Locations - Inspection 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** Accomplishment of the inspections in this service bulletin will make sure that fuselage skin cracks at stringers S-1 and S-2R, between Body Stations STA 827 and STA 847 are found and repaired. An Emergency Locator Transmitter (ELT) Antenna structural full pad up doubler provision is at this location on the affected airplanes. All airplanes listed in this service bulletin require inspection even if the ELT antenna was not installed or has been removed. This action is necessary to find and repair fatigue cracking of the skin panel at the chem-mill steps which could result in rapid decompression of the airplane. Boeing has received one report from an operator of a hole in the fuselage skin common to stringer S-1 and S-2L, between STA 827 and STA 847. The crack started along the chem-mill edge along stringer S-1. The airplane skin in the area had 20 inch tear strap bays. The airplane diverted to an alternate airport due to cabin depressurization and subsequent deployment of the oxygen masks. The airplane had accumulated 42,569 total flight cycles. Airplanes with 10 inch tear strap bays are also susceptible to cracks at this location. The cause of cracking is under investigation. Boeing Service Related Problem (SRP) 737-SRP-53-0346 is related to this service bulletin. **ACTION** Get external access to the area adjacent to the ELT Antenna provision at stringers S-1 and S-2R, between STA 827 and STA 847. Do one of the external Non Destructive Inspections (NDI) specified in the compliance section of this service bulletin for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R, between STA 827 and STA 847. The NDIs that can be used are Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan. If any crack is found, contact Boeing for repair instructions and do the repair. If no cracking is found, do the repeat inspection in accordance with this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 5 of 24**EFFECTIVITY** 737-300/ -400/ -500 Airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes. **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. Refer to Paragraph 1.E. Compliance. **INDUSTRY SUPPORT INFORMATION** At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent revision or Information Notice will address the warranty remedies available, if any. **MANPOWER Elapsed Hours**  **Total Task Hours Airplanes**  3.00 4.00 Group 1 3.00 4.00 Group 2
**MATERIAL INFORMATION** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 6 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 7 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 8 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-53A1301**  Original Issue: September 03, 2009 ATA System: 5331 **SUBJECT:** FUSELAGE - Skin - Cracks at Chem-milled Steps in Crown Skins at Specified Locations - Inspection 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

**DESCRIPTION CONFIGURATION**  **GROUP** 737-300/-500 Airplanes with ELT Antenna provisions and 10 inch tear strap bays - 1
737-300/-400/-500 Airplanes with ELT Antenna provisions and 20 inch tear strap bays - 2

Airplane Models: 737-300, 737-400, 737-500 **Group Variable Number**  2 PJ604 - PJ615 2 PM543 - PM550 2 PP518 - PP520 2 PP876 - PP877 2 PQ297 - PQ299 2 PQ345 - PQ348 2 PQ370 - PQ373

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 9 of 24**Group Variable Number**  2 PQ391 - PQ395 2 PQ408 - PQ410 2 PQ414 - PQ418 2 PQ431 - PQ438 2 PQ447 - PQ448 2 PQ451 2 PQ454 2 PQ473 - PQ475 2 PQ772 1 PQ931 - PQ932 2 PQ933 - PQ935 2 PQ951 2 PQ971 - PQ997 2 PR001 - PR017 2 PR021 - PR034 2 PR041 - PR045 2 PR061 - PR072 2 PR077 - PR082 2 PR091 - PR092 2 PR096 2 PR101 2 PR121 - PR122 2 PR131 - PR132 2 PR141 - PR143 2 PR161 - PR172 2 PR181 2 PS617 - PS630 2 PS704 - PS706 2 PS763 - PS799 2 PS811 2 PS836 - PS837 2 PS841 - PS846 2 PS851 - PS852

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 10 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT Group**  **Variable Number** 2 PS856 2 PS861 - PS863 2 PS866 - PS868 2 PS871 - PS874 2 PS896 - PS897 2 PS901 - PS941 2 PS956 - PS957 2 PS961 - PS963 2 PS971 - PS978 2 PT012 - PT015 2 PT029 - PT031 2 PT064 2 PT126 - PT138 1 PT181 - PT187 2 PT188 1 PT295 2 PT307 - PT309 2 PT513 - PT517 2 PT585 - PT586 2 PT643 - PT644 2 PT656 2 PT681 - PT685 1 PT701 - PT703 2 PT716 - PT717 2 PT721 - PT725 2 PT801 - PT834 2 PT851 - PT854 2 PT871 - PT886 2 PT901 - PT930 2 PT971 - PT973 2 PT981 - PT985 2 PT996 2 PU301

