# Boeing Alert Service Bulletin 747-78A2184: Revision 1

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- Document: [Boeing Alert Service Bulletin 747-78A2184](https://openairdocs.org/service-documents/boeing/747-78a2184.md)
- Title as filed: U.S. DOT/FAA - Service Bulletin (2)
- Pages: 33
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## Text

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### Page 1

Commercial 
Airplanes
747
Service Bulletin
ALERT
Number: 747-78A2184
Original Issue: January 12, 2010
Revision 1: December 23, 2010
ATA System: 7834
SUBJECT: EXHAUST (PW4000 Series Engines) - Thrust Reverser Control System - Automatic
Leading Edge Flap Retraction System Wiring Change
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.
9E991ECCN:
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Unpublished Work - All Rights Reserved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.
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Table of Contents
Revision Transmittal Sheet ............................................ 5
Summary ...................................................... 7
1. PLANNING INFORMATION ........................................ 1 1
A. Effectivity ............................................... 1 1
1. Airplanes ............................................ 1 1
2. Spares Affected ........................................ 1 2
B. Concurrent Requirements ...................................... 1 2
C. Reason ................................................ 1 3
D. Description .............................................. 1 4
E. Compliance .............................................. 1 4
F. Approval ............................................... 1 4
G. Manpower .............................................. 1 4
H. Weight and Balance Changes .................................... 1 5
I. Electrical Load Data ......................................... 1 5
J. References .............................................. 1 5
1. Existing Data .......................................... 1 5
2. Data supplied with this Service Bulletin ............................ 1 5
3. Installation Drawings Used in the Preparation of this Service Bulletin ............ 1 6
K. Publications Affected ........................................ 1 6
L. Interchangeability and Intermixability of Parts ........................... 1 6
2. MATERIAL INFORMATION ........................................ 1 7
A. Material - Price and Availability ................................... 1 7
B. Industry Support Information .................................... 1 7
C. Parts Necessary For Each Airplane ................................. 1 7
1. Kits/Parts ............................................ 1 7
2. Parts and Materials Supplied by the Operator ........................ 1 7
3. Parts Modified and Reidentified ................................ 1 7
4. Parts Removed and Not Replaced .............................. 1 8
D. Parts Necessary to Change Spares ................................. 1 8
E. Special Tooling - Price and Availability ............................... 1 8
F. Special Tooling Necessary to do this Service Bulletin ....................... 1 8
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 1 9
A. GENERAL INFORMATION ..................................... 1 9
B. WORK INSTRUCTIONS ....................................... 1 9
FIGURE 1: NO.1 AND NO.2 ENGINE THRUST REVERSER CONTROL WIRING - P252 PANEL ROUTING
.................................................. 2 8
FIGURE 2: NO.1 AND NO.2 ENGINE THRUST REVERSER CONTROL WIRING, P252 PANEL - CHANGE
.................................................. 3 0
FIGURE 3: NO.3 AND NO.4 ENGINE THRUST REVERSER CONTROL WIRING - P253 PANEL ROUTING
.................................................. 3 1
FIGURE 4: NO.3 AND NO.4 ENGINE THRUST REVERSER CONTROL WIRING, P253 PANEL - CHANGE
.................................................. 3 3
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Commercial 
Airplanes
747
Service Bulletin
ALERT
Revision Transmittal SheetNumber: 747-78A2184Original Issue: January 12, 2010
Revision 1: December 23, 2010
ATA System: 7834
SUBJECT: EXHAUST (PW4000 Series Engines) - Thrust Reverser Control System - Automatic
Leading Edge Flap Retraction System Wiring Change
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
Federal Aviation Administration (FAA) Notice of Proposed Rule Making NPRM 2010-NM-064-AD is related to
this service bulletin.
No more work is necessary on airplanes changed in accordance with the original issue of this service bulletin.
REASON FOR REVISION
This revision is sent to change the functional test in the work instructions to give a better sequence and to better
describe the use of pneumatic and electrical power during its accomplishment.
These sections are changed:
– Summary Manpower and Paragraph 1.G., Manpower; Changed to show adjusted functional test hours.
– Summary Compliance and Paragraph 1.E., Compliance; Changed to add FAA NPRM.
– Paragraph 2.C.2., Part and Material Supplied by the Operator; Changed to add supplier information for a
part.
– Paragraph 1.J.1., Existing Data; SWPM, AMM and FAA NPRM references added.
– Paragraph 3.B., Work Instructions; Tasks added and sequence changed.
– Figure 2 and 4; SWPM references added for the disassembly of equipment related to this change.
The data given in Information Notice 747-78A2184 IN 01 is included in this revision.
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
January 12, 2010Original Issue:
December 23, 2010Revision 1:
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Commercial 
Airplanes
747
Service Bulletin
ALERT
SummaryNumber: 747-78A2184Original Issue: January 12, 2010
Revision 1: December 23, 2010
ATA System: 7834
SUBJECT: EXHAUST (PW4000 Series Engines) - Thrust Reverser Control System - Automatic
Leading Edge Flap Retraction System Wiring Change
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
CONCURRENT REQUIREMENTS
None.
BACKGROUND
This service bulletin is sent to prevent the Group A Leading Edge (LE) flaps from automatically retracting if the
Flap Control Unit (FCU) receives dual cowl unstowed indications from the thrust reversers. If this service bulletin
is not done, the Group A LE flaps can automatically retract if the FCU gets dual cowl unstowed indications from
the thrust reverser which could result in decreased climb performance of the airplane during takeoff.
During takeoff roll, an operator of a Rolls-Royce RB211 powered 747-400 airplane had a REV Amber indication
occurrence on the No.3 engine thrust reverser. This was followed thirteen seconds later by a REV Amber
indication on the No.2 engine thrust reverser. At the time of the second REV amber, the aircraft was beyond
V1. To prevent impingement from the thrust reversers, the FCU of the 747-400 is designed to automatically
retract the Group A LE flaps when a REV Amber signal is transmitted from the two inboard or the two outboard
thrust reversers and the aircraft is on the ground. The FCU performed as designed, and retracted the Group A
leading edge flaps. After takeoff, the air/ground logic took over and the Group A LE flaps re-deployed. During
the event, the flight crew reported buffeting and momentary stick shaker activation. The aircraft jettisoned fuel
and returned to the airport with a usual landing. All four thrust reversers deployed and stowed normally after
landing.
The automatic LE flap retraction logic for PW4000 engines automatically retracts the Group A LE flaps during
