July 24, 1997

Revision 3 July 29, 2004 747-78A2166

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 1 of 26

Commercial

Airplane

Group 747

Service Bulletin

Number: 747-78A2166

Date: July 24, 1997

Revision 3 July 29, 2004

ATA System: 7830

SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System -

Center Drive Unit (CDU) Cone Brake Integrity Test

BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET

Copyright © 1997 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Unpublished Work - All Rights Reserved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, BBJ, DC-8, DC-9,

DC-10, MD-10, MD-11, MD-80, MD-88, MD-90, and the red-white-and-blue 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.
BLANK PAGE

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BLANK PAGE
Table of Contents

July 24, 1997

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BOEING SERVICE BULLETIN 747-78A2166

Table of Contents

Revision Transmittal Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1. PLANNING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

A. Effectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

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

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . 21

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

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

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

FIGURE 1: CDU MANUAL BRAKE RELEASE LEVER, LOCKOUT PLATE AND DRIVE PAD LOCATIONS

26
Table of Contents

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BOEING SERVICE BULLETIN 747-78A2166

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Commercial

Airplane

Group 747

Service Bulletin

Number: 747-78A2166 Revision Transmittal Sheet

Date: July 24, 1997

Revision 3 July 29, 2004

ATA System: 7830

SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System -

Center Drive Unit (CDU) Cone Brake Integrity Test

This revision includes all pages of the service bulletin.

COMPLIANCE INFORMATION RELATED TO THIS REVISION

Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2003-16-16, Amendment 39-13269, is

related to this service bulletin revision. AD 2003-16-16, Amendment 39-13269 supersedes AD 2000-09-03.

No airplanes were added to this service bulletin effectivity.

No more work is necessary on airplanes changed as shown in the Revision 2 of this service bulletin.

REASON FOR REVISION

This revision is sent to remove reference "767" and add reference "747/747-400" in Paragraph 3.B.1.a,

Accomplishment Instructions.

Paragraph 1.A., Effectivity, shows changes of airplane operators. Each operator should examine the Effectivity

paragraph for changes.

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

Initial Release: July 24, 1997

Revision 1: October 9, 1997

Revision 2: March 15, 2001

Revision 3: July 29, 2004
July 24, 1997

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BOEING SERVICE BULLETIN 747-78A2166

BLANK PAGE
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Commercial

Airplane

Group 747

Service Bulletin

Number: 747-78A2166 Summary

Date: July 24, 1997

Revision 3 July 29, 2004

ATA System: 7830

SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System -

Center Drive Unit (CDU) Cone Brake Integrity Test

CONCURRENT REQUIREMENTS

None

BACKGROUND

This inspection will make sure that the center drive unit (CDU) cone brake continues to provide holding torque

against an in-flight thrust reverser deployment.

Two operators have returned five CDU's to the vendor AlliedSignal because of low holding torque. The CDU's

had accumulated between 3,400 and 3600 flight hours. AlliedSignal is currently analyzing the returned units to

determine the cause of low holding torque.

The cone brake consists of a semi-stationary, spring loaded, friction cone and its rotating mating cone mounted

on the CDU, air motor shaft. The brake is disengaged by a pivoted lever, actuated by the translation of the

directional control valve (DCV), actuator piston. While the brake is released, it will allow free rotation of the air

motor in the direction to stow and deploy the reverser. The cone brake ensures against rotation of the CDU air

motor to deploy the reverser when it is engaged by the translation of the DCV actuation piston.

Currently, the CDU cone brake is required to be inspected at 1,000 flight hour intervals. Reducing the inspection

interval for the CDU, cone brake from 1,000 to 650 flight hours will make sure that the CDU cone brake

continues to provide holding torque against an in-flight, thrust reverser deployment.

Boeing Service Related Problem (SRP) 747-SRP-78-0036 is related to this service bulletin.

ACTION

For Group 1 airplanes that have incorporated Boeing Service Bulletin 747-78-2151 or 747-78-2144, and on

Group 2 airplanes, on each thrust reverser half, do a functional test on the Electro-Mechanical brake and CDU

cone brake to verify the holding torque. Repeat this test every 1,000 flight hours.

