July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 1 of 64 ALERT ALERT 

### Commercial **Airplane Group**  

# 737

**ALERT ALERT**  

# Service Bulletin

**Number: 737-27A1277** Date: July 21, 2005 Revision 2: January 08, 2010 ATA System: 2741
**SUBJECT:** FLIGHT CONTROLS - Horizontal Stabilizer Trim Control System - Ballscrew and Ball Nut Inspection , Lubrication, and Repair/Overhaul 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2005 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, 707, 717, 727, 737, 747, 757, 767, 777, BBJ, BOEING BUSINESS JET, DC-8, DC-9, DC-10, MD-10, MD-11, MD-80, MD-90, the Boeing logo and the Boeing livery are among the trademarks owned by Boeing or its subsidiaries. No intellectual property license (express or implied) is granted in connection with this document or otherwise.**BLANK PAGE** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 2 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

BLANK PAGE**Table of Contents** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 3 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**Table of Contents** Revision Transmittal Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 1. Existing Data: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 2. Data supplied with this Service Bulletin: . . . . . . . . . . . . . . . . . . . . . . . . . 43 3. Installation Drawings Used in the Preparation of this Service Bulletin: . . . . . . . . . . 44 K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . 44 2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 1. Kits/Parts: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2. Parts and Materials Supplied by the Operator: . . . . . . . . . . . . . . . . . . . . . . 45 3. Parts Modified and Reidentified: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 4. Parts Removed and Not Replaced: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . 46 3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS . . . . . . . . . . . . 54 FIGURE 2: LUBRICATION OF THE HORIZONTAL STABILIZER TRIM ACTUATOR . . . . . . . . . 60 FIGURE 3: HORIZONTAL STABILIZER TRIM ACTUATOR BALLSCREW AND BALL NUT - REPAIR/ REPLACEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 APPENDIX A: Inspection report form for SB 737-27A1277 . . . . . . . . . . . . . . . . . . . . . . . 64**Table of Contents** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 4 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

BLANK PAGEOriginal Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 5 of 64 ALERT ALERT 

### Commercial **Airplanes** 

# 737

**ALERT ALERT**  

# Service Bulletin

**Number: 737-27A1277** 

### Revision Transmittal Sheet Original Issue: July 21, 2005 Revision 2: January 08, 2010 ATA System: 2741
**SUBJECT:** FLIGHT CONTROLS - Horizontal Stabilizer Trim Control System - Ballscrew and Ball Nut Inspection , Lubrication, and Repair/Overhaul

This Revision includes all pages of the service bulletin.

**COMPLIANCE INFORMATION RELATED TO THIS REVISION** 737-900ER airplanes were added to Group 2 of this service bulletin effectivity. No more work is necessary on airplanes changed as shown in the original issue of this service bulletin dated July 21, 2005, or Revision 1 of this service bulletin dated July 25, 2007 (airplanes that incorporated UNMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01). However, Operators have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul as given in Paragraph 1.E., Compliance, Table 1.

**NOTE:** The Operators that performed the initial Detailed Inspection, Lubrication, and Overhaul do not have to do another initial inspection, but have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator as given in paragraph 1.E, Compliance, Table 1. The Operators that incorporated UMBRA CUSCINETTI, S.p.A service bulletin 07322-27-01 as given in WORK PACKAGE 2, have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator as given in paragraph 1.E, Compliance, Table 1. The Operators that did not incorporate UMBRA CUSCINETTI S.p.A. service bulletin, have to incorporate UNMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01 as given in WORK PACKAGE 2, and have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator as given in paragraph 1.E, Compliance, Table 1.

**REASON FOR REVISION** This revision is sent to tell the operators that 737-900 ER airplanes have been added to Group 2 of the service bulletin effectivity. Also, this revision is sent to inform the Operators that the Warranty statement has been changed. Paragraph 1.A., Effectivity, shows changes of airplane operators. Each operator should examine the Effectivity paragraph for changes. These following sections of the service bulletin are changed:Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 6 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** 1. Changed throughout the bulletin the term "as given in" with the term "in accordance with". 2. In Summary Page, Action Paragraph - Added additional data for clarification. 3. Revised note (a) of Table 1, and added note (b) to Table 1. 4. In Summary Page, Effectivity Paragraph - Added 737-900 ER airplanes 5. Planning Information, Paragraph 1.A., Effectivity - Added 737-900 ER airplanes. 6. Planning Information, Paragraph 1.C., Reason - Added the list of all important changes done to the service bulletin. 7. Planning Information, Paragraph 1.D., Description - Added the work statement for Revision 2. 8. Revised note (a) of Table 1, and added note (b) to Table 1. 9. Material Information, Paragraph 2.B., Industry Support Information - Changed the Warranty information. 10. Accomplishment Instructions, Paragraph 3.A., General Information - Changed Note 7 to replace the term "as given in" with the term "in accordance with". 11. Accomplishment Instructions, Paragraph 3.B., Work Instructions - Added some clarification notes and more data to some step instructions, deleted some unnecessary step instructions. 12. Accomplishment Instructions, Paragraph 3.B. - Changed Figure 1, Figure 2, and Figure 3 for clarification. Vertical lines are put on the left edge of each page, except in Paragraph 1.A., Effectivity, to show the location of important changes. Pages with no vertical lines have no important changes.

**REVISION HISTORY** Original Issue: July 21, 2005 Revision 1: July 25, 2007 Revision 2: January 8, 2010July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 7 of 64 ALERT ALERT 

### Commercial **Airplane Group**  

# 737

**ALERT ALERT**  

# Service Bulletin

**Number: 737-27A1277** 

### Summary Date: July 21, 2005 Revision 2: January 08, 2010 ATA System: 2741
**SUBJECT:** FLIGHT CONTROLS - Horizontal Stabilizer Trim Control System - Ballscrew and Ball Nut Inspection , Lubrication, and Repair/Overhaul

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH 1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO THE NEW OWNER.

**CONCURRENT REQUIREMENTS**

None.

**BACKGROUND** This service bulletin is issued to maintain the frequency of the detailed inspection of the Horizontal Stabilizer Trim Actuator Ballscrew and Ball Nut as specified in the Maintenance Planning Document. This service bulletin also gives instructions to remove/replace and repair the Horizontal Stabilizer Trim Actuator if a damaged Ballscrew or Ball Nut is found. This service bulletin also adds the recommended intervals for repeat lubrication and overhaul. The airplanes effective for this service bulletin are divided in two groups, Group 1 and Group 2. The detailed inspection, overhaul, and lubrication tasks are required for Group 1 and Group 2 airplanes. Also, for Group 1 airplanes only, this service bulletin gives recommended compliance time for incorporation of supplier UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01, Rev 00, dated December 21, 2004. The supplier service bulletin 07322-27-01 provides instructions to remove and replace the Ball Nut Tube Retainers on the 737 Horizontal Stabilizer Trim Actuator Ballscrew assembly with new Tube Retainers that have sufficient stiffness to retain the load carrying balls in all known failure mode conditions. The changes given in this bulletin will reduce the probability of loss of the primary and secondary load paths of the Stabilizer Trim Actuator. Loss of primary and secondary load paths of the Stabilizer Trim Actuator could result in the loss of control of the airplane. After a Horizontal Stabilizer Jackscrew incident related to a MD-80 airplane, Boeing initiated a design review of the Boeing heritage horizontal stabilizer ballscrew primary and secondary load paths. During this review, one 757 operator reported a Horizontal Stabilizer Ballscrew with extensive corrosion. An investigation was initiated. This investigation identified that a maintenance procedure to check the stabilizer Ballscrew primary load path was required. In addition, the design review found that the Ball Nut Tube Retainers on the 737 Horizontal Stabilizer Trim Actuator should be stiffened, so that the balls are retained within the assembly when the balls are jammed and not free to circulate.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 8 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** Boeing Service Related Problem (SRP) 737NG-SRP-27-0153 is related to this bulletin.

**ACTION** (PRR 38275-74S) Get access to the Horizontal Stabilizer Trim Actuator and do the procedures that follow below at the intervals shown in the compliance section.

1. INSPECTION: – Do a detailed inspection of the Stabilizer Trim Actuator lower and upper Gimbal for cracks and other damage. Inspect the areas around the bushings. Do a general visual inspection to see if large amount of grease exit the Ball Nut. Do a detailed inspection of the grease on and around the Ballscrew and Ball Nut for existence of metallic particles or other solid particles or corrosion products in the grease. Do a general visual inspection of the external areas of the Stabilizer Trim Actuator, and the areas below the Stabilizer Trim Actuator, for loose ball bearings. Clean the actuator Ballscrew. Do a detailed inspection of the Ball Nut Tube Retainers for deformation, corrosion, and lifted or damaged Return Tubes. Do a detailed inspection of the actuator Ballscrew threads for cross threading, distortion, stripping, metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, worn areas, and differences in thread shape (between thread grooves in the lower, middle, and upper portion of the Ballscrew). Move the Horizontal Stabilizer to a different setting to get access to the Ballscrew area covered by the Ball Nut. Repeat the inspections for the new exposed area of the ballscrew. Replace the Stabilizer Trim Actuator before further flight if any of these conditions exist. Lubricate the actuator Ball Nut and Ballscrew. – Do the Detailed Inspection at the intervals given in Paragraph 1.E, Compliance, Table 1.

LUBRICATE THE STABILIZER TRIM ACTUATOR: – Lubricate the Stabilizer Trim Actuator Ballscrew, Ball Nut, and the upper and lower Gimbals. – Do the Lubrication at the intervals given in Paragraph 1.E, Compliance, Table 1. REMOVE/REPLACE THE STABILIZER TRIM ACTUATOR: Replace the Stabilizer Trim Actuator if damage is found.

**NOTE:** If you replace a damaged Stabilizer Trim Actuator with a serviceable Stabilizer Trim Actuator that is not new or not overhauled, then you must do the Detailed Inspection for the replacement Stabilizer Trim Actuator as given in this service bulletin, and the Horizontal Stabilizer Gearbox Backlash Inspection in accordance with 737-600/700/800/900 AMM 27-41-81. 2. INCORPORATE UMBRA CUSCINETTI, S.p.A. SERVICE BULLETIN 07322-27-01, Rev 00, Dated December 21, 2004: Install the new Ball Nut Tube Retainers in accordance with supplier UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01.

**NOTE:** Incorporate the UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01 no later than the time given in Paragraph 1.E, Compliance, Table 2.