reverse thrust operation. This is to prevent thrust reverser efflux air from impinging onto the Group A LE flaps
to improve the Group A LE flap panel’s structural life. This function is armed when the airplane is on the ground.
The Group A LE flaps retract when the FCU gets a signal from the LE Flap relay in the reverser circuitry on the
two inboard engines or the two outboard engines. The LE Flap relay is energized by the microswitch of the
reverse thrust lever or the unstow proximity sensor on the thrust reverser cowl.
The initial signal to the FCU comes from the microswitch in the aisle stand when thrust reverser deployment is
commanded. The signal to the FCU is kept after stow is commanded by the proximity switches. This signal is
removed 5 seconds after the thrust reverser is stowed.
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The Group A LE flaps retract (or extend) in ten seconds. Once auto-retracted, there is a five second time delay
after the thrust reverser signal is removed from the FCU before the Group A LE flaps return to the commanded
position. The thrust reverser extends in two seconds and stows in three seconds. This time can slightly increase
during cold weather operation.
Accomplishment of this service bulletin will remove the thrust reverser unstow signal from the FCU. The timing
of the thrust reverser stow versus the time delay in the FCU accomplishes the original intent of the design. The
thrust reversers are fully stowed prior to the FCU time delay lapsing and Group A LE flap movement starting.
The signal from the thrust reverser lever will not be affected by this change, but the CMC message, "ENG X
AUTO RESTOW EVENT" will be permanently inhibited. Instead, if there is an auto restow event on an airplane
the "ENG X PRESSURE SWITCH FAIL" message will be set.
Boeing Service Related Problem (SRP) 747-SRP-78-0069 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) 747 FTD 78-09002 is related to this service bulletin.
ACTION (PRR 85665-R)
Get access to the P252 and P253 Thrust Reverser Relay panels in the Electrical and Electronics Compartment.
Make wiring changes in the panels to wires related to the thrust reverser control system of the No.1 thru No.4
engines. Do tests of the thrust reverser control and the Group A Leading Edge (LE) flap systems.
EFFECTIVITY
747-400/400F Airplanes powered by PW4000 engines. Refer to Paragraph 1.A., Effectivity for the list of affected
airplanes.
COMPLIANCE
Federal Aviation Administration (FAA) Notice of Proposed Rule Making NPRM 2010-NM-064-AD is related to
this service bulletin.
Boeing recommends that the change given in this service bulletin be done within 36 months after the original
issue date of this service bulletin.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the configuration changes given in this service bulletin.
MANPOWER
Elapsed HoursTotal Task HoursAirplanes
6.8011.30Group 1
MATERIAL INFORMATION
Operator Supplied Parts/Materials.
Refer to Paragraph 2.A., Material - Price and Availability.
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BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
P253 PANEL
P252 PANEL
MAKE WIRING CHANGES IN THE P252 AND P253
PANELS TO CAP AND STOW WIRES RELATED  TO THE THRUST REVERSER CONTROL SYSTEM  1905895
FOR THE NO. 1 THRU NO. 4 ENGINES
Original Issue: January 12, 2010
Revision 1: December 23, 2010  747-78A2184
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Commercial 
Airplanes
747
Service Bulletin
ALERT
Number: 747-78A2184
Original Issue: January 12, 2010
Revision 1: December 23, 2010
ATA System: 7834
SUBJECT: EXHAUST (PW4000 Series Engines) - Thrust Reverser Control System - Automatic
Leading Edge Flap Retraction System Wiring Change
THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH
1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO
THE NEW OWNER.
1.    PLANNING INFORMATION
A. Effectivity
1. Airplanes
Refer to Service Bulletin Index Document D6-30300 Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
This service bulletin is for the airplanes shown below. Refer to PRR 85665-R for data about this
change.
DESCRIPTIONCONFIGURATIONGROUP
747-400/400F airplanes with Pratt & Whitney (PW) 4000 series
engines.
-1
Airplane Models:
747-400, 747-400F
GroupVariable Number
1RL431 - RL436
1RL451 - RL456
1RL491 - RL492
1RL501 - RL502
1RL581 - RL586
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GroupVariable Number
1RL751 - RL752
1RM011 - RM013
1RM021 - RM024
1RM036 - RM045
1RM091
1RM166 - RM177
1RM241 - RM246
1RM341
1RM366 - RM367
1RM811 - RM813
1RM851 - RM855
1RM871 - RM880
1RR851 - RR856
1RR861 - RR862
1RT031 - RT035
1RT061
1RT101 - RT103
1RT401 - RT412
1RT501 - RT530
1RT571 - RT590
1RT601 - RT640
1RT743 - RT750
1RT811 - RT814
1RT831 - RT837
1RT876 - RT880
1RU001 - RU006
1RU016 - RU017
1RU081 - RU083
2. Spares Affected
None.
B. Concurrent Requirements
None.
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C. Reason
This service bulletin is sent to prevent the Group A Leading Edge (LE) flaps from automatically retracting
if the Flap Control Unit (FCU) receives dual cowl unstowed indications from the thrust reversers. If this
service bulletin is not done, the Group A LE flaps can automatically retract if the FCU gets dual cowl
unstowed indications from the thrust reverser which could result in decreased climb performance of
the airplane during takeoff.
During takeoff roll, an operator of a Rolls-Royce RB211 powered 747-400 airplane had a REV Amber
indication occurrence on the No.3 engine thrust reverser. This was followed thirteen seconds later by
a REV Amber indication on the No.2 engine thrust reverser. At the time of the second REV amber, the
aircraft was beyond V1. To prevent impingement from the thrust reversers, the FCU of the 747-400 is
designed to automatically retract the Group A LE flaps when a REV Amber signal is transmitted from
the two inboard or the two outboard thrust reversers and the aircraft is on the ground. The FCU performed
as designed, and retracted the Group A leading edge flaps. After takeoff, the air/ground logic took over
and the Group A LE flaps re-deployed. During the event, the flight crew reported buffeting and momentary
stick shaker activation. The aircraft jettisoned fuel and returned to the airport with a usual landing. All
four thrust reversers deployed and stowed normally after landing.
The automatic LE flap retraction logic for PW4000 engines automatically retracts the Group A LE flaps
during reverse thrust operation. This is to prevent thrust reverser efflux air from impinging onto the
Group A LE flaps to improve the Group A LE flap panel’s structural life. This function is armed when
the airplane is on the ground. The Group A LE flaps retract when the FCU gets a signal from the LE
Flap relay in the reverser circuitry on the two inboard engines or the two outboard engines. The LE
Flap relay is energized by the microswitch of the reverse thrust lever or the unstow proximity sensor
on the thrust reverser cowl.
The initial signal to the FCU comes from the microswitch in the aisle stand when thrust reverser
deployment is commanded. The signal to the FCU is kept after stow is commanded by the proximity
switches. This signal is removed 5 seconds after the thrust reverser is stowed.
The Group A LE flaps retract (or extend) in ten seconds. Once auto-retracted, there is a five second
time delay after the thrust reverser signal is removed from the FCU before the Group A LE flaps return
to the commanded position. The thrust reverser extends in two seconds and stows in three seconds.
This time can slightly increase during cold weather operation.
Accomplishment of this service bulletin will remove the thrust reverser unstow signal from the FCU.
The timing of the thrust reverser stow versus the time delay in the FCU accomplishes the original intent
of the design. The thrust reversers are fully stowed prior to the FCU time delay lapsing and Group A
LE flap movement starting. The signal from the thrust reverser lever will not be affected by this change,
but the CMC message, "ENG X AUTO RESTOW EVENT" will be permanently inhibited. Instead, if
there is an auto restow event on an airplane the "ENG X PRESSURE SWITCH FAIL" message will be
set.
Boeing Service Related Problem (SRP) 747-SRP-78-0069 is related to this service bulletin.
Boeing Fleet Team Digest (FTD) 747 FTD 78-09002 is related to this service bulletin.
Revision 1 is sent to change the functional test in the work instructions to give a better sequence and
to better describe the use of pneumatic and electrical power during its accomplishment.
The data given in Information Notice 747-78A2184 IN 01 is included in Revision 1.
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D. Description
Get access to the P252 and P253 Thrust Reverser Relay panels in the Electrical and Electronics
Compartment. Make wiring changes in the panels to wires related to the thrust reverser control system
of the No.1 thru No.4 engines. Do tests of the thrust reverser control and the Group A Leading Edge
(LE) flap systems.
Revision 1 - No more work is necessary on airplanes changed in accordance with the original issue of
this service bulletin.
The work in this service bulletin is done in the maintenance zone(s) given below.
Affected Maintenance Zones
ZoneModel
117, 118747-400, 747-400F
E. Compliance
Federal Aviation Administration (FAA) Notice of Proposed Rule Making NPRM 2010-NM-064-AD is
related to this service bulletin.
Boeing recommends that the change given in this service bulletin be done within 36 months after the
original issue date of this service bulletin.
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 change for each airplane.
This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator
task hour data if necessary. The estimate does not include lost time. These are some examples of lost
time:
 Time to adjust to the workplace
 Time to schedule the work
 Time to inspect the work
 Time to cure the materials
 Time to make the parts
 Time to find the tools.
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Elapsed HoursTask HoursNumber of PersonsTask
0.750.751Open Access
-FIGURE 1 (Wire
Routing Only)
0.400.401FIGURE 2
-FIGURE 3 (Wire
Routing Only)
0.400.401FIGURE 4
0.750.751Close Access
4.509.002Test
6.8011.30TOTAL FOR EACH AIRPLANE
H. Weight and Balance Changes
None.
I. Electrical Load Data
None.
J. References
1. Existing Data
a. Engineering Change Memo PRR 85665-R.
b. Boeing Service Related Problem (SRP) 747-SRP-78-0069.
c. Boeing Standard Wiring Practices Manual (SWPM) 20-00-11, 20-10-11, 20-10-12, 20-10-14,
20-10-19, 20-30-16, 20-81-12, 20-90-11.
d. Federal Aviation Administration (FAA) Notice of Proposed Rule Making (NPRM)
2010-NM-064-AD.
e. 747 Fleet Team Digest (FTD) 747 FTD 78-09002.
f. 747-400 Aircraft Maintenance Manual (AMM) 06-09-09, 24-22-00, 27-62-00, 27-81-00,
36-00-00, 54-62-00, 71-11-04, 78-31-00, 78-34-05, 78-34-13, 78-36-07.
g. 747-400 Wiring Diagram Manual (WDM) 78-34-12, 78-34-22, 78-34-32, 78-34-42.
2. Data supplied with this Service Bulletin
None.
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3. Installation Drawings Used in the Preparation of this Service Bulletin
TitleDrawing Number
PANEL INSTL P252 AND P253284U4255
This drawing was used to prepare this service bulletin. This drawing is not necessary to make the
specified changes, and is not supplied with this service bulletin. This drawing may not be applicable
to all airplane configurations or operators.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
78-34747 Wiring Diagram Manual
71-00747 Fault Isolation Manual
2. Damage Tolerance Based Structural Inspections:
Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue
Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the
Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.
L. Interchangeability and Intermixability of Parts
Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each
Airplane. As an alternative, operators can purchase the parts from Boeing Spares. This service bulletin
does not show the Boeing price and supply data.
The parts are subject to the terms and conditions of the Boeing standard purchase order
acknowledgment. Prices are in United States dollars. Terms: Net 30 days.
Reference this service bulletin and submit your purchase order by one of the methods that follow:
1. Order on-line via ATA Spec 2000 or Boeing Part Page
2. Fax to (206) 662-7145
3. Mail to:
Spares Customer Support - MC 36-65
Boeing Spares Department
P.O. Box 3707
Seattle, Washington 98124-2207 USA
B. Industry Support Information
Boeing warranty remedies are not available for the configuration changes given in this service bulletin.
C. Parts Necessary For Each Airplane
1. Kits/Parts
None.
2. Parts and Materials Supplied by the Operator
NotesNameQTYPart Number /
Specification
(a)Insulation Tubing, Heat Shrinkable,
Flexible, Adhesive Lined (3/16 Inch
Dia., 0.75 Inch Length)
4DWP-125-3/16-0
(b)End Cap8BACT63D2
(a) Refer to Boeing Standard Wiring Practices Manual SWPM 20-00-11 for material and
supplier information.
(b) Refer to Paragraph 2.A., Material - Price and Availability for procurement information.
3. Parts Modified and Reidentified
None.
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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
None.
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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 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. 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.
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 "in
accordance with" are included in the instruction, the procedure in the Boeing document
must be used.
6. The instructions in Paragraph 3.B., Work Instructions and the figures can include
operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated
Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing
Index contain data on versions of the tools or test equipment that you can use. It is
permitted to use replaced tools. It is not permitted to use superseded tools.
7. If it is necessary to remove more parts for access, you can remove those parts. If
you can get access without removing identified parts, it is not necessary to remove
all of the identified parts. Jacking and shoring limitations must be observed.
8. This service bulletin includes functional test procedures for the systems changed by
this service bulletin. More functional tests can possibly be necessary in accordance
with standard maintenance practices because of interruption to other airplane systems.
B. WORK INSTRUCTIONS
1. In the Flight Compartment, open the circuit breakers specified in the table below and attach
DO-NOT-CLOSE tags:
MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C10934T/R LOCK CONT ENG 1F11P6
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
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ALERTALERT

### Page 20

MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C00405T/R IND ENG 1F12P6
C01703T/R CONT ENG 1F13P6
C10935T/R LOCK CONT ENG 2E11P6
C00402T/R IND ENG 2E12P6
C01704T/R CONT ENG 2 or ENG 2, T/R CONTE13P6
C10936T/R LOCK CONT ENG 3D11P6
C00403T/R IND ENG 3D12P6
C01442T/R CONT ENG 3D13P6
C10937T/R LOCK CONT ENG 4C11P6
C00404T/R IND ENG 4C12P6
C01441T/R CONT ENG 4 or ENG 4, T/R CONTC13P6
2. Get access to the P252 and P253 thrust reverser relay panels in the Electrical and Electronics
Compartment. Refer to 747-400 AMM 78-36-07 for the location of the relay panels.
3. Change the thrust reverser control wiring in the P252 and P253 thrust reverser relay panels for
each engine in accordance with:
FigureEngine
FIGURE 1 and FIGURE 2No.1 and No.2
FIGURE 3 and FIGURE 4No.3 and No.4
4. In the Flight Compartment, remove the DO-NOT-CLOSE tags and close the circuit breakers
specified in the table below:
MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C10934T/R LOCK CONT ENG 1F11P6
C00405T/R IND ENG 1F12P6
C01703T/R CONT ENG 1F13P6
C10935T/R LOCK CONT ENG 2E11P6
C00402T/R IND ENG 2E12P6
C01704T/R CONT ENG 2 or ENG 2, T/R CONTE13P6
C10936T/R LOCK CONT ENG 3D11P6
C00403T/R IND ENG 3D12P6
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
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20 of 33
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### Page 21

MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C01442T/R CONT ENG 3D13P6
C10937T/R LOCK CONT ENG 4C11P6
C00404T/R IND ENG 4C12P6
C01441T/R CONT ENG 4 or ENG 4, T/R CONTC13P6
5. Close access to the P252 and P253 relay panels.
WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF THE LEADING
EDGE (LE), TRAILING EDGE (TE) FLAPS AND FLAP DRIVE MECHANISMS BEFORE
THE FLAP CONTROL LEVER IS MOVED. WITH HYDRAULIC POWER REMOVED,
THE FLAPS WILL MOVE AUTOMATICALLY BY ELECTRICAL POWER WHEN THE
FLAP CONTROL LEVER IS MOVED. THIS CAN CAUSE INJURY TO PERSONS OR
DAMAGE TO EQUIPMENT.
6. Supply electrical power to the airplane. Refer to 747-400 AMM 24-22-00 as an accepted procedure.
7. Do the functional test as follows:
a. In the Flight Compartment, make sure the applicable engine START and ENGINE BLEED
switches, on the overhead panel, are in the OFF position.
b. In the Flight Compartment, make sure the reverse thrust lever is in the forward thrust position.
c. Do the 'Automatic Speed Brake System Deactivation'. Refer to 747-400 AMM 27-62-00 as
an accepted procedure.
WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF THE LE FLAPS
AND CONTROL SURFACES BEFORE PNEUMATIC POWER IS SUPPLIED. THIS
CAN CAUSE INJURY TO PERSONS AND DAMAGE EQUIPMENT.
d. Make sure the Leading Edge (LE) flaps are retracted. Refer to 747-400 AMM 27-81-00 as an
accepted procedure.
NOTE: If this task is accomplished by pneumatic power, it is not necessary to remove
pneumatics from the airplane at the end of the procedure.
e. In the Flight Compartment, open the circuit breakers specified in the table below and attach
DO-NOT-CLOSE tags:
MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C10934T/R LOCK CONT ENG 1F11P6
C01703T/R CONT ENG 1F13P6
C10935T/R LOCK CONT ENG 2E11P6
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
747-78A2184Revision 1: December 23, 2010
21 of 33
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ALERTALERT

### Page 22

MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C01704T/R CONT ENG 2 or ENG 2, T/R CONTE13P6
C10936T/R LOCK CONT ENG 3D11P6
C01442T/R CONT ENG 3D13P6
C10937T/R LOCK CONT ENG 4C11P6
C01441T/R CONT ENG 4 or ENG 4, T/R CONTC13P6
f. Make sure pneumatic power is supplied to the airplane. Refer to 747-400 AMM 36-00-00 as
an acceptable procedure.
g. Remove the access doors on the No.1 thru No.4 engine nacelle struts. Refer to 747-400 AMM
54-62-00 as an accepted procedure.
h. Open the access panels specified in the table below. Refer to 747-400 AMM 06-09-09.
Name/LocationAccess Panel / Door
No.
ACCESS DOOR - THRUST REVERSER ISOLATION
VALVE
451BL
THRUST REVERSER ISOLATION VALVE, UPPER
MIDSPAR, SPRING BEAM GREASE FITTING,
PRESSURE RELIEF (AFT)
462EL
THRUST REVERSER ISOLATION VALVE, UPPER
MIDSPAR, SPRING BEAM GREASE FITTING,
PRESSURE RELIEF (AFT)
472EL
ACCESS DOOR - CORE COWL TO STRUT (AFT)481BL
i. Deactivate the isolation valves for the No.1 thru No.4 engines as follows. Refer to 747-400
AMM 78-34-05 for the location of the isolation valves.
(1) Push the deactivation slide into the isolation valve housing.
(2) Install a streamered pin in the deactivation slide.
(3) Install a hitch pin the streamered pin.
NOTE: Use a ground lock, SPL-5635, where necessary.
j. Open the bypass valve (of the isolation valve) for the No.1 thru No.4 engines as follows. Refer
to 747-400 AMM 78-34-05 for the location of the bypass valves.
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
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### Page 23

NOTE: The bypass valve must be open before you manually extend or retract the thrust
reverser. This will prevent a hydraulic lock, which can prevent the movement of the
thrust reverser. But the bypass valve must be closed again if thrust reverser
components or hydraulic tubes are removed (after you extend or retract the thrust
reverser). If the bypass valve is not closed again, hydraulic fluid leakage will occur
when the components or tubing are removed.
(1) Remove the lockwire, if applicable, on the bypass valve lever.
NOTE: There are two types of bypass valves, one that has a spring that controls the
position of the lever, and one that does not have a spring. Lockwire is not installed
on bypass valve levers that have a spring.
(2) Push in the bypass valve lever to open the bypass valve of the isolation valve.
(3) Install a streamered pin to hold the bypass valve lever in the open position.
(4) Install a hitch pin in the streamered pin.
NOTE: Use a ground lock, SPL-5635, where necessary.
k. After the deactivation procedure is completed, make sure the REMOVE-BEFORE-FLIGHT
streamers can be seen outside of the No.1 thru No.4 engine nacelle struts.
l. Open the left or right fan cowl panels on the No.1 thru No.4 engines. Refer to 747-400 AMM
71-11-04 as an accepted procedure.
NOTE: Open and unlock the applicable sleeve. It is only necessary to manually deploy one
sleeve for each engine to complete this functional test.
CAUTION: DO NOT USE A SCREWDRIVER BETWEEN THE LOCK PROXIMITY SENSOR
AND THE TARGET TO MOVE THE LOCK LEVER TO THE UNLOCKED POSITION.
IF A SCREWDRIVER OR OTHER TOOL IS USED TO SUPPLY A SEPARATION
FORCE, DAMAGE CAN BE CAUSED TO THE LOCK PROXIMITY SENSOR OR
THE TARGET.
m. On the No.1 thru No.4 engines, move the lock lever on the left or right locking actuator away
from the sensor. Refer to 747-400 AMM 78-31-00 for the location of the locking actuators.
NOTE: If the lock lever does not move easily, turn the manual crank counter-clockwise to
relieve pressure on the actuator locks.
n. In the Flight Compartment, remove the DO-NOT-CLOSE tags and close the circuit breakers
specified in the tables below:
MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C10934T/R LOCK CONT ENG 1F11P6
C01703T/R CONT ENG 1F13P6
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
747-78A2184Revision 1: December 23, 2010
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### Page 24

MAIN POWER DISTRIBUTION PANEL
NumberNameLocationPanel Number
C10935T/R LOCK CONT ENG 2E11P6
C01704T/R CONT ENG 2 or ENG 2, T/R CONTE13P6
C10936T/R LOCK CONT ENG 3D11P6
C01442T/R CONT ENG 3D13P6
C10937T/R LOCK CONT ENG 4C11P6
C01441T/R CONT ENG 4 or ENG 4, T/R CONTC13P6
OVERHEAD CIRCUIT BREAKER PANEL
NumberNameLocationPanel Number
C10263FLT CONT ELEC 2L-ACC10P7
C10264FLT CONT ELEC 2L-DCC11P7
C08782FLT CONT ELEC 1L-ACC12P7
C08783FLT CONT ELEC 1L-DCC13P7
C08784FLT CONT ELEC 1R-ACC14P7
C08785FLT CONT ELEC 1R-DCC15P7
C10265FLT CONT ELEC 2R-ACC16P7
C10266FLT CONT ELEC 2R-DCC17P7
CAUTION: ONLY EXTEND OR RETRACT THE FLAPS ELECTRICALLY ONCE IN A FIVE
MINUTE PERIOD TO PREVENT OVERHEATING OF THE MOTOR.
o. In the Flight Compartment, move the flap control lever to the 1-unit detent to extend the LE
flaps.
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
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### Page 25

WARNING: MAKE SURE PERSONS AND EQUIPMENT ARE CLEAR OF THE LE FLAPS
BEFORE THE THRUST REVERSER SLEEVES ARE MOVED MANUALLY.
CAUTION: DO NOT MOVE THE THRUST REVERSER WHILE THE THRUST REVERSER OR
THE CORE COWL PANELS ARE OPEN. DAMAGE TO THE THRUST REVERSER
AND THE CORE COWL PANELS CAN OCCUR.
CAUTION: DO NOT EXTEND THE THRUST REVERSER SLEEVE WHEN THE THRUST
REVERSER IS OPEN MORE THAN 23 DEGREES. DAMAGE TO THE SLEEVE
AND THE STRUT CAN OCCUR.
CAUTION: THE EXTENSION OF THE SLEEVE WITH THE THRUST REVERSER OPEN IS
PERMITTED IN THE 23 DEGREE POSITION ONLY. THE CORE COWL PANELS
MUST BE REMOVED TO EXTEND THE SLEEVE WITH THE THRUST REVERSER
OPEN.
CAUTION: MAKE SURE THERE IS NO EQUIPMENT IN THE AREA BEHIND THE THRUST
REVERSER. DAMAGE CAN OCCUR IF THE THRUST REVERSER HITS THE
EQUIPMENT.
CAUTION: MAKE SURE THE MANUAL DRIVE IS FULLY ENGAGED WITH THE SYNC LOCK
DRIVE SHAFT BEFORE IT IS TURNED. DO NOT USE FORCE TO ENGAGE THE
MANUAL DRIVE. ALSO, MAKE SURE THE MANUAL DRIVE STAYS FULLY
ENGAGED WHILE THE SQUARE DRIVE IS OPERATED. IF THE MANUAL DRIVE
IS NOT FULLY ENGAGED OR IF FORCE IS USED TO ENGAGE IT, DAMAGE TO
THE SYNC LOCK CAN OCCUR.
p. Do the test as follows for the position of the Group A LE flaps during the reverse thrust operation
of the inboard engines:
(1) Manually extend the left or right sleeve on the No.2 and No.3 engine thrust reversers as
follows. Refer to 747-400 AMM 78-34-13 for the location of the sync lock.
(a) Put a 3/8 inch square drive into the end of the manual drive mechanism on the sync
lock:
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
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### Page 26

