### Commercial **Airplanes** 

# 737 Service Bulletin **Number: 737-27-1289** Original Issue: April 07, 2010 ATA System: 2741 **SUBJECT:** 737 STABILIZER TAKEOFF WARNING SWITCHES - TEST OF THE TAKEOFF WARNING INDICATION Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15 CFR 730-774). An export license may be required before it is used for development, production or use by foreign persons from specific countries. The controller of this data has the individual responsibility to abide by all export laws. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2010 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 1 of 29 2.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 2 of 29 **BOEING SERVICE BULLETIN 737-27-1289**

BLANK PAGE**Table of Contents** Summary...................................................... 5 1. PLANNING INFORMATION........................................ 9 A. Effectivity................................................ 9 1. Airplanes............................................. 9 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 1. Existing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2. Data supplied with this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3. Installation Drawings Used in the Preparation of this Service Bulletin. . . . . . . . . . . . 23 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1. Kits/Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2. Parts and Materials Supplied by the Operator. . . . . . . . . . . . . . . . . . . . . . . . 25 3. Parts Modified and Reidentified. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4. Parts Removed and Not Replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 26 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 3 of 29 **BOEING SERVICE BULLETIN 737-27-1289**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 4 of 29 **BOEING SERVICE BULLETIN 737-27-1289**

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### Commercial **Airplanes** 

# 737 Service Bulletin **Summary Number: 737-27-1289**  Original Issue: April 07, 2010 ATA System: 2741 **SUBJECT:** 737 STABILIZER TAKEOFF WARNING SWITCHES - TEST OF THE TAKEOFF WARNING INDICATION **CONCURRENT REQUIREMENTS** None. **BACKGROUND** This service bulletin gives instructions to periodically test the Stabilizer Takeoff Warning Switches (for Stabilizer Takeoff Warning System) to make sure that the "NOSE UP STAB TAKEOFF WARNING SWITCH" S132, and "NOSE DOWN STAB TAKEOFF WARNING SWITCH" S546 are operating correctly. The current installation includes potential latent failures that could allow the stabilizer to be set out of the takeoff range without a takeoff configuration aural warning. Some operators have reported that during the Takeoff Warning System Test of the S132 "NOSE UP STAB TAKEOFF WARNING SWITCH" the warning horn did not sound. Airplanes were found to have switch failures which resulted in lack of aural warning when the Stabilizer was positioned outside of the green band limits. Troubleshooting found that both internal contacts would not actuate during the switch rotation. This switch failure mode is latent. No other switches have been reported with similar mechanical failure Boeing Service Related Problem (SRP) 737NG-SRP-27-0194 is related to this service bulletin. **ACTION (PRR 38275-133S)** At the times given in Paragraph 1.E, Compliance, test the Stabilizer Takeoff Warning Switches in accordance with paragraph 3.B., Accomplishment Instructions. Repeat the Test at the intervals given in paragraph 1.E., Compliance. **EFFECTIVITY** 737-600/700/700C/-800/-900/-900ER Airplanes. Refer to Paragraph 1.A.1., Airplanes for the list of affected airplanes. **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. See Service Bulletin Paragraph 1.E. for Compliance information.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 5 of 29**INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are available for 737 airplanes in warranty as of November 11, 2006. Please refer to Paragraph 2.B., Industry Support Information. **MANPOWER** Refer to Paragraph 1.G., Manpower. **MATERIAL INFORMATION** Operator Supplied Parts/Materials. Refer to Paragraph 2.A., Material - Price and Availability

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 6 of 29 **BOEING SERVICE BULLETIN 737-27-1289**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 7 of 29 **BOEING SERVICE BULLETIN 737-27-1289**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 8 of 29 **BOEING SERVICE BULLETIN 737-27-1289**

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### Commercial **Airplanes** 

# 737 Service Bulletin **Number: 737-27-1289** Original Issue: April 07, 2010 ATA System: 2741 **SUBJECT:** 737 STABILIZER TAKEOFF WARNING SWITCHES - TEST OF THE TAKEOFF WARNING INDICATION **1. PLANNING INFORMATION A. Effectivity**  1. Airplanes This service bulletin is for the airplanes shown below. An equivalent change is on subsequent production airplanes. Refer to PRR 38275-133S for data about this change. Refer to Service Bulletin Index Document D6-19567 Part 3 for Airplane Variable Number, Line Number, and Serial Number data.
**DESCRIPTION CONFIGURATION**  **GROUP** 737-600/-700/700C/-800/-900/-900ER line number 1 through 3099.

