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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Unpublished Work - All Rights Reserved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.
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ALERT ALERT

BLANK PAGE
 Table of Contents

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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

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ALERT ALERT

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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:
 

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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, 2010
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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.
 

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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.
 

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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. 
 

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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.

D34249
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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.
 

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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–YC932
 

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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–YC387
 

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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 YK460
 

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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 YD414
 

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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 YG117
 

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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–YK713
 

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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–YM694
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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 YG019
 

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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 YH302
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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 YD321
 

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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 YL604
 

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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 YG029
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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 YG066
 

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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 YC179
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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 1
 

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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
 

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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
 

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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
 

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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
 

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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
 

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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
 

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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
 

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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
 

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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
 

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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.
 

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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.
 

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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 ACTUATOR: 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. 
 

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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.
 

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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.
 

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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.
 

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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.
 

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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

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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 1 
 

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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. 
 

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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.
 

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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. 
 

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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

C00840
 

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(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.
 

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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

C00840
 

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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.
 

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(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

C00840
 

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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

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ALERT ALERT

FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE 

BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS

DOOR, 311BL

SERVICE ACCESS

SEE B

SEE A

A

FWD

D34433

(SHEET 1 OF 6)
 FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE 

BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS

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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

9

D34684

(SHEET 2 OF 6)
 FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE 

BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS

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ALERT ALERT

C

BALLSCREW

FITTING

BALLSCREW

UPPER GIMBAL

(2 LOCATIONS)

FITTING

BALL NUT

BALL NUT

FWD

1 2 LOCATIONS

4 6

2 5

8 10

4

7

3

9

9

4 6 9

D35451

(SHEET 3 OF 6)
 FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE 

BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS

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ALERT ALERT

FWD

D

4 5 7

BALLSCREW

GEAR BOX

4

AFT CABLE DRUM

4

2 3 10

BALLSCREW

9

D34460

(SHEET 4 OF 6)
 FIGURE 1: HORIZONTAL STABILIZER TRIM ACTUATOR - DETAILED INSPECTION OF THE 

BALLSCREW, BALL NUT, AND THE ATTACHMENT FITTINGS

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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

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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

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FIGURE 2: LUBRICATION OF THE HORIZONTAL STABILIZER TRIM ACTUATOR 

FWD

SERVICE ACCESS

DOOR, 311BL

HORIZONTAL

STABILIZER

LOWER GIMBAL

(2 LOCATIONS)

UPPER GIMBAL

BALL NUT (2 LOCATIONS)

1

BALLSCREW

1 2

2 3

1

1

BALLSCREW

FITTING

D35298

(SHEET 1 OF 2)
 FIGURE 2: LUBRICATION OF THE HORIZONTAL STABILIZER TRIM ACTUATOR

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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 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. 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

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ALERT ALERT

FIGURE 3: HORIZONTAL STABILIZER 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

HORIZONTAL

D34862

(SHEET 1 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. 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 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. 

(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