1) The square drive must be pushed in until it stops and held in that position to
manually disengage the synch lock and engage the manual drive shaft.
2) Make small position adjustments of the manual drive as necessary to align it
with the sync lock drive shaft.
3) If a 3/8 inch square drive cannot be inserted, use a 5/8 inch hex drive on the
outer hex nut and turn counter-clockwise and clockwise a very small amount
until a 3/8 inch square drive can be put in.
CAUTION: MAKE SURE ALL THE ACTUATORS OPERATE CORRECTLY WHEN
THE THRUST REVERSER IS EXTENDED. IF THE FLEXSHAFT BETWEEN
THE ACTUATORS IS BROKEN, OR IS NOT INSTALLED, ONLY THE
BOTTOM ACTUATOR WILL OPERATE. IF THRUST REVERSER
OPERATION CONTINUES WITH THIS CONDITION, DAMAGE TO THE
THRUST REVERSER CAN OCCUR.
(b) At the same time as the sync lock is kept disengaged, turn the square drive to extend
the applicable thrust reverser sleeve to between 0.5 and 2.0 inches:
1) Make sure the square drive is turned in the direction that extends the thrust
reverser sleeve:
a) For the left sleeve, turn the manual drive counter-clockwise.
b) For the right sleeve, turn the manual drive clockwise.
(2) Make sure the LE flaps do not retract.
(3) Manually return the No.2 and No.3 engine thrust reversers to the stowed position.
(a) Make sure the square drive is turned in the direction that retracts the thrust reverser
sleeve.
1) For the left sleeve, turn the manual drive clockwise.
2) For the right sleeve, turn the manual drive counter-clockwise.
q. Do the test as follows for the position of the Group A LE flaps during the reverse thrust operation
of the outboard engines:
(1) Manually extend the left or right sleeve on the No.1 and No.4 engine thrust reversers as
follows. Refer to 747-400 AMM 78-34-13 for the location of the sync lock.
(a) Put a 3/8 inch square drive into the end of the manual drive mechanism on the sync
lock:
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
747-78A2184Revision 1: December 23, 2010
26 of 33
BOEING SERVICE BULLETIN 747-78A2184
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### Page 27

1) The square drive must be pushed in until it stops and held in that position to
manually disengage the synch lock and engage the manual drive shaft.
2) Make small position adjustments of the manual drive as necessary to align it
with the sync lock drive shaft.
3) If a 3/8 inch square drive cannot be inserted, use a 5/8 inch hex drive on the
outer hex nut and turn counter-clockwise and clockwise a very small amount
until a 3/8 inch square drive can be put in.
CAUTION: MAKE SURE ALL THE ACTUATORS OPERATE CORRECTLY WHEN
THE THRUST REVERSER IS EXTENDED. IF THE FLEXSHAFT BETWEEN
THE ACTUATORS IS BROKEN, OR IS NOT INSTALLED, ONLY THE
BOTTOM ACTUATOR WILL OPERATE. IF THRUST REVERSER
OPERATION CONTINUES WITH THIS CONDITION, DAMAGE TO THE
THRUST REVERSER CAN OCCUR.
(b) At the same time as the sync lock is kept disengaged, turn the square drive to extend
the applicable thrust reverser sleeve to between 0.5 and 2.0 inches:
1) Make sure the square drive is turned in the direction that extends the thrust
reverser sleeve:
a) For the left sleeve, turn the manual drive counter-clockwise.
b) For the right sleeve, turn the manual drive clockwise.
(2) Make sure the LE flaps do not retract.
(3) Manually return the No.1 and No.4 engine thrust reversers to the stowed position:
(a) Make sure the square drive is turned in the direction that retracts the thrust reverser
sleeve:
1) For the left sleeve, turn the manual drive clockwise.
2) For the right sleeve, turn the manual drive counter-clockwise.
r. Put the LE flaps back to the normal stowed position.
s. Do the 'Thrust Reverser Activation After Ground Maintenance' for the No.1 thru No.4 engines.
Refer to 747-400 AMM 78-31-00 as an accepted procedure.
t. Do the 'Automatic Speed Brake System Reactivation'. Refer to 747-400 AMM 27-62-00 as
an accepted procedure.
u. Do the 'Group A Leading Edge Flaps during Reverse Thrust Operation - Operational Test'.
Refer to 747-400 AMM 27-81-00 as an accepted procedure.
v. Do the 'Thrust Reverser Operational Test'. Refer to 747-400 AMM 78-31-00 as an accepted
procedure.
8. Put the airplane back to a serviceable condition.
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: January 12, 2010
747-78A2184Revision 1: December 23, 2010
27 of 33
BOEING SERVICE BULLETIN 747-78A2184
ALERTALERT

### Page 28 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
NO. 1 ENGINE
RELAY PANEL
NO. 2 ENGINE
RELAY PANEL
P252 PANEL (NO. 1 AND NO. 2 ENGINES) TYPICAL
FIGURE 1: NO.1 AND NO.2 ENGINE THRUST REVERSER CONTROL WIRING - P252 PANEL ROUTING
(SHEET 1 OF 2)
Original Issue: January 12, 2010
Revision 1 December 23, 2010  BOEING PROPRIETARY -  +8128L-L+L
Copyright © Unpublished Work - See page 1 for details.  EE 1O 87

### Page 29 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
R7311  NO. 1 ENGINE
RELAY PANEL
W2281.  TD17
(W2481)
GROUNDING
BLOCK
NO. 2 ENGINE
RELAY PANEL
R7312
• TD18
W2283
(W2483)
GROUNDING
BLOCK
FWD  1905901
FIGURE 1: NO.1 AND NO.2 ENGINE THRUST REVERSER CONTROL WIRING - P252 PANEL ROUTING
(SHEET 2 OF 2)
Original Issue: January 12, 2010
Revision 1 December 23, 2010  BOEING PROPRIETARY -  747-78A2184
Copyright © Unpublished Work - See page 1 for details.  29 of 33