- 1

Airplane Models: 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER **Group Variable Number**  1 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

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 9 of 29**Group Variable Number**  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 YA811 - YA814 1 YA831 - YA835 1 YA841 - YA862 1 YA881 - YA882 1 YA891 - YA892 1 YA961 - YA978 1 YB001 - YB006 1 YB101 - YB132 1 YB151 - YB153

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 10 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YB156 - YB158 1 YB161 - YB164 1 YB171 - YB172 1 YB181 - YB184 1 YB201 - YB208 1 YB271 1 YB276 1 YB301 - YB310 1 YB371 - YB392 1 YB501 - YB502 1 YB521 - YB526 1 YB541 - YB544 1 YB551 1 YB561 - YB598 1 YB601 - YB634 1 YB651 1 YB656 1 YB671 - YB672 1 YB851 - YB863 1 YB871 - YB874 1 YB881 - YB893 1 YB901 - YB903 1 YB911 1 YB961 - YB974 1 YB986 - YB992 1 YC001 - YC030 1 YC051 - YC084 1 YC091 - YC095 1 YC101 - YC104 1 YC111 - YC113 1 YC121 1 YC126 - YC127 1 YC136 - YC141

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 11 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YC146 - YC147 1 YC151 - YC156 1 YC166 - YC171 1 YC176 - YC179 1 YC186 - YC190 1 YC201 - YC203 1 YC206 - YC207 1 YC301 - YC305 1 YC321 - YC387 1 YC391 - YC394 1 YC396 1 YC401 - YC417 1 YC421 - YC422 1 YC426 - YC428 1 YC436 - YC439 1 YC441 - YC448 1 YC451 - YC455 1 YC459 1 YC461 - YC467 1 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 - YC752 1 YC761 - YC770 1 YC781 - YC793 1 YC801 - YC892 1 YC901 - YC907

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 12 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 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 - YD110 1 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 YD412 - YD416 1 YD481 - YD485 1 YD491 - YD499 1 YD501 - YD512 1 YD531 - YD535 1 YD541 - YD547 1 YD561 - YD564 1 YD571 - YD572 1 YD591 - YD595 1 YD601 - YD612 1 YD651 - YD655

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 13 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 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 1 YF001 - YF006 1 YF021 - YF037 1 YF051 - YF059 1 YF086 1 YF106 - YF107 1 YF111 - YF114 1 YF116 1 YF176 - YF178 1 YF191 - YF192 1 YF201 - YF226 1 YF401 - YF402 1 YF451 - YF452 1 YF501 - YF548 1 YF701 - YF703 1 YF801 1 YF831 - YF832 1 YG001 - YG044 1 YG061 - YG064 1 YG066 - YG089 1 YG091 - YG099 1 YG101 - YG103 1 YG111 - YG114 1 YG116 - YG123 1 YG201 - YG205

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 14 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YG211 - YG214 1 YG221 - YG222 1 YG251 - YG252 1 YG501 - YG509 1 YG601 - YG602 1 YG701 1 YG711 1 YH001 - YH012 1 YH031 - YH042 1 YH051 - YH055 1 YH101 - YH130 1 YH201 - YH202 1 YH206 - YH207 1 YH301 - YH304 1 YH321 - YH322 1 YJ001 - YJ013 1 YJ021 1 YJ471 - YJ480 1 YJ501 - YJ517 1 YJ531 - YJ570 1 YJ591 - YJ599 1 YJ631 - YJ632 1 YJ671 - YJ694 1 YJ801 - YJ867 1 YJ871 - YJ880 1 YJ901 - YJ904 1 YJ908 - YJ929 1 YJ931 - YJ937 1 YJ941 - YJ956 1 YJ976 - YJ977 1 YK001 - YK007 1 YK101 - YK104 1 YK111 - YK112