For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or 747-78-2144, on each

thrust reverser half, do a functional test on the CDU cone brake to verify the holding torque. Repeat this test

every 650 flight hours.
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BOEING SERVICE BULLETIN 747-78A2166

EFFECTIVITY

All 747/747-400 airplanes powered by CF6-80C2 engines.

COMPLIANCE

Boeing recommends the operators do this service bulletin within 650 flight hours after receipt of this service

bulletin.

For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or 747-78-2144, Boeing

recommends the operators repeat the CDU cone brake tests every 650 flight hours.

For Group 1 airplanes on which Boeing Service Bulletin 747-78-2151 or 747-78-2144 have been incorporated,

and on Group 2 airplanes, Boeing recommends the operators repeat the Electro-Mechanical brake and the CDU

cone brake tests every 1,000 flight hours.

Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2003-16-16, Amendment 39-13269, is

related to this service bulletin. AD 2003-16-16, Amendment 39-13269 supersedes AD 2000-09-03.

INDUSTRY SUPPORT INFORMATION

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

MANPOWER

MATERIAL INFORMATION

None

Total Task Hours Elapsed Hours

12 6
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BOEING SERVICE BULLETIN 747-78A2166

FOR EACH THRUST REVERSER HALF:

DO A FUNCTIONAL TEST ON THE

CENTER DRIVE UNIT (CDU) CONE BRAKE

ELECTRO-MECHANICAL BRAKE

DO A FUNCTIONAL TEST ON THE

FOR EACH THRUST REVERSER HALF:

LEFT SIDE SHOWN,

RIGHT SIDE OPPOSITE

S11892
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BOEING SERVICE BULLETIN 747-78A2166

BLANK PAGE
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Commercial

Airplane

Group 747

Service Bulletin

Number: 747-78A2166

Date: July 24, 1997

Revision 3 July 29, 2004

ATA System: 7830

SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System -

Center Drive Unit (CDU) Cone Brake Integrity Test

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

Note: This service bulletin is for airplanes indentified below. The effectivity list shown below is

complete for airplanes through line number 1348. However, airplanes after line number

1348 are also affected by this service bulletin.

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 CONDITION DESCRIPTION

1 - 747-200/300/400 airplanes with CF6-80C2 engines.

1 747-200/300/400 airplanes with CF6-80C2 engines

that have been modified in accordance with Boeing

Service Bulletin 747-78-2151 or 747-78-2144 or

equivalent modification (Production Revision Record

PRR 80452-101R and -102) incorporated in

production.

2 747-200/300/400 airplanes with CF6-80C2 engines

that have not been modified in accordance with Boeing

Service Bulletin 747-78-2151 or 747-78-2144 or

equivalent modification (Production Revision Record

PRR 80452-101R and -102) incorporated in

production.

2 - 747-400 airplanes with CF6-80C2 engines production

line number 1064 through 1348.
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BOEING SERVICE BULLETIN 747-78A2166

Airplane models:

747-200B 747-300 747-400 747-400D

747-400F

IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER

AEROLINEAS ARGENTINAS (ARG)

1 RT704

AIR ATLANTA ICELANDIC (AID)

1 RS332–RS333

AIR CANADA (ACN)

1 RT701

AIR FRANCE (AFA)

1 RT071–RT075 RT121 RT591 RT711–RT716

2 RL671–RL674 RM401–RM403

AIR INDIA (AIN)

1 RS781–RS782

AIR NAMIBIA (NAM)

2 RT137

AIR NEW ZEALAND (ANZ)

1 RT703 RT932

2 RM082 RM191–RM192

AIR PULLMANTUR (PUL)

1 RS331

ALL NIPPON AIRWAYS (ANA)

1 RT751–RT755 RT776–RT777 RU831–RU840

2 RM231–RM233 RT756–RT757 RU841

AMIRI FLIGHT (ABD)

2 RM084

ASIANA AIRLINES (AAR)

1 RR746 RT131–RT134 RU032

2 RM071 RM861–RM862 RR747–RR748 RT135–RT136

ATLAS AIR (TLS)

