### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-52A1079**  Original Issue: December 16, 1983 Revision 7: December 17, 2010 ATA System: 5231 **SUBJECT:**DOORS - Aft Cargo - Frame and Beam Inspection, Repair and Modification 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## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 1989 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter.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BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details.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Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 1 of 103 4.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 2 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 9 1. PLANNING INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 A. Effectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. Airplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 1. Existing Data:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2. Data supplied with this Service Bulletin:. . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3. Installation Drawings Used in the Preparation of this Service Bulletin:. . . . . . . . . . . 42 4. Process Data:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 43 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1. Kits/Parts:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2. Parts and Materials Supplied by the Operator:. . . . . . . . . . . . . . . . . . . . . . . . 52 3. Parts Modified and Reidentified:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4. Parts Removed and Not Replaced:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 55 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 FIGURE 1: AFT CARGO DOOR INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 FIGURE 2: CORNER INSPECTION AND REWORK. . . . . . . . . . . . . . . . . . . . . . . . . . . 70 FIGURE 3: LOWER BEAM REPAIR - FORWARD END. . . . . . . . . . . . . . . . . . . . . . . . . 72 FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END. . . . . . . . . . . . . . . . . . . . . 77 FIGURE 5: LOWER BEAM REPAIR - AFT END. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 FIGURE 6: REPAIR PARTS - LOWER BEAM AFT END. . . . . . . . . . . . . . . . . . . . . . . . . 87 FIGURE 7: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 FIGURE 8: AFT CARGO DOOR - LOWER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 3 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**FIGURE 9: AFT CARGO DOOR - UPPER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 FIGURE 10: AFT CARGO DOOR - UPPER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 FIGURE 11: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION FOR AIRPLANES WITH LOWER BEAM OUTER 'T' CHORD REPAIR INSTALLED ON THE FORWARD END. . . . . . . . . . . . . . . . . . . . . . 101

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 4 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**

### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Revision Transmittal Sheet**  **Number: 737-52A1079** Original Issue: December 16, 1983 Revision 7: December 17, 2010 ATA System: 5231 **SUBJECT:**DOORS - Aft Cargo - Frame and Beam Inspection, Repair and Modification This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** More work is necessary on airplanes that have not accomplished the repair or preventive modification in accordance with previous releases of this service bulletin. Do an ultrasonic inspection for cracks in the upper and lower corner frames and a HFEC inspection for cracks in the upper and lower cross beams at the revised time specified in Paragraph 1.E., Compliance. More work is necessary on airplanes that have repair angles 65C25180-9, -43, -10, -11 or -12 installed in accordance with previous issues of this service bulletin. Do the work in Paragraph 3.B., Work Instructions, Part V - Corner Inspection and Rework in accordance with Revision 7 of this service bulletin at the revised time specified in Paragraph 1.E., Compliance. More work is necessary on airplanes that have accomplished the repair or preventive modification of the upper or lower cross beams in accordance with previous releases of this service bulletin. Do supplemental structural inspections of the cross beams at the times specified in Paragraph 1.E., Compliance. These supplemental structural inspections provide compliance with 14 CFR 26.43 (c). Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2000-06-13 R1 supersedes Airworthiness Directive (AD) 98-25-06. No new airplanes have been added or removed from the effectivity of this bulletin. **REASON FOR REVISION** This revision is sent to: — Remove the option for repeat inspections and add a High Frequency Eddy Current (HFEC) inspection for cracks in the beam. — Remove the option to repair the upper edge frame using a Structural Repair Manual (SRM) procedure. — Replace the HFEC inspection of the frames with an ultrasonic inspection. — Inform operators that the corner reinforcing angles given in previous releases of this service bulletin have been superseded by corner reinforcing angles with an increased edge margin. — Inform operators that this revision provides supplemental structural inspections in compliance with 14 CFR 26.43 (c). — Change the Lower Beam Outer 'T' Chord Repair on the forward end of the lower beam to include a joggle of the replacement 'T' Chord.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 5 of 103— Change the heat treatment of the replacement 'T' Chord A to 2024-0. — Instruct operators to identify the aft cargo door part number which is currently installed on each airplane in accordance with the original issue of Boeing Service Bulletin 737-52A1153 before further work is done. — Instruct operators to also accomplish all applicable actions in accordance with the original issue of Service Bulletin 737-52-1154 at the time specified in Paragraph 1.E., Compliance, if any cracks are found. These sections were changed: 1. The Summary Background and Action sections are updated. 2. Summary illustration - Reinforcement angles are added to the lower corners of the aft cargo door. 3. Paragraph 1.C., Reason is updated. 4. Paragraph 1.D., Description is updated. 5. Paragraph 1.E., Compliance - The compliance information is changed. 6. Paragraph 1.F, Approval - An Alternative Method of Compliance (AMOC) statement is added. Also, supplemental structural inspection information is added. 7. Paragraph 1.G., Manpower - The manpower information is updated. 8. Paragraph 1.H., Weight and Balance Changes - The SRM repair is removed from the table. 9. Paragraph 1.J., References - Non Destructive Test (NDT) Manual references, reference service bulletin numbers and Federal Aviation Administration (FAA) Airworthiness Directives (AD) are added. Supplemental Structural Inspection Document numbers are also added. SRM 51-40-3 reference is removed. 10. Paragraph 1.K., Publications Affected - A statement for Damage Tolerance Based Structural Inspections is added. 11. Paragraph 2.C.1., Kits/Parts - Replacement parts are added to one kit table. 12. Paragraph 2.C.2., Parts and Materials Supplied by the Operator - Fasteners are added to the table for the repair parts. 13. Paragraph 3.A., General Information - Note added, reference the use of the words "refer to" and "in accordance with". 14. Paragraph 3.B., Work Instructions - Supplemental Structural Inspections are added. Also, the option to repair the upper edge frame using an SRM procedure is removed. 15. Figures 1 through 5 are updated. 16. Figures 7 through 11 are added to provide Supplemental Structural Inspections. Paragraph 1.A., Effectivity, shows changes of airplane operators. Each operator should examine the Effectivity paragraph for changes. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location of important changes.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 6 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**Pages with no vertical lines have no important changes. **REVISION HISTORY** December 16, 1983 Original Issue: December 15, 1988 Revision 1: July 20, 1989 Revision 2: May 17, 1990 Revision 3: February 21, 1991 Revision 4: May 16, 1996 Revision 5: November 18, 1999 Revision 6: December 17, 2010 Revision 7:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 7 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 8 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Summary**  **Number: 737-52A1079** Original Issue: December 16, 1983 Revision 7: December 17, 2010 ATA System: 5231 **SUBJECT:**DOORS - Aft Cargo - Frame and Beam Inspection, Repair and Modification 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** Based on a structural review of the 737 airplane, incorporation of the modification in accordance with this service bulletin is recommended on aging airplanes. As of 1996, several operators had reported cracks 0.75 to 20 inches long in the forward and aft lower corner of the aft cargo door frames. The airplanes had 10,100 to 38,000 flight hours and 14,000 to 54,000 flight cycles. In addition, some of the doors had a cracked web in the beam common to the forward lower stop fitting, approximately 3 inches aft of the fitting. In some of the cases, the frame and beam cracks were discovered after the airplane had experienced pressurization problems. Cracking is caused by fatigue as a result of cabin pressurization cycles. Since 1996, there have been additional reports of cracked frames and cracked beam webs. One airplane with 86,400 hours and 35,400 flight cycles experienced a rapid decompression caused by an approximately 12 inch long crack in the aft lower frame corner. The lower beam web and outer 'T' chord were also cracked. Since 1996, there have also been at least two reports of cracking in the lower beam outer "T" chord. One airplane had only the outer "T" chord cracked and had about 63,800 flight hours and 66,500 flight cycles. On the other airplane, the frame and "T" chord were cracked all the way through. The inspection, repair and preventive modification of cross beam D on the aft cargo door is the subject of the original issue of Boeing Service Bulletin 737-52-1154 . The Federal Aviation Administration (FAA) has issued an Airworthiness Directive (AD) which requires incorporation of Revision 5 or 6 of this bulletin. Boeing Service Related Problem (SRP) 737-SRP-52-0077 is related to this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 9 of 103**ACTION** Identify the aft cargo door assembly part number which is currently installed on each airplane in accordance with Boeing Service Bulletin 737-52A1153 , Original Issue, Paragraph 3.B.1. If the door is found to be from an airplane in the line number range greater than 873, accomplish all applicable actions in accordance with Service Bulletin 737-52A1153 , Original Issue. For Groups 1, 2 and 3 airplane doors: If an airplane is found to have a door configuration that was delivered between line numbers 6 and 873, inclusive, do the following: Do an inspection for cracks in the forward and aft frames at the upper and lower corners. Use visual and ultrasonic inspection techniques to look for cracking in the radius of the frames. Also, do a HFEC inspection for cracking in the lower and upper beam web and outer "T" chord. For airplanes that have previously installed reinforcement angle 65C25180-9, -43, -10, -11 or -12, do an inspection for adequate edge margin and cracks. For airplanes that have previously installed repairs or modifications to the upper or lower cross beam, do supplemental structural inspections at the times given in Paragraph 1.E., Compliance . These supplemental structural inspections provide compliance with 14 CFR 26.43 (c). The modification requires installation of a steel reinforcement angle in each corner of the door and the installation of a web doubler on the upper and lower beams. In addition, if any cracks are found, accomplish all applicable actions in accordance with the original issue of Service Bulletin 737-52-1154 at the time specified in Paragraph 1.E., Compliance . **EFFECTIVITY** 737-200, -200C, -300, and -400 series airplanes. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes. **COMPLIANCE** See Paragraph 1.E., Compliance. Federal Aviation Administration (FAA) Airworthiness Directive AD 90-06-02, AD 98-25-06, AD 98-11-04 R1, AD 2000-06-13 R1, AD 2008-08-23 and AD 2008-09-13 are related to this service bulletin. **INDUSTRY SUPPORT INFORMATION** This service bulletin was first released before October of 1994. Thus industry support for affected airplanes depends upon whether you ever filed a warranty claim with Boeing on this service bulletin. **MANPOWER** See Paragraph 1.G., Manpower. **MATERIAL INFORMATION** Refer to Paragraph 2.A., Material - Price and Availability.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 10 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 11 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 12 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**

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### Commercial **Airplanes** 

# 737 Service Bulletin **ALERT Number: 737-52A1079**  Original Issue: December 16, 1983 Revision 7: December 17, 2010 ATA System: 5231 **SUBJECT:**DOORS - Aft Cargo - Frame and Beam Inspection, Repair and Modification 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.
**DESCRIPTION CONFIGURATION**  **GROUP** 737-200 and -200C airplanes, line numbers 6 - 571. These airplanes are the same as Group 2 airplanes except for slightly different door stop cutouts in the frame which required different repair kit parts. - 1

737-200 and -200C airplanes, line numbers 510 - 873. These airplanes are the same as Group 1 airplanes except for slightly different door stop cutouts in the frame which required different repair kit parts. - 2

737-200/-200C/-300 and -400 airplanes, line numbers 874 - 1642. These airplanes require an inspection to determine the aft cargo door configuration. - 3

Airplane Models: 737-200, 737-200C, 737-300, 737-400

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 13 of 103**Group Variable Number** 1 PG001 - PG0751 PG199 1 PG201 - PG2301 PG251 - PG2551 PG271 - PG2791 PG301 - PG3141 PG331 - PG332 1 PG351 - PG3561 PG375 1 PG401 - PG4031 PG431 - PG442 1 PG471 - PG4751 PG501 - PG5051 PG571 - PG5861 PG621 - PG6301 PG651 - PG652 1 PG701 - PG7051 PH001 1 PH011 - PH013 1 PH021 - PH024 1 PH701 - PH715 1 PH731 - PH732 1 PH741 - PH743 1 PJ001 - PJ006 2 PJ007 - PJ009 1 PJ031 - PJ032 1 PJ071 - PJ072 1 PJ101 - PJ111 2 PJ112 - PJ119 1 PJ201 - PJ219 1 PK026 - PK029 1 PK041 - PK053

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 14 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**1 PK061 - PK070 1 PK081 2 PK082 1 PK091 - PK099 1 PK101 - PK103 1 PK111 - PK120 1 PK141 - PK146 2 PK201 - PK204 1 PK211 - PK212 2 PK213 - PK215 3 PK216 - PK220 1 PK221 2 PK222 - PK223 1 PK231 - PK235 2 PK236 - PK240 1 PK241 1 PK251 - PK258 1 PK271 - PK273 2 PK274 1 PK281 2 PK282 - PK289 1 PK291 1 PK301 - PK306 2 PK307 - PK310 1 PK311 - PK314 2 PK315 - PK318 1 PK341 1 PK351 - PK352 2 PK353 - PK361 1 PK391 2 PK431 - PK433 1 PK451 2 PK452