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 15 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YK121 - YK122 1 YK131 - YK133 1 YK136 - YK139 1 YK141 - YK142 1 YK146 - YK148 1 YK151 - YK154 1 YK161 - YK167 1 YK171 1 YK176 - YK177 1 YK186 1 YK191 1 YK196 1 YK201 - YK202 1 YK301 - YK312 1 YK321 - YK340 1 YK361 - YK378 1 YK401 - YK406 1 YK426 - YK427 1 YK431 - YK450 1 YK456 - YK464 1 YK471 1 YK476 1 YK480 - YK487 1 YK495 - YK496 1 YK511 - YK516 1 YK521 - YK529 1 YK551 - YK571 1 YK576 - YK577 1 YK580 - YK585 1 YK601 - YK602 1 YK606 - YK607 1 YK611 - YK616 1 YK621 - YK634

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 16 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YK641 - YK644 1 YK651 - YK663 1 YK671 - YK672 1 YK676 - YK677 1 YK681 - YK686 1 YK691 1 YK701 - YK713 1 YK716 - YK719 1 YK721 - YK741 1 YK751 - YK770 1 YK791 - YK792 1 YK796 - YK797 1 YK801 - YK899 1 YK901 - YK912 1 YK918 - YK919 1 YK921 - YK927 1 YK941 - YK955 1 YK961 - YK975 1 YK981 - YK992 1 YL001 - YL005 1 YL011 - YL016 1 YL021 - YL024 1 YL051 - YL052 1 YL056 - YL057 1 YL061 1 YL066 - YL069 1 YL076 - YL077 1 YL101 - YL130 1 YL201 - YL214 1 YL271 - YL272 1 YL281 - YL284 1 YL301 - YL303 1 YL311 - YL312

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 17 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YL316 - YL321 1 YL351 - YL353 1 YL371 - YL374 1 YL401 1 YL421 - YL429 1 YL431 - YL442 1 YL461 - YL477 1 YL501 - YL509 1 YL531 - YL534 1 YL541 - YL544 1 YL561 - YL568 1 YL591 - YL592 1 YL601 - YL606 1 YL611 - YL612 1 YL616 - YL617 1 YL621 1 YL626 1 YL631 - YL632 1 YL661 - YL664 1 YL676 - YL681 1 YL691 1 YL701 1 YL731 1 YL761 - YL762 1 YL901 - YL910 1 YL921 - YL926 1 YL931 - YL936 1 YL951 - YL955 1 YM101 - YM103 1 YM201 - YM242 1 YM251 - YM299 1 YM301 - YM387 1 YM471

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 18 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Group**  **Variable Number** 1 YM481 - YM484 1 YM501 - YM515 1 YM521 - YM522 1 YM541 1 YM551 - YM553 1 YM571 - YM572 1 YM581 - YM582 1 YM591 - YM599 1 YM631 - YM634 1 YM641 - YM652 1 YM671 - YM672 1 YM691 - YM694 1 YM701 - YM710 1 YM761 1 YN001 - YN016 1 YN021 - YN024 1 YN061 1 YN071 - YN082 1 YN091 - YN092 1 YN101 - YN112 1 YN121 1 YN201 - YN202 1 YN211 - YN219 1 YN231 - YN235 1 YN261 1 YQ001 - YQ002 2. Spares Affected None. **B. Concurrent Requirements** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 19 of 29 **BOEING SERVICE BULLETIN 737-27-1289 C. Reason**  This service bulletin gives instructions to periodically test the Stabilizer Takeoff Warning Switches (for Stabilizer Takeoff Warning System) to make sure that the "NOSE UP STAB TAKEOFF WARNING SWITCH" S132, and "NOSE DOWN STAB TAKEOFF WARNING SWITCH" S546 are operating correctly. The current installation includes potential latent failures that could allow the stabilizer to be set out of the takeoff range without a takeoff configuration aural warning. Some operators have reported that during the Takeoff Warning System Test of the S132 "NOSE UP STAB TAKEOFF WARNING SWITCH" the warning horn did not sound. Airplanes were found to have switch failures which resulted in lack of aural warning when the Stabilizer was positioned outside of the green band limits. Troubleshooting found both internal contacts would not actuate during the switch rotation. This switch failure mode is latent. No other switches have been reported with similar mechanical failure. Boeing Service Related Problem (SRP) 737NG-SRP-27-0194 is related to this service bulletin. **D. Description** At the times given in Paragraph 1.E, Compliance test the Stabilizer Takeoff Warning Switches in accordance with paragraph 3.B., Accomplishment Instructions. Repeat the Test at the intervals given in paragraph 1.E., Compliance. The work in this service bulletin is done in the maintenance zone(s) given below.
**Affected Maintenance Zones Zone**  **Model** 112, 211, 212, 313, 314 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER **E. Compliance** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. **Table 1: Test of the Stabilizer Takeoff Warning Switches S132 and S546 Repeat Interval**  **(Not to Exceed) Compliance Time**  **Action Condition**  750 Flight Hours Within 180 days from the date of this service bulletin Test Stabilizer Takeoff Warning Switches S132 and S546 in accordance with Paragraph 3.B.,Work Instructions, paragraphs 3.B.8.a.,3.B.8.a.(1), and paragraphs 3.B.8.b. and 3.B.8.b.(1). (a) All Airplanes