3. REMOVE AND REPAIR/OVERHAUL THE HORIZONTAL STABILIZER TRIM ACTUATOR: – Remove the Horizontal Stabilizer Trim Actuator and repair/overhaul at the intervals given in Paragraph 1.E, Compliance, Table 1.

**EFFECTIVITY** All 737-600/-700/700C/-800/-900/-900ER airplanes, divided in two groups. See Service Bulletin Paragraph 1.A.1 for effectivity.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 9 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**COMPLIANCE** Refer to Paragraph 1.E for Compliance.

**INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are available for WORK PACKAGE 2, Group 1, 737 airplanes in warranty as of June 14, 2001. Please refer to Paragraph 2.B., Industry Support Information.

**MANPOWER** Refer to Paragraph 1.G, Manpower.

**MATERIAL INFORMATION**

None.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 10 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

ASSEMBLY AT SPECIFIED INTERVALS. REPAIR/OVERHAUL THE STABILIZER TRIM ACTUATOR SERVICE BULLETIN 07322-27-01. INCORPORATE UMBRA CUSCINETTI INC. SUPPLIER ACTUATOR IF DAMAGE IS FOUND. REMOVE/REPLACE THE HORIZONTAL STABILIZER TRIM AT SPECIFIED INTERVALS . LUBRICATE THE STABILIZER TRIM ACTUATOR ASSEMBLY NUT, AND THE ATTACHMENT FITTINGS. OF THE STABILIZER TRIM ACTUATOR BALLSCREW, BALL DO A DETAILED INSPECTION AT SPECIFIED INTERVALS

3. 2. 1. HORIZONTAL STABILIZER TRIM ACTUATOR ASSEMBLY.D34249July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 11 of 64 ALERT ALERT 

### Commercial **Airplane Group**  

# 737

**ALERT ALERT**  

# Service Bulletin

**Number: 737-27A1277** Date: July 21, 2005 Revision 2: January 08, 2010 ATA System: 2741
**SUBJECT:** FLIGHT CONTROLS - Horizontal Stabilizer Trim Control System - Ballscrew and Ball Nut Inspection , Lubrication, and Repair/Overhaul

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 Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line Number, and Serial Number data. Refer to PRR 38275-74S for data about this change. This service bulletin is for the airplanes shown below. The list below is not complete, and does not include all 737-600/-700/-700C/-800/-900/-900ER airplanes delivered after May, 2006.

Airplane models:

**GROUP CONFIGURATION DESCRIPTION** 1 - Airplanes line numbers 1 through 1713, and airplane line number 1715. These airplanes did not have the stiffened Ball Nut Tube Retainers installed. 2 - Airplane line number 1714 and airplanes line numbers 1716 and on. These airplanes had the stiffened Ball Nut Tube Retainers installed in production.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 12 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

