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.

ECCN: 9E991

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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Unpublished Work - All Rights Reserved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

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2.0
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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

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BLANK PAGE
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.

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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

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BOEING SERVICE BULLETIN 737-27-1289

BLANK PAGE
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.

GROUP CONFIGURATION DESCRIPTION

1 - 737-600/-700/700C/-800/-900/-900ER line number 1 through 3099.

Airplane Models:

737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER

Variable Number 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

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Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

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Variable Number Group

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 1

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BOEING SERVICE BULLETIN 737-27-1289
Variable Number Group

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 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

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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

Model Zone

737-600, 737-700, 737-700C, 112, 211, 212, 313, 314

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)

Condition Action Compliance Time

Within 180 days 750 Flight Hours

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

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BOEING SERVICE BULLETIN 737-27-1289
Table 1: Test of the Stabilizer Takeoff Warning Switches S132 and S546

Repeat Interval

(Not to Exceed)

Condition Action Compliance Time

Before Further -

Flight

Replace the failed Stabilizer Takeoff Warning

Switches and do the Stabilizer Takeoff Warning

Switches - 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

Within 750 Flight 750 Flight Hours

Hours after the

switches are replaced

Test the new 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)

(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:

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• 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

Number of Per- Task Hours Elapsed Hours

sons

Task

Open Access 1 2.00 2.00

Test the Takeoff 1 0.75 0.75

Warning Switches

Close Access 1 1.50 1.50

TOTAL FOR EACH AIRPLANE 4.25 4.25

Table 2 - Replace Takeoff Warning Switches

Task Number of Persons Task Hours Elapsed Hours

Open Access 1 0.50 0.50

Replace Takeoff Warning 1 1.00 (a) 1.00 (a)

Switches

Test 1 0.25 (a) 0.25 (a)

Close Access 1 0.50 0.50

TOTAL FOR EACH SWITCH 2.25 2.25

(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

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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

Drawing Number Title

251A4700 Limit And Warning Switch Instl - Stabilizer Trim

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.

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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

Part Number / QTY Name Notes

Specification

MS20995NC20 As necessary Lockwire

MS20995NC32 As necessary Lockwire

32EN21-4 or 2 Switch (a)

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.

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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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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:

Circuit Breaker Panel Location (Row/Col) Number Name

P6-1 D13 C00120 Weather Radar RT

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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.

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(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:

Circuit Breaker Panel Location (Row/Col) Number Name

P6-1 D13 C00120 Weather Radar RT

10. Put the airplane back to a serviceable condition.

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