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 15 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**1 PK461 - PK465 2 PK466 - PK469 2 PK495 1 PK501 2 PK502 - PK503 3 PK504 1 PK511 2 PK512 - PK514 3 PK515 3 PK519 2 PK521 - PK524 3 PK525 - PK528 2 PK541 - PK564 3 PK565 2 PK581 2 PK591 - PK599 2 PK601 - PK617 2 PK621 - PK630 3 PK631 - PK637 2 PK641 - PK642 2 PK661 - PK663 3 PK664 - PK666 2 PK671 - PK678 3 PK679 - PK681 2 PK691 - PK696 3 PK697 2 PK711 - PK716 2 PK731 - PK749 3 PK750 - PK765 2 PK771 - PK779 2 PK801 - PK802 3 PK803 - PK804 2 PK819 - PK826

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 16 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**3 PK827 2 PK830 2 PK861 - PK863 2 PK871 - PK874 2 PK881 - PK884 2 PK901 - PK932 3 PK933 - PK938 2 PK971 - PK974 1 PL001 2 PL002 - PL023 3 PL024 - PL028 2 PL061 2 PL081 2 PL101 - PL112 3 PL113 2 PL151 2 PL171 3 PL172 2 PL201 - PL203 3 PL221 2 PL401 - PL412 3 PL413 - PL417 2 PL421 2 PL441 2 PL451 - PL454 3 PL455 - PL456 2 PL471 2 PL491 2 PL501 - PL506 2 PL551 - PL561 3 PL562 2 PL581 2 PL601

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 17 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**3 PL602 - PL603 3 PL611 3 PL621 - PL626 3 PL631 - PL632 1 PL711 - PL712 1 PL716 - PL743 2 PL744 - PL745 3 PL746 - PL747 1 PL756 1 PL758 1 PL761 - PL767 2 PL768 - PL770 1 PL781 - PL782 2 PL783 3 PL784 - PL788 1 PL793 1 PL801 - PL803 2 PM001 - PM0023 PM003 - PM0063 PM016 - PM0172 PM021 - PM0233 PM051 - PM0662 PM101 - PM1043 PM105 - PM1192 PM141 - PM1423 PM171 3 PM181 3 PM251 - PM2553 PM281 - PM2833 PM381 3 PN001 - PN002 3 PN021 - PN043 3 PN081 - PN086

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 18 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**3 PN101 - PN117 3 PN131 - PN163 3 PN401 - PN420 3 PN431 - PN433 3 PN451 - PN456 3 PN471 - PN474 3 PN481 3 PN491 - PN493 3 PN501 - PN502 3 PN511 - PN512 3 PN521 3 PP001 - PP047 3 PP101 - PP139 3 PP161 - PP169 3 PP181 - PP197 3 PP201 - PP205 3 PP221 3 PP231 - PP243 3 PP281 - PP286 3 PP301 - PP305 3 PP351 - PP353 3 PP376 - PP384 3 PP391 - PP393 3 PP401 - PP440 3 PP471 - PP475 3 PP501 - PP507 3 PP521 - PP522 3 PP631 - PP634 3 PP651 - PP652 3 PP671 - PP699 3 PP701 - PP733 3 PP771 - PP779 3 PP801 - PP804

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 19 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**3 PP821 - PP827 3 PP831 - PP848 3 PP851 - PP852 3 PP861 - PP872 3 PP891 - PP899 3 PP901 - PP914 3 PP931 - PP936 3 PP946 - PP948 3 PP951 - PP952 3 PP961 - PP965 3 PP981 - PP984 3 PP991 3 PQ001 - PQ0123 PQ026 - PQ041 3 PQ051 - PQ0653 PQ086 - PQ0903 PQ101 - PQ1453 PQ221 - PQ2223 PQ231 - PQ2363 PQ241 - PQ2433 PQ251 3 PV001 - PV010 3 PW001 - PW0053 PW061 3 PW091 1 PX071 1 PX701 1 PY001 - PY008 1 PY021 - PY022 1 PY031 1 PY036 - PY037 1 PY046 - PY048 1 PY051 - PY053

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 20 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**3 PY056 - PY057 1 PY101 - PY103 1 PY111 - PY113 1 PY131 - PY133 2 PY134 - PY135 1 PY141 - PY143 1 PY151 - PY152 2 PY153 - PY154 1 PY156 - PY157 1 PY161 - PY162 1 PY166 1 PY191 1 PY201 1 PY221 - PY222 2 PY231 2 PY241 - PY244 2 PY270 1 PY271 - PY274 2 PY275 1 PY281 1 PY286 1 PY301 - PY304 1 PY321 - PY323 1 PY341 - PY346 1 PY361 - PY362 1 PY381 1 PY401 3 PY409 - PY410 1 PY411 2 PY421 3 PY422 2 PY441 2 PY451

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 21 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group**  **Variable Number**2 PY461 - PY462 3 PY463 3 PY591 - PY595 1 PY611 2 PY612 2 PY621 2 PY631 2 PY651 3 PY671 - PY672 3 PY721 3 PY741 2. Spares Affected Examine your spares supply for the parts or components identified in Paragraph 2.C., Parts Necessary for Each Airplane. If any parts or components are found, refer to Paragraph 2.C. for the recommended use. **B. Concurrent Requirements** None. **C. Reason** As a result of the FAA sponsored Aging Fleet conference, a 737 Structures Working Group with Airline and Boeing members and FAA observers was formed to review structural service bulletin modifications and recommend selected bulletins for incorporation on aging airplanes. This service bulletin modification has been recommended for incorporation on aging 737 airplanes. Accomplishment of the modification in accordance with this bulletin will reduce the possibility of fatigue cracks in the aft cargo door. Cracks in the aft cargo door frame may propagate and result in an inability to maintain cabin pressurization. As of 1996, several operators had reported cracks 0.75 to 20 inches long in the forward and aft lower corner of the aft cargo door frames. The airplanes had 10,100 to 38,000 flight hours and 14,000 to 54,000 flight cycles. In addition, some of the doors had a cracked web in the beam common to the forward lower stop fitting, approximately three inches aft of the fitting. In some of the cases, the frame and beam cracks were discovered after the airplane had experienced cabin pressurization problems. Cracking is caused by fatigue as a result of cabin pressurization cycles. Since 1996, there have been additional reports of cracked frames and cracked beam webs. One airplane with 86,400 hours and 35,400 flight cycles experienced a rapid decompression caused by an approximately 12 inch long crack in the aft lower frame corner. The lower beam web and outer "T" chord were also cracked.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 22 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**Since 1996, there have also been at least two reports of cracking in the lower beam outer "T" chord. One airplane had only the outer "T" chord cracked and had approximately 63,800 flight hours and 66,500 flight cycles. The other airplane had the outer "T" chord and the frame cracked all the way through. The inspection, repair and preventive modification of cross beam D on the aft cargo door is the subject of the original issue of Boeing Service Bulletin 737-52-1154 . Boeing is aware that doors requiring inspection, repair, and modification in accordance with this service bulletin may be used on airplanes (Group 3 airplanes) originally delivered with doors which do not require the service bulletin inspections or modifications. This service bulletin addresses these doors. The Federal Aviation Administration (FAA) has issued an Airworthiness Directive (AD) which requires incorporation of Revision 5 or 6 of this bulletin. Revision 1 was issued to advise operators that some aft cargo door corner reinforcement kits may have been delivered with an incorrectly manufactured angle that if installed may have four fasteners with inadequate edge margin. New Kit and supplemental kit information was provided and updated drawings provided. Revision 2 of this bulletin was issued to provide the recommendations of the Aging Fleet 737 Structures Working Group and to lower the inspection threshold on the door frames and beams from 25,000 flight cycles to 12,000 flight cycles. Revision 3 of this service bulletin was issued to advise operators that installation of reinforcement angle 65C25180-9 or -43 may result in a short edge margin condition. This condition may appear between the angle and fastener locations common to the outer skin. New kit and part information were provided, along with updated drawings. Revision 4 of this service bulletin was sent to add the circle note indicators to Figure 2 that were accidentally ignored when Revision 3 was released. Indicators were added to the text notes and locations in the illustration were corrected. Revision 5 of this service bulletin was sent to advise operators that installation of reinforcement angles 65C25180-10, -11 and -12, included in corner reinforcement kits 65C25180-3, -44 and -46, can result in a short edge margin condition. Also, the minimum allowable edge margin was changed from 0.38 inch to 0.32 inch. This service bulletin revision provided corner reinforcement kit 65C25180-47 and supplemental kit 65C25180-51 that included reinforcement angles with sufficient material added to both flanges. The new reinforcement angles were for the upper aft, lower forward and lower aft corners. New kit and part information were provided, along with updated drawings. Revision 6 of this service bulletin was sent to: — Add Group 3 airplanes to the effectivity. These airplanes may have a Group 1 or 2 airplane aft cargo door installed on them which requires inspection, repair, or modification. — Add a High Frequency Eddy Current (HFEC) inspection for cracks in the frames of doors that do not have steel reinforcement angles. — Add an inspection for cracks in the upper and lower beam outer 'T' chord of doors that do not have the lower beam reinforcement doubler.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 23 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**— Add repair instructions for the lower beam outer "T" chord. — Remove the two inch stop-drilled crack allowable. — Update Paragraph 1.F., Approval, to make Revisions 4, 5, and 6 of this service bulletin an Alternative Method of Compliance (AMOC) to AD 90-06-02, and to make Revision 6 of this service bulletin an AMOC to AD 98-25-06. Revision 7 of this service bulletin is sent to: — Remove the option for repeat inspections and add a High Frequency Eddy Current (HFEC) inspection for cracks in the beam. — Remove the option to repair the upper edge frame using a Structural Repair Manual (SRM) procedure. — Replace the HFEC inspection of the frames with an ultrasonic inspection. — Inform operators that the corner reinforcing angles given in previous releases of this service bulletin have been superseded by corner reinforcing angles with an increased edge margin. — Inform operators that this revision provides supplemental structural inspections in compliance with 14 CFR 26.43 (c). — Change the Lower Beam Outer 'T' Chord Repair on the forward end of the lower beam to include a joggle of the replacement 'T' Chord. — Change the heat treatment of the replacement 'T' Chord A to 2024-0. — Instruct operators to identify the aft cargo door part number which is currently installed on each airplane in accordance with the original issue of Boeing Service Bulletin 737-52A1153 before further work is done. — Instruct operators to also accomplish all applicable actions in accordance with the original issue of Service Bulletin 737-52-1154 at the time specified in Paragraph 1.E., Compliance, if any cracks are found. Boeing Service Related Problem (SRP) 737-SRP-52-0077 is related to this service bulletin. **D. Description** Identify the aft cargo door assembly part number which is currently installed on each airplane in accordance with Boeing Service Bulletin 737-52A1153 , Original Issue, Paragraph 3.B.1. If the door is found to be from an airplane in the line number range greater than 873, accomplish all applicable actions in accordance with Service Bulletin 737-52A1153 , Original Issue. For Groups 1, 2 and 3 airplane doors: If an airplane is found to have a door configuration that was delivered between line numbers 6 and 873, inclusive, do the following: Do an inspection for cracks in the forward and aft frames at the upper and lower corners. Use visual and ultrasonic inspection techniques to look for cracking in the radius of the frames. Also, do a HFEC inspection for cracking in the web and outer "T" chord of the upper and lower beams.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 24 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**— If a crack is found in an upper or lower corner frame web, replace the damaged frame and install the preventive modification kits on the frames and on the beams. — If a crack is found in the web of the upper or lower beam, trim out the crack and install the repair kits on the frames and on the beams. The frame preventive modification kit requires the installation of a steel reinforcement angle in each corner of the door on the exterior of the door frame under the outer skin and door seal retainer. The beam preventive modification/repair kit requires the installation of a bent-up web doubler on the forward and aft ends of the beam. — If a crack is found in the web and "T" chord of the lower beam, or in the outer "T" chord only, trim out the web crack and do the repair in accordance with this bulletin. The repair for the aft end of the lower beam requires the installation of the preventive modification kit, two splice angles (operator supplied), and a new section of "T" chord (operator supplied). The repair for the forward end of the lower beam requires the installation of new repair parts which are all operator supplied: a new bent-up repair doubler, fillers, splice angles, and a new section of "T" chord. — If a crack is found in the "T" chord of the upper beam, contact Boeing. — If no cracks are found in the frames or beams, do the preventive modification in accordance with this service bulletin. — Do Supplemental Structural Inspections at the times shown in Paragraph 1.E., Compliance . — In addition, if any cracks are found, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . If you have previously installed reinforcement angles 65C25180-9 or -43, -10, -11 or -12, do an inspection for adequate edge margin and cracks. If cracks are found or the edge margin is not adequate, replace the angles with 65C25180-52, 53, 54 and 55. If no cracks are found and the edge margins are adequate, no further action is required on the retrofit angles in accordance with this service bulletin. More work is necessary on airplanes that have accomplished the repair or preventive modification of the upper or lower cross beams in accordance with previous releases of this service bulletin. Do supplemental structural inspections of the cross beams at the times specified in Paragraph 1.E., Compliance. These supplemental structural inspections provide compliance with 14 CFR 26.43 (c). Airplane effectivity is divided into three groups. Group 1 and 2 airplanes are 737-200 and -200C airplanes line numbers 6 through 873. Group 1 airplane doors are the same as Group 2 airplane doors except for slightly different door stop cutouts in the frame which required different repair kit parts. Group 3 airplanes are 737-200, -200C, -300, and -400 airplanes line numbers 874 through 1642. Based on a structural review of the 737 airplane, the modifications in accordance with the inspections of this service bulletin should be accomplished within 4,500 flight cycles from the date of Revision 7 of this service bulletin. Revision 1 - Airplanes previously modified with corner reinforcement kit 65C25180-3 require inspection to ensure that a correctly configured angle was installed. If an incorrectly configured angle was installed inspection is required to ensure that adequate edge margin exists for attach fasteners common to reinforcement angle and the two forward upper door stops. If an inadequate edge margin exists inspection is required for cracks in the angle. If cracks are found, the angle is replaced. If no cracks are found, repeat inspections at every structural inspection period (D check) intervals until the angle is replaced with a correctly configured angle, in accordance with Revision 3. Revision 2 - Airplanes modified in accordance with Part II of the Accomplishment Instructions of Revision 1 of this service bulletin do require additional work, in accordance with Revision 3.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 25 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**Revision 3 or 4 - Airplanes previously modified with corner reinforcement kit 65C25180-44 or have had angle 65C25180-9 or -43 installed required additional inspection to ensure that adequate edge margin exists for attach fasteners common to reinforcement angle and outer skin. If inadequate edge margin exists, inspect angle for cracks. If cracks were found, replace angle. If no cracks were found, repeat inspection every Structural Inspection Period (D check) until angle is replaced with 65C25180-45 to provide proper edge margin. Revision 5 - Airplanes previously modified with the installation of angles 65C25180-10, 65C25180-11, and 65C25180-12 will require additional inspections to ensure that adequate edge margin exists for attach fasteners common to door stop fittings and reinforcement angle. If inadequate edge margin exists, inspect angle for cracks. If cracks are found, replace angle. If no cracks are found, repeat inspection every Structural Inspection Period (D check) until angles are replaced with 65C25180-48, 65C25180-49 and 65C25180-50 to provide proper edge margin. Revision 6 - Airplanes modified in accordance with Revision 5 of this service bulletin require no more work. Revision 7 - More work is necessary as follows: — More work is necessary on airplanes that have not accomplished the repair or preventive modification in accordance with previous releases of this service bulletin. Do an ultrasonic inspection for cracks in the upper and lower corner frames and a HFEC inspection for cracks in the upper and lower cross beams at the revised time specified in Paragraph 1.E., Compliance. — More work is also necessary on airplanes that have repair angles 65C25180-9, -43, -10, -11 or -12 installed in accordance with previous issues of this service bulletin. Do the work in Paragraph 3.B., Work Instructions, Part V - Corner Inspection and Rework in accordance with Revision 7 of this service bulletin at the revised time specified in Paragraph 1.E., Compliance. — More work is necessary on airplanes that have accomplished the repair or preventive modification of the upper or lower cross beams in accordance with previous releases of this service bulletin. Do supplemental structural inspections of the cross beams at the times specified in Paragraph 1.E., Compliance. Prior or concurrent incorporation of the Service Bulletins listed below are suggested on commonly affected airplanes. These bulletins have some common access requirements: 737-52-1051 - Lower Cargo Door Latch Spring Relocation and Replacement. 737-52-1063 - Lower Cargo Door Hinge Attach Bolt Inspection. 737-52-1065 - Forward and Aft Cargo Door Stop Fittings Inspection and Replacement. 737-52-1154 - Aft Cargo Door Cross Beam D Inspection, Repair and Preventive Modification. This service bulletin is listed in Boeing Document D6-38505. The work in this service bulletin is done in the maintenance zone(s) given below.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 26 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Group 1-3:** 
**Affected Maintenance Zones Zone**  **Model** 2-19 737-200, 737-200C **Group 3:**
**Affected Maintenance Zones Zone**  **Model** 219 737-300, 737-400 **E. Compliance** Federal Aviation Administration (FAA) Airworthiness Directives AD 90-06-02 , AD 98-25-06 , AD 98-11-04 R1, AD 2000-06-13 R1, AD 2008-08-23 and AD 2008-09-13 are related to this service bulletin. Accomplish the work in accordance with Revision 7 of this service bulletin at the times shown in the tables that follow. **Table 1: Determination of door configuration (all airplanes), and High Frequency Eddy Current (HFEC) and Ultrasonic Inspections for airplanes not modified and not repaired in accordance with the Original**  **Issue or Revisions 1, 2, 3, 4, 5, 6 of this service bulletin. Compliance Time**  **Action Condition**  Within 4,500 door flight cycles from the date ofRevision 7 to this Service Bulletin. (a) Determine door configuration in accordance with Service Bulletin 737-52A1153, Original Issue, Paragraph 3.B.1. All Groups.