737-600 737-700 737-700C 737-800 737-900 737-900ER IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER AEROMEXICO (AMX) 1 YB207 YB851–YB859 YB861–YB863 YB871–YB873 2 YB860 YB874 YK580–YK585 YM501–YM515 AIR ALGERIE (ALG) 1 YD101–YD107 YE301–YE305 2 YD108–YD110 AIR BERLIN (BER) 1 YA356–YA357 YA614–YA615 YB201 YB203 YB911 YC051–YC070 YC151 YC391 YC461 YC701 YC703 YC705 YC730 YD151–YD159 YD218 YD261 2 YL023–YL024 YL951–YL954 YN231–YN235 AIR CHINA (BEJ) 1 YA681–YA682 YB584–YB586 YC943–YC951 YC981–YC983 2 YB587–YB588 YB592–YB598 YF001–YF002 YK161–YK165 YK651–YK660 YL001–YL005 YL901–YL910 YL921 AIR CHINA CHONGQING BRANCH (CHO) 1 YC941–YC942 2 YB589 AIR CHINA SOUTHWEST BRANCH (XIN) 1 YC426–YC428 YE201–YE206 AIR CHINA TIANJIN BRANCH (TJA) 1 YB581–YB583 AIR EUROPA (ARE) 1 YC761–YC770 YD046–YD049 YD206–YD209 YK002–YK003 YK361–YK364 YK601 2 YK365–YK367 YK370–YK372 YK602 AIR INDIA EXPRESS (IDC) 1 YJ942–YJ943 YK007 2 YK151–YK154 YL461–YL475 AIR NATIONAL GUARD (USK) 1 YG044 YG067 YG069 AIR NIPPON (ANK) 2 YF051–YF054 YG251–YG252 YN001–YN015 AIR PACIFIC (APC) 1 YA291 YC931–YC932July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 13 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** AIR SENEGAL INTERNATIONAL (SNG) 1 YA683–YA684 2 YM541 AIR VANUATU (VAN) 2 YJ929 AIRCRAFT MAINTENANCE CORP. (AMF) 2 YK631–YK634 AIRTRAN AIRWAYS (CQT) 1 YB371–YB381 YM201–YM202 2 YB382–YB392 YM203–YM223 YM226–YM234 YM237–YM241 ALASKA AIRLINES (ASA) 1 YA841–YA856 YA858 YA860–YA862 YD501–YD512 YK403 YK431 2 YK432–YK450 YL101–YL128 ALL NIPPON AIRWAYS (ANA) 2 YN016 AMERICAN AIRLINES (AAL) 1 YC801–YC877 2 YF201–YF202 AMIRI FLIGHT (ABD) 1 YD410 YG039 ANDROMEDA LIMITED (DPK) 2 YG118 ARAMCO ASSOCIATED COMPANY (RAS) 1 YB151–YB153 YG601–YG602 ARIK AIR (AKD) 2 YK676–YK677 YM224–YM225 YM235–YM236 YN213–YN214 ARKEFLY (HXL) 2 YK918–YK919 ASTRAEUS, LTD. (AUA) 1 YA671–YA672 AUSTRALIAN WEDGETAIL PROGRAM (ZVI) 1 YG089 YG201 2 YG203–YG205 AUSTRIAN AIRLINES AG (AUL) 1 YB171–YB172 YC381–YC385 YE171–YE172 2 YC386–YC387July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 14 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** AVENIR WORLDWIDE (BBJ) LIMITED (AWO) 1 YG034 AVJET (AJT) 2 YG095 AWAS (AWW) 1 YA732–YA733 2 YB590–YB591 BANCO SAFRA (BNS) 1 YG040 BEL AIR LIMITED (ULL) 1 YG022 BELAVIA (ITU) 1 YD408 BLUE AIR (BTR) 1 YC480 BOEING DEMONSTRATOR JET (BCJ) 1 YG035–YG036 BOETTI AIR INC. (BBI) 1 YG068 BURAQ AIR (BQA) 2 YK791–YK792 CANJET (CNJ) 1 YC476 YC478 CARIBBEAN AIRLINES LIMITED (CBL) 1 YC136–YC141 YD317 CHARTWELL (CHP) 1 YG017 CHINA AIRLINES (CHI) 1 YC571 YC574–YC582 CHINA EASTERN AIRLINES (CEA) 1 YA811–YA814 YB206 YB561–YB574 YK457–YK459 2 YB575–YB580 YJ010 YK461 YM591–YM593 YN021–YN024 CHINA EASTERN AIRLINES WUHAN (WUH) 1 YD171–YD172 YK456 2 YK460July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 15 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** CHINA SOUTHERN AIRLINES (GUN) 1 YB881–YB883 YB886–YB888 YC027 YC921–YC922 YD313 YD316 YD320 YD322 YD324–YD327 YD329 YJ671–YJ682 2 YB889–YB893 YJ683–YJ694 YL431–YL437 YN071–YN079 CHINA UNITED AIRLINES (CUL) 1 YB631–YB632 CHINA UNITED AIRLINES LTD. (CUA) 1 YA272 2 YD496 YD499 YJ009 CHINA XINJIANG AIRLINES (XIJ) 1 YA255–YA256 YA645 YA656 YB884–YB885 2 YM571–YM572 CLAY LACY AVIATION (CYA) 1 YG037 COLOMBIAN AIR FORCE (CLB) 1 YG028 COMMONWEALTH OF AUSTRALIA (GAU) 1 YG072 YG075 CONTINENTAL AIRLINES (CAL) 1 YA501–YA536 YC321–YC380 YD601–YD612 YJ501–YJ517 YJ531–YJ545 2 YH101–YH121 YJ546–YJ570 COPA AIRLINES (COP) 1 YA755–YA756 YA961–YA976 YJ591–YJ594 2 YA977–YA978 YJ595–YJ598 CYPRUS TURKISH AIRLINES (KTHY) (KHT) 1 YC467 YD021–YD022 DALLAH AL BARAKA (KAM) 1 YG063 DELTA AIR LINES (DAL) 1 YC601–YC655 YC681–YC696 2 YM701–YM707 DOBRO LIMITED (DOB) 1 YG008 2 YL281 DUBAI AIR WING (DAW) 1 YD402 YD412 YG007 2 YD414July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 16 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** E & A AVIATION (RSB) 1 YG082 EASYJET (EZY) 1 YB101–YB103 YB106–YB132 EGYPTAIR (EGP) 2 YK981–YK987 EIE EAGLE (EIE) 1 YD409 EL AL ISRAEL AIRLINES (ELA) 1 YA881–YA882 YC147 YC405 YC591–YC593 YD219 2 YL616–YL617 ETHIOPIAN AIRLINES (ETH) 1 YA666–YA667 YB156–YB157 2 YB158 EUROCYPRIA AIRLINES (ECY) 1 YC186–YC189 2 YC190 YJ947 EVA AIR (EVA) 1 YG083 FEDERAL GOVERNMENT OF NIGERIA (NGA) 2 YG091 FIRST VIRTUAL AIR II, LLC (FVA) 1 YG001 FLYGLOBESPAN.COM (FGS) 1 YE105–YE106 YJ941 YK136–YK137 2 YB671–YB672 YJ976–YJ977 FTC (SEH) 2 YG096 FUNAIR (FUN) 1 YG027 FUTURA (FUA) 1 YC406–YC407 YC410 YC451 YC463–YC464 YC466 YC727 YJ011–YJ013 YK426 2 YH201–YH202 YK427 G5 EXECUTIVE (GFE) 2 YG117July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 17 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** GAMA AVIATION LTD (GAV) 1 YG010 GARUDA INDONESIA (GIA) 1 YJ473 YJ475 GAZPROMAVIA (GAZ) 1 YA621–YA622 2 YG097 GECAS (GEF) 1 YA608 YA610 YA627–YA629 GERMANIA (GER) 1 YA231 YA233 YA235–YA240 GLOBAL JET AUSTRIA (GLJ) 1 YD404 GLOBAL JET LUXEMBOURG (SIQ) 1 YG038 2 YG093 GOL AIRLINES (GOT) 1 YA201–YA202 YA211 YA221 YA232 YA234 YA241–YA242 YA251–YA252 YA321–YA323 YA571–YA572 YA602 YA605 YA607 YA611–YA612 YA631 YA646–YA648 YA650 YA657 YB104–YB105 YB202 YB271 YC101 YC453 YC728–YC729 YD256–YD257 YD302–YD303 YD306–YD307 YJ471–YJ472 2 YJ944 YK721–YK723 YK725–YK741 YK753–YK764 GOVT OF EQUATORIAL GUINEA (EGR) 1 YG085 HAINAN AIRLINES (HNA) 1 YA544 YA546 YA603–YA604 YA606 YA857 YA859 YC126–YC127 YC401 YC404 YC409 YC452 YC971–YC978 YD042–YD045 YD216 YK402 2 YF021–YF030 YF106–YF107 YJ953 YK406 YK681–YK684 YK701–YK710 YK716–YK719 YL012–YL016 YL021–YL022 YL051–YL052 HAMBURG INTERNATIONAL (HAU) 1 YA575–YA576 YA578 YB276 HAPAG LLOYD EXPRESS (HLX) 2 YM652 HONG KONG AIRLINES (CWY) 2 YK711–YK713July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 18 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** ILFC (ILF) 1 YD308 YD318–YD319 YD323 INDIAN AIR FORCE (IDF) 2 YG112–YG114 INTEGRATED DEFENSE SYSTEMS (BSP) 2 YG202 YG212 YG214 YG221 JAL INTERNATIONAL (JAL) 2 YL201–YL211 YL501–YL507 JEJU AIR (JJU) 1 YC704 YC707 JET AIRWAYS (JPL) 1 YA630 YA734 YA751–YA754 YB181–YB184 YC402–YC403 YC731–YC741 YD309 YD311–YD312 YD328 YD330 YD334 YD571–YD572 YK401 YK404 2 YC742–YC750 YL371–YL374 YL602–YL603 YN091–YN092 YN121 JET AVIATION (JTA) 1 YD405 YG015 JET AVIATION BUSINESS JET INC (JBJ) 1 YG071 JET LITE (JPQ) 1 YA253–YA254 YA351 YA367 YB651 YC462 YC901–YC902 YM102–YM103 2 YK141–YK142 YK576–YK577 JET4YOU.COM (JFU) 1 YC010 JETAIRFLY (TLB) 1 YA609 YD217 YJ931 2 YK910–YK912 JETX (JXL) 1 YC454 YJ001 2 YK138–YK139 KENYA AIRWAYS (KEN) 1 YA635–YA636 YA641–YA642 2 YK186 YK671–YK672 YL302–YL303 KLM - ROYAL DUTCH AIRLINES (KLM) 1 YC781–YC793 YD531–YD535 2 YJ945 YK921–YK927 YM691–YM694July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 19 of 64 KOREAN AIR (KAL) 1 YC441–YC448 YD121–YD126 YD541–YD547 YD561–YD564 YD591–YD594 2 YD595 YL271–YL272 LAS VEGAS JET (LVJ) 1 YG002 LEGATUM (LGM) 1 YG062 LIMITED BRAND INC. (LII) 1 YG005 LINEAS AEREAS AZTECA (AZX) 1 YB502 LION AIR (MLI) 2 YH001–YH012 YH031–YH034 LOWA CORPORATION (LWA) 1 YD406 LUXAIR (LUX) 1 YB901–YB903 MALEV HUNGARIAN AIRLINES LTD. (HGA) 1 YA371–YA377 YC201–YC203 YC206–YC207 YE321–YE326 MANDARIN AIRLINES (MDN) 1 YC587–YC589 MGM MIRAGE (MGM) 1 YG042 2 YG119 MIAMI AIR (MIB) 1 YC146 YC904–YC905 YD304 YK121–YK122 2 YK571 MID EAST JET (SKL) 1 YD407 YG013–YG014 YG021 MONGOLIAN AIRLINES MIAT (MNG) 1 YC477 YJ476 MWWMMWM LIMITED (MWW) 2 YG116 N720CH, INC. (NCH) 1 YG019July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 20 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** NATIONAL (NJI) 1 YG032 NATIONAL AIR SERVICES (NAR) 1 YD403 YG080 YG086–YG087 NEOS (NEO) 1 YJ002 YJ021 YJ631–YJ632 NETJETS (NJL) 1 YG031 YG033 NEWS AMERICA INCORPORATED (NWS) 1 YG020 NOFA LTD. (NFA) 2 YD413 NORWEGIAN AIR SHUTTLE AS (NSB) 1 YC412 YC455 YC907 2 YF111 YK176–YK177 YK661 OKAY AIRWAYS COMPANY LIMITED (OKY) 1 YD332–YD333 2 YK171 YL282–YL284 OMAN AIR (OMR) 1 YA366 YB551 YC171 YJ901–YJ902 2 YF112 YJ903–YJ904 YJ908–YJ910 YJ956 ORENBURG AIRLINES (ORG) 1 YC479 OREX (ORX) 2 YG121 ORIENT GLOBAL AVIATION (VTU) 1 YG011 PACIFIC BLUE AIRLINES (BLP) 1 YJ865–YJ866 YK321 YK324 YK326 YK328 2 YK332 YK338–YK339 PEGASUS AIRLINES (PGS) 1 YC392 YC414–YC415 YC572–YC573 YD391 2 YL061 YL931–YL934 PEREGRINE (PGN) 2 YG701 PERIDOT (PID) 2 YH302July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 21 of 64 PEROLUX S.A.R.L. (PLX) 2 YG099 PICTON II (UNU) 1 YG006 PRIME AVIATION KZ (PKZ) 1 YG077 PRINCE SULTAN BIN ABDULAZIZ (PZI) 2 YH301 PRIVATAIR (PTS) 1 YG064 YK006 2 YG092 YK133 QANTAS (QAN) 1 YC878–YC892 YJ911–YJ921 2 YJ922–YJ928 YL561–YL565 QATAR AIRWAYS VIP (QAF) 2 YD415 RANK SERVICES LIMITED (RGR) 1 YG016 REPUBLIC OF CHINA AIR FORCE (CAF) 1 YC396 ROYAL AIR MAROC (RAM) 1 YA831–YA835 YC301–YC305 YK301–YK304 2 YK305–YK310 YK368–YK369 YN061 ROYAL JET (RJT) 1 YG018 YG023–YG026 ROYAL MALAYSIA AIR FORCE (MAF) 1 YG061 ROYAL THAI AIR FORCE (TAF) 2 YK476 RYANAIR (RYR) 1 YC481–YC499 YJ801–YJ853 2 YF501–YF516 YJ854–YJ860 YK801–YK899 S7 AIRLINES (SBR) 1 YD301 YD310 YD314–YD315 SAGA AIRLINES (SGV) 1 YD305 YD321July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 22 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** SAMSUNG TECHWIN CO. (SST) 1 YG079 2 YG111 SAS (SAS) 1 YD051–YD052 YD055 YD057 YD082 YE001 YE003–YE005 YE007 YE009 YE011 YE016 YE018 YE020 YE051 YE101–YE102 YE107–YE108 SAS INSTITUTE INC. (SJS) 1 YG041 SAS NORWAY (BRT) 1 YA311 YA543 YA545 YA547–YA552 YB001–YB006 YD041 YD050 YD053–YD054 YD056 YD081 YD083–YD084 YE002 YE006 YE008 YE010 YE012–YE015 YE017 YE019 YE103–YE104 YE109 2 YK373–YK375 YM671–YM672 SAUDI OGER (SAO) 1 YD401 YG073 SHANDONG AIRLINES (SHG) 2 YK511–YK516 YK521–YK524 YL066–YL069 YL311–YL312 YM551–YM553 SHANGHAI AIRLINES (SHA) 1 YA312–YA314 YA891–YA892 YC166–YC170 YC394 YD491 YJ003–YJ004 YJ871 2 YD492–YD495 YD497–YD498 YJ005–YJ007 YJ872–YJ876 YL531–YL534 SHENZHEN AIRLINES (SHZ) 1 YA613 YA626 YA686–YA687 YA721–YA722 YA801–YA803 YA809 YC153–YC154 YC411 YC413 YK101–YK104 2 YD651–YD655 YJ008 YJ948–YJ949 YK606–YK607 YL316–YL320 YL661–YL664 YL676–YL677 SIVA (SVM) 2 YG094 SKY AIRLINES (SYC) 2 YJ950 SKYEUROPE (SKP) 2 YN101–YN112 YN211–YN212 YN215 SKYMARK AIRLINES (SKM) 2 YK191 YK611–YK616 YL601 YL604July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 23 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** SOJITZ AIRCRAFT LEASING (SNR) 1 YD025 SONAIR (SON) 2 YG711 YN201–YN202 SOUTH AFRICAN AIRFORCE (SFF) 1 YG076 SOUTH AFRICAN AIRWAYS (SAA) 1 YC708–YC715 YC720–YC725 YD023–YD024 YD481–YD485 SOUTHERN AIRCRAFT SERVICES (HUZ) 1 YG009 SOUTHWEST AIRLINES (SWA) 1 YA001–YA099 YA101–YA199 YA271 YA301 YA541–YA542 YB204–YB205 YM251–YM260 2 YM261–YM299 YM301–YM378 SPICEJET (ROJ) 1 YC465 YD331 2 YH051–YH055 YK641–YK644 YK941–YK945 YK948–YK955 STERLING AIRLINES A/S (STR) 1 YA203–YA210 YA302 YA573–YA574 YA731 YC102–YC104 YJ933–YJ934 YK001 YK004 2 YM581–YM582 SUN COUNTRY AIRLINES (SCA) 1 YB656 YC121 YC152 YC155–YC156 YJ935–YJ936 YK132 2 YJ937 YJ952 SUNEXPRESS (SNS) 1 YC416–YC417 YC702 YC706 YD201–YD202 YJ477–YJ480 2 YL591–YL592 YL605–YL606 SUNWING AIRLINES INC. (SUG) 2 YJ951 YL011 YL611 SWIFLITE AIRCRAFT CORPORATION (OSF) 1 YG078 TAAG (ANGOLA AIRLINES) (ANG) 2 YM631–YM634 TAROM - ROMANIAN AIR TRANSPORT (TRM) 1 YB161–YB164 TBN AVIATION AVV (TBE) 1 YG029July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 24 of 64 THOMSONFLY (BRI) 1 YD001–YD004 2 YK907–YK908 YL421–YL427 TOWN & COUNTRY FOODS INC. (RUF) 1 YG003 TRACINDA CORP. (TRD) 1 YG004 TRANSAVIA AIRLINES (TAV) 1 YB521–YB526 YB541–YB544 YC071–YC083 YC091–YC094 2 YC084 TRANSAVIA FRANCE (TVF) 1 YC751–YC752 2 YF176–YF178 YK946–YK947 TRAVEL SERVICE (TSF) 1 YC408 YC459 YD203 YJ474 YK005 YK405 2 YK166–YK167 TUIFLY (HAP) 1 YA577 YC001–YC009 YC011–YC026 YC028–YC030 2 YK901–YK906 YK909 YL401 YM641–YM651 TUIFLY NORDIC (TNS) 1 YD005–YD007 TUNISAIR (TUN) 1 YE151–YE157 YG030 TURKEY AIR FORCE AEW&C PGM (ZXN) 1 YG211 2 YG213 TURKISH AIRLINES (THY) 1 YC501–YC526 2 YK551–YK570 YL351–YL353 TURKMENISTAN AIRLINES (TUE) 2 YK796–YK797 YN216 TURNBERRY (TNY) 1 YG012 TUTOR-SALIBA CORPORATION (TTS) 1 YG070 TY AIR (YIP) 1 YG066July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 25 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** UNITED STATES NAVY (USN) 1 YG501–YG508 2 YG509 US AIR FORCE (USF) 1 YG074 YG081 YG084 YG088 USAF RESERVES (URV) 2 YG101–YG103 VIRGIN BLUE AIRLINES (VOZ) 1 YA336–YA345 YA649 YA658–YA659 YA685 YA688–YA691 YB208 YC393 YC421–YC422 YD251–YD254 YJ861–YJ864 YJ867 YJ932 YK111–YK112 YK322–YK323 YK325 YK327 YK329–YK330 YM101 2 YJ954–YJ955 YK331 YK333–YK337 YM521–YM522 VRG LINHAS AEREAS S.A. (VGG) 1 YA601 YB501 YC471–YC475 2 YK751–YK752 YL621 WAKEFIELD BAHAMAS LTD. (WKB) 2 YG120 WESTJET (WJI) 1 YB301–YB310 YB601–YB629 YK480 2 YB630 YB961–YB974 YB986–YB988 YE371–YE383 YK481–YK487 YK495 WHITE SAPPHIRE (WSP) 2 YG098 XIAMEN AIRLINES (XIA) 1 YA701–YA710 YM471 2 YK621–YK630 YK961–YK971 YL076–YL077 YL541–YL543 YM481–YM484 XL AIRWAYS (SBE) 1 YC111–YC113 YC436–YC437 YC903 YC906 YK131 2 YC438–YC439 YH206–YH207 YJ946 YK146–YK147 YL056 XL AIRWAYS FRANCE (FXL) 2 YF086 XL AIRWAYS GERMANY (SXL) 2 YK148 YL057 YEMENIA (YEM) 1 YC176–YC178 2 YC179July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 26 of 64 YONA (IOP) 1 YG043