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 20 of 29 **BOEING SERVICE BULLETIN 737-27-1289 Table 1: Test of the Stabilizer Takeoff Warning Switches S132 and S546**  **Repeat Interval (Not to Exceed)**  **Compliance Time Action**  **Condition**

- Before Further FlightReplace the failed Stabilizer Takeoff WarningSwitches and do the Stabilizer Takeoff WarningSwitches - Adjustment/Test for the switches replaced in accordance with Paragraph 3.B., Work Instructions, paragraphs 3.B.8.a.(2) and 3.B.8.b.(2). (a)Airplanes found with Stabilizer Takeoff Warning Switches failed.

And 750 Flight Hours Within 750 Flight Hours after theswitches are replaced Test the new StabilizerTakeoff Warning Switches S132 and S546 in accordance with Paragraph 3.B., Work Instructions, paragraphs 3.B.8.a.,3.B.8.a.(1), and paragraphs 3.B.8.b. and 3.B.8.b.(1) (a) (a) There is no terminating action if the switches are found failed and replaced with new switches or if existing switches installed on the airplane are replaced with new switches. Continue to test these switches as given in this table. **F. Approval** This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified in this service bulletin comply with the applicable regulations and are FAA approved, as well as European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on the airplane in its original Boeing delivery configuration or as modified by other approved Boeing changes. If an airplane has a non-Boeing modification or repair that affects a component or system also affected by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval before incorporating this service bulletin. **G. Manpower** The table below shows an estimate of the task hours necessary to do the inspection and replacement (if necessary) in accordance with this service bulletin 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:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 21 of 29 **BOEING SERVICE BULLETIN 737-27-1289**• Time to adjust to the workplace • Time to schedule the work • Time to inspect the work • Time to cure the materials • Time to make the parts • Time to find the tools. **Table 1 - Test Takeoff Warning Switches Elapsed Hours**  **Task Hours Number of Per-**  **sons Task** 

2.00 2.00 1 Open Access 0.75 0.75 1 Test the Takeoff Warning Switches 1.50 1.50 1 Close Access 4.25 4.25 TOTAL FOR EACH AIRPLANE **Table 2 - Replace Takeoff Warning Switches Elapsed Hours**  **Task Hours Number of Persons**  **Task** 0.50 0.50 1 Open Access 1.00 (a) 1.00 (a) 1 Replace Takeoff Warning Switches 0.25 (a) 0.25 (a) 1 Test 0.50 0.50 1 Close Access 2.25 2.25 TOTAL FOR EACH SWITCH (a) Time given is per switch. Multiply time given by number of switches replaced and added to open and close time to obtain the total. **H. Weight and Balance Changes** None. **I. Electrical Load Data** Not changed. **J. References** 1. Existing Data a. Engineering Change Memo PRR 38275-133S b. Service Related Problem (SRP) 737NG-SRP-27-0194 c. Boeing Drawing 65-88700