2 RM891–RM899 RM901–RM906

BAHRAIN ROYAL FLIGHT (BHR)

2 RM426

BOEING (TBC)

1 RT021–RT022
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BOEING SERVICE BULLETIN 747-78A2166

CARGOLUX AIRLINES (CLX)

1 RR701 RR721–RR722

2 RR723–RR724

CHINA AIRLINES (CHI)

2 RL411–RL425

EVA AIR (EVA)

1 RT161–RT166 RT951–RT954

2 RL401–RL403 RM116–RM117 RT167–RT168 RT955

GARUDA INDONESIA (GIA)

1 RT931 RU061–RU062

GOVERNMENT OF JAPAN (JAG)

1 RT681–RT682

JAPAN AIRLINES (JAL)

1 RT641–RT657 RT861–RT864 RT966–RT967 RU801–RU809

2 RM126–RM132 RM316–RM318

KLM - ROYAL DUTCH AIRLINES (KLM)

1 RT001–RT011 RT531–RT535

2 RL681–RL683 RM801–RM803 RT012–RT014

KUWAIT AIRWAYS (KUW)

1 RT151

LUFTHANSA GERMAN AIRLINES (DLH)

1 RT041–RT047 RT431–RT439 RT441

2 RM001–RM007 RT442–RT447

NISSHO IWAI CORPORATION (ZNY)

1 RT702

OMAN ROYAL FLIGHT (RFO)

2 RM010

PHILIPPINE AIRLINES (PAL)

1 RU051–RU052 RU059–RU060

2 RT152

POLAR AIR CARGO (PAO)

2 RL651–RL655

QANTAS (QAN)

1 RT741–RT742 RU031

2 RF001–RF006

ROYAL AIR MAROC (RAM)

1 RT717
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BOEING SERVICE BULLETIN 747-78A2166

S583 (583)

1 RD166–RD167

SAUDI ARABIAN AIRLINES (SVA)

2 RM156–RM158 RU101–RU102

SOUTH AFRICAN AIRWAYS (SAA)

2 RM081 RM083

THAI AIRWAYS INTERNATIONAL (TII)

1 RS341–RS342 RT691–RT698

2 RM026–RM030 RM431 RT699 RT801–RT803

THE SULTAN'S FLIGHT (BWN)

1 RT440

US AIR FORCE (USF)

2 RM911

VIRGIN ATLANTIC AIRWAYS (VAA)

1 RT945–RT946

2 RM051–RM053 RM351–RM355 RT947–RT949

IDENTIFICATION BY VARIABLE NUMBER

Variable Group

RD166–RD167 1

RF001–RF006 2

RL401–RL403 2

RL411–RL425 2

RL651–RL655 2

RL671–RL674 2

RL681–RL683 2

RM001–RM007 2

RM010 2

RM026–RM030 2

RM051–RM053 2

RM071 2

RM081–RM084 2

RM116–RM117 2

RM126–RM132 2

RM156–RM158 2

RM191–RM192 2

RM231–RM233 2

RM316–RM318 2

RM351–RM355 2
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BOEING SERVICE BULLETIN 747-78A2166

RM401–RM403 2

RM426 2

RM431 2

RM801–RM803 2

RM861–RM862 2

RM891–RM899 2

RM901–RM906 2

RM911 2

RR701 1

RR721–RR722 1

RR723–RR724 2

RR746 1

RR747–RR748 2

RS331–RS333 1

RS341–RS342 1

RS781–RS782 1

RT001–RT011 1

RT012–RT014 2

RT021–RT022 1

RT041–RT047 1

RT071–RT075 1

RT121 1

RT131–RT134 1

RT135–RT137 2

RT151 1

RT152 2

RT161–RT166 1

RT167–RT168 2

RT431–RT441 1

RT442–RT447 2

RT531–RT535 1

RT591 1

RT641–RT657 1

RT681–RT682 1

RT691–RT698 1

RT699 2

RT701–RT704 1

RT711–RT717 1

RT741–RT742 1

Variable Group
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BOEING SERVICE BULLETIN 747-78A2166

2. Spares Affected

None

B. Concurrent Requirements

None

C. Reason

This inspection will make sure that the center drive unit (CDU) cone brake continues to provide holding

torque against an in-flight thrust reverser deployment.

Two operators have returned five CDU's to the vendor AlliedSignal because of low holding torque. The

CDU's had accumulated between 3,400 and 3600 flight hours. AlliedSignal is currently analyzing the

returned units to determine the cause of low holding torque.

The cone brake consists of a semi-stationary, spring loaded, friction cone and its rotating mating cone

mounted on the CDU, air motor shaft. The brake is disengaged by a pivoted lever, actuated by the

translation of the directional control valve (DCV), actuator piston. While the brake is released, it will

allow free rotation of the air motor in the direction to stow and deploy the reverser. The cone brake

ensures against rotation of the CDU air motor to deploy the reverser when it is engaged by the

translation of the DCV actuation piston.

Currently, the CDU cone brake is required to be inspected at 1,000 flight hour intervals. Reducing the

inspection interval for the CDU, cone brake from 1,000 to 650 flight hours will make sure that the CDU

cone brake continues to provide holding torque against an in-flight, thrust reverser deployment.

RT751–RT755 1

RT756–RT757 2

RT776–RT777 1

RT801–RT803 2

RT861–RT864 1

RT931–RT932 1

RT945–RT946 1

RT947–RT949 2

RT951–RT954 1

RT955 2

RT966–RT967 1

RU031–RU032 1

RU051–RU052 1

RU059–RU062 1

RU101–RU102 2

RU801–RU809 1

RU831–RU840 1

RU841 2

Variable Group
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BOEING SERVICE BULLETIN 747-78A2166

Boeing Service Related Problem (SRP) 747-SRP-78-0036 is related to this service bulletin.

Revision 1 was sent to change the inspection interval for the CDU cone brake test from 600 to 650

flight hours to coincide with operators maintenance schedule.

Revision 2 adds the inspection interval of the Electro-Mechanical brake and CDU cone brake, for

airplanes equipped with thrust reversers, that have been modified in accordance with Boeing Service

Bulletin 747-78-2151or 747-78-2144 or after the equivalent modification (Production Revision Record

PRR 80452-101R and -102) incorporated in production. Revise the service bulletin effectivity to add

Group 2 airplanes which is included all 747-400 airplanes (including future 747-400 airplanes) with

CF6-80C2 engines after production line number 1060. Also, the Industry Support Information

statement has been changed.

Revision 3 is sent to remove reference "767" and add reference "747/747-400" in Paragraph 3.B.1.a.,

Accomplishment Instructions.

D. Description

For Group 1 airplanes that have incorporated Boeing Service Bulletin 747-78-2151 or 747-78-2144

and on Group 2 airplanes, on each thrust reverser half, do a functional test on the Electro-Mechanical

brake and CDU cone brake to verify the holding torque. Repeat this test every 1,000 flight hours.

For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or 747-78-

2144, on each thrust reverser half, do a functional test on the CDU cone brake to verify the holding

torque. Repeat this test every 650 flight hours.

Revision 1 - No more work is necessary on airplanes changed as shown in the initial release of this

service bulletin.

Revision 2 - More work is necessary on airplanes changed as shown in the Revision 1 of this service

bulletin.

Revision 3 - No more work is necessary on airplanes changed as shown in the Revision 2 of this

service bulletin.

E. Compliance

Boeing recommends the operators do this service bulletin within 650 flight hours after receipt of this

service bulletin.

For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or 747-78-

2144, Boeing recommends the operators repeat CDU cone brake test every 650 flight hours.

For Group 1 airplanes on which Boeing Service Bulletin 747-78-2151 or 747-78-2144 has been

incorporated and on Group 2 airplanes, Boeing recommends the operators repeat the ElectroMechanical brake and CDU cone brake tests every 1,000 flight hours.

Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2003-16-16, Amendment 39-

13269, is related to this service bulletin. AD 2003-16-16, Amendment 39-13269 supersedes AD 2000-

09-03.
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F. Approval

This service bulletin was examined by the Federal Aviation Administration (FAA). The changes

specified in this service bulletin comply with the applicable Federal Aviation Regulations (FAR) and

are FAA approved. This service bulletin and the FAA approval were based on the airplane in its

original Boeing delivery configuration or as modified by other FAA 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.