At the time given in 737-52A1153, Original Issue. Accomplish all applicable actions in accordance with the original issue of Service Bulletin 737- 52A1153. Door found to be from an airplane with a line number range greater than 873. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. (a) Do one-time HFEC and ultrasonic inspections of the upper and lower corner frames and theupper and lower cross beams for cracks in accordance with Work Instructions, Part I - Access and Part II - Inspection. (a) Doors found to be from an airplane in the line number range between6 and 873 without either the Modification or Repair accomplished in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5 and 6 of this service bulletin. Before further flight. (a) Do the modification in accordance with Work Instructions, Part III - Preventive Modification. No crack(s) found in the upper and lower corner frames or the upper and lower cross beams.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 27 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 1: Determination of door configuration (all airplanes), and High Frequency Eddy Current (HFEC)**  **and Ultrasonic Inspections for airplanes not modified and not repaired in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5, 6 of this service bulletin.**  **Compliance Time Action**  **Condition** Before further flight. Do the beam repair in accordance with Work Instructions. Crack(s) found in the upper or lower beam. Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. (a) Before further flight. Replace the frame. Do the frame modification in accordance with Work Instructions, Part III - Preventive Modification. Crack(s) found in an upper corner frame. Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. (a) Before further flight. Replace the damaged frame in accordance with Work Instructions, Part IV - Lower Frame Replacement for Aft and Forward Frames and do the modification in accordance with Work Instructions, Part III - Preventive Modification. Crack(s) found in a lower corner frame.

Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. (a) (a) NOTE: This is a new requirement of Revision 7 of this service bulletin. Compliance requirements of AD 90-06-02 amendment 39-6489 and AD 2000-06-13 R1 amendment 39-12317 still apply. **Table 2: Supplemental Inspection for airplanes with reinforcement angles 65C25180-9, -43, -10, -11 or -12 installed**  **Compliance Time Action**  **Condition** Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. (a) Inspect lower corner frames to determine if door has reinforcement angles 65C25180-9, -43, - 210, -11, or -12 installed in accordance with the original issues, Revision 1, 2, 3 or 4 of this service bulletin. All Groups.

Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. (a) Do a one-time general visual inspection for edge margin and detailed inspection for cracks in accordance with Work Instructions, Part V - Corner Inspection and Rework. Airplanes with reinforcement angles 65C25180-9, -43, -10, -11 or -12 installed in accordance with the original issue, Revision 1, 2, 3 or 4 of this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 28 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 2: Supplemental Inspection for airplanes with reinforcement angles 65C25180-9, -43, -10, -11 or**  **-12 installed Compliance Time**  **Action Condition** 

- No further action is required. Airplanes without reinforcement angles 65C25180-9, -43, -10, -11 or -12 installed. Before further flight. (a) Replace the corner reinforcement angle in ac-cordance with Work Instructions, Part III - Preventive Modification.Crack(s) found in corner reinforcement angle or edge margin is not adequate. Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. (a)

- No further action is required. No crack(s) found in corner rein- forcement angles and edge margin is adequate. (a) NOTE: This is a new requirement of Revision 7 of this service bulletin. Compliance requirements of AD 90-06-02 amendment 39-6489 and AD 2000-06-13 R1 amendment 39-12317 still apply. **Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord**  **Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per**  **this Revision of this Service Bulletin Repeat Inter**  **val (Not to Exceed)**  **Compliance Time (Whichever Occurs Later) Action**  **Condition**

4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after thepreventive modification is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modificationinstalled on the forward end of the lower cross beam in accordance with theOriginal Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are known.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 29 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after thepreventive modification is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modificationinstalled on the forward end of the lower cross beam in accordance with theOriginal Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are not known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 30 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after thepreventive modification is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modification installed on the aft end of the lowercross beam in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after thepreventive modification is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modification installed on the aft end of the lowercross beam in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are not known.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 31 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after thepreventive modification is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modificationinstalled on the forward end of the upper cross beam in accordance with theOriginal Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before urther flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 32 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after thepreventive modification is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modificationinstalled on the forward end of the upper cross beam in accordance with theOriginal Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are not known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after thepreventive modification is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modification installed on the aft end of the uppercross beam in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are known.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 33 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after thepreventive modification is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a preventive modification installed on the aft end of the uppercross beam in accordance with the Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this service bulletin and the door flight cycles are not known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after the lower beam outer "T"chord repair is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a lower beam outer "T" chord repair installed on the forward end of the lower cross beam in accordance with this revision of this service bulletin and the door flight cycles are known.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 34 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after the lower beam outer "T"chord repair is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a lower beam outer "T" chord repair installed on the forward end of the lower cross beam in accordance with this revision of this service bulletin and the door flight cycles are not known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Before 56,000 total door flight cycles, or, Within 18,000 door flight cycles after the lower beam outer "T"chord repair is installed, whichever comes first. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a lower beam outer "T" chord repair installed on the aft end of the lower cross beam inaccordance with Revision 6 or 7 of this service bulletin and the door flight cycles are known.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 35 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 3: Supplemental Structural Inspections for Airplanes with a Preventive Modification Installed per**  **Original Issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Aft End of the Lower Beam per Revision 6 through Revision 7 of this Service**  **Bulletin or Lower Beam Outer "T" Chord Repair Installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin**  **Repeat Inter val (Not to**  **Exceed) Compliance Time (Whichever Occurs Later)**  **Action Condition** 

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 4,500 door flight cycles from the date ofRevision 7 to this service bulletin. Within 4,500 door flight cycles after the lower beam outer "T"chord repair is installed. Do a detailed inspection and a LFEC inspection of the cross beam for cracks in accordance with Work Instructions, Part VII - Supplemental Structural Inspections.Airplanes with a lower beam outer "T" chord repair installed on the aft end of the lower cross beam inaccordance with Revision 6 or 7 of this service bulletin and the door flight cycles are not known.

- Before further flight. Contact Boeing for repairinstructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in ac- cordance with Tables 1through 4 of Service Bulletin 737-52-1154, Original Issue, Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 36 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 4: Supplemental Structural Inspections for Airplanes with a Lower Beam Outer "T" Chord Repair**  **on the Forward End of the Lower Beam per Revision 6 of this Service Bulletin Repeat Inter**  **val (Not to Exceed)**  **Compliance Time (Whichever Occurs Later) Action**  **Condition**

17,000 door flight cycles. Within 17,000 door flight cycles from the date of Revision 7 to this service bulletin.66,000 door flight cycles after installation of the Lower Beam Outer 'T' Chord Repair on theforward end of the lower cross-beam or 100,000 total door flight cycles, whichever comes first.Do Open-Hole HFEC inspections of the forward end of the lower crossbeam for cracks in accordance with Work Instructions, Part VIII - Forward End Lower Beam Outer'T' Chord Repair Supplemental Inspections. Airplanes with a Lower Beam Outer'T' Chord Repair installed on the forward end of thelower beam in accordance with Revision 6 of this Service Bulletin andthe door flight cycles since the repair are known.

- Before further flight. Contact Boeing for repair instructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154,Original Issue, Paragraph 1.E., Compliance. 17,000 door flight cycles.17,000 door flight cycles from the date ofRevision 7 to this bulletin. 100,000 total door flight cycles.Do Open-Hole HFEC inspections of the forward end of the lower crossbeam for cracks in accordance with Work Instructions, Part VIII - Forward End Lower Beam Outer'T' Chord Repair Supplemental Inspections. Airplanes with a Lower Beam Outer'T' Chord Repair installed on the forward end of thelower beam in accordance with Revision 6 of this Service Bulletin andthe door flight cycles since the repair are not known.

- Before further flight. Contact Boeing for repair instructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154,Original Issue, Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 37 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 4: Supplemental Structural Inspections for Airplanes with a Lower Beam Outer "T" Chord Repair**  **on the Forward End of the Lower Beam per Revision 6 of this Service Bulletin Repeat Inter**  **val (Not to Exceed)**  **Compliance Time (Whichever Occurs Later) Action**  **Condition**

17,000 door flight cycles.17,000 door flight cycles from the date of Revision 7 to this bulletin.Do Open-Hole HFEC inspections of the forward end of the lower crossbeam for cracks in accordance with Work Instructions, Part VIII - Forward End Lower Beam Outer'T' Chord Repair Supplemental Inspections. Airplanes with a Lower Beam Outer'T' Chord Repair installed on the forward end of thelower beam in accordance with Revision 6 of this Service Bulletin and the total door flight cycles are not known.