IDENTIFICATION BY VARIABLE NUMBER **Variable Group** YA001–YA099 1 YA101–YA199 1 YA201–YA211 1 YA221 1 YA231–YA242 1 YA251–YA256 1 YA271–YA272 1 YA291 1 YA301–YA302 1 YA311–YA314 1 YA321–YA323 1 YA336–YA345 1 YA351 1 YA356–YA357 1 YA366–YA367 1 YA371–YA377 1 YA501–YA536 1 YA541–YA552 1 YA571–YA578 1 YA601–YA615 1 YA621–YA622 1 YA626–YA631 1 YA635–YA636 1 YA641–YA642 1 YA645–YA650 1 YA656–YA659 1 YA666–YA667 1 YA671–YA672 1 YA681–YA691 1 YA701–YA710 1 YA721–YA722 1 YA731–YA734 1 YA751–YA756 1 YA801–YA803 1 YA809 1July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 27 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YA811–YA814 1 YA831–YA835 1 YA841–YA862 1 YA881–YA882 1 YA891–YA892 1 YA961–YA976 1 YA977–YA978 2 YB001–YB006 1 YB101–YB132 1 YB151–YB153 1 YB156–YB157 1 YB158 2 YB161–YB164 1 YB171–YB172 1 YB181–YB184 1 YB201–YB208 1 YB271 1 YB276 1 YB301–YB310 1 YB371–YB381 1 YB382–YB392 2 YB501–YB502 1 YB521–YB526 1 YB541–YB544 1 YB551 1 YB561–YB574 1 YB575–YB580 2 YB581–YB586 1 YB587–YB598 2 YB601–YB629 1 YB630 2 YB631–YB632 1 YB651 1 YB656 1 YB671–YB672 2 YB851–YB859 1 YB860 2 YB861–YB863 1 YB871–YB873 1 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 28 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YB874 2 YB881–YB888 1 YB889–YB893 2 YB901–YB903 1 YB911 1 YB961–YB974 2 YB986–YB988 2 YC001–YC030 1 YC051–YC083 1 YC084 2 YC091–YC094 1 YC101–YC104 1 YC111–YC113 1 YC121 1 YC126–YC127 1 YC136–YC141 1 YC146–YC147 1 YC151–YC156 1 YC166–YC171 1 YC176–YC178 1 YC179 2 YC186–YC189 1 YC190 2 YC201–YC203 1 YC206–YC207 1 YC301–YC305 1 YC321–YC385 1 YC386–YC387 2 YC391–YC394 1 YC396 1 YC401–YC417 1 YC421–YC422 1 YC426–YC428 1 YC436–YC437 1 YC438–YC439 2 YC441–YC448 1 YC451–YC455 1 YC459 1 YC461–YC467 1 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 29 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YC471–YC499 1 YC501–YC526 1 YC571–YC583 1 YC587–YC589 1 YC591–YC593 1 YC601–YC655 1 YC681–YC696 1 YC701–YC715 1 YC720–YC725 1 YC727–YC741 1 YC742–YC750 2 YC751–YC752 1 YC761–YC770 1 YC781–YC793 1 YC801–YC892 1 YC901–YC907 1 YC921–YC922 1 YC931–YC932 1 YC941–YC951 1 YC971–YC978 1 YC981–YC983 1 YD001–YD007 1 YD021–YD025 1 YD041–YD057 1 YD081–YD084 1 YD101–YD107 1 YD108–YD110 2 YD121–YD126 1 YD151–YD159 1 YD171–YD172 1 YD201–YD203 1 YD206–YD209 1 YD216–YD219 1 YD251–YD254 1 YD256–YD257 1 YD261 1 YD301–YD334 1 YD391 1 YD401–YD410 1 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 30 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YD412 1 YD413–YD415 2 YD481–YD485 1 YD491 1 YD492–YD499 2 YD501–YD512 1 YD531–YD535 1 YD541–YD547 1 YD561–YD564 1 YD571–YD572 1 YD591–YD594 1 YD595 2 YD601–YD612 1 YD651–YD655 2 YE001–YE020 1 YE051 1 YE101–YE109 1 YE151–YE157 1 YE171–YE172 1 YE201–YE206 1 YE301–YE305 1 YE321–YE326 1 YE371–YE383 2 YF001–YF002 2 YF021–YF030 2 YF051–YF054 2 YF086 2 YF106–YF107 2 YF111–YF112 2 YF176–YF178 2 YF201–YF202 2 YF501–YF516 2 YG001–YG044 1 YG061–YG064 1 YG066–YG089 1 YG091–YG099 2 YG101–YG103 2 YG111–YG114 2 YG116–YG121 2 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 31 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YG201 1 YG202–YG205 2 YG211 1 YG212–YG214 2 YG221 2 YG251–YG252 2 YG501–YG508 1 YG509 2 YG601–YG602 1 YG701 2 YG711 2 YH001–YH012 2 YH031–YH034 2 YH051–YH055 2 YH101–YH121 2 YH201–YH202 2 YH206–YH207 2 YH301–YH302 2 YJ001–YJ004 1 YJ005–YJ010 2 YJ011–YJ013 1 YJ021 1 YJ471–YJ480 1 YJ501–YJ517 1 YJ531–YJ545 1 YJ546–YJ570 2 YJ591–YJ594 1 YJ595–YJ598 2 YJ631–YJ632 1 YJ671–YJ682 1 YJ683–YJ694 2 YJ801–YJ853 1 YJ854–YJ860 2 YJ861–YJ867 1 YJ871 1 YJ872–YJ876 2 YJ901–YJ902 1 YJ903–YJ904 2 YJ908–YJ910 2 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 32 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YJ911–YJ921 1 YJ922–YJ929 2 YJ931–YJ936 1 YJ937 2 YJ941–YJ943 1 YJ944–YJ956 2 YJ976–YJ977 2 YK001–YK007 1 YK101–YK104 1 YK111–YK112 1 YK121–YK122 1 YK131–YK132 1 YK133 2 YK136–YK137 1 YK138–YK139 2 YK141–YK142 2 YK146–YK148 2 YK151–YK154 2 YK161–YK167 2 YK171 2 YK176–YK177 2 YK186 2 YK191 2 YK301–YK304 1 YK305–YK310 2 YK321–YK330 1 YK331–YK339 2 YK361–YK364 1 YK365–YK375 2 YK401–YK405 1 YK406 2 YK426 1 YK427 2 YK431 1 YK432–YK450 2 YK456–YK459 1 YK460–YK461 2 YK476 2 YK480 1 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 33 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YK481–YK487 2 YK495 2 YK511–YK516 2 YK521–YK524 2 YK551–YK571 2 YK576–YK577 2 YK580–YK585 2 YK601 1 YK602 2 YK606–YK607 2 YK611–YK616 2 YK621–YK634 2 YK641–YK644 2 YK651–YK661 2 YK671–YK672 2 YK676–YK677 2 YK681–YK684 2 YK701–YK713 2 YK716–YK719 2 YK721–YK741 2 YK751–YK764 2 YK791–YK792 2 YK796–YK797 2 YK801–YK899 2 YK901–YK912 2 YK918–YK919 2 YK921–YK927 2 YK941–YK955 2 YK961–YK971 2 YK981–YK987 2 YL001–YL005 2 YL011–YL016 2 YL021–YL024 2 YL051–YL052 2 YL056–YL057 2 YL061 2 YL066–YL069 2 YL076–YL077 2 YL101–YL128 2 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 34 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

YL201–YL211 2 YL271–YL272 2 YL281–YL284 2 YL301–YL303 2 YL311–YL312 2 YL316–YL320 2 YL351–YL353 2 YL371–YL374 2 YL401 2 YL421–YL427 2 YL431–YL437 2 YL461–YL475 2 YL501–YL507 2 YL531–YL534 2 YL541–YL543 2 YL561–YL565 2 YL591–YL592 2 YL601–YL606 2 YL611 2 YL616–YL617 2 YL621 2 YL661–YL664 2 YL676–YL677 2 YL901–YL910 2 YL921 2 YL931–YL934 2 YL951–YL954 2 YM101–YM103 1 YM201–YM202 1 YM203–YM241 2 YM251–YM260 1 YM261–YM299 2 YM301–YM378 2 YM471 1 YM481–YM484 2 YM501–YM515 2 YM521–YM522 2 YM541 2 YM551–YM553 2 **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 35 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

2. Spares Affected Examine your spares supply for Stabilizer Ballscrew Assembly part numbers given in the table below and incorporate the applicable supplier service bulletin to make sure that you do not install Ballscrew Assemblies that are not reworked on airplanes that incorporated the applicable supplier service bulletin:

**B. Concurrent Requirements**

None. YM571–YM572 2 YM581–YM582 2 YM591–YM593 2 YM631–YM634 2 YM641–YM652 2 YM671–YM672 2 YM691–YM694 2 YM701–YM707 2 YN001–YN016 2 YN021–YN024 2 YN061 2 YN071–YN079 2 YN091–YN092 2 YN101–YN112 2 YN121 2 YN201–YN202 2 YN211–YN216 2 YN231–YN235 2

**Name Umbra Cuscinetti Part Number**  **Boeing Part Number**  Stabilizer Ballscrew Assy 07322P000-02 (a) 10-62210-3

Stabilizer Ballscrew Assy 07322P000-03 (a) 10-62210-4

(a) Incorporate UMBRA CUSCINETTI, S.p.A. Service Bulletin 07322-27-01 on these Ballscrew assemblies prior to installing the Horizontal Stabilizer Trim Actuator with spare Ballscrew Assembly on the airplane, if the Horizontal Stabilizer Trim Actuator removed had a Ballscrew Assembly with the UMBRA CUSCINETTI Service Bulletin 07322-27-01 incorporated. **Variable Group**July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 36 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**C. Reason** This service bulletin is issued to maintain the frequency of the detailed inspection of the Horizontal Stabilizer Trim Actuator Ballscrew and Ball Nut as specified in the Maintenance Planning Document. This service bulletin also gives instructions to remove/replace and repair the Horizontal Stabilizer Trim Actuator if a damaged Ballscrew or Ball Nut is found. This service bulletin also adds the recommended intervals for repeat lubrication and overhaul. The airplanes effective for this service bulletin are divided in two groups, Group 1 and Group 2. The detailed inspection, overhaul, and lubrication tasks are required for Group 1 and Group 2 airplanes. Also, for Group 1 airplanes only, this service bulletin gives recommended compliance time for incorporation of supplier UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01, Rev 00, dated December 21, 2004. The supplier service bulletin 07322-27-01 provides instructions to remove and replace the Ball Nut Tube Retainers on the 737 Horizontal Stabilizer Trim Actuator Ballscrew assembly with new Tube Retainers that have sufficient stiffness to retain the load carrying balls in all known failure mode conditions. The changes given in this bulletin will reduce the probability of loss of the primary and secondary load paths of the Stabilizer Trim Actuator. Loss of the Horizontal Stabilizer Ballscrew primary and secondary load paths could result in the loss of control of the airplane. After a Horizontal Stabilizer Jackscrew incident related to a MD-80 airplane, Boeing initiated a design review of the Boeing heritage horizontal stabilizer ballscrew primary and secondary load paths. During this review, one 757 operator reported a Horizontal Stabilizer Ballscrew with extensive corrosion. An investigation was initiated. This investigation identified that a maintenance procedure to check the stabilizer Ballscrew primary load path was required. In addition, the design review found that the Ball Nut Tube Retainers on the 737 Horizontal Stabilizer Trim Actuator should be stiffened, so that the balls are retained within the assembly when the balls are jammed and not free to circulate. Boeing Service Related Problem (SRP) 737NG-SRP-27-0153 is related to this bulletin. Revision 1 is sent to include the following changes: 1. All service bulletin sections - Replaced throughout the service bulletin "UMBRA CUSCINETTI, Inc." with "UMBRA CUSCINETTI, S.p.A. 2. Summary page, Background Paragraph - Moved the end-level effect statement of the unsafe condition on the airplane from the middle of the Background section to the end of the first paragraph to conform with the new format requirements. 3. Summary page, Action Paragraph - Changed the name of the "Detailed Inspection" paragraph to "Inspection". Changed the paragraph. 4. Summary page, Compliance Paragraph - Added statement to inform operators that FAA will possibly release an Airworthiness Directive related to this service bulletin. 5. Planning Information, Paragraph 1.A.2., Spares Affected - Added clarification statement for reworking spare Horizontal Stabilizer Trim Actuators supply. 6. Planning Information, Paragraph 1.C., Reason - Added the list of all changes included in this revision. 7. Planning Information, Description Paragraph - Changed "Detailed Inspection" paragraph to "Inspection". Changed the paragraph. 8. Planning Information, Paragraph 1.D., Description - Added the work statement for Revision 1.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 37 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

9. Planning Information, Paragraph 1.E., Compliance - Added statement to inform operators that FAA will possibly release an Airworthiness Directive related to this service bulletin and removed the recommendation statement for the incorporation of the service bulletin. Changed the existing Note. 10. Planning Information, Paragraph 1.E, Compliance, Table 1 - Changed Table 1 format. Changed the Compliance Time and the Repeat Interval Time for the Detailed Inspection process. Added also clarification note to Compliance Time for the Overhaul of the Horizontal Stabilizer Trim Actuator. Removed two redundant flag notes. 11. Planning Information, Paragraph 1.E, Compliance, Table 2 - Added clarification note to Compliance Time for the incorporation of UMBRA CUSCINETTI, S.p.A. service bulletin 07322- 27-01. 12. Material Information, Paragraph 2.C.2., Parts and Materials Supplied by Operator - Added marking material and protective enamel. 13. Material Information, Paragraph 2.B., Industry Support Information - Changed the Warranty information. 14. Accomplishment Instructions, Paragraph 3.A, General Information - Deleted one note and added two notes. 15. Accomplishment Instructions, Paragraph 3.B, Work Instructions - Replaced throughout "Refer" with "as given in", and replaced at two location "Refer to 737-600/700/800/900 AMM 06-42-00" with "Refer to 737-600/700/800/900 AMM 06-42-00" as an accepted procedure" to conform with the new format requirements. 16. Accomplishment Instructions, Paragraph 3.B, Work Instructions - Specified at multiple location "detailed inspection" and "general visual inspection" to conform with the new format requirements. Changed the format of some step instructions. 17. Accomplishment Instructions, Paragraph 3.B., Work Instructions, Work Package 2 - Added a step instruction to mark the service bulletin incorporation data on the Horizontal Stabilizer Trim Actuator. 18. Accomplishment Instructions, Figure 1, Figure 2, and Figure 3 - Replaced "Refer" with "as given in" to conform with the new format requirements. Revision 2 is sent to include the following changes: 1. Changed throughout the bulletin the term "as given in" with the term "in accordance with". 2. In Summary Page, Action Paragraph - Added additional data for clarification. 3. In Summary Page, Effectivity Paragraph - Added 737-900 ER airplanes 4. Planning Information, Paragraph 1.A., Effectivity - Added 737-900 ER airplanes. 5. Planning Information, Paragraph 1.C., Reason - Added the list of all important changes done to the service bulletin. 6. Planning Information, Paragraph 1.D., Description - Added the work statement for Revision 2.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 38 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

7. Revised note (a) of Table 1, and added note (b) to Table 1. 8. Material Information, Paragraph 2.B., Industry Support Information - Changed the Warranty information. 9. Accomplishment Instructions, Paragraph 3.A., General Information - Changed Note 7 to replace the term "as given in" with the term "in accordance with". 10. Accomplishment Instructions, Paragraph 3.B., Work Instructions - Added some clarification notes and more data to some step instructions, deleted some unnecessary step instructions. 11. Accomplishment Instructions, Paragraph 3.B. - Changed Figure 1, Figure 2, and Figure 3 for clarification. **D. Description** Get access to the Horizontal Stabilizer Trim Actuator and do the procedures that follow below at the intervals shown in the compliance section:

1. INSPECTION: – Do a detailed inspection of the Stabilizer Trim Actuator lower and upper Gimbal for cracks and other damage. Inspect the areas around the bushings. Do a general visual inspection to see if large amount of grease exit the Ball Nut. Do a detailed inspection of the grease on and around the Ballscrew and Ball Nut for existence of metallic particles or other solid particles or corrosion products in the grease. Do a general visual inspection of the external areas of the Stabilizer Trim Actuator, and the areas below the Stabilizer Trim Actuator, for loose ball bearings. Clean the actuator Ballscrew. Do a detailed inspection of the Ball Nut Tube Retainers for deformation, corrosion, and lifted or damaged Return Tubes. Do a detailed inspection of the actuator Ballscrew threads for cross threading, distortion, stripping, metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, worn areas, and differences in thread shape (between thread grooves in the lower, middle, and upper portion of the Ballscrew). Move the Horizontal Stabilizer to a different setting to get access to the Ballscrew area covered by the Ball Nut. Repeat the inspections for the new exposed area of the ballscrew. Replace the Stabilizer Trim Actuator before further flight if any of these conditions exist. Lubricate the actuator Ball Nut and Ballscrew. – Do the Detailed Inspection at the intervals given in paragraph 1.E, Compliance, Table 1.

LUBRICATE THE STABILIZER TRIM ACTUATOR: – Lubricate the Stabilizer Trim Actuator Ballscrew, Ball Nut, and the upper and lower Gimbals. – Do the Lubrication at the intervals given in Paragraph 1.E, Compliance, Table 1.

REMOVE/REPLACE THE STABILIZER TRIM ACTUAT OR: Remove/Replace the Stabilizer Trim Actuator Ballscrew and Ball Nut if damage is found.

**NOTE:** If you replace a worn Stabilizer Trim Actuator with a serviceable Stabilizer Trim Actuator that is not new or not overhauled, then you must do the Detailed Inspection and Lubrication for the replacement Stabilizer Trim Actuator as given in this service bulletin, and the Horizontal Stabilizer Trim Actuator Gearbox Backlash Inspection in accordance with 737-600/700/800/900 AMM 27-41-81. 2. INCORPORATE UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01, Rev 00, Dated December 21, 2004: Install the new Ball Nut Tube Retainers in accordance with supplier UMBRA CUSCINETTI, S.p.A service bulletin 07322-27-01.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 39 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**NOTE:** Incorporate the UMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01 no later than the time given in Paragraph 1.E, Compliance, Table 2.

3. REMOVE AND REPAIR/OVERHAUL THE HORIZONTAL STABILIZER TRIM ACTUATOR: – Remove and repair/overhaul the Horizontal Stabilizer Trim Actuator at the intervals given in paragraph 1.E, Compliance, Table 1.

PLEASE SEND THE RESULTS FOR THE FAILED INSPECTIONS TO BOEING. Send your report to: BOEING COMMERCIAL AIRPLANES GROUP ATTENTION: MANAGER, SERVICE BULLETIN ENGINEERING P.O. BOX 3707, MAIL CODE 2H-36 SEATTLE, WA 98124-2207 USA

Revision 1: Airplanes were added to Group 2 of this service bulletin effectivity. No more work is necessary on airplanes changed as shown in the original issue of this service bulletin. However, Operators have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul in accordance with Paragraph 1.E., Compliance, Table 1.

**NOTE:** The Operators that performed the initial Detailed Inspection, Lubrication, and Overhaul do not have to do another initial inspection, but have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1. The Operators that incorporated UMBRA CUSCINETTI, S.p.A service bulletin 07322-27-01 as given in WORK PACKAGE 2, have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1. The Operators that did not incorporate UMBRA CUSCINETTI S.p.A. service bulletin, have to incorporate UNMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01 as given in WORK PACKAGE 2, and have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1.

Revision 2: Airplanes were added to Group 2 of this service bulletin effectivity. No more work is necessary on airplanes changed as shown in the original issue of this service bulletin dated July 21, 2005, or Revision 1 of this service bulletin dated July 25, 2007 (airplanes that incorporated UNMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01). However, Operators have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul in accordance with Paragraph 1.E., Compliance, Table 1.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 40 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**NOTE:** The Operators that performed the initial Detailed Inspection, Lubrication, and Overhaul do not have to do another initial inspection, but have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1. The Operators that incorporated UMBRA CUSCINETTI, S.p.A service bulletin 07322-27-01 as given in WORK PACKAGE 2, have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1. The Operators that did not incorporate UMBRA CUSCINETTI S.p.A. service bulletin, have to incorporate UNMBRA CUSCINETTI, S.p.A. service bulletin 07322-27-01 as given in WORK PACKAGE 2, and have to continue to do the repeat Detailed Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator in accordance with paragraph 1.E, Compliance, Table 1.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 41 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT E. Compliance**  Boeing recommends that the Maintenance Planning Document (MPD) intervals be observed for the “Lubrication” and “Detailed Inspection” actions prior to compliance with this service bulletin. Group 1-2: Table 1 - Inspection, Lubrication, and Overhaul of the Horizontal Stabilizer Trim Actuator **Condition Action Compliance Time (Whichever Occurs First)**  **Repeat Interval Notes**

Group 1 and Group 2 Detailed Inspection (in accordance with Accomplishment Instruction 3.B.1.d. Work Package 1 and 3.B.1.m. Work Package 1) Within 6,400 Flight Hours or 18 months from the last Detailed Inspection. 6,400 Flight Hours or 2 years (Whichever Occurs First). (a)

Lubricate (in accordance with Accomplishment Instruction 3.B.1.n. Work Package 1) Within 1,600 Flight Hours or 1 Year from the last Lubrication. 1,600 Flight Hours or 1 year (Whichever Occurs First). (b)

Horizontal Stabilizer Trim Actuator Overhaul (in accordance with Accomplishment Instructions 3.B., Work Package 3) Before the accumulation of 25,000 Flight Hours since the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness, or within 25,000 Flight Hours since last HSTA Overhaul. 25,000 Flight Hours (Not To Exceed).

Group 1 and Group 2 with damaged Horizontal Stabilizer Trim Actuator Repair/Replace the Horizontal Stabilizer Trim Actuator in accordance with Accomplishment Instructions, paragraph 3.B., WORK PACKAGE 3. Before further flight

-

(a) This task accomplishes a detailed inspection of the Horizontal Stabilizer Trim Actuator Ballscrew, Ball Nut, Ball Nut Tube Retainers and Return Tubes, and also accomplishes a detailed inspection of the lower and upper Gimbal and of the attachment points. The detailed inspection done in accordance with the service bulletin partially satisfies the intent of the task given in 737-600/-700/-800/-900 Maintenance Planning Data (MPD), Section 1, Item Number 27-110-00, and given in 737-700/-800 IGW (BBJ) Maintenance Planning Data (MPD), Section 6, Item Number 27-110-00 which also accomplishes a detail inspection of the Cable Drum and Cables for damage, and an inspection of the electrical connectors of the Stabilizer Trim Motor for damage. You must accomplish the detailed inspection of the Horizontal Stabilizer Trim Actuator as given in this service bulletin to establish and remain in compliance with this service bulletin. (b) Accomplishment of this task satisfies the intent of the task given in 737-600/-700/-800/-900 Maintenance Planning Data (MPD), Section 1, Item Number 27-102-00, and given in 737-700/-800 IGW (BBJ) Maintenance Planning Data (MPD), Section 6, Item Number 27-102-00. However you must accomplish this task as given in this service bulletin to establish and remain in compliance with this service bulletin.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 42 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**F. Approval** This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified in this service bulletin comply with the applicable regulations and are FAA approved, as well as European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/ JAA approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on the airplane in its original Boeing delivery configuration or as modified by other approved Boeing changes. If an airplane has a non-Boeing modification or repair that affects a component or system also affected by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval before incorporating this service bulletin. **G. Manpower** The table below shows an estimate of the task-hours necessary to perform a detailed inspection, and to replace the Stabilizer Trim Actuator for each airplane. This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator task-hour data if necessary. The estimate does not include lost time. These are some examples of lost time: — Time to adjust to the workplace — Time to schedule the work — Time to examine the work — Time to cure the materials — Time to make the parts Group 1: Table 2 - Incorporation of UMBRA CUSCINETTI, S.p.A. Service Bulletin 07322-27-01 **Condition Action Compliance Time (Not To Exceed)**  **Repeat Interval Notes**

Group 1 Install new Ball Nut Tube Retainers in accordance with Accomplishment Instructions 3.B., Work Package 2 and UMBRA CUSCINETTI, S.p.A. Service Bulletin 07322-27- 01 Within 25,000 Flight Hours since the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness, or within 25,000 Flight Hours since the latest HSTA Overhaul from the date of Revision 1 of this Service Bulletin which ever occurs later. - (a)

(a) Installing the new Ball Nut Tube Retainers is not a terminating action for HSTA Detailed Inspection, Lubrication, and Overhaul specified in Table 1. Operators have to continue to do the Detailed Inspection, Lubrication, and Horizontal Stabilizer Trim Actuator Overhaul at the specified times or intervals given in Table 1.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 43 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

— Time to find the tools.

**H. Weight and Balance Changes**

None.

**I. Electrical Load Data** Not changed.

**J. References** 1. Existing Data: a. Engineering Change Memo PRR 38275-74S b. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 06-42-00, 12-22-41, 27-41-00, 27-41-81 c. Boeing Parts Standards Document D-590 d. Component Maintenance Manual (CMM) 27-41-01 e. Component Maintenance Manual (CMM) 27-45-12 f. UMBRA CUSCINETTI, S.p.A. Service Bulletin 07322-27-01 a. Service Related Problem (SRP) 737NG-SRP-27-0153.

**NOTE:** The supplier was told to send copies of the service bulletin to each operator. 2. Data supplied with this Service Bulletin:

None. **Task Number of**  **Persons Task-Hours Elapsed Hours** Open Access 2 1.0 0.50 Detailed Inspection 2 2.0 1.0 Lubrication 2 1.0 0.50 Replace Stabilizer Trim Actuator (a) (b) 2 2.5 (b) 1.25 (b)

Close Access 2 1.0 0.50 Test 2 4.0 2.0 TOTAL FOR EACH AIRPLANE 9.0 (a) 4.5(a) (a) Total hours does not include actuator replacement. (b) Hours are for replacement only, additional time required for Stabilizer Trim Actuator overhaul.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 44 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

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

None.

**K. Publications Affected**

**L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts. **Publication Chapter-Section** 737 Maintenance Manual 12-22-41, 27-41-81 737 Component Maintenance Manual 27-45-12 Maintenance Planning Document (MPD) Section 1July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 45 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**2. MATERIAL INFORMATION A. Material - Price and Availability** 

None. **B. Industry Support Information** Boeing warranty remedies are available for WORK PACKAGE 2, Group 1, 737 airplanes in warranty as of June 14, 2001. For task hour and material reimbursement for airplanes in warranty as of that date, send a warranty claim to Boeing Commercial Airplanes Group - Warranty. **C. Parts Necessary For Each Airplane**

1. Kits/Parts:

None. 2. Parts and Materials Supplied by the Operator:

None.

3. Parts Modified and Reidentified:

None. 4. Parts Removed and Not Replaced:

None. **D. Parts Necessary to Change Spares**

None. **Part Number / Specification QTY Name Notes**  BMS 3-33 As Necessary Grease Recommended (a)

MIL-G-23827 As Necessary Grease Alternate to BMS 3-33

BMS 10-60, Type 2, Clear or equivalent As Necessary Protective Enamel (Clear), Hydraulic Fluid Resistant (a)

Permanent Marking Material As Necessary Ink or Paste Ink (b)
(a) See the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data. (b) Refer to SOPM 20-50-10 for the list of permanent marking materials.July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 46 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT E. Special Tooling - Price and Availability** 

None. **F. Special Tooling Necessary to do this Service Bulletin** No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 47 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**3. ACCOMPLISHMENT INSTRUCTIONS**

**A. GENERAL INFORMATION**

**CAUTION:** KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE.

**NOTE:** 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 2. Obey all of the warnings and cautions given in the specified manual sections. 3. The work instructions are divided into work packages. Task Hours and Elapsed Hours for each package are given in Paragraph 1.G., Manpower. You can do each work package independently. 4. For approved fastener and process material substitutions, refer to 737 Structural Repair Manual, Chapter 51. Alternate fasteners are given in 737 Structural Repair Manual, Chapter 51 and Boeing Drawing 65-88700. 5. 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. 6. 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. 7. These work instructions refer to procedures included on other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. 8. Operators will find the term "Stabilizer Trim Actuator" in the Airplane Maintenance Manual documents. The "Stabilizer Trim Actuator" includes the Ball Nut, Jackscrew, and Jackscrew Gearbox. The term "Jackscrew" called out in the Airplane Maintenance Manual documents is referred to as "Ballscrew" in this service bulletin.Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 48 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**B. WORK INSTRUCTIONS**

**WORK PACKAGE 1 Group 1-2: Detailed Inspection and Lubrication of**  **the Horizontal Stabilizer Trim Actuator Ballscrew, Ball Nut, and attachment (Gimbal) fittings:**  1. Paragraph 1.E., Compliance, Table 1 gives the intervals at which the Detailed Inspection and Lubrication of Stabilizer Trim Actuator Ballscrew, Ball Nut, and attachment fittings (Gimbal Fittings) need to be accomplished/repeated. a. Get access to the Stabilizer Trim Actuator through service access door 311BL. Refer to 737-600/700/800/900 AMM 06-42-00 as an accepted procedure. b. Set the Main Cutout switch, S272 located on the aft area of the control stand, to the CUTOUT position. c. Open the circuit breakers shown below and attach DO-NOT-CLOSE tags:

d. Do the following inspections of the Stabilizer Trim Actuator and as given in Figure 1: (1) Do a detailed inspection of all attachment points of the Lower and Upper Gimbal for cracks and other damage. Inspect the areas around the holes and bushings. Make sure that the Stabilizer Trim Actuator is correctly attached to the airplane structure. If any damage is found, repair or replace the damaged parts. Refer to 737-600/700/800/900 AMM 27-41-81 and CMM 27-45-12 as accepted procedures. (2) Do a general visual inspection of the area under, on, and around the Stabilizer Trim Actuator to see if grease is escaping from Ball Nut. Large amounts of grease present around the Stabilizer Trim Actuator indicate that a faulty seal or lifted return tube may be present on the Ball Nut.

**NOTE:** If a large amount of grease is present due to a faulty seal or lifted/leaking return tube, repair/replace the Stabilizer Trim Actuator in accordance with Figure 3. **Location (Panel, Position)**  **Name Circuit Breaker**

P18-1, C2 AFCS STABILIZER TRIM C00849

P6-2, B10 FLIGHT CONTROL STAB TRIM CONT C00207

P6-2, D10 FLIGHT CONTROL STAB TRIM ACTUATOR C00840Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 49 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** (3) Do a detailed inspection of the grease on and around the Ballscrew and Ball Nut for existence of metallic particles, other solid particles, and corrosion products in the grease. If metallic particles, or other solid particles, or corrosion products are found in the grease, Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3.

**NOTE:** Metallic particles in the grease may be an indication of degradation of the balls in the Ball Nut. (4) Check if any of the Ball Nut ball bearings are found in the vicinity of the Ball Nut, on the Ballscrew, or directly below the Stabilizer Trim Actuator. If Ball Nut ball bearings are found Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3.

**NOTE:** The Ball Nut ball bearings used inside the 737 Ball Nut are approximately 0.218 inch diameter. (5) Remove any old grease and dirt from the Ballscrew threads by wiping them with a clean, dry, non-abrasive cloth. (6) Do a detailed inspection of the Ball Nut Tube Retainers for deformation and corrosion or lifted Return Tubes. If the Ball Nut Tube Retainers have deformation or corrosion or the Return Tubes are lifted, Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3. (7) Do a detailed inspection of the Ballscrew for the following problems in accordance with Figure 1: (a) Inspect the Ballscrew threads for cross-threading, distortion, or stripping. If you find any of these conditions Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3. (b) Check the Ballscrew for metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, and worn areas in the threads. If pitting, or gouging, or corrosion, or spalling, or brinelling, cracks, or worn areas in the Ballscrew threads is observed, repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with Figure 3.

**NOTE:** If visible metallic particles are observed in the grease there may be some damage in the Ballscrew/Ball Nut assembly. Normal wear of the Ballscrew actuator can happen but this will not release visible metallic particles in the grease. (c) Check for obvious differences in thread shape between thread grooves in the lower, middle, and upper portions of the Ballscrew. If obvious differences in thread shape between thread grooves in the lower, middle, and upper portions of the Ballscrew is observed, repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with Figure 3.Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 50 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** e. Remove the DO-NOT-CLOSE tags and close the circuit breakers shown below:

f. Make sure that the STAB TRIM switch on the stab trim and cabin door panel, P8-47 module, is in the NORMAL position. g. Set the Main Cutout switch, S272 located on the aft area of the control stand, to the NORMAL position. h. Push and hold the Stabilizer Trim Control switches on the Captain’s Control Wheel (NOSE UP or NOSE DOWN) to move the ballscrew to another location other than the current setting. i. Set the Main Cutout switch, S272 located on the aft area of the control stand, to the CUTOUT position. j. Open the circuit breakers shown below and attach DO-NOT-CLOSE tags:

k. Do a detailed inspection of the grease on the newly exposed area of the Ballscrew for metallic particles, other solid particles, and corrosion products in the grease. If metallic particles, or other solid particles, or corrosion products are found in the grease Repair/ Replace the Stabilizer Trim Actuator in accordance with Figure 3. **Location (Panel, Position)**  **Name Circuit Breaker**

P18-1, C2 AFCS STABILIZER TRIM C00849

P6-2, B10 FLIGHT CONTROL STAB TRIM CONT C00207

P6-2, D10 FLIGHT CONTROL STAB TRIM ACTUATOR C00840

**Location (Panel, Position)**  **Name Circuit Breaker**

P18-1, C2 AFCS STABILIZER TRIM C00849

P6-2, B10 FLIGHT CONTROL STAB TRIM CONT C00207

P6-2, D10 FLIGHT CONTROL STAB TRIM ACTUATOR C00840Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 51 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**NOTE:** If visible metallic particles are observed in the grease there may be some damage in the Ballscrew/Ball Nut assembly. Normal wear of the Ballscrew actuator can happen but this will not release visible metallic particles in the grease. l. Remove any grease from the newly exposed portion of the Ballscrew threads by wiping them with a clean, dry, non abrasive cloth. m. Do a detailed inspection of the newly exposed Ballscrew for the following problems in accordance with Figure 1. (1) Inspect the Ballscrew threads for cross-threading, distortion, or stripping. If you find any of these conditions Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3 (2) Check the Ballscrew for metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, and worn areas in the Ballscrew threads. The presence of metallic particles can be an indication of damage of the Ballscrew. If pitting, or gouging, or corrosion, or spalling, or brinelling, or cracks, or worn areas in the Ballscrew threads is observed, repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with Figure 3.

**NOTE:** If visible metallic particles are observed in the grease there may be some damage in the Ballscrew/Ball Nut assembly. Normal wear of the Ballscrew actuator can happen but this will not release visible metallic particles in the grease. (3) Check for obvious differences in thread shape between thread grooves in the lower, middle, and upper portions of the Ballscrew. If obvious differences in thread shape between thread grooves in the lower, middle, and upper portions of the Ballscrew is observed, repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with Figure 3. n. Apply grease (Lubricate) the Ballscrew and Ball Nut in accordance with Figure 2. Apply the grease slowly until clean, new, fresh grease exits through the grease vent. If clean, new, fresh grease fails to exit the grease vent OR the upper seal, repair/replace the Stabilizer Trim Actuator in accordance with Figure 3. (1) Inspect if grease exits the Ball Nut through Upper Seal, Lower Seal, and around the Tube Retainer areas: (a) Clean, new fresh grease, that exits from the upper seal is also an acceptable indication of proper lubrication of the ballnut. (b) Small amounts of grease may exit the lower seal and is considered acceptable as long as the general visual inspection of the area under, on, and around the stabilizer trim actuator given in step B.1.d.2 was found satisfactory.Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 52 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT** (c) Small amounts of grease may exit the ball nut through the Tube Retainer areas (from the Return Tubes). If small amount of grease is observed around the Tube Retainers do a detailed inspection of the Ball Nut Tube Retainers for deformation and corrosion or lifted Return Tubes. If the Ball Nut Tube Retainers have deformation or corrosion Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3. If no damage of the Tube Retainers is found the condition is acceptable.

**NOTE:** If large amount of grease exit through the Tube Retainer areas, the Return Tubes may be lifted and the Stabilizer Trim Actuator must be repaired or replaced in accordance with Figure 3. (2) Inspect the grease that is exiting the Ball Nut for indication of metallic particles, discolored water, rust, or other solid particles. If any of these conditions exist Repair/ Replace the Stabilizer Trim Actuator in accordance with Figure 3.

**NOTE:** If visible metallic particles are observed in the grease there may be some damage in the Ballscrew/Ball Nut assembly. Normal wear of the Ballscrew actuator can happen but this will not release visible metallic particles in the grease. 2. Remove the DO-NOT-CLOSE tags and close the circuit breakers shown below:

3. Close the service access door 311BL. Refer to 737-600/700/800/900 AMM 06-42-00 as an accepted procedure. 4. Put the airplane back to a serviceable condition.

**WORK PACKAGE 2 Group 1: Remove/Replace the Stabilizer Trim Actuator Ball Nut Tube Retainers:**  1. Install the new Ball Nut Tube Retainers as given in supplier UMBRA CUSCINETTI, S.p.A. SB 07322-27-01 and in paragraph 1.E, Compliance, Table 2. 2. After you incorporate UMBRA CUSCINETTI, S.p.A. Service Bulletin 07322-27-01, hand letter with a permanent ink or paste ink, in the area adjacent to the HSTA name plate (gear box area) the following: **Location (Panel, Position)**  **Name Circuit Breaker**

P18-1, C2 AFCS STABILIZER TRIM C00849

P6-2, B10 FLIGHT CONTROL STAB TRIM CONT C00207

P6-2, D10 FLIGHT CONTROL STAB TRIM ACTUATOR C00840Original Issue: July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 53 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT "SB 737-27A1277 R02, WORK PACKAGE 2 and SB 07322-27-01 ARE INCORPORATED ON**  **THIS HSTA"** Apply BMS 10-60, Type 2, Clear, over the marking, to protect the marking from hydraulic fluid. Refer to SOPM 20-50-10 as an accepted procedure for the marking process and marking materials.