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 11 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT Group**  **Variable Number** 2 PU311 - PU313 2 PV229 2 PV356 - PV357 2 PW168 - PW171 2 PW263 - PW264 2 PW405 - PW408 2 PW416 - PW418 2 PW421 - PW424 2 PW431 - PW435 2 PW441 - PW450 2 PW853 - PW856 2. Spares Affected None. **B. Concurrent Requirements** None. **C. Reason** Accomplishment of the inspections in this service bulletin will make sure that fuselage skin cracks at stringers S-1 and S-2R, between Body Stations STA 827 and STA 847 are found and repaired. An Emergency Locator Transmitter (ELT) Antenna structural full pad up doubler provision is at this location on the affected airplanes. All airplanes listed in this service bulletin require inspection even if the ELT antenna was not installed or has been removed. This action is necessary to find and repair fatigue cracking of the skin panel at the chem-mill steps which could result in rapid decompression of the airplane. Boeing has received one report from an operator of a hole in the fuselage skin common to stringer S-1 and S-2L, between STA 827 and STA 847. The crack started along the chem-mill edge along stringer S-1. The airplane skin in the area had 20 inch tear strap bays. The airplane diverted to an alternate airport due to cabin depressurization and subsequent deployment of the oxygen masks. The airplane had accumulated 42,569 total flight cycles. Airplanes with 10 inch tear strap bays are also susceptible to cracks at this location. The cause of cracking is under investigation. Boeing Service Related Problem (SRP) 737-SRP-53-0346 is related to this service bulletin. **D. Description** Get external access to the area adjacent to the ELT Antenna provision at stringers S-1 and S-2R, between STA 827 and STA 847.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 12 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**Do one of the external Non Destructive Inspections (NDI) specified in the compliance section of this service bulletin for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R, between STA 827 and STA 847. The NDIs that can be used are Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan. If any crack is found, contact Boeing for repair instructions and do the repair. If no cracking is found, do the repeat inspection in accordance with this service bulletin. The work in this service bulletin is done in the maintenance zone(s) given below. **Group 1:**
**Affected Maintenance Zones Zone**  **Model** 108 737-300, 737-500 **Group 2:**
**Affected Maintenance Zones Zone**  **Model** 108 737-300, 737-400, 737-500 **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: Fuselage Skin Inspections at Stringers S-1 and S-2R, STA 827 - STA 847 Repeat Interval**  **(Not to Exceed) Compliance Time (Whichever**  **Occurs Later) Action**  **Condition** 500 flight cycles from the previous (NDI) inspection. Within 500 flight cycles after thedate on this service bulletin. Before 35,000total flight cycles.Do an external Non Destructive Inspection (NDI): Medium Frequency EddyCurrent (MFEC) or Magneto Optical Imaging(MOI) or C-Scan, Inspection for cracking in the fuselage skin chem-mill steps at stringers S-1 and S-2R between STA 827and STA 847 in accordance with Accomplishment Instructions 3.B.1 or 3.B.2. (a) All Airplanes

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 13 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT Table 1: Fuselage Skin Inspections at Stringers S-1 and S-2R, STA 827 - STA 847**  **Repeat Interval (Not to Exceed)**  **Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Do not cut out the dam-age prior to receiving repair instructions from Boeing. It is likely that the cutout will be requested for further metallurgical analysis so the cutout will likely be larger than a typical repair. ContactBoeing for repair instructions and do the repair. Any crack found in the fuselage skin

(a) It is not necessary to inspect the chem-mill steps under an existing external repair doubler provided all of the following apply: 1. The repair was installed after the release date of this service bulletin. 2. The repair was approved by the FAA or by a Boeing company authorized representative who was authorized by the FAA to make such findings, and 3. The repair extends a minimum of three rows of fasteners on each side of the chem-mill line in the circumferential direction.

**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 inspect the work

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 14 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**• Time to cure the materials • Time to make the parts • Time to find the tools.

**Group 1: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 1.00 1.00 1 Get Access 1.00 2.00 2 Figure 2 1.00 1.00 1 Close Access 3.00 4.00 TOTAL FOR EACH AIRPLANE **Group 2: Elapsed Hours**  **Task Hours Number of Persons**  **Task** 1.00 1.00 1 Get Access 1.00 2.00 2 Figure 1 1.00 1.00 1 Close Access 3.00 4.00 TOTAL FOR EACH AIRPLANE **H. Weight and Balance Changes** None. **I. Electrical Load Data** Not changed. **J. References** 1. Existing Data a. Service Related Problem (SRP) 737-53-0346 b. 737 Nondestructive Test (NDT) Manual, Part 6, Subject Eddy Current 2. Data supplied with this Service Bulletin None. 3. Installation Drawings Used in the Preparation of this Service Bulletin
**Title Drawing Number**  SKIN INSTL - STA 727 TO STA 908, S-10L TO S-10R 65C35772 SKIN PANEL INSTL - S-10L TO S-10R STA 727 TO STA 1016 65-45772

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 15 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**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** 1. Publications: None. 2. Damage Tolerance Based Structural Inspections: Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This service bulletin affects FCS but no new DTIs are necessary. **L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 16 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** None. **B. Industry Support Information** At the time of release of this service bulletin, warranty remedies have not been determined. A subsequent revision or Information Notice will address the warranty remedies available, if any. **C. Parts Necessary For Each Airplane** 1. Kits/Parts None. 2. Parts and Materials Supplied by the Operator None. 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 17 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 18 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**

BLANK PAGE**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. The instructions identified in Paragraph 3.B., Work Instructions, and the Figure(s) give the recommended sequence of steps. The sequence of steps to do this service bulletin can be changed. 2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 3. Obey all of the warnings and cautions given in the specified manual sections. 4. A Special Detailed Inspection is defined as: An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. The examination is likely to make extensive use of specialized Inspection Techniques and/or equipment. Intricate cleaning and substantial access or disassembly procedure may be required. 5. These work instructions refer to procedures included in 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 "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. **B. WORK INSTRUCTIONS**
1. **Group 1:** a. Initial Inspection (1) Get external access to the area around the ELT antenna provision at stringer S-1 and S-2R between STA 827 and STA 847. (2) Do an NDI Inspection using one of the following methods - Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan, for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R between STA 827 and STA 847 in accordance with FIGURE 2. (3) If any crack is found, contact Boeing for repair instructions and do the repair. (4) If no crack is found do the repeat inspection in accordance with Paragraph 1.E., Compliance. b. Repeat Inspections

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 19 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**(1) Get external access to the area around the ELT antenna provision at stringer S-1 and S-2R between STA 827 and STA 847. (2) Do an NDI Inspection using one of the following methods - Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan, for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R between STA 827 and STA 847 in accordance with FIGURE 2. (3) If any crack is found, contact Boeing for repair instructions and do the repair. (4) If no crack is found do the repeat inspection in accordance with Paragraph 1.E., Compliance.
2. **Group 2:** a. Initial Inspection (1) Get external access to the area around the ELT antenna provision at stringer S-1 and S-2R between STA 827 and STA 847. (2) Do an NDI Inspection using one of the following methods - Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan, for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R between STA 827 and STA 847 in accordance with FIGURE 1 (3) If any crack is found, contact Boeing for repair instructions and do the repair. (4) If no crack is found do the repeat inspection in accordance with Paragraph 1.E., Compliance. b. Repeat Inspections (1) Get external access to the area around the ELT antenna provision at stringer S-1 and S-2R between STA 827 and STA 847. (2) Do an NDI Inspection using one of the following methods - Medium Frequency Eddy Current (MFEC), Magneto Optical Imaging (MOI) or C-Scan, for cracking in the fuselage skin along the chem-mill step at stringer S-1 and S-2R between STA 827 and STA 847 in accordance with FIGURE 1. (3) If any crack is found, contact Boeing for repair instructions and do the repair. (4) If no crack is found do the repeat inspection in accordance with Paragraph 1.E., Compliance. 3. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 20 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT This Figure applies only to: Group 2.** 

**FIGURE 1: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 21 of 24 **BOEING SERVICE BULLETIN 737-53A1301 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 for this figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - Skin Inspect 1 (a) Do an external eddy current inspection for chem-mill cracks as given in 737 NDT [Part 6, 53-30-09] or 737 NDT [Part 6, 53-30-18] or 737 NDT [Part 6, 53-30-19] or 737 NDT [Part 6, 53-30-25].

**FIGURE 1: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 22 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT This Figure applies only to: Group 1.** 

**FIGURE 2: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 23 of 24 **BOEING SERVICE BULLETIN 737-53A1301 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 for this figure.
**MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP**  (a)

- - Skin Inspect 1 (a) Do an external eddy current inspection for chem-mill cracks as given in 737 NDT [Part 6, 53-30-09] or 737 NDT [Part 6, 53-30-18] or 737 NDT [Part 6, 53-30-19] or 737 NDT [Part 6, 53-30-25].

**FIGURE 2: FUSELAGE - SKIN AT AREA WITH ELT ANTENNA PROVISION BETWEEN STA 827 AND STA 847 - NON DESTRUCTIVE INSPECTION**  **(SHEET 2 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 03, 2009 737-53A1301 24 of 24 **BOEING SERVICE BULLETIN 737-53A1301 ALERT**  **ALERT**