### Commercial **Airplanes** 

# 747 Service Bulletin **Number: 747-78-2178** Original Issue: January 22, 2009 Revision 1: August 04, 2011 ATA System: 7834 **SUBJECT:** EXHAUST - Thrust Reverser Control System - Rolls Royce RB211-524 Powered Uncommanded Thrust Reverser Unlock Event, 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. 9E991 ECCN: 

## BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2009 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter. Boeing also claims copyright in this document as a compilation and/or collective work. This document includes proprietary information owned by The Boeing Company and/or one or more third parties. Treatment of the document and the information it contains is governed by contract with Boeing. For more information, contact The Boeing Company, P.O. Box 3707, Seattle, Washington 98124. Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner, BBJ, DC-8, DC-9, DC-10, KC-10, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8A, Poseidon and the Boeing livery are all trademarks owned by The Boeing Company; and no trademark license is granted in connection with this document unless provided in writing by Boeing.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 1 of 52 3.0BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 2 of 52 **BOEING SERVICE BULLETIN 747-78-2178**

BLANK PAGE**Table of Contents** Revision Transmittal Sheet............................................ 5 Summary...................................................... 7 1. PLANNING INFORMATION........................................ 9 A. Effectivity................................................ 9 1. Airplanes............................................. 9 2. Spares Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 B. Concurrent Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 C. Reason. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 D. Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 E. Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 F. Approval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 G. Manpower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 H. Weight and Balance Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 I. Electrical Load Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 J. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1. Existing Data:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2. Data supplied with this Service Bulletin:. . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3. Installation Drawings Used in the Preparation of this Service Bulletin:. . . . . . . . . . . 13 K. Publications Affected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 L. Interchangeability and Intermixability of Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2. MATERIAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 A. Material - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 B. Industry Support Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 C. Parts Necessary For Each Airplane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1. Kits/Parts:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2. Parts and Materials Supplied by the Operator:. . . . . . . . . . . . . . . . . . . . . . . . