Commercial 

Airplane

Group 747

Service Bulletin

SPECIAL ATTENTION

Number: 747-34-2925

Date: June 04, 2008

ATA System: 2732 3412

SUBJECT: NAVIGATION - Stall Warning System - Angle of Airflow Sensor Inspection

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

BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET

Copyright © 2008 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Unpublished Work - All Rights Reserved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, MD-10, MD-11, MD-80, MD-88, MD-90, 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.

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2.0
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BOEING SERVICE BULLETIN 747-34-2925

BLANK PAGE
Table of Contents

Summary ..................................................... 5

1. PLANNING INFORMATION ......................................... 7

A. Effectivity ................................................ 7

1. Airplanes ............................................. 7

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1. Existing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2. Data supplied with this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3. Installation Drawings Used in the Preparation of this Service Bulletin . . . . . . . . . . . . 19

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 21

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 22

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

FIGURE 1: ANGLE OF AIRFLOW SENSOR - INSPECTION . . . . . . . . . . . . . . . . . . . . . . . 26

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BOEING SERVICE BULLETIN 747-34-2925
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BOEING SERVICE BULLETIN 747-34-2925

BLANK PAGE
Commercial 

Airplane

Group 747

Service Bulletin

SPECIAL ATTENTION

Summary Number: 747-34-2925

Date: June 04, 2008

ATA System: 2732 3412

SUBJECT: NAVIGATION - Stall Warning System - Angle of Airflow Sensor Inspection

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

This service bulletin gives instructions for a one-time inspection of Conrac/Ametek/Gulton Angle of Airflow (AOA)

sensors with part numbers 2566A21/A30 (10-60878-3/-4) for 747-100/200/300 airplanes and part numbers

2566A40S (S233T913-2) for 747-400 airplanes. This inspection will do a check for a misalignment between the

AOA sensor shaft and the sensor synchro transmitter. This misalignment is caused by a defective set screw

condition.The airplane could have incorrect control column shaker activation if the inspection given in this service

bulletin is not accomplished.

One 747-400 operator reported a control column shaker activation on takeoff. The control column shaker

activation continued while the airplane was in flight and EICAS messages ALT DISAGREE and IAS DISAGREE

were displayed. The flight crew used the alternative Air Data Computer (left ADC) and the altitude and airspeed

indications cancelled. After landing the right ADC was replaced. On the subsequent flight the control column

shaker operated again at takeoff and the flight crew had to do a Rejected Takeoff (RTO). Troubleshooting steps

found that the right AOA sensor was unserviceable.

The inspection of the AOA sensor showed that the set screw connected to the synchro transmitter was not

correctly attached to the AOA sensor shaft. Accomplishment of this service bulletin will stop incorrect control

column shaker activation.

Boeing Service Related Problem (SRP) 747-SRP-34-0114 is related to this service bulletin.

Fleet Team Digest (FTD) 747 FTD 34-07001 is related to this service bulletin.

ACTION

Part 1: Do a visual inspection of the AOA sensors. If an AOA sensor is found to be a Conrac/Ametek/Gulton

sensor, do Part 2 of the service bulletin.

Group 1:

Part 2: Do a test of the AOA sensor. If the AOA sensor fails to activate the control column shaker, do Part 3 of

the service bulletin.

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June 04, 2008

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Group 2:

Part 2: Do a test of the AOA sensor. If the AOA sensor fails the test, replace the AOA sensor.

Group 1:

Part 3: Do an Aircraft Maintenance Manual (AMM) Operational Test of the Stall Warning System. If the AOA

sensor fails to activate the control column shaker, replace the AOA sensor.

NOTE: New part is only necessary if the inspection and test indicate that the existing sensor must be replaced.

EFFECTIVITY

747-100/100B/100B SUD/200B/200C/200F/300/400/400D/400F/747SP/747SR Airplanes. Refer to Paragraph

1.A., Effectivity, Airplanes for the list of affected airplanes.

COMPLIANCE

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the inspection given in this service bulletin.

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

None.

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BOEING SERVICE BULLETIN 747-34-2925
Commercial 

Airplane

Group 747

Service Bulletin

SPECIAL ATTENTION

Number: 747-34-2925

Date: June 04, 2008

ATA System: 2732 3412

SUBJECT: NAVIGATION - Stall Warning System - Angle of Airflow Sensor Inspection

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

Refer to Service Bulletin Index Document D6-30300 Part 3 for Airplane Variable Number, Line

Number, and Serial Number data.

This service bulletin is for the airplanes shown below.

GROUP CONFIGURATION DESCRIPTION

747-100/200/300 airplanes that require different Angle of Airflow

(AOA) sensor inspection

1 -

747-400 airplanes that require different Angle of Airflow (AOA) sensor

inspection

2 -

Airplane Models:

747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D,

747-400F, 747SP, 747SR

Variable Number Group

RA001 - RA034 1

RA101 - RA115 1

RA161 - RA164 1

RA201 - RA203 1

RA216 - RA217 1

RA245 - RA246 1

RA251 - RA266 1

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Variable Number Group

RA301 - RA318 1

RA351 - RA360 1

RA369 - RA373 1

RA401 - RA418 1

RA501 - RA502 1

RA521 - RA528 1

RA532 - RA548 1

RA551 - RA552 1

RA559 - RA561 1

RA581 - RA582 1

RA585 1

RA601 - RA602 1

RA631 - RA635 1

RA651 - RA652 1

RA671 - RA677 1

RA701 - RA702 1

RA721 - RA731 1

RA741 - RA745 1

RA749 - RA750 1

RA761 - RA762 1

RA781 - RA784 1

RA901 - RA916 1

RB001 - RB016 1

RB041 - RB044 1

RB071 - RB075 1

RB101 - RB102 1

RB411 - RB413 1

RB421 1

RB601 - RB607 1

RB681 - RB697 1

RB711 1

RB721 - RB723 1

RB741 - RB748 1

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RD001 - RD004 1

RD021 - RD022 1

RD041 - RD059 1

RD071 - RD072 1

RD081 - RD083 1

RD091 - RD092 1

RD101 - RD104 1

RD121 - RD127 1

RD131 - RD144 1

RD166 - RD167 1

RD171 - RD172 1

RD181 - RD183 1

RD201 - RD204 1

RD221 - RD227 1

RD231 - RD235 1

RD241 - RD243 1

RD251 - RD262 1

RD271 - RD272 1

RD291 - RD292 1

RD301 - RD302 1

RD311 1

RD351 - RD358 1

RD361 - RD366 1

RD381 - RD383 1

RD411 - RD414 1

RD421 - RD426 1

RD431 - RD435 1

RD441 - RD442 1

RD451 - RD456 1

RD461 1

RD471 - RD475 1

RD513 - RD519 1

RD531 - RD533 1

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RD551 1

RD561 1

RD571 1

RD581 - RD583 1

RD591 - RD593 1

RD601 - RD607 1

RD621 - RD623 1

RD641 - RD649 1

RD651 - RD659 1

RD661 1

RD671 1

RD681 - RD682 1

RD691 - RD692 1

RD701 - RD702 1

RD721 - RD722 1

RD741 - RD742 1

RD751 - RD755 1

RD761 1

RD771 - RD775 1

RD781 - RD783 1

RD791 - RD792 1

RE001 1

RF001 - RF006 2

RG001 - RG009 1

RG091 1

RG095 1

RG101 - RG104 1

RG121 - RG126 1

RG141 - RG142 1

RG161 - RG164 1

RG171 - RG174 1

RG191 - RG193 1

RG211 - RG213 1

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RG221 - RG222 1

RH101 - RH102 1

RH111 - RH112 1

RH121 - RH122 1

RJ131 - RJ133 1

RJ151 - RJ152 1

RJ301 - RJ303 1

RJ321 - RJ322 1

RJ331 - RJ333 1

RL401 - RL403 2

RL411 - RL436 2

RL451 - RL456 2

RL461 - RL462 2

RL471 - RL475 2

RL481 2

RL491 - RL492 2

RL501 - RL502 2

RL511 - RL515 2

RL521 - RL522 2

RL531 - RL533 2

RL561 - RL562 2

RL576 2

RL651 - RL655 2

RL671 - RL675 2

RL681 - RL684 2

RL751 - RL752 2

RM001 - RM007 2

RM010 - RM013 2

RM021 - RM024 2

RM026 - RM030 2

RM036 - RM045 2

RM051 - RM053 2

RM071 2

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RM081 - RM084 2

RM091 2

RM096 - RM097 2

RM116 - RM117 2

RM126 - RM132 2

RM136 - RM147 2

RM156 - RM158 2

RM166 - RM177 2

RM191 - RM192 2

RM231 - RM233 2

RM241 - RM246 2

RM261 - RM264 2

RM316 - RM318 2

RM331 - RM333 2

RM341 2

RM351 - RM355 2

RM366 - RM367 2

RM401 - RM403 2

RM426 2

RM431 2

RM441 - RM443 2

RM445 2

RM801 - RM803 2

RM811 - RM813 2

RM851 - RM859 2

RM861 - RM863 2

RM871 - RM899 2

RM901 - RM906 2

RM911 2

RR001 - RR005 1

RR021 - RR025 1

RR031 1

RR201 - RR206 1

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RR221 - RR226 1

RR261 - RR267 1

RR301 - RR310 1

RR331 - RR332 1

RR336 1

RR341 - RR345 1

RR361 - RR362 1

RR421 - RR422 1

RR431 - RR432 1

RR441 - RR442 1

RR451 1

RR501 - RR504 1

RR521 - RR522 1

RR526 1

RR531 1

RR551 - RR556 1

RR561 1

RR566 1

RR701 2

RR721 - RR724 2

RR746 - RR748 2

RR851 - RR856 2

RR861 - RR862 2

RR951 - RR952 2

RS001 - RS002 1

RS201 1

RS211 - RS212 1

RS221 - RS222 1

RS231 - RS241 1

RS251 - RS259 1

RS263 1

RS265 - RS268 1

RS271 - RS276 1

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RS291 - RS292 1

RS301 - RS306 1

RS311 - RS320 1

RS331 - RS333 1

RS341 - RS342 1

RS699 1

RS701 - RS703 1

RS711 - RS713 1

RS721 - RS722 1

RS741 - RS743 1

RS751 - RS752 1

RS761 - RS762 1

RS771 1

RS781 - RS782 1

RS786 1

RT001 - RT014 2

RT021 - RT022 2

RT031 - RT035 2

RT041 - RT047 2

RT061 2

RT071 - RT075 2

RT101 - RT103 2

RT121 2

RT131 - RT137 2

RT151 - RT152 2

RT161 - RT168 2

RT401 - RT412 2

RT431 - RT447 2

RT451 - RT469 2

RT471 - RT499 2

RT501 - RT535 2

RT551 - RT568 2

RT571 - RT591 2

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BOEING SERVICE BULLETIN 747-34-2925
Variable Number Group

RT601 - RT657 2

RT671 - RT673 2

RT681 - RT682 2

RT691 - RT699 2

RT701 - RT704 2

RT711 - RT717 2

RT741 - RT757 2

RT776 - RT777 2

RT781 - RT784 2

RT801 - RT803 2

RT811 - RT814 2

RT831 - RT837 2

RT861 - RT864 2

RT876 - RT880 2

RT931 - RT932 2

RT945 - RT949 2

RT951 - RT955 2

RT966 - RT967 2

RU001 - RU006 2

RU016 - RU017 2

RU031 - RU032 2

RU051 - RU052 2

RU059 - RU062 2

RU081 - RU083 2

RU101 - RU102 2

RU121 - RU132 2

RU801 - RU809 2

RU831 - RU841 2

2. Spares Affected

None.

B. Concurrent Requirements

None.

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BOEING SERVICE BULLETIN 747-34-2925
C. Reason

This service bulletin gives instructions for a one-time inspection of Conrac/Ametek/Gulton Angle of

Airflow (AOA) sensors with part numbers 2566A21/A30 (10-60878-3/-4) for 747-100/200/300 airplanes

and part numbers 2566A40S (S233T913-2) for 747-400 airplanes. This inspection will do a check for

a misalignment between the AOA sensor shaft and the sensor synchro transmitter. This misalignment

is caused by a defective set screw condition. The airplane could have incorrect control column shaker

activation if the inspection given in this service bulletin is not accomplished.

One 747-400 operator reported a control column shaker activation on takeoff. The control column

shaker activation continued while the airplane was in flight and EICAS messages ALT DISAGREE and

IAS DISAGREE were displayed. The flight crew used the alternative Air Data Computer (left ADC) and

the altitude and airspeed indications cancelled. After landing the right ADC was replaced. On the

subsequent flight the control column shaker operated again at takeoff and the flight crew had to do a

Rejected Takeoff (RTO). Troubleshooting steps found that the right AOA sensor was unserviceable.

The inspection of the AOA sensor showed that the set screw connected to the synchro transmitter was

not correctly attached to the AOA sensor shaft. Accomplishment of this service bulletin will stop incorrect

control column shaker activation.

Boeing Service Related Problem (SRP) 747-SRP-34-0114 is related to this service bulletin.

Fleet Team Digest (FTD) 747 FTD 34-07001 is related to this service bulletin.

D. Description

Part 1: Do a visual inspection of the AOA sensor. If the AOA sensor is found to be a

Conrac/Ametek/Gulton sensor, do Part 2 of the service bulletin.

Group 1:

Part 2: Do a test of the AOA sensor. If the AOA sensor fails to activate the control column shaker, do

Part 3 of the service bulletin.

Group 2:

Part 2: Do a test of the AOA sensor. If the AOA sensor fails the test, replace the AOA sensor.

Group 1:

Part 3: Do an Aircraft Maintenance Manual (AMM) Operational Test of the Stall Warning System. If the

AOA sensor fails to activate the control column shaker, replace the AOA sensor.

NOTE: New part is only necessary if the inspection and test indicate that the existing sensor must be

replaced.

Group 1:

Affected Maintenance Zones

Model Zone

747-100, 747-100B, 747-100B 113, 114

SUD, 747-200B, 747-200C,

747-200F, 747-300, 747SP,

747SR

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BOEING SERVICE BULLETIN 747-34-2925
Group 2:

Affected Maintenance Zones

Model Zone

747-400, 747-400D, 747-400F 211, 212

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.

Boeing recommends that the inspection given in this service bulletin be done within 36 months after

the date on this service bulletin.

If an AOA check (such as Maintenance Planning Document (MPD) Task 4-27-0160 for 747-100/200/300

operators or an equivalent task for 747-400 operators associated with a 'C' check) has been

accomplished within the last 15 months or if one is scheduled within the compliance time, it can take

the place of the required check and the service bulletin is considered accomplished.

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 this inspection for each sensor.

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 inspect the work

• Time to cure the materials

• Time to make the parts

• Time to find the tools.

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BOEING SERVICE BULLETIN 747-34-2925
PART 1

Number of Task Hours Elapsed Hours

Persons

Task

Inspection 1 0.10 0.10

TOTAL FOR EACH SENSOR 0.10 0.10

PART 2

Number of Task Hours Elapsed Hours

Persons

Task

Test 2 0.50 0.25

TOTAL FOR EACH SENSOR 0.50 0.25

Group 1:

PART 3

Number of Task Hours Elapsed Hours

Persons

Task

Test 2 0.50 0.25

TOTAL FOR EACH SENSOR 0.50 0.25

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

J. References

1. Existing Data

a. 747-100/200/300 Maintenance Planning Data (MPD) Task 4-27-0160

a. Boeing Service Related Problem (SRP) 747-SRP-34-0114

b. 747 Fleet Team Digest (FTD) 34-07001

c. 747-100/200/300 Aircraft Maintenance Manual (AMM) 24-22-00, 27-32-00, 27-32-01, 27-51-00

d. 747-400 Aircraft Maintenance Manual (AMM) 24-22-00, 34-12-03

e. 747-100/200/300 Maintenance Planning Data (MPD) Task 4-27-0160

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BOEING SERVICE BULLETIN 747-34-2925
2. Data supplied with this Service Bulletin

None.

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

None.

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.

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BOEING SERVICE BULLETIN 747-34-2925
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BOEING SERVICE BULLETIN 747-34-2925

BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

Boeing warranty remedies are not available for the configuration changes inspection given in this

service bulletin.

C. Parts Necessary For Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

Part Number / QTY Name Notes

Specification

2566A21 or 1 Angle of Attack Sensor (a) (b) (c) (d)

2566A30

(10-60878-3 or

10-60878-4)

2566A40S or 1 Angle of Attack Sensor (a) (b) (c) (e)

S233T913-2

(a) Each airplane has 2 stall warning system angle of attack sensors installed.

(b) This part is only necessary if the inspection and tests indicate the existing sensor must

be replaced.

(c) Ametek Aerospace (V92627), 1644 Whittier Ave, Costa Mesa, California 92627-4415.

(d) For 747-100/200/300 airplanes.

(e) For 747-400 airplanes.

3. Parts Modified and Reidentified

None.

4. Parts Removed and Not Replaced

None.

D. Parts Necessary to Change Spares

None.

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BOEING SERVICE BULLETIN 747-34-2925
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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BOEING SERVICE BULLETIN 747-34-2925
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. Obey all of the warnings and cautions given in the specified manual sections.

4. 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.

5. 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 "as

given in" are included in the instruction, the procedure in the Boeing document must

be used.