- Before further flight. Contact Boeing for repair instructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154,Original Issue, Paragraph 1.E., Compliance. 4,500 door flight cycles. Within 17,000 door flight cycles from the date of Revision 7 of this Service Bulletin. Before 56,000 total door flight cycles. Do a detailed inspection of the outer skin in the inspection area for cracks in accordance with Work Instructions, Part VIII - Forward End Lower Beam Outer 'T'Chord Repair Supplemental Inspections. Airplanes with a Lower Beam Outer "T" Chord Repairinstalled on the forward end of thelower beam in accordance with Revision 6 of this Service Bulletin andthe door flight cycles are known.

- Before further flight. Contact Boeing for repair instructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154,Original Issue, Paragraph 1.E., Compliance. Bulletin

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 38 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Table 4: Supplemental Structural Inspections for Airplanes with a Lower Beam Outer "T" Chord Repair**  **on the Forward End of the Lower Beam per Revision 6 of this Service Bulletin Repeat Inter**  **val (Not to Exceed)**  **Compliance Time (Whichever Occurs Later) Action**  **Condition**

4,500 door flight cycles.4,500 door flight cycles from the date of Revision 7 to this bulletin. Do a detailed inspection of the outer skin in the inspection area for cracks in accordance with Work Instructions, Part VIII - Forward End Lower Beam Outer 'T'Chord Repair Supplemental Inspections. Airplanes with a Lower Beam Outer "T" Chord Repairinstalled on the forward end of thelower beam in accordance with Revision 6 of this Service Bulletin and the total door flight cycles are not known.

- Before further flight. Contact Boeing for repair instructions and do the repair. Crack(s) found.

- Before further flight. Accomplish actions in accordance with Tables 1 through 4 of Service Bulletin 737-52-1154,Original Issue, Paragraph 1.E., Compliance. **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. In addition, the Manager of the FAA Seattle Aircraft Certification Office approves the modification defined in Revision 3, 4, 5, 6 and 7 of Service Bulletin 737-52A1079, Door - Aft Cargo, Frame and Beam Inspection, Repair and Modification as an alternative method of compliance to the requirements of paragraph (a) of AD 90-06-02 , amendment 39-6489. This alternative method of compliance applies only to the modification specified in Boeing document D6-38505 for Service Bulletin 737-52A1079.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 39 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**For airplanes identified in this service bulletin, Revision 7, the repairs and/or modifications of this service bulletin have been reviewed as required by paragraphs (g) and (i) of Airworthiness Directive AD 2008-08-23, paragraphs (g), (h) and (i) of AD 98-11-04 R1, and paragraphs (g) and (i) of AD 2008-09-13. The repairs and/or modifications are found to affect Structurally Significant Item (SSI) F-1 of Supplemental Structural Inspection Documents (SSID) D6-37089, Revisions D and E, and D6-82669, but the F-1 inspections remain effective with the repairs and/or modifications installed. Therefore, an alternative inspection is not necessary for F-1. Do the existing F-1 inspections as required per paragraphs (g), (h) and (i) of AD 2008-08-23, paragraphs (b) and (c) of AD 98-11-04 R1, and paragraphs (g), (h), and (i) of AD 2008-09-13. The Manager of the FAA Seattle Aircraft Certification Office (ACO) approves the supplemental inspections defined in paragraph 1.E, Compliance, Tables 3 and 4 of Revision 7 of this service bulletin as an alternative method of compliance (AMOC) to the inspections of SSI F-1 required by paragraphs (g) and (h) of AD 2008-08-23 (SSID D6-37089, Revision E), and paragraphs (g) and (h) of AD 2008-09-13 (SSID D6-82669). The Manager of the FAA Seattle ACO also approves the supplemental inspections defined in paragraph 1.E, Compliance, Tables 3 and 4 of Revision 7 of this service bulletin as a method of compliance to paragraph (g) of AD 98-11-04 R1 (SSID D6-37089, Revision E). This approval applies only to SSI F-1 of the applicable SSID and only for the portions of the upper and lower cross beams of the aft door that have been repaired and/or modified in accordance with this service bulletin. All provisions of AD 2008-08-23, AD 98-11-04 R1, and AD 2008-09-13 that are not specifically referenced in this paragraph remain fully applicable and must be satisfied. In addition, the Manager of the FAA Seattle ACO approves the inspection, repair and modification with the corresponding compliance times specified in Tables 1 and 2 of paragraph 1.E, Compliance, of this service bulletin as an AMOC to the inspections, repairs, and modifications required by paragraphs (a), (c), (d) and (e) of AD 2000-06-13 R1. This AMOC only applies to areas inspected, repaired or modified by this service bulletin. All provisions of AD 2000-06-13 R1 that are not specifically referenced in this paragraph remain fully applicable and must be satisfied. When this service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be approved by the FAA in accordance with paragraph (i) of AD 98-11-04 R1, paragraph (l) of AD 2008-08-23, paragraph (l) of AD 2008-09-13, or paragraph (f) of AD 2000-06-13 R1, as applicable. **G. Manpower** Approximately 180 man hours are required to accomplish this modification per airplane. The following breakdown of manpower requirements is suggested as a guide to assist operators in planning and accomplishing this modification. This estimate is for direct labor performed by an experienced crew. It does not include setup, planning, familiarization, cure time, part fabrication, tool acquisition, or lost time. Factor this estimate as necessary based on your own experience. **Elapsed Time (Hours) Man-Hours**  **Number of Persons Task**  3 6 2 Access 10 20 2 Inspection 72 144 2 Modification 5 10 2 Restoration 90 180 TOTAL FOR EACH AIRPLANE

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 40 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Elapsed Time (Hours)**  **Man-Hours Number of Persons**  **Task** Add 24 man-hours and 12 hours downtime to the total modification for each lower frame that requires replacement. For airplane doors with retrofit angles 65C25180-9, -43, -10, -11 or -12: Approximately 116 man hours and a crew of 2 men are required to accomplish this upper corner reinforcement angle inspection and replacement. **Part VII - Supplemental Structural Inspections Elapsed Time (Hours)**  **Man-Hours Number of Persons**  **Task** 12 12 1 Inspection 12 12 TOTAL FOR EACH AIRPLANE **H. Weight and Balance Changes Change in Moment**  **(Pound-Inches) Change in Weight**  **(Pounds) Applicability** 
Modification + 5,319.70 + 6.15 - Corner straps and beam doublers Repair No Change No Change - Lower and/or upper beam web repair No Change No Change - Lower beam "T" chord repair
**I. Electrical Load Data** Not changed. **J. References** 1. Existing Data: a. Engineering Change Memo PRR 33098. b. 737-100/200 Aircraft Maintenance Manual (AMM) 52-09-121, 52-31-0. c. 737-100/200 Structural Repair Manual (SRM) 51-10-2 . d. 737 Non-Destructive Testing (NDT) Manual Part 4, 52-10-02 , Part 6, 51-00-00 , Part 6, 52-30-01 . e. Standard Overhaul Practices Manual (SOPM) 20-41-02 , 20-43-03 . f. Overhaul Manual (OHM) 52-36-12. g. 737 Structural Item Interim Advisory (SIIA) 737-71.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 41 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**h. Boeing Service Bulletin 737-52-1051 , 737-52-1063 , 737-52-1065 , 737-52-1154 , 737-52A1153

. i. Boeing Document D6-38505 Structural Modification Program - Model 737-100/-200/-200C. j. Boeing Service Related Problem (SRP) 737-SRP-52-0077 . k. Federal Aviation Administration (FAA) Airworthiness Directive 2000-06-13 R1, 2008-08-23 , 2008-09-13 , 90-06-02 , 98-11-04 R1, 98-25-06 . l. Boeing Document D6-82669 Supplemental Structural Inspection Document Model 737-300/400/500 Airplanes, Original Release. m. Boeing Document D6-37089 Supplemental Structural Inspection Document Model 737-100/200/200C Airplanes, Revisions E and D. n. Boeing Drawing 65C25180. 2. Data supplied with this Service Bulletin: a. Drawings:
**ADCN DCN/REV**  **Sheet Title**  **Drawing No**

- C 1 Frame and Beam Reinforcement Repair - Aft Cargo Door 65C25180

- D 2 3 B 3 4 B 4

- A 5 3 B 6

- G PL 3. Installation Drawings Used in the Preparation of this Service Bulletin:
**Title Drawing Number**  Door Assy - Aft Cargo 65-47952 This drawing was used to prepare this service bulletin. This drawing is not necessary to make the specified changes, and is not supplied with this service bulletin. This drawing may not be applicable to all airplane configurations or operators. 4. Process Data: Boeing Process specifications referred to on the drawings are not given in this service bulletin since these procedures are frequently used as standard shop practices.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 42 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT K. Publications Affected**  1. Publications **Chapter-Section Publication**  52-30-2 737 Structural Repair Manual OHM 52-36-12 Overhaul Manual 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 and new DTI requirements for the structure affected are contained in Paragraph 1.E., Compliance of this service bulletin. **L. Interchangeability and Intermixability of Parts** Refer to Paragraph 2.C., Parts Necessary for Each Airplane, for interchangeability and intermixability information.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 43 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 44 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**

BLANK PAGE**2. MATERIAL INFORMATION A. Material - Price and Availability**  Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary for Each Airplane, and Paragraph 2.D., Parts Necessary to Change Spares, as shown below. Kit availability is shown in the Reorder Lead Time (ROLT). ROLT is calculated from the date Boeing gets the purchase order. Improved flow times may be possible if necessary to support operator's planned modification schedule. Therefore, operators are requested to include planned dates of incorporation on their purchase orders. **Unit Price thru Sept. 30, 1996**  **ROLT (weeks)**  **Name Kit Number**  Inactive for procurement Modification Kit 65-91434-3 $ 4,530.00 29 Modification Kit 65-91434-4 $ 286.00 26 Supplemental Kit 65-91434-5 $ 737.00 22 Repair Kit 65C25180-5 $ 973.00 24 Repair Kit 65C25180-6 $ 764.00 22 Repair Kit 65C25180-7 $ 967.00 23 Repair Kit 65C25180-8 $ 174.00 33 Angle 65C25180-45 Inactive for procurement Reinforcement Kit 65C25180-46 $ 2,768.00 29 Reinforcement Kit 65C25180-47 The prices quoted are subject to the terms and condition of Boeing's standard purchase order acknowledgment. Quotations are subject to acceptance within 180 days from date hereon. Prices quoted in United States Dollars. Terms: Net 30 days. Address purchase orders and correspondence pertaining to this quotation to Director of Spares, and refer to this service bulletin number. **B. Industry Support Information** This service bulletin was first released before October of 1994. Thus industry support for affected airplanes depends upon whether you ever filled a warranty claim with Boeing on this service bulletin.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 45 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT C. Parts Necessary For Each Airplane**  1. Kits/Parts: To get the kits shown below, refer to Paragraph 2.A., Material - Price and Availability. **NOTE:** Modification top kit is divided into subkits for convenience of installation. Only one top kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied by the Operator, are necessary to modify each airplane. 1.

2. An applicable forward and aft frame repair kit should be available during door modification.
**AFT CARGO DOOR MODIFICATION TOP KIT 65-91434** 

- -1 -2 -3 -4 -5 Name Part Number Quantity Modification Top Kit 65-91434-1 (a)

- . . . . Modification Top Kit 65-91434-2 (a)

. - . . . Modification Top Kit 65-91434-3 (b)

. . - . . Modification Top Kit 65-91434-4 (c)

. . . - . Modification Suppl Kit 65-91434-5 (d)

. . . . - Corner Reinforcement Kit 65C25180-3 1

. . . . Lower Beam Reinforcement Kit 65C25180-4 1 1 1 1

. Upper Beam Reinforcement Kit 65C25180-42 1 1 1 1

. Corner Reinforcement Kit 65C25180-44

. 1

. . . Corner Reinforcement Kit 65C25180-46

. . 1

. . Corner Reinforcement Kit 65C25180-47

. . . 1

. Corner Reinforcement Suppl Kit 65C25180-51

. . . . 1 (a) Inactive for procurement. Rework 65-91434-1 or 65-91434-2 by reworking subkit 65C25180- 3 or 65C25180-44 to subkit 65C25180-47. (b) Inactive for procurement. Replaced by 65-91434-4. (c) Preferred Modification Top Kit. Replaces 65-91434-3. (d) Supplemental Kit. 65-91434-5 plus 65-91434-3 is equivalent to 65-91434-4. **FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT) 65C25180**  **-3 -4**  **-42 -44**  **-46 -47**  **-51 Name**  **Existing Part Number**  **New Part Number Quantity** 
Corner Reinforcement Kit - 65C25180-3 (a)

- . . . . . .