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 22 of 29 **BOEING SERVICE BULLETIN 737-27-1289**d. Boeing Parts Standards Document D-590 e. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19 f. 737-600/700/800/900 Aircraft Maintenance Manual (AMM) 24-22-00, 29-11-00, 31-51-02, 32-09-00 2. Data supplied with this Service Bulletin None. 3. Installation Drawings Used in the Preparation of this Service Bulletin
**Title Drawing Number**  Limit And Warning Switch Instl - Stabilizer Trim 251A4700 These drawings were used to prepare this service bulletin. These drawings are not necessary to make the specified changes, and are not supplied with this service bulletin. These drawings may not be applicable to all airplane configurations or operators. **K. Publications Affected** None. **L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 23 of 29 **BOEING SERVICE BULLETIN 737-27-1289**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 24 of 29 **BOEING SERVICE BULLETIN 737-27-1289**

BLANK PAGE**2. MATERIAL INFORMATION A. Material - Price and Availability**  None. **B. Industry Support Information** Boeing warranty remedies are available for 737airplanes in warranty as of November 16, 2006. For man-hour reimbursement for airplanes in warranty as of that date, send a warranty claim to Boeing Commercial Airplanes Group - Warranties & Product Assurance Contracts. **C. Parts Necessary For Each Airplane** 1. Kits/Parts None. 2. Parts and Materials Supplied by the Operator
**Notes Name**  **QTY Part Number /**  **Specification** Lockwire As necessary MS20995NC20 Lockwire As necessary MS20995NC32 (a) Switch 2 32EN21-4 or 32EN61-4 or, 32EN14-4 (a) Honeywell Inc. Micro Switch Div, 11West Spring Street, Freeport, Illinois 61032, cage code cage 91929.
3. Parts Modified and Reidentified None. 4. Parts Removed and Not Replaced None. **D. Parts Necessary to Change Spares** None. **E. Special Tooling - Price and Availability** None.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 25 of 29 **BOEING SERVICE BULLETIN 737-27-1289 F. Special Tooling Necessary to do this Service Bulletin**  No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine operator tool supply to make sure all necessary tools are available.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 26 of 29 **BOEING SERVICE BULLETIN 737-27-1289 3. ACCOMPLISHMENT INSTRUCTIONS**  **A. GENERAL INFORMATION CAUTION:**  KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL, METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR OTHER ELECTRICAL DAMAGE. **NOTE:** 1. The instructions identified in Paragraph 3.B., Work Instructions and the Figure(s) give the recommended sequence of steps. The sequence of steps to do this service bulletin can be changed. 2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 3. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures, and SWPM 20-10-19 for the wire separation requirements, as accepted procedures. 4. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. **B. WORK INSTRUCTIONS** 1. Install the chocks on the Landing Gear Wheels. **NOTE:**The parking brake is released during the Takeoff warning test. This prevents the parking brake function of the Takeoff Warning horn from overriding. 2. Supply Electrical Power to the airplane. Refer to 737-600/700/800/900 AMM 24-22-00 AMM 24-22-00-860-811 as an accepted procedure. 3. Open Forward Access door 112A to access the Proximity Switch Electronics Unit (PSEU). 4. Use the Proximity Switch Electronics Unit (PSEU) to make sure SYS 1 and SYS 2 are in the ground mode. Set the airplane in the ground mode (if it is not in the ground mode). Refer to 737-600/700/800/900 AMM 32-09-00 as an accepted procedure. 5. Open this circuit breaker and install a "DO NOT CLOSE" safety tag:
**Name Number**  **Location (Row/Col) Circuit Breaker Panel**  Weather Radar RT C00120 D13 P6-1