B. WORK INSTRUCTIONS

PART 1: ANGLE OF AIRFLOW (AOA) SENSOR

1. Do a General Visual Inspection of the AOA sensors as given in FIGURE 1.

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BOEING SERVICE BULLETIN 747-34-2925
a. If an AOA sensor is a Conrac/Ametek/Gulton AOA sensor with a paddle type vane is installed,

do PART 2: TEST THE STALL WARNING SYSTEM for that sensor.

b. If a BF Goodrich/Rosemount AOA sensor with a swept vane is installed, no more work is

necessary.

Group 1:

PART 2:TEST THE STALL WARNING SYSTEM

1. Supply electrical power to the airplane. Refer to 747-100/200/300 AMM 24-22-00 as an accepted

procedure.

2. Make sure the applicable circuit breakers for the Stall Warning System are closed. Refer to

747-100/200/300 AMM 27-32-00 as an accepted procedure.

3. At the P5 Overhead panel, move the stall warning HTR OFF-NORMAL-TEST switch to HTR OFF

position.

4. Move the trailing edge flaps to the 30 detent position. Refer to 747-100/200/300 AMM 27-51-00

as an accepted procedure.

WARNING: SUFFICIENT TIME MUST BE ALLOWED FOR SENSOR VANES TO COOL BEFORE

CONTINUING TEST. VANES MAY BE HOT ENOUGH TO CAUSE BURNS.

CAUTION: VANES MUST NOT BE SPUN. DAMAGE TO SYNCHROS COULD OCCUR.

5. Make sure the AOA sensors are at the horizontal position.

6. Move the left AOA sensor vane trailing edge up from the zero degrees position to approximately

24 degrees (7.5 degrees position on the AOA sensor scale).

7. On the flight deck, make sure the control column shaker is activated within a tolerance of +/-1

degree.

a. If the control column shaker is activated, no more work is necessary. Put the airplane back

to a serviceable condition.

b. If the control column shaker is not activated, do Part 3: Operational Test of the Stall Warning

System.

8. If necessary, repeat steps 6. and 7. again for the right AOA sensor.

Group 1:

PART 3: OPERATIONAL TEST OF THE STALL WARNING SYSTEM

1. Do an Operational Test of the Stall Warning System. Refer to 747-100/200/300 AMM 27-32-00

as an accepted procedure.

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BOEING SERVICE BULLETIN 747-34-2925
a. If the AOA sensor fails to activate the control column shaker in this operational test, replace

the AOA sensor. Refer to 747-100/200/300 AMM 27-32-01 as an accepted procedure.

2. Put the airplane back to a serviceable condition.

Group 2:

PART 2:TEST THE STALL WARNING SYSTEM

1. Supply electrical power to the airplane. Refer to 747-400 AMM 24-22-00 as an accepted procedure.

2. Make sure the applicable circuit breakers for the Stall Warning System are closed. Refer to 747-400

AMM 34-12-03 as an accepted procedure.

3. Open and attach DO-NOT-CLOSE tags to the circuit breakers for the Left and Right AOA heaters.

Refer to 747-400 AMM 34-12-03 as an accepted procedure.

WARNING: DO NOT TOUCH THE AOA SENSOR WHEN THE SENSOR HEAT IS ON.YOU CAN

BURN YOURSELF ON THE AOA SENSOR.

4. Attach an angular displacement tool to the AOA sensor vane to be tested.

5. Connect an ARINC 429 bus reader to the Air Data Computer (ADC) test connector (the left ADC

for the left AOA sensor, the right ADC for the right AOA sensor).

NOTE: The "HI" pin is on the left of the "TEST ONLY" connector and the "LO" pin is on the right

of the test connector.

6. Move the angular displacement tool on the AOA vane to the values given in the table that follows:

NOTE: Make sure the data bus reader shows the values on the table that follows in decimal

format.

NOTE: A positive angle of attack is produced when the trailing edge of the AOA vane is above

the horizontal axis.

ADC TEST

VANE POSITION OCTAL LABEL 221, 222 and 223 OUTPUT

0 Degrees 0 Degrees +/- 0.75

+10 Degrees +10 Degrees +/- 0.75

-10 Degrees -10 Degrees +/- 0.75

7. If you cannot get the values given in the table, replace the AOA sensor. Refer to 747-400 AMM

34-12-03 as an accepted procedure.

8. If necessary do steps 4. thru 7. to test the other AOA sensor.

9. Put the airplane back to a serviceable condition.

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BOEING SERVICE BULLETIN 747-34-2925
FIGURE 1: ANGLE OF AIRFLOW SENSOR - INSPECTION

(SHEET 1 OF 1)

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BOEING SERVICE BULLETIN 747-34-2925