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 46 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -3**  **-4 -42**  **-44 -46**  **-47 -51**  **Name Existing Part**  **Number New Part Number**  **Quantity**
Lower Beam Reinforcement Kit - 65C25180-4

. - . . . . . Upper Beam Reinforcement Kit - 65C25180-42

. . - . . . . Corner Reinforcement Kit - 65C25180-44 (a)

. . . - . . . Corner Reinforcement Kit - 65C25180-46 (b)

. . . . - . . Corner Reinforcement Kit - 65C25180-47 (c)

. . . . . - . Supplemental Kit, Corner Reinforcement - 65C25180-51 (d)

. . . . . . - Angle Strap-Lwr Fwd

- 65C25180-10 (e) 1

. . 1 1

. . Angle Strap-Lwr Aft

- 65C25180-11 (f) 1

. . 1 1

. . Angle Strap-Upr Aft

- 65C25180-12 (g) 1

. . 1 1

. . Seal Retainer

- 65C25180-13 1

. . 1 1 1

. Seal Retainer

- 65C25180-14 1

. . 1 1 1

. Seal Retainer

- 65C25180-15 1

. . 1 1 1

. Seal Retainer

- 65C25180-16 1

. . 1 1 1

. Filler

- 65C25180-17 1

. . 1 1 1

. Filler

- 65C25180-18 1

. . 1 1 1

. Filler

- 65C25180-19 1

. . 1 1 1

. Filler

- 65C25180-20 1

. . 1 1 1

. Web

- 65C25180-25

. 1

. . . . . Web

- 65C25180-26

. 1

. . . . . Filler

- 65C25180-27

. 1

. . . . . Filler

- 65C25180-28

. 1

. . . . . Radius Strap

- 65C25180-29

. 1

. . . . . Radius Strap

- 65C25180-30

. 1

. . . . . Web

- 65C25180-33

. . 1

. . . . Angle

- 65C25180-34

. . 1

. . . . Filler

- 65C25180-35

. . 1

. . . Radius Strap

- 65C25180-36

. . 1

. . . .

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 47 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -3**  **-4 -42**  **-44 -46**  **-47 -51**  **Name Existing Part**  **Number New Part Number**  **Quantity**
Web

- 65C25180-38

. . 1

. . . . Filler

- 65C25180-40

. . 1

. . . . Radius Strap

- 65C25180-41

. . 1

. . . . Angle Strap-Upr Fwd

- 65C25180-43

. . . 1

. . . Angle Strap-Upr Fwd

- 65C25180-45 (i)

. . . . 1

. . Angle Strap-Lwr Fwd

- 65C25180-48 (i)

. . . . . . . Angle Strap-Lwr Aft

- 65C25180-49 (i)

. . . . . . . Angle Strap-Upr Aft

- 65C25180-50 (i)

. . . . . . . Angle Strap-Upr Fwd 65C25180-9 (j) 65C25180-52 (i)

. . . . . 1

. 65C25180-43 (j)Angle Strap-Lwr Fwd 65C25180-10 (j) 65C25180-53 (e) (i)

. . . . . 1 1 Angle Strap-Lwr Aft 65C25180-11 (j) 65C25180-54 (f) (i)

. . . . . 1 1 Angle Strap-Upr Aft 65C25180-12 (j) 65C25180-55 (g) (i)

. . . . . 1 1 Angle Strap-Upr Fwd

- 65C25180-9 1

. . . . . . Washer

- 66-2955-10 10

. . 10 10 10

. Bracket

- 69-43929-4

. . 1

. . . . Bracket

- 69-43929-5

. . 1

. . . . Hi-Lok Csk 100 Deg

- BACB30FM6-3 101

. . 101 101 101

. Hi Lok-Csk 100 Deg

- BACB30FN6A3 113

. . 113 113 113

. Hi Lok-Csk 100 Deg

- BACB30FN6A4 25

. . 25 25 25

. Hi-Lok,Shear

- BACB30FP8-6

. 4 4

. . . . Hi-Lok,Shear

- BACB30FP8-7

. 8 8

. . . . Hi-Lok,Shear

- BACB30FP8-8

. 8 8

. . . . Hi Lok-Csk 100 Deg

- BACB30FQ6A5 4

. . 4 4 4

. Hi-Lok Csk 100 Deg

- BACB30KF6-3 1

. . 1 1 1

. Hi-Lok Csk 100 Deg

- BACB30KF6-5 9

. . 9 9 9

. Hi Lok-Csk 100 Deg

- BACB30KF6A5 18

. . 18 18 18

. Hi-Lok Shear

- BACB30KF6A6

. 2 2

. . . . Hi Lok-Csk 100 Deg

- BACB30KF6A7 4

. . 4 4 4

. Hi-Lok Csk 100 Deg

- BACB30KK6-3 9

. . 9 9 9

.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 48 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -3**  **-4 -42**  **-44 -46**  **-47 -51**  **Name Existing Part**  **Number New Part Number**  **Quantity** Hi-Lok Csk 100 Deg

- BACB30KK6-4 8

. . 8 8 8

. Hi-Lok Csk 100 Deg

- BACB30KK6-6 3

. . 3 3 3

. Bolt-Blind

- BACB30VH06-02S

. 23

. . . . . Bolt-Blind

- BACB30VH06-03S

. . 14

. . . . Bolt-Blind

- BACB30VH06-04S

. 8 13

. . . . Bolt-Blind

- BACB30VH06-05S

. 2 14

. . . . Bolt-Blind

- BACB30VH06-06S

. . 7

. . . . Collar

- BACC30AG8 20 20 20 20 20 20

. Collar

- BACC30M6 243

. . 243 243 243

. Collar

- BACC30R6 52

. . 52 52 52

. Filler-Tapered

- BACF3T01A11-16 15

. . 15 15 15

. Filler-Tapered

- BACF3T01A11-9 2

. . 2 2 2

. Filler-Tapered

- BACF3T01A12-9 1

. . 1 1 1

. Filler-Tapered

- BACF3T01A13-16 2

. . 2 2 2

. Filler-Tapered

- BACF3T01A13-8 2

. . 2 2 2

. Rivet

- BACR15AD7D7

. . 7

. . . . Rivet

- BACR15BB5D5 6

. 2 6 6 6

. Rivet

- BACR15BB6D5

. 53 32

. . . . Rivet

- BACR15BB6D6

. 41 55

. . . . Rivet

- BACR15BB6D7

. 106 77

. . . . Rivet

- BACR15BB6D8

. . 4

. . . . Rivet

- BACR15BB8D8

. 2 2

. . . . Rivet

- BACR15CE3D5

. . 30

. . . . Rivet

- BACR15CE3D7

. . 2

. . . . Rivet

- BACR15CE5D7

. . 2

. . . . Rivet

- BACR15CE6D4

. . 6

. . . . Rivet

- BACR15CE6D5

. . 4

. . . . Rivet-Csk 100 Deg

- BACR15CE6D6 73

. 20 73 73 73

. Rivet-Csk 100 Deg

- BACR15CE6D7 24

. 5 24 24 24

. Rivet-Csk 100 Deg

- BACR15CE6D8 2 23

. 2 2 2

.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 49 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -3**  **-4 -42**  **-44 -46**  **-47 -51**  **Name Existing Part**  **Number New Part Number**  **Quantity**
Rivet

- BACR15CE6D9

. . 22

. . . . Rivet-Csk 100 Deg

- BACR15DS7D6 2

. . 2 2 2

. Rivet-Csk 100 Deg

- BACR15DS7D7 6

. . 6 6 6

. Rivet-Csk 100 Deg

- BACR15DS7D8 28

. . 28 28 28

. Rivet

- BACR15ET7D10

. . 8

. . . . Rivet

- BACR15ET7D5

. 15

. . . . . Rivet

- BACR15ET7D6

. 9 41

. . . . Rivet

- BACR15ET7D7

. 49 102

. . . . Rivet

- BACR15ET7D8

. 2 46

. . . . Rivet

- BACR15ET7D9

. 2 13

. . . . Rivet-Blind

- MS90354-0602

. 6

. . . . . Bolt-Blind (OPTIONAL BACB30VH06-02S) - 0SBPT6-2 (h)

. 23

. . . . . Bolt-Blind (OPTIONAL BACB30VH06-03S) - 0SBPT6-3 (h)

. . 14

. . . . Bolt-Blind (OPTIONAL BACB30VH06-04S) - 0SBPT6-4 (h)

. 8 13

. . . . Bolt-Blind (OPTIONAL BACB30VH06-05S) - 0SBPT6-5 (h)

. 2 14

. . . . Bolt-Blind (OPTIONAL BACB30VH06-06S) - 0SBPT6-6 (h)

. . 7

. . . . Bolt-Blind

- 0SB100T6-3

. . 1

. . . . (a) Inactive for procurement. Rework 65C25180-3 or 65C25180-44 to 65C25180-47 by replacing angle 65C25180-9 or 65C25180-43 with 65C25180-52 and by replacing angle 65C25180-10, -11 and -12 with 65C25180-53, -54 and -55, respectively. (b) Inactive for procurement. Rework 65C25180-46 to 65C25180-47 by replacing angles 65C25180-10, -11 and -12 with 65C25180-53, -54 and -55, respectively. (c) 65C25180-47 replaces 65C25180-46. (d) 65C25180-51 plus 65C25180-46 is equivalent to 65C25180-47. (e) 65C25180-10 is replaced by 65C25180-53. (f) 65C25180-11 is replaced by 65C25180-54. (g) 65C25180-12 is replaced by 65C25180-55. (h) Huck Manufacturing Company (V17446), 900 Watson Center Road, Carson, CA 90745.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 50 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -3**  **-4 -42**  **-44 -46**  **-47 -51**  **Name Existing Part**  **Number New Part Number**  **Quantity** (i) 65C25180-45 is superseded by 65C25180-52, 65C25180-48 is superseded by 65C25180-53, 65C25180- 49 is superseded by 65C25180-54, 65C25180-50 is superseded by 65C25180-55. (j) You can use the existing part to replace the new or changed part. If you use the existing part, you cancel the effect of the change given in this service bulletin. **FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT) 65C25180**  **-5 -6**  **-7 -8**  **Name Part Number**  **Quantity** Subkit, Frame Instl-Lwr Fwd 65C25180-5 (a)

- . . . Subkit, Frame Instl-Lwr Aft 65C25180-6 (a)

. - . . Subkit, Frame Instl-Lwr Fwd 65C25180-7 (b)

. . - . Subkit, Frame Instl-Lwr Aft 65C25180-8 (b)

. . . - Frame-Lwr Fwd 65C25180-21 1

. . . Frame-Lwr Fwd 65C25180-22

. . 1

. Frame-Lwr Aft 65C25180-23

. 1

. . Frame-Lwr Aft 65C25180-24

. . . 1 Washer AN960-416 3 3 3 3 Washer AN960PD10L 4

. 4

. Washer AN960PD416L 2 2 2 2 Hi-Lok BACB30FP6-3 3 3 3 3 Hi-Lok BACB30FP6-4 6 6 6 6 Bolt BACB30LK3-4X 1

. 1

. Bolt-Csk 100 Deg BACB30LU3-5X 1

. 1

. Bolt-Blind BACB30VH06-04S 6 8 6 8 Bolt-Blind BACB30VH06-05S 4 3 4 3 Bolt-Blind BACB30VH06-06S

. 2

. 2 Bolt-Blind BACB30VH06-07S

. 4

. 4 Collar BACC30AG6 9 9 9 9 Nut Plate BACN10JR3F 7 5 7 5 Nutplate BACN10KB3F 2

. 2

. Rivet BACR15BB5D5 5 1 5 1

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 51 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FRAME AND BEAM REINFORCEMENT/REPAIR - AFT CARGO DOOR (SUB KIT)**  **65C25180 -5**  **-6 -7**  **-8 Name**  **Part Number Quantity**  Rivet BACR15BB6D6 4 4 4 4 Rivet-Csk 100 Deg BACR15CE6D6 4 4 4 4 Rivet-Csk 100 Deg BACR15DS7D6 8

. 8

. Rivet-Csk 100 Deg BACR15DS7D7 7 8 7 8 Rivet BACR15ET7D10 4 4 4 4 Rivet BACR15ET7D6 8 6 8 6 Rivet BACR15ET7D7 9 23 9 23 Rivet BACR15ET7D8 8 12 8 12 Rivet BACR15ET7D9 3 2 3 2 Shim BACS40R06C30 1 1 1 1 Nut MS21042L3 2

. 2

. Nut MS21042L4 5 5 5 5 Screw NAS623-3-4 2

. 2

. Bolt NAS6604-10X 2 2 2 2 Bolt NAS6604-4X 3 3 3 3 Bolt-Blind (OPTIONAL BACB30VH06-04S) 0SBPT6-4 (c) 6 8 6 8 Bolt-Blind (OPTIONAL BACB30VH06-05S) 0SBPT6-5 (c) 4 3 4 3 Bolt-Blind (OPTIONAL BACB30VH06-06S) 0SBPT6-6 (c)

. 2

. 2 Bolt-Blind (OPTIONAL BACB30VH06-07S) 0SBPT6-7 (c)

. 4

. 4 (a) Applicable for Group 1 airplanes. (b) Applicable for Group 2 airplanes. (c) Huck Manufacturing Company (V17446), 900 Watson Center Road, Carson, CA 90745.