**WORK PACKAGE 3 Group 1-2: Remove the Horizontal Stabilizer Trim Actuator for Repair/Overhaul:** 

1. Remove and do the Overhaul of the Horizontal Stabilizer Trim Actuator at or before the time given in Paragraph 1.E., Compliance, Table 1. Remove the Horizontal Stabilizer Trim Actuator as given in Figure 3. Repeat the Overhaul in accordance with Paragraph 1.E., Compliance, Table 1.

**NOTE:** Remove the Horizontal Stabilizer Trim Actuator in accordance with 737-600/700/800/ 900 AMM 27-41-81. Repair the Stabilizer Trim Actuator components in accordance with CMM 27-41-01 (UMBRA CUSCINETTI, S.p.A. CMM) and CMM 27-45-12.**FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 54 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**FIGURE 1: HORIZONTAL STAB ILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS**

DOOR, 311BL SERVICE ACCESS

SEE B SEE A



### A FWDD34433

**(SHEET 1 OF 6) FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 55 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

B FWD LOWER GIMBAL

1 SEE D 2 4 5 10 8 1

UPPER GIMBAL BALLSCREW FITTING SEE C

2 PLACES 7 3 9D34684

**(SHEET 2 OF 6) FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 56 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

C BALLSCREW FITTING BALLSCREW

UPPER GIMBAL (2 LOCATIONS) FITTING

BALL NUT BALL NUT

FWD 1 2 LOCATIONS 4 6 2 5 10 8 4 7 3 9

9

4 6 9D35451

**(SHEET 3 OF 6) FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 57 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

FWD



### D 4 5 7

BALLSCREW GEAR BOX

4 AFT CABLE DRUM 4 3 10 2 BALLSCREW 9D34460

**(SHEET 4 OF 6) FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 58 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**STEP TASK NAME**  **PART NUMBER**  **QTY MORE DATA**  1 Inspect Stabilizer Trim Actuator attachment points - Do a detailed inspection of the lower and upper gimbal for cracks and other damage. Inspect the area around the bushings. Make sure that the Stabilizer Trim Actuator is correctly attached to the airplane structure. 2 Inspect Area Under, On, and Around Stabilizer Trim Actuator - Do a general visual inspection to see if large amount of grease is escaping the Ball Nut.(a)

3 Inspect Grease - Do a detail inspection of the grease on and around the Ballscrew and the Ball Nut for existence of metallic particles, other solid particles, or corrosion products. (b) 4 Inspect Ballscrew and Ball Nut, Trim Actuator Housing, and area below Stabilizer Trim Actuator - for escaped Ball Nut ball bearings.(c)

5 Remove Grease - from Ballscrew threads by wiping with a clean, dry, non-abrasive cloth. 6 Inspect Ball Nut and Ball Nut Tube Retainers Do a detailed inspection for deformation and corrosion or lifted return tubes. 7 Inspect Ballscrew - Do a detailed inspection for cross-threading, distortion, and stripping, metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, worn areas, and differences in thread shape (between thread grooves in the lower, middle, and upper portion of the Ballscrew). If any of the damage listed is observed, remove, inspect, and repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with CMM 27-41-01 (UMBRA CUSCINETTI, S.p.A.). 8 Move Ballscrew - to another location. 9 Inspect Ballscrew and Ball Nut - for large amount of grease that exits the Ball Nut and for existence of metal particles or other debris.(a)(b)

**(SHEET 5 OF 6) FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE**  **BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS** July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 59 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

10 Inspect Ballscrew - Do a detailed inspection for cross-threading, distortion, stripping, metallic particles, pitting, gouging, corrosion, spalling, brinelling, cracks, worn areas, and differences in thread shape (between thread grooves in the lower, middle, and upper portion of the Ballscrew). If any of the damage listed is observed, remove, inspect, and repair/replace (as necessary) the Stabilizer Trim Actuator in accordance with CMM 27-41-01 (UMBRA CUSCINETTI, S.p.A.).(a) Large amount of grease present around the Ballscrew indicate that a faulty seal or lifted Ball Nut Return Tubes may be present. (b) Metallic particles and debris in grease may be indication of degradation of the balls in the Ball Nut. (c) The Ball Nut bearings are approximately 0.218 inch in diameter. **STEP TASK NAME**  **PART NUMBER**  **QTY MORE DATA** 

**(SHEET 6 OF 6) FIGURE 2: LUBRICATION OF THE HORIZONTAL STABILIZER TRIM ACTUATOR**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 60 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**FIGURE 2: LUBRICATION OF THE HO RIZONTAL STABILIZER TRIM ACTUATOR** 

FWD SERVICE ACCESS DOOR, 311BL HORIZONTAL STABILIZER

LOWER GIMBAL (2 LOCATIONS) UPPER GIMBAL (2 LOCATIONS) BALL NUT 1

BALLSCREW 1 2 2 3 1

1 BALLSCREW FITTINGD35298

**(SHEET 1 OF 2) FIGURE 2: LUBRICATION OF THE HORIZONTAL STABILIZER TRIM ACTUATOR**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 61 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**STEP TASK NAME PART NUMBER QTY MORE DATA** 1 Apply Grease D00633 1 in accordance with 737-600/700/800/ 900 AMM 12-22-41 until clean, new, fresh grease exits through the grease vent. (a) 2 Inspect Ball Nut - - if grease exits through the Upper Seal, Lower Seal, and around the Tube Retainer areas. (b) (c) (d)3 Inspect Grease - - that exits the ballnut for signs of metallic particles, discolored water, rust, or other solid particles.(e) (a) If clean, new, fresh grease fails to exit the grease vent OR the upper seal, repair/replace the Stabilizer Trim Actuator in accordance with Figure 3.(b) Clean, new fresh grease, that exits from the upper seal is also an acceptable indication of proper lubrication of the Ball Nut. (c) Small amounts of grease may exit the lower seal and is considered acceptable as long as the general visual inspection of the area under, on, and around the stabilizer trim actuator given in step B.1.d.2 was found satisfactory. (d) Small amounts of grease may exit the ball nut through the Tube Retainer areas (from the Return Tubes). If small amount of grease is observed around the Tube Retainers do a detailed inspection of the Ball Nut Tube Retainers for deformation and corrosion or lifted Return Tubes. If the Ball Nut Tube Retainers havedeformation or corrosion Repair/Replace the Stabilizer Trim Actuator in accordance with Figure 3. If no damage of the Tube Retainers is found the condition is acceptable. If large amount of grease exit through the Tube Retainer areas, the Return Tubes may be lifted and the Stabilizer Trim Actuator must be repaired or replaced in accordance with Figure 3. (e) If visible metallic particles are observed in the grease there may be some damage in the Ballscrew/Ball Nut assembly. Normal wear of the Ballscrew actuator can happen but this will not release visible metallic particles in the grease.

**(SHEET 2 OF 2) FIGURE 3: HORIZONTAL**  **STABILIZER TRIM ACTUATOR BALLSCREW AND BALL NUT - REPAIR/ REPLACEMENT**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 62 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**FIGURE 3: HORIZONTAL ST ABILIZER TRIM ACTUATOR BALLSCREW AND BALL NUT - REPAIR/**  **REPLACEMENT**

DOOR, 311BL SERVICE ACCESS

1 2 3 4 BALL NUT

GIMBAL UPPER

AFT CABLE DRUM

TRIM WHEEL CABLES STABILIZER MANUAL GIMBAL LOWER BALLSCREW FITTING BALLSCREW STABILIZER HORIZONTALD34862

**(SHEET 1 OF 2) FIGURE 3: HORIZONTAL ST**  **ABILIZER TRIM ACTUATOR BALLSCREW AND BALL NUT - REPAIR/ REPLACEMENT**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 63 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT**

**STEP TASK NAME PART NUMBER QTY MORE DATA** 1 Remove Horizontal Stabilizer Trim Actuator - 1 in accordance with 737 737-600/700/ 800/900 AMM 27-41-81. 2 Repair/ Overhaul Horizontal Stabilizer Trim Actuator - 1 in accordance with CMM 27-41-01 (UMBRA CUSCINETTI, S.p.A.), and CMM 27-45-12. 3 Install Horizontal Stabilizer Trim Actuator - 1 in accordance with 737-600/700/800/ 900 AMM 27-41-81. (a) 4 Test Horizontal Stabilizer Trim Actuator - 1 in accordance with 737-600/700/800/ 900 AMM 27-41-00. (a) If you replace a damaged Stabilizer Trim Actuator with a serviceable Stabilizer Trim Actuator that is notnew or not overhauled, then you must do the Detailed Inspection for the replacement Stabilizer Trim Actuator as given in this service bulletin, and the Horizontal Stabilizer Gearbox Backlash Inspection in accordance with 737-600/700/800/900 AMM 27-41-81.

**(SHEET 2 OF 2) APPENDIX A: Inspection report form for SB 737-27A1277**  July 21, 2005 Revision 2: January 08, 2010 737-27A1277 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 64 of 64 

### BOEING SERVICE BULLETIN 737-27A1277 **ALERT ALERT APPENDIX A: Inspection report form for SB 737-27A1277**  Use this Inspection Report form to provide data to Boeing for the Horizontal Stabilizer Trim Actuator that is inspected at specified intervals as given in this service bulletin: Operator: ______________________________________ Today’s Date: _________________________ Prepared by: ___________________________________ Title: _________________________________ Telephone Number: _____________________________ Base: _______________________________ Stabilizer Trim Actuator assembly Pin part number and dash number: _______________________________ Stabilizer Trim Actuator Assembly Serial Number: ___________________________________ Date of inspection: ________________________ Airplane Variable Number/ Line Number: __________________________ Total number of Flight Cycles and Flight Hours on the airplane at the inspection date: ____________________ Cycles ______________________Flight Hours Metallic debris found in grease: YES ____ NO ____ Ball Nut bearings found in vicinity of the Ball Nut, Gear Box, or below the Stabilizer Trim Actuator:
YES ____ NO ____ Ballscrew with threads damage: YES ____ NO ____ Stabilizer Trim Actuator attachment points with cracks or other damage:
YES ____ NO ____ Upper and lower Gimbal with damage: YES ____ NO ____

Please provide a brief description of the damage, a sketch or a picture. When any portion of the detailed inspection failed, give the completed Inspection Report form and attachments, sketches, or pictures to your Boeing Field Service Representative or send the Inspection Report directly to this address: Manager, Service Bulletin Engineering Boeing Commercial Airplane Group P.O. Box 3707, mail Code 2H-36 Seattle, WA 98124-2207