This service bulletin has been approved by the FAA. In addition, the Manager of the FAA Seattle

Aircraft Certification Office approves the action inspection defined in this service bulletin as an

alternative method of compliance to the requirements of paragraph (e) and (j) of AD 2003-16-16. All

provisions of AD 2003-16-16 that are not specifically referenced in the above sentence remain fully

applicable and must be complied with.

G. Manpower

Approximately 12 man-hours and 2 persons are necessary to do this test for each airplane.

Time does not include CDU replacement.

This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator

man-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

— Time to find the tools.

H. Weight and Balance Changes

None

I. Electrical Load Data

Not applicable

J. References

1. Existing Data:

a. Service Related Problem (SRP) 747-SRP-78-0036

b. 747/747-400 Maintenance Manual (AMM) Subject 71-11-04, 78-31-21

c. Boeing Service Bulletin 747-78A2113, "Exhaust (CF6-80C2 Engines) - Thrust Reverser -

Thrust Reverser Control System - Operational Test"
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d. Boeing Service Bulletin 747-78A2130, "Exhaust (CF6-80C2 Engines With PMC) - Thrust

Reverser - Thrust Reverser Control System - Operational Test"

e. Boeing Service Bulletin 747-78-2144, "Exhaust (CF6-80C2 PMC Engines) - Thrust

Reverser - Thrust Reverser Actuation System (TRAS) Brake Installation"

f. Boeing Service Bulletin 747-78-2151, "Exhaust (CF6-80C2 Engines) - Thrust Reverser -

Thrust Reverser Hydraulic Actuator - Synchronous Lock Installation"

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

Refer to Paragraph 2.C., Parts Necessary For Each Airplane, for interchangeability and intermixability

information.
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2. MATERIAL INFORMATION

A. Material - Price and Availability

None

B. Industry Support Information

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

C. Parts Necessary For Each Airplane

1. Kits/Parts:

None

2. Parts and Materials Supplied by the Operator:

Note: Part quantity dependent on test results.

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

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.

Part Number QTY Name Notes

126784-() 8 Center Drive Unit (a)

(a) Replace this part when the sleeve translates to deploy with a torque less than 15 pound

inches.
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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 numbered paragraphs contain the test to be accomplished at the specific interval.

2. Obey all of the warnings and cautions given in the specified manual sections.

3. Refer to Compliance Paragraph for recommendation and repeat inspection requirements.

4. For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or

747-78-2144, repeat CDU cone brake test every 650 flight hours.

For Group 1 airplanes on which Boeing Service Bulletin 747-78-2151 or 747-78-2144 has

been incorporated and on Group 2 airplanes, repeat the Electro-Mechanical brake and

CDU cone brake tests every 1,000 flight hours.

B. WORK INSTRUCTIONS

1. Do the functional test on both thrust reverser for the Electro-Mechanical brakes of both engines

as follows:

a. Open the engine fan cowl panels as shown in 747/747-400 Maintenance Manual Subject

71-11-04 or your own equivalent procedure.

b. Do a check of the running torque of the thrust reverser system:

(1) Manually extend the thrust reverser six inches and measure the running torque. Make

sure the torque is less than 10 pound-inches.

c. Do a check of the electro-mechanical brake holding torque:

(1) Make sure the thrust reverser translating cowl is extended at least one inch.

(2) Make sure the CDU lock handle is released.

(3) Pull down on the manual release handle on the electro-mechanical brake until the

handle fully engages the retaining clip.

Note: This will lock the electro-mechanical brake.

(4) With the manual drive lockout cover removed from the CDU, install a 1/4-inch

extension tool and dial -type torque wrench into the drive pad.

Note: You will need a 24-inch extension to provide adequate clearance for the torque
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wrench.

(5) Apply 90 pound-inches of torque to the system.

(a) The electro-mechanical brake system is working correctly if the torque is reached

before you turn the wrench 450 degrees (1-1/4 turns).