2. Parts and Materials Supplied by the Operator:

**INSPECTION AND MODIFICATION SUPPLIES**
**Name Specification**  **Quantity** Sealant BMS 5-95, Class B As Required Leveling Compound BMS 5-125, Type 1 (a) As Required Bonding Compound BMS 5-92, Type 3 As Required (a) Epibond 1542 A/B, M&T Chemicals (V99384), Furane Products Division, 5121 San Fernando Road West, Los Angeles, CA 90039.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 52 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT REPAIR PARTS - LOWER BEAM FORWARD END (FIG 4)** 
**Name Specification**  **Quantity** Filler A 0.056 x 1.9 x 10.9, clad 7075-T6 or 2024-T3 1 Radius Filler A Make from BAC1512-3355 x 0.65 wide x 11.0 long, 7075- T6511 or 2024-T3511 1
Radius Filler B Make from BAC1512-3355 x 0.60 wide x 6.5 long, 7075- T6511 or 2024-T3511 1
Radius Filler C Make from BAC1512-3355 x 0.65 wide x 0.90 long, 7075- T6511 or 2024-T3511 2 Angle A 1.55 x 8.30 x 0.040, 2024-0 1 Angle B 1.44 x 6.40 x 0.050, 2024-0 1 Replacement 'T' Chord A BAC1505-100570 x 8.0, 2024-0 (a) 1 Doubler 4.83 x 11.67 x 0.071, 7075-0 1 Rivet BACR15BB7D9 8 Rivet MS20470D6-7. Optional: BACR15BB6D7 2 Rivet BACR15CE6D6. Optional: BACR15GF6D6 2 Rivet BACR15CE6D8. Optional: BACR15GF6D8 13 Rivet BACR15CE6D9. Optional: BACR15GF6D9 7 Chemical Film Treatment (Alodine 1200S) MIL-C-5541 As Required Primer BMS 10-11, Type 1 As Required (a) As an option to joggling the 2024-0 extrusion and heat-treating in accordance with Figure 4, replacement 'T' chord A can be made from part 65C80735-25 by trimming part to length. **REPAIR PARTS - LOWER BEAM AFT END (FIG 6) (a)**
**Name Specification**  **Quantity** Radius Filler B Make from BAC1512-3355 x 0.60 wide x 6.50 long, 7075- T6511 or 2024-T3511 1
Radius Filler C Make from BAC1512-3355 x 0.65 wide x 0.90 long, 7075- T6511 or 2024-T3511 2 Angle C 1.55 x 8.50 x 0.040, 2024-0 1 Angle D 1.44 x 6.50 x 0.050, 2024-0 1 Replacement 'T' Chord B BAC1505-100570 x 9.0, 2024-0 (b) 1 Rivet BACR15BB7D9 8 Rivet BACR15CE6D6. Optional: BACR15GF6D6 3 Rivet BACR15CE6D8. Optional: BACR15GF6D8 2 Rivet BACR15CE6D9. Optional: BACR15GF6D9 7

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 53 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT REPAIR PARTS - LOWER BEAM AFT END (FIG 6) (a)** 
**Name Specification**  **Quantity** Chemical Film Treatment (Alodine 1200S) MIL-C-5541 As Required Primer BMS 10-11, Type 1 As Required (a) In addition to the parts shown below, you will need doubler 65C25180-25, filler 65C25180-27, and radius strap 65C25180-30. These parts are contained in subkit 65C25180-4. (b) As an option to joggling the 2024-0 extrusion and heat-treating in accordance with Figure 6, replacement 'T' chord B can be made from part 65C80735-25 by trimming part to length.
3. Parts Modified and Reidentified: The parts shown below are changed in accordance with this service bulletin. The quantity (QTY) is the number of parts changed on each airplane.
**Notes New Part Number**  **Name QTY**  **Existing Part Number**  (a) (b) (c)

- Door Assembly 1 65-47952-1 (a) (b) (c)

- Door Assembly 1 65-47952-524 (a) Make the change in accordance with this service bulletin. (b) There is no equivalent Boeing part number for the changed part. Identify on the part that the change in accordance with this service bulletin was made. (c) You can use the existing part to replace the new or changed part. If you use the existing part, you cancel the effect of the change given in this service bulletin. 4. Parts Removed and Not Replaced: None. **D. Parts Necessary to Change Spares** To get the kits shown below, refer to Paragraph 2.A., Material - Price and Availability.
**Name Part Number**  **Quantity** Modification Top Kit 65-91434-4 1 **E. Special Tooling - Price and Availability** The operator can supply the tools shown in Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin. Tool price and supply data are not given.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 54 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT F. Special Tooling Necessary to do this Service Bulletin**  To get the tools shown below, refer to Paragraph 2.E., Special Tooling - Price and Availability. Maintenance and overhaul tools in the manuals shown in Paragraph 1.J., References, can also be necessary. Examine operator tool supply to make sure all necessary tools are available.
**Notes Name**  **Tool Kit Number** (a) (c) Transducer SUS 1015-10MHz-70A (b) (c) Transducer HS-7520-10-70A (a) Available from: NDT Engineering Corporation (Cage Code 61100) 19620 Russell Road Kent, WA 98032-1115 (b) Available from: Staveley Sensors Inc. (Cage Code 59334) 91 Prestige Park Circle East Hartford, CT 06108-1918 (c) A different vendor can make the transducer. But it must have the properties specified below, that the transducer: - Puts a shear wave in aluminum that is between 65 and 75 degrees. - Operates at a frequency of between 9 MHz and 11 MHz. - Has a maximum outer case length of 0.315 inches (8.0 mm). - Can give satisfactory results during calibration as specified in 737 NDT Manual, Part 4, 52-10-02.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 55 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 56 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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. 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 linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch. — Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch — Angular tolerance is plus or minus 2 degrees — For hole dimensions for standard solid rivets, refer to 737 Structural Repair Manual, Chapter 51 — For torque limits to tighten nuts and bolts, refer to 737 Structural Repair Manual, Chapter 51. — Shim all gaps greater than 0.005 inch. 4. For approved fastener and process material substitutions, refer to 737 Structural Repair Manual, Chapter 51. For alternate fasteners, refer to 737 Structural Repair Manual Chapter 51. 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. As recommended by the 737 Aging Fleet Structures Working Group, accomplish the modification in accordance with this service bulletin, Part II, prior to, or upon the accumulation of 75,000 flight cycles as required by AD 90-06-02.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 57 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**7. 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. 8. A General Visual Inspection is defined as: A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normal available lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may require removal or opening of access panels or doors. Stands, ladders or platforms may be required to gain proximity to the area being checked. 9. 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 "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. **B. WORK INSTRUCTIONS GROUP 1 AND 2 AIRPLANES**  1. PART I - Access **NOTE:** If you previously installed reinforcement angles 65C25180-9 or -43 (upper forward), -10 (lower forward), -11 (lower aft) or -12 (upper aft), in accordance with the original issue, Revision 1, 2, 3, or 4 of this service bulletin, then do Part V - 'Corner Inspection and Rework'. 1.

2. The following instructions supplement information contained on Drawing 65C25180. Unless otherwise noted all references herein are to that drawing. a. Remove or push aside the insulation in the aft cargo door as required to gain access to the inside of the four corner frames and the ends of the upper and lower cross beams. b. Identify the aft cargo door assembly part number which is currently installed on each airplane in accordance with Boeing Service Bulletin 737-52A1153 , Original Issue, Paragraph 3.B.1. If the door is found to be from an airplane in the line number greater than 873, accomplish all applicable actions in accordance with the original issue of Boeing Service Bulletin 737-52A1153

. c. Remove the aft cargo door. Refer to 737-100/200 AMM 52-31-0 as an accepted procedure. d. Remove the aft cargo door flap type seal. Refer to 737-100/200 AMM 52-09-121 as an accepted procedure.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 58 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**e. Remove and discard corner seal retainers in accordance with Sheet 2, Views 1A5-1 and 1A7-1 and Sheet 3, Views 3B5 and 3C11. Remove and retain the forward and aft seal retainers in accordance with Sheet 2, Views 1A5-1 and 1A7-1. f. Remove exterior skin fasteners in accordance with Sheet 1, View 3A2. **NOTE:**Remove any sealant found in each frame corner radius before inspection. If cracks do exist in this inspection area they could be hidden under the existing sealant. g. Do Part II - Inspection. 2. PART II - Inspection a. Remove or push aside the insulation in the aft cargo door as required to gain access to the inside of the four corner frames and the ends of the upper and lower cross beams. b. Identify the aft cargo door assembly part number which is currently installed on each airplane in accordance with Boeing Service Bulletin 737-52A1153 , Original Issue, Paragraph 3.B.1. If the door is found to be from an airplane in the line number greater than 873, accomplish all applicable actions in accordance with Service Bulletin 737-52A1153 , Original Issue. c. Do the inspection in accordance with FIGURE 1. d. If no cracks are found, modify the door in accordance with Part III. e. If cracks up to complete severance are found in the upper or lower beam web, repair the beam in accordance with the beam modification in Part III. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . f. For the lower beam, if cracks are found in the web and outer "T" chord or in the outer "T" chord only, then repair the beam in accordance with Part VI - Lower Beam Outer "T" Chord Repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . g. For the upper beam, if cracks are found in the outer "T" chord, contact Boeing for repair instructions and do the repair before further flight. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 59 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**h. If cracks are found in the forward or aft upper corner frame, replace the frame and install the preventive modification in accordance with Part III. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . i. If cracks are found in the forward or aft lower door frame, replace the damaged frame in accordance with Part IV Lower Forward and Aft Frame Replacement and modify in accordance with Part III - Preventive Modification. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . j. Put the airplane back to a serviceable condition. 3. PART III - Preventive Modification **NOTE:**The following instructions supplement information contained on Drawing 65C25180. Unless otherwise noted all references herein are to that drawing. a. Gain access to the lower beam by removing the door inner skin in accordance with Sheet 1, View 1A2. Retain removed parts for reinstallation. b. Gain access to the upper beam by removing the door inner skin in accordance with Sheet 5, View 4A2-1. Retain removed parts for reinstallation. c. If cracks are found during inspection of the lower and upper cross beams, trim out the web cracks with a 0.40 minimum trim radius. Do a HFEC surface inspection within 0.20 of the edge of the trim out. If cracks are found, trim them out and repeat the HFEC surface inspection. When no cracks are found, make a 0.20 insurance cut to the edge of the trim out. Maintain 0.38 minimum edge margins. Replace trim out with a 7075-T6 aluminum filler. Finish filler with one coat of chemical conversion coating (Alodine 1200S, Type II), refer to SOPM 20-43-03 and one coat of primer (BMS 10-11, Type I), refer to SOPM 20-41-02 . Do the Preventive Modification to the upper and lower cross beams in accordance with paragraphs d and e. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . d. Use Kit 65C25180-4 and modify the lower cross beam in accordance with Sheet 2, Views B1-1 and B3-1. e. Use Kit 65C25180-42 and modify the upper cross beam in accordance with Sheets 5 and 6. f. Use Kit 65C25180-47 and locate and drill corner reinforcement angles and seal retainers in accordance with Sheet 1, View 3A2; Sheet 2, Views 1A5-1 and 1A7-1; and Sheet 3, Views 3B5 and 3C11. **NOTE:**Trim corner strap angles on installation as required to fit door stops, latch torque tube housing and water drain seal retainer in accordance with Sheet 2, View 1A5-1 and 1A7-1. g. Remove seal retainers and trim ends in accordance with Sheet 1, View C8. Apply chemical film treatment (Alodine or Iridite, Refer to 737-100/200 SRM 51-10-2 as an accepted procedure) and one coat of epoxy primer (Ref. BMS 10-11, Type 1).