### Page 30 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
> 2 LOCATIONS  YA30  Ц|' GDX2-S
HAS W2481-108-20  + YC30  R8709
R7311 RLY-T/R  DR7311  D17881J-1+  TD17  RLY-T/R HIV  SEQ ENG 1
STOW ENG 1
1 → 2 LOCATIONS  YA30  •|| GDX4-S
3111C W2483-108-20-  \ R8710
R7312 RLY-T/R  DR7312  D17882J-1 F  / TD18  SEQ ENG 2  RLY-T/R HIV
STOW ENG 2
P252 PANEL-LEFT THRUST REVERSER RELAY
ADDED WIRE OR NEW ROUTING
+ DELETED WIRE OR FORMER ROUTING
EXISTING WIRE
REFERENCE: 747-400 WDM 78-34-12, 747-400 WDM 78-34-22.
The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure.
FLAG
NOTE  NAME  IDENTIFICATION  QTY  MORE DATA
END CAP  BACT63D2  Refer to SWPM 20-30-16 as an
accepted procedure. (a)
2  INSULATION TUBING,  DWP-125-3/16-0  Refer to SWPM 20-10-14 as an
HEAT SHRINKABLE,  accepted procedure.
FLEXIBLE, ADHESIVE
LINED (3/16 INCH DIA.,
0.75 INCH LENGTH)
(a) Refer to SWPM 20-81-12 as an accepted procedure for the disassembly of the DR7311 and DR7312 relay
sockets. Refer to SWPM 20-90-11 as an accepted procedure for the disassembly of the TD17 and TD18
terminal blocks.
FIGURE 2: NO.1 AND NO.2 ENGINE THRUST REVERSER CONTROL WIRING, P252 PANEL - CHANGE
(SHEET 1 OF 1)
Original Issue: January 12, 2010
Revision 1 December 23, 2010  747-78A2184
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.  30 of 33

### Page 31 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
NO. 3 ENGINE
RELAY PANEL
NO. 4 ENGINE
RELAY PANEL
DOOR
(SHOWN OPENED)  1905908
P253 PANEL (NO. 3 AND NO. 4 ENGINES) TYPICAL
FIGURE 3: NO.3 AND NO.4 ENGINE THRUST REVERSER CONTROL WIRING - P253 PANEL ROUTING
(SHEET 1 OF 2)
Original Issue: January 12, 2010
Revision 1 December 23, 2010  747-78A2184
Copyright © Unpublished Work - See page 1 for details.  31 of 33

### Page 32 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
GROUNDING
BLOCK
• TD19
arrrrrrrrr
NO. 3 ENGINE  errrrrr
RELAY PANEL  W2285
(W2485)
R7313
GROUNDING
BLOCK
NO. 4 ENGINE
RELAY PANEL  TD20
W2287
(W2487)
R7314
FWD
TYPICAL  1905910
FIGURE 3: NO.3 AND NO.4 ENGINE THRUST REVERSER CONTROL WIRING - P253 PANEL ROUTING
(SHEET 2 OF 2)
Original issue: January 12, 2010
Revision 1 December 23, 2010  747-78A2184
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.  32 of 33

### Page 33 (OCR)

BOEING SERVICE BULLETIN 747-78A2184
ALERT  ALERT
1 → 2 LOCATIONS  YA30  ЦІ' GDХ4-S
311111CC W228510820-  +/ YC30  1 R8711
RLY-T/R HIV
R7313 RLY-T/R  DR7313  D17883J-1  TD19  SEQ ENG 3
STOW ENG 3
1 → 2 LOCATIONS  • YA30  ЦІ1 GDX2-S
31111C W287108 20-  | R8712
RLY-T/R HIV
R7314 RLY-T/R  DR7314  D17884J-17  / TD20  SEQ ENG 4
STOW ENG 4
P253 PANEL-RIGHT THRUST REVERSER RELAY
• ADDED WIRE OR NEW ROUTING
+ DELETED WIRE OR FORMER ROUTING
- EXISTING WIRE
REFERENCE: 747-400 WDM 78-34-32, 747-400 WDM 78-34-42.
The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure.
FLAG
NOTE  NAME  IDENTIFICATION  QTY  MORE DATA
1  END CAP  BACT63D2  4  Refer to SWPM 20-30-16 as an
accepted procedure. (a)
2  INSULATION TUBING,  DWP-125-3/16-0  2  Refer to SWPM 20-10-14 as an
HEAT SHRINKABLE,  accepted procedure.
FLEXIBLE, ADHESIVE
LINED (3/16 INCH DIA.,
0.75 INCH LENGTH)
(a) Refer to SWPM 20-81-12 as an accepted procedure for the disassembly of the DR7313 and DR7314 relay
sockets. Refer to SWPM 20-90-11 as an accepted procedure for the disassembly of the TD19 and TD20
terminal blocks.
FIGURE 4: NO.3 AND NO.4 ENGINE THRUST REVERSER CONTROL WIRING, P253 PANEL - CHANGE
(SHEET 1 OF 1)
Original Issue: January 12, 2010
Revision 1 December 23, 2010  747-78A2184
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.  33 of 33

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