(b) If the flexshaft turns more than 450 degrees (1-1/4 turns) before you reach the

specified torque, you must replace the long flexshaft between the CDU and the

upper angle gearbox.

(c) If you do not get 90 pound-inches of torque, inspect the short flexshaft between

the upper angle gearbox and the electro-mechanical brake. If the flexshaft is

twisted, broken or otherwise damaged, replace the flexshaft and repeat (5). If you

still do not get 90 pound-inches of torque, you must replace the electromechanical brake.

(6) Release the torque by turning the wrench in the position direction until you read zero

pound-inches.

(a) If the wrench does not turn to within 30 degrees of initial starting point, you must

replace the long flexshaft between the CDU and upper angle gearbox.

d. Fully retract the thrust reverser.

e. Repeat this procedure on other reverser half and on the remaining engines.

f. End the Electro-Mechanical brake check.

2. For Group 1 airplanes on which Boeing Service Bulletin 747-78-2151 or 747-78-2144 has been

incorporated and on Group 2 airplanes, repeat the Electro-Mechanical brake test at 1,000 flight

hours intervals

3. Do the functional test on both thrust reverser for the Center Drive Unit (CDU) cone brakes of all

four engines as follows:

a. Open the engine fan cowl panels as shown in 747/747-400 Maintenance Manual Subject

71-11-04 or your own equivalent procedure.

b. Pull up on the manual release handle to unlock the electro-mechanical brake (if so

equipped).

c. Pull the manual release lever on the CDU to release the cone brake. Refer to Figure 1 for

location.

Note: This will release the pre-load tension that may occur during a stow cycle.

d. Return the manual brake release lever to the locked position to engage the cone brake.

Refer to Figure 1 for location.

e. Remove the two bolts that hold the lockout plate to the CDU and remove the lockout plate.

Refer to Figure 1 for location.
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f. Install a 1/4-inch drive and a dial-type torque wrench into the CDU drive pad.

WARNING: DO NOT USE MORE THAN 100 POUND-INCHES OF TORQUE WHEN

CARRYING OUT THIS CHECK. EXCESSIVE TORQUE WILL DAMAGE THE

CDU.

g. Turn the torque wrench to try to manually extend the translating cowl until you get at least

15 pound-inches of torque.

Note: The cone brake prevents movement in the extend direction only. If you try to measure

the torque in the retract direction, you will get a false reading.

h. If the sleeve translates to deploy with a torque less than 15 pound inches, you must replace

the CDU as shown in 747/747-400 Maintenance Manual Subject 78-31-21.

i. Reinstall the lockout plate.

j. Fully retract the thrust reverser.

k. Pull down on the manual release handle on the electro-mechanical brake until the handle

fully engages the retaining clip (if so equipped).

Note: This will lock the electro-mechanical brake.

l. Repeat this procedure on other reverser half and on the remaining engines.

m. Close the engine fan cowl panels as shown in 747/747-400 Maintenance Manual Subject

71-11-04 or your own equivalent procedure.

n. End the CDU cone brake check.

4. For Group 1 airplanes that have not incorporated Boeing Service Bulletin 747-78-2151 or 747-

78-2144, repeat CDU cone brake test every 650 flight hours.

5. For Group 1 airplanes on which Boeing Service Bulletin 747-78-2151 or 747-78-2144 has been

incorporated and on Group 2 airplanes, repeat the CDU cone brake tests every 1,000 flight

hours.
FIGURE 1: CDU MANUAL BRAKE RELEASE LEVER, LOCKOUT PLATE AND DRIVE PAD LOCATIONS

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FIGURE 1: CDU MANUAL BRAKE RELEASE LEVER, LOCKOUT PLATE AND DRIVE PAD LOCATIONS

ELECTRO-MECHANICAL BRAKE

UPPER ANGLE

GEAR BOX

(LEFT SIDE SHOWN,

RIGHT SIDE TURNED 180 DEGREES)

CENTER

(CDU)

DRIVE UNIT

DRIVE PAD

PLATE AND

LOCKOUT

BRAKE RELEASE

CDU MANUAL

LEVER

CENTER DRIVE UNIT

S11864

(SHEET 1 OF 1)