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 60 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**h. Remove corner reinforcement angles and install repair washers in accordance with Flag Note 14 on Sheet 2, Views 1A5-1 and 1A7-1. i. Install corner reinforcement angles and seal retainer with faying surface sealant (Ref. BMS 5-95, Class B) between all surfaces. j. Reapply all fillet seals that were disturbed during modification using sealant (Ref. BMS 5-95, Class B). k. Position door as if it was installed on the airplane with door closed and airplane level. Apply leveling compound (Ref. BMS 5-125, Type 1) level with bottom of drain hole in accordance with Sheet 1, View 2A5, see Flag Note 10. l. Reinstall inner skins in accordance with Sheet 1, View 1A2 and Sheet 5. m. Install the flap type seal. Refer to 737-100/200 AMM 52-09-121 as an accepted procedure. n. Install the door. Refer to 737-100/200 AMM 52-31-0 as an accepted procedure. Use the procedure for installing a new door. o. Put the airplane back to a serviceable condition. p. Do Part VII - Supplemental Structural Inspections at the times given in Paragraph 1.E., Compliance . 4. PART IV - Lower Frame Replacement for Aft and Forward Frames. **NOTE:**The following instructions supplement information contained on Drawing 65C25180. Unless otherwise noted all references herein are to that drawing. a. Remove inner skin fasteners for frame removal as required in accordance with Sheet 4, View 2A2-1. b. Remove and retain the lower seal retainer in accordance with Sheet 4, View 1B4. c. Remove and retain roller arm. Refer to OHM 52-36-12 as an accepted procedure. d. For aft frame replacement remove and retain housing assembly, reinforcement plate, channel assembly and bracket in accordance with Sheet 4, View D2. Remove remaining attachment fasteners and remove frame. e. For forward frame replacement remove and retain housing assembly, reinforcement plate, channel assembly, guide assembly, pulley bracket, radius fillers and latch channel in accordance with Sheet 4, View D4. Remove remaining attachment fasteners and remove frame. f. For aft frame installation use Kit 65C25180-6 for Group 1 airplanes or 65C25180-8 for Group 2 airplanes. Locate frame in accordance with Sheet 4, View D2. g. For forward frame installation use Kit 65C25180-5 for Group 1 airplanes or 65C25180-7 for Group 2 airplanes. Locate frame in accordance with Sheet 4, View D4.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 61 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**h. Drill frame to match existing hole locations. Locate components removed in Paragraph d or e above and drill frame to match existing hole locations. **NOTE:**The hole pattern from old frame may be used as an aid to locate components on new frame. i. Accomplish Part III, Paragraph f and g. j. Reinstall applicable frame components in accordance with Paragraph d or e, plus the reinforcement angles and seal retainers in accordance with Paragraph i, with faying surface sealant (Ref. BMS 5-95, Class B) between all surfaces. k. Install inner and outer skin fasteners. l. Reinstall roller arm removed in Paragraph c. Refer to OHM 52-36-12 as an accepted procedure. m. Reapply all fillet seals that were disturbed during frame replacement using sealant (Ref. BMS 5-95, Class B). n. Install the flap type seal. Refer to 737-100/200 AMM 52-09-121 as an accepted procedure. o. Install the door. Refer to 737-100/200 AMM 52-31-0 as an accepted procedure. Use the procedure for installing a new door. p. Put the airplane back to a serviceable condition. 5. PART V - Corner Inspection and Rework. a. On airplanes with repair angles 65C25180-9, -43, -10, -11 or -12 installed, open the aft cargo door and inspect the upper forward, upper aft, lower aft and lower forward corners. Inspect for tabs, correct edge margin and cracks in each corner reinforcement angle in accordance with FIGURE 2 . b. If the edge margin is less than the noted dimension or cracks are found, replace the corner reinforcement angles. If no cracks are found and edge margin is adequate, no more work is necessary. c. Put the airplane back to a serviceable condition. 6. PART VI - Lower Beam Outer "T" Chord Repair. a. Gain access to the lower beam by removing the door inner skin in accordance with View 1A2 of Sheet 1. b. If cracks are found during inspection of the lower beam, trim out the web cracks with a 0.40 minimum trim radius. Do a HFEC surface inspection within 0.20 of the edge of the trim out. If cracks are found, trim them out and repeat the HFEC surface inspection. When no cracks are found, make a 0.20 insurance cut to the edge of the trim out. Maintain 0.38 minimum edge margins. Replace trim out with a 7075-T6 aluminum filler. Finish filler with one coat of chemical

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 62 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**conversion coating (Alodine 1200S, Type II), refer to SOPM 20-43-03 and one coat of primer (BMS 10-11, Type I), refer to SOPM 20-41-02 . Do the Repair to the lower cross beam in accordance with paragraphs c and d. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154 , Original Issue, at the time specified in Paragraph 1.E., Compliance . c. To repair the forward end of the beam, do the repair in accordance with FIGURE 3. Make the necessary repair parts in accordance with FIGURE 4. d. To repair the aft end of the beam, do the repair in accordance with FIGURE 5. Make the necessary repair parts in accordance with FIGURE 6. e. Reinstall lower inner skin in accordance with View 1A2 of Sheet 1. f. Install the flap type seal. Refer to 737-100/200 AMM 52-09-121 as an accepted procedure. g. Install the cargo door. Refer to 737-100/200 AMM 52-31-0 as an accepted procedure. Use the procedure for installing a new door. h. Put the airplane back to a serviceable condition. i. Do Part VII - Supplemental Structural Inspections at the times given in Paragraph 1.E., Compliance . 7. PART VII - Supplemental Structural Inspections. a. Airplanes with a Part III - Preventive Modification installed per the original issue or Revisions 1, 2, 3, 4, 5, 6 or 7 of this Service Bulletin or a Part VI - Lower Beam Outer "T" Chord Repair installed on the Aft End of the Lower Beam per Revision 6 through 7 of this Service Bulletin or Lower Beam Outer "T" Chord Repair installed on the Forward End of the Lower Beam per this Revision of this Service Bulletin. (1) Do detailed and LFEC inspections of the forward end of the aft cargo door lower cross beam for cracks in accordance with FIGURE 7 at the times shown in Paragraph 1.E., Compliance. (a) If any crack is found, contact Boeing for repair instructions and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance. (2) Do detailed and LFEC inspections of the aft end of the aft cargo door lower cross beam for cracks in accordance with FIGURE 8 at the times shown in Paragraph 1.E., Compliance. (a) If any crack is found, contact Boeing for repair instructions and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance. (3) Do detailed and LFEC inspections of the forward end of the aft cargo door upper cross beam for cracks in accordance with FIGURE 9 at the times shown in Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 63 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**(a) If any crack is found, contact Boeing for repair instructions and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance. (4) Do detailed and LFEC inspections of the aft end of the aft cargo door upper cross beam for cracks in accordance with FIGURE 10 at the times shown in Paragraph 1.E., Compliance. (a) If any crack is found, contact Boeing for repair instructions and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance. b. Put the airplane back to a serviceable condition. 8. PART VIII - Supplemental Structural Inspections for a Part VI - Lower Beam Outer "T" Chord Repair installed on the Forward End of the Lower Beam per Revision 6 of this Service Bulletin. a. Verify that a Lower Beam Outer "T" Chord Repair has been accomplished on the forward end of the lower beam in accordance with Revision 6 of this Service Bulletin. **NOTE:**Beams with the Outer "T" Chord Repair will have two repair angles installed common to the Outer "T" Chord, next to the Stop Fitting. (1) If a Lower Beam Outer "T" Chord Repair has been accomplished on the forward end of the lower beam in accordance with Revision 6 of this Service Bulletin, do an Open-Hole HFEC inspections of the forward end of the aft cargo door lower cross beam for cracks in accordance with FIGURE 11 at the times shown in Paragraph 1.E., Compliance. (a) If any crack is found, contact Boeing for repair instruction and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance. (2) If a Lower Beam Outer "T" Chord Repair has been accomplished on the forward end of the lower beam in accordance with Revision 6 of this Service Bulletin, do a detailed inspection of the outer skin in the inspection area for cracks in accordance with FIGURE 11 at the times shown in Paragraph 1.E., Compliance. (a) If any crack is found, contact Boeing for repair instruction and do the repair. In addition, accomplish all applicable actions in accordance with Service Bulletin 737-52-1154, Original Issue, at the time specified in Paragraph 1.E., Compliance.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 64 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT GROUP 3 AIRPLANES**  1. Remove or push aside the insulation in the aft cargo door as required to gain access to the inside of the four corner frames and one end of the lower cross beam. 2. Identify the aft cargo door assembly part number which is currently installed on each airplane in accordance with Boeing Service Bulletin 737-52A1153 , Original Issue, Paragraph 3.B.1. If the door is found to be from an airplane in the line number range greater than 873, accomplish all applicable actions in accordance with the original issue of Boeing Service Bulletin 737-52A1153

. 3. If the door is found to be from an airplane in the line number range between 6 and 873, accomplish all applicable actions in accordance with Revision 7 of this service bulletin. 4. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7: December 17, 2010 65 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 1: AFT CARGO DOOR INSPECTION**  **(SHEET 1 OF 4)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 66 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 1: AFT CARGO DOOR INSPECTION**  **(SHEET 2 OF 4)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 67 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**MORE DATA REFERENCES**  **PROCEDURE NAME**  **TASK STEP**  (a)

- - Outer Skin Remove 1 (b)

- - Cross Beams Get Access Adjacent to the beam and stop fitting. - - Seal Retainer Remove 2 Related to the stop fitting and frame. - - Fasteners Related to the stop fitting and cross beam. - - Fasteners
From the door and move to get access forinspection of the Tchord radius. (f) - - Stop Fitting Detach

Inspect for cracks in the fastener holes. In accordance with 737NDT Part 6, 51-00-00 Figure 1, 11 or 16.HFEC (High Frequency Eddy Current) Beam Web Inspect 3 T-chord Flange Inspect for cracks in the fastener holes. In accordance with 737NDT Part 6, 51-00-00 Figure 1, 11 or 16. HFEC Beam Web Inspect 4 Beam Inner Chord (c) In accordance with 737NDT Part 6, 51-00-00 Figure 4 or 23. HFEC Beam Web Inspect 5

(d) In accordance with 737NDT Part 6, 51-00-00 Figure 4 or 23. HFEC T-chord Flange Inspect 6

(d) In accordance with 737NDT Part 6, 51-00-00 Figure 4 or 23. HFEC Beam Inner Chord Inspect 7

Inspect the radius surface on both sides for cracks. In accordance with 737NDT Part 6, 51-00-00 Figure 4 or 23. HFEC T-chord Radius Inspect 8

(e) In accordance with 737 NDT Part 4, 52-10-02. Ultrasonic Frame Inspect 9 (a) Detach the outer skin to allow for the installation of the corner reinforcement angle in accordance with FIGURE 2, Detail I. (b) Get access to the cross beams to allow for the installation of the repair in accordance with FIGURE 3 and FIGURE 5.

**FIGURE 1: AFT CARGO DOOR INSPECTION (SHEET 3 OF 4)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 68 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT MORE DATA**  **REFERENCES PROCEDURE**  **NAME TASK**  **STEP** (c) Inspect the surface for cracks around each hole within 0.2 inches and within 0.2 inches from the edge of the stop fitting. (d) Inspect the surface for cracks around each hole within 0.2 inches. (e) Locally detach the pressure seal adjacent to the corner stop and detach the seal retainer corner segment. (f) It is possible that the stop fitting cannot be fully removed because there is not sufficient clearance with the adjacent structure. If this is the condition, it is satisfactory to detach the stop fitting.

**FIGURE 1: AFT CARGO DOOR INSPECTION (SHEET 4 OF 4)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 69 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 2: CORNER INSPECTION AND REWORK**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 70 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
**NOTES REFERENCES**  **PROCEDURE NAME**  **TASK STEP**  (a)

- General visual Edge margin Inspect 1 Inspect on both sides of door stop fittings for tabs above the seal retainer. - General visual Corner Rein-forcement Angle Inspect 2

NOTE: If inspection reveals satisfactory edge margin, no further action is required.This step is only necessary if the corner reinforcement angle tabs on either side of the door stop fittings are not visible. - - Seal and Seal Retainer Remove/ Keep 3

If edge margin is less than noted dimension, do a detailed inspection for cracks in edge of angle. (a) - General visual Edge Margin Inspect 4

Use BACB30FM6-3 bolts.

- - Seal and Seal Retainer Install/ Kept 5 (a) If the edge margin is less than the noted dimension or cracks are found, replace the angle in accordance with Part III. If edge margin is adequate and no cracks are found, no more work is necessary on the corner reinforcement angles in accordance with this service bulletin.