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 27 of 29 **BOEING SERVICE BULLETIN 737-27-1289 WARNING:** KEEP PERSONS AND EQUIPMENT CLEAR OF FLIGHT CONTROL SURFACES, THRUST REVERSERS, AND THE LANDING GEAR. THESE COMPONENTS CAN MOVE SUDDENLY WHEN YOU SUPPLY HYDRAULIC POWER . IT CAN CAUSE INJURIES TO PERSONS AND DAMAGE TO EQUIPMENT. 6. Pressurize the Hydraulic System A or B. Refer to 737-600/700/800/900 AMM 29-11-00 as an acceptable procedure. 7. Set the airplane in the Take Off configuration: **NOTE:**The takeoff warning horn will sound when the airplane is not in a Takeoff configuration and you move the Thrust levers forward for takeoff. a. Move the Trailing Edge Flaps to the 15 unit position. b. Set the Stabilizer within 1 unit center of the green band. c. Set the speed brake lever to the DOWN position. d. Release the parking brakes. **WARNING:**MAKE SURE THAT YOU OPEN THE CIRCUIT BREAKER FOR THE WEATHER RADAR SYSTEM. THE FORWARD MOVEMENT OF A TRUST LEVER CAN CAUSE THE AUTOMATIC OPERATION OF THE SYSTEM. THE OPERATION OF THIS SYSTEM CAN CAUSE SERIOUS INJURY TO PERSONS AND DAMAGE TO EQUIPMENT IN THE AREA OF THE NOSE RADOME. e. Set the Thrust lever No. 2 to the idle position. f. Set the Thrust lever No. 1 to the full forward thrust position. g. Make sure that the Warning Horn does not sound. **NOTE:**The Takeoff warning horn will sound when the airplane is on the ground and you move one or both of the Thrust levers forward for takeoff and at least one of these conditions exist: The stabilizer is not in the green band, The trailing edge flaps are at less than 1 unit or more than 25 units, The leading edge slats are not extended or in transit, The speedbrake handle is not down, The parking brake is set, The ground spoilers are not down. **NOTE:**The Takeoff warning horn will also sound when the airplane is in the air and all of the following conditions exist: The ground spoiler valve is not closed, the leading edge flaps are not extended, and the landing warning cutoff switch is closed. 8. Do the following steps to check the operation of Stabilizer Takeoff Warning Switches. a. Use the Stabilizer Trim Wheel or the STAB TRIM switches on the captain's control wheel to move the Stabilizer Leading Edge Down ("Airplane Nose Up"), outside of the green band.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 28 of 29 **BOEING SERVICE BULLETIN 737-27-1289**(1) Make sure the warning horn comes ON when the green band pointer is outside of the green band range. (2) If the horn does not come ON when the green band pointer is outside of the green band range with the Stabilizer Leading Edge down, ("Airplane Nose Up") the Stabilizer Takeoff Warning Switch S132 is failed. Replace the failed Stabilizer Takeoff Warning Switch S132 with a new switch. For the switch removal procedure refer to "737-600/700/800/900 AMM 31-51-02 - Stabilizer Takeoff Warning Switches - Removal/Installation" as an accepted procedure. Test the new switch installed. To test the new switch refer to "737-600/700/800/900 AMM 31-51-02 - Stabilizer Takeoff Warning Switches - Adjustment/Test" as an accepted procedure. **NOTE:**The switch S132 is located on the brackets along the Stabilizer Jackscrew Fitting Assy, on the right side of the Jackscrew Fitting looking Aft. b. Use the Stabilizer Trim Wheel or the STAB TRIM switches on the captain's control wheel to move the Stabilizer Leading Edge Up ("Airplane Nose Down") outside of the green band: (1) Make sure the warning horn comes on when the green band pointer is outside of the green band range. (2) If the horn does not come ON when the green band pointer is outside of the green band range with the stabilizer leading edge up ("Airplane Nose Down") the Stabilizer Takeoff Warning Switch S546 is failed. Replace the failed Stabilizer Takeoff Warning Switch S546 with a new switch. For the switch removal procedure refer to "737-600/700/800/900 AMM 31-51-02 - Stabilizer Takeoff Warning Switches - Removal/Installation". To test the new switch installed. Refer to "737-600/700/800/900 AMM 31-51-02 - Stabilizer Takeoff Warning Switches - Adjustment/Test" as an accepted procedure. **NOTE:**The switch S546 is located on the brackets along the Stabilizer Jackscrew Fitting Assy, on the right side of the Jackscrew Fitting looking Aft. c. Set the Thrust lever No.1 to idle position. 9. Do the following instructions: a. Set the parking brakes. b. Remove the chocks from the landing gear wheels. c. Remove the hydraulic pressure from system A and system B. Refer to "737-600/700/800/900 AMM 29-11-00 AMM - Hydraulic System A or B Power Removal" as an accepted procedure. d. Remove the "DO NOT CLOSE" safety tag and close this circuit breaker:
**Name Number**  **Location (Row/Col) Circuit Breaker Panel**  Weather Radar RT C00120 D13 P6-1 10. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: April 07, 2010 737-27-1289 29 of 29 **BOEING SERVICE BULLETIN 737-27-1289**