**FIGURE 2: CORNER INSPECTION AND REWORK (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 71 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 3: LOWER BEAM REPAIR - FORWARD END**  **(SHEET 1 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 72 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 3: LOWER BEAM REPAIR - FORWARD END**  **(SHEET 2 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 73 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 3: LOWER BEAM REPAIR - FORWARD END**  **(SHEET 3 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 74 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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.
**NOTES QTY**  **SPECIFICATION NAME**  **TASK STEP**  (a) 1
- Existing "T" Chord Trim and Remove 1

- 1 BACF3T01A11-16 Tapered Filler Remove /Keep 2
0.056 x 1.9 x 10.9, clad 7075-T6 or 2024-T3. 1
- Filler A Make 3 BAC1512-3370 x 9.8 long, 7075-T6. 1
- Filler B 0.060 thick tapering to 0.01 thick x 0.72 wide x 0.36 long, clad 7075-T6. 1
- Tapered Filler
Make from BAC1512-3355 x 0.65 wide x 11.0 long, 7075-T6511 or 2024-T3511. 1
- Radius Filler A

Make from BAC1512-3355 x 0.6 wide x 6.5 long, 7075-T6511 or 2024- T3511. 1
- Radius Filler B

Make from BAC1512-3355 x 0.65 wide x 0.90 long, 7075-T6511 or 2024-T3511. 2
- Radius Filler C

(b) 1 layer (Alodine 1200S) MIL-C-5541 Chemical Film Treatment Apply 4 (c) 1 layer BMS 10-11, Type 1 Primer Kept from Step 2. 1 BACF3T01A11-16 Tapered Filler Install 5 Make in accordance with FIGURE 4or make from 65C80735-25 by trimming to length. 1
- Replacement "T" Chord A

- 1
- Filler A Make in accordance with FIGURE 4. 1
- Doubler

- 1
- Filler B

- 1
- Tapered Filler

- 1
- Radius Filler A Make in accordance with FIGURE 4. 1
- Angle A Make in accordance with FIGURE 4. 1
- Angle B

- 1
- Radius Filler B

- 2
- Radius Filler C

**FIGURE 3: LOWER BEAM REPAIR - FORWARD END (SHEET 4 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 75 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT NOTES**  **QTY SPECIFICATION**  **NAME TASK**  **STEP** (a) Trim the chord at the location shown in View A-A. Maintain an edge margin of at least 0.38 inches on both flanges of the "T" chord. (b) Apply to the radius fillers and the trimmed edges of the fillers and the existing "T" chord as necessary. (c) Apply to the fillers, radius fillers and trimmed edge of the "T" chord. 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.
**MORE DATA HOLE DIA**  **IDENTIFICATION NAME**  **CODE** Use existing hole in "T" chord or web to locate the hole. 0.221 - 0.233 (#2 drill bit) BACR15BB7D9 Rivet A New hole. Locate approximately in accordance with View A-A. Locate 0.8 to 1.2 inch from other fasteners and 0.38 inch minimum from the edge of Filler A. 0.191 - 0.202 (#10 drill bit) MS20470D6-7 Rivet B

BACR15BB6D7 optional to MS20470D6- 7. 0.191 - 0.202 (#10 drill bit) OPTIONAL: BACR15BB6D7 Use existing hole in skin to locate hole. 100 degree countersink. 0.190 - 0.198 (#10 drill bit) BACR15CE6D( ) Rivet C BACR15GF6D( ) optional to BACR15CE6D( ). 0.190 - 0.198 (#10 drill bit) OPTIONAL: BACR15GF6D( )

**FIGURE 3: LOWER BEAM REPAIR - FORWARD END (SHEET 5 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 76 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END**  **(SHEET 1 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 77 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END**  **(SHEET 2 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 78 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END**  **(SHEET 3 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 79 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT Doubler A - Flat Pattern Coordinates** 
**Y Coordinate X Coordinate**  **Location** 0 0 1 0.78 0.12 2 0.60 -0.72 3 2.78 -1.26 4 2.98 -0.29 5 3.48 -0.67 6 4.62 -0.67 7 4.62 9.61 8 4.40 9.98 9 4.00 10.41 10 4.00 10.09 11 0 9.83 12 0.16 R1 0.31 R2 0.43 R3 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.
**NOTES QTY**  **PART NUMBER NAME**  **TASK STEP**  Cut the angle to shape out of 0.040 thick clad 2024-0 sheet. 1
- Angle A Cut Out 1 Cut the angle to shape out of 0.050 thick clad 2024-0 sheet. 1
- Angle B Bend up 90 degrees. Bend to 0.12R. Heat treat to T42. - - Angle A Bend Up 2 Bend up 90 degrees. Bend to 0.12R. Heat treat to T42. - - Angle B Make from extrusion BAC1505-100570, 2024-T0. Joggle as shown. Make the cuts 125 microinches Ra. Heat treat to T42 condition. (a) 1
- Replacement "T" Chord A Make 3

Trim the end of the replacement 'T' chord as necessary to fit the existing trimmed 'T' chord. Make the cut 125 microinches Ra. - - Replacement "T" Chord A Trim 4

**FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END (SHEET 4 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 80 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT NOTES**  **QTY PART NUMBER**  **NAME TASK**  **STEP** Cut the doubler to shape out of 0.071 thick clad 7075-0 sheet. 1
- Doubler Cut Out 5 Bend the doubler up 90 degrees on two flanges and 45 degrees on the other. Bend to 0.12R. Heat treat to T62. - - Doubler Bend Up 6

Trim the doubler in accordance with View A-A. Make the cut 125 microinches Ra. - - Doubler Trim 7 Apply to replacement 'T' chord A and the cut edges of doubler A, Angle A, and Angle B.1 Layer (Alodine 1200S) MIL-C-5541 Chemical Film Treatment Apply 8

Apply to doubler, Angle A, Angle B, and replacement 'T' chord A.1 Layer BMS 10-11, Type 1 Primer (a) This step is not necessary if the replacement "T" chord is made from part number 65C80735-25.

**FIGURE 4: REPAIR PARTS - LOWER BEAM FORWARD END (SHEET 5 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 81 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 5: LOWER BEAM REPAIR - AFT END**  **(SHEET 1 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 82 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 5: LOWER BEAM REPAIR - AFT END**  **(SHEET 2 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 83 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 5: LOWER BEAM REPAIR - AFT END**  **(SHEET 3 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 84 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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**  Trim the chord at the location shown in View A-A. Maintain an edge margin of at least 0.38 inches. 1
- Existing "T" Chord Trim and Remove 1

- 1 BACF3T01A11-16 Tapered Filler Re- move/Keep 2
Make from BAC1512-3355 x 0.60 wide x 6.5 long, 7075-T6511 or 2024-T3511. 1
- Radius Filler B Make 3
Make from BAC1512-3355 x 0.65 wide x 0.90 long, 7075-T6511 or 2024-T3511. 2
- Radius Filler C Apply to radius fillers B and C and to the cut edge of the 'T' chord. 1 layer (Alodine 1200S) MIL-C-5541 Chemical Film Treatment Apply 4 Apply to radius fillers B and C and to the cut edge of the 'T' chord. 1 layer BMS 10-11, Type 1 Primer Kept from Step 2. 1 BACF3T01A11-16 Tapered Filler Install 5 Make in accordance with Figure 6 or make from part 65C80735-25 by trimming part to length as necessary. 1
- Replacement "T" Chord B
Contained in subkit 65C25180-4. 1 65C25180-27 Filler Contained in subkit 65C25180-4. 1 65C25180-25 Doubler Contained in subkit 65C25180-4. 1 65C25180-30 Radius Strap Make in accordance with FIGURE 6. 1
- Angle C Make in accordance with FIGURE 6. 1
- Angle D

- 1
- Radius Filler B

- 2
- Radius Filler C 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.
**MORE DATA HOLE DIA**  **IDENTIFICATION NAME**  **CODE** Use existing hole in "T" chord to locate the hole. 0.221 - 0.233 (#2 drill bit) BACR15BB7D9 Rivet A

- - - Not used B

**FIGURE 5: LOWER BEAM REPAIR - AFT END (SHEET 4 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 85 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT MORE DATA**  **HOLE DIA IDENTIFICATION**  **NAME CODE**  Use existing hole in skin to locate hole. 100 degree countersink. 0.190 - 0.198 (#10 drill bit) BACR15CE6D( ) Rivet C BACR15GF6D( ) optional to BACR15CE6D( ) 0.190 - 0.198 (#10 drill bit) OPTIONAL: BACR15GF6D( )

**FIGURE 5: LOWER BEAM REPAIR - AFT END (SHEET 5 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 86 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 6: REPAIR PARTS - LOWER BEAM AFT END**  **(SHEET 1 OF 2)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 87 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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.
**NOTES QTY**  **PART NUMBER NAME**  **TASK STEP**  Cut the angle to shape out of 0.040 thick clad 2024-0 sheet. 1
- Angle C Make 1 Cut the angle to shape out of 0.050 thick clad 2024-0 sheet. 1
- Angle D Bend it up 90 degrees x 0.12R. Heat treat to T42. - - Angle C Bend Up 2 Bend it up 90 degrees x 0.12R. Heat treat to T42. - - Angle D Make from extrusion BAC1505-100570, 2024-0. Joggle as shown. Make cuts 125 microinches Ra. Heat treat to T42 condition. (a) 1
- Replacement "T" Chord B Make 3

Trim the end of replacement "T" chord B as necessary to fit the existing trimmed 'T' chord. Make the cut 125 microinches Ra. - - Replacement "T" Chord B Trim 4

Apply to the replacement "T" chord B and the cut edges of Angle C and Angle D. 1 Layer (Alodine 1200S) MIL-C-5541 Chemical Film Treatment Apply 5 Apply to Angle C, Angle D, and replacement "T" chord B. 1 Layer BMS 10-11, Type 1 Primer (a) This step can be skipped if you make the replacement 'T' chord from part 65C80735-25.

**FIGURE 6: REPAIR PARTS - LOWER BEAM AFT END (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 88 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 7: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 89 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 7: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 90 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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)

- - All Visible Struc- ture Inspect 1 (b)

- - Cross Beam Inspect 2 (a) Do a Detailed Inspection of all visible structure from both sides of the beam. NOTE: Get access through the lightening holes on the inner skin and access covers on the outer skin as necessary. (b) Do a Low Frequency Eddy Current (LFEC) inspection of the cross beam through the outer skin as necessary for cracks in accordance with 737 NDT Part 6, 52-30-01.

**FIGURE 7: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION**  **(SHEET 3 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 91 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 8: AFT CARGO DOOR - LOWER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 92 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 8: AFT CARGO DOOR - LOWER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 93 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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)

- - All Visible Struc- ture Inspect 1 (b)

- - Cross Beam Inspect 2 (a) Do a Detailed Inspection of all visible structure from both sides of the beam. NOTE: Get access through the lightening holes on the inner skin and access covers on the outer skin as necessary. (b) Do a Low Frequency Eddy Current (LFEC) inspection of the cross beam through the outer skin as necessary for cracks in accordance with 737 NDT Part 6, 52-30-01.

**FIGURE 8: AFT CARGO DOOR - LOWER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL INSPECTION**  **(SHEET 3 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 94 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 9: AFT CARGO DOOR - UPPER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 95 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 9: AFT CARGO DOOR - UPPER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 96 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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)

- - All Visible Struc- ture Inspect 1 (b)

- - Cross Beam Inspect 2 (a) Do a Detailed Inspection of all visible structure from both sides of the beam. NOTE: Get access through the lightening holes on the inner skin and access covers on the outer skin as necessary. (b) Do a Low Frequency Eddy Current (LFEC) inspection of the cross beam through the outer skin as necessary for cracks in accordance with 737 NDT Part 6, 52-30-01.

**FIGURE 9: AFT CARGO DOOR - UPPER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION**  **(SHEET 3 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 97 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 10: AFT CARGO DOOR - UPPER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 1 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 98 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 10: AFT CARGO DOOR - UPPER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL**  **INSPECTION (SHEET 2 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 99 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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)

- - All Visible Struc- ture Inspect 1 (b)

- - Cross Beam Inspect 2 (a) Do a Detailed Inspection of all visible structure from both sides of the beam. NOTE: Get access through the lightening holes on the inner skin and access covers on the outer skin as necessary. (b) Do a Low Frequency Eddy Current (LFEC) inspection of the cross beam through the outer skin as necessary for cracks in accordance with 737 NDT Part 6, 52-30-01.

**FIGURE 10: AFT CARGO DOOR - UPPER CROSS BEAM - AFT END - SUPPLEMENTAL STRUCTURAL INSPECTION**  **(SHEET 3 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 100 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 11: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL**  **STRUCTURAL INSPECTION FOR AIRPLANES WITH LOWER BEAM OUTER 'T' CHORD REPAIR INSTALLED ON THE FORWARD END**  **(SHEET 1 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 101 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT FIGURE 11: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL**  **STRUCTURAL INSPECTION FOR AIRPLANES WITH LOWER BEAM OUTER 'T' CHORD REPAIR INSTALLED ON THE FORWARD END**  **(SHEET 2 OF 3)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 102 of 103 **BOEING SERVICE BULLETIN 737-52A1079 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. **Lower Cross Beam Open-Hole HFEC Inspection MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (a)

- - Fasteners Remove 1 (b)

- - Cross Beam Inspect 2 (c)

- - Replacement Fas- teners Install 3 (a) Remove fasteners in the web flange of Outer T-Chord in the inspection area. Be careful when removing fasteners, it will not be possible to oversize the holes. (b) Do an Open-Hole HFEC inspection of the fastener holes in the inspection area for cracks. Refer to 737 NDT Part 6, 51-00-00 Figure 1, 11 or 16 as an accepted procedure. (c) Install fasteners same type and size as those removed. Oversizing of fastener holes is not allowed. **Outer Skin Detailed Inspection MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** (d)

- - Outer Skin Inspect 4 (d) Do a detailed inspection of the outer skin in the inspection area.

**FIGURE 11: AFT CARGO DOOR - LOWER CROSS BEAM - FORWARD END - SUPPLEMENTAL STRUCTURAL INSPECTION FOR AIRPLANES WITH LOWER BEAM OUTER 'T' CHORD REPAIR INSTALLED**  **ON THE FORWARD END (SHEET 3 OF 3)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: December 16, 1983 737-52A1079 Revision 7 December 17, 2010 103 of 103 **BOEING SERVICE BULLETIN 737-52A1079 ALERT**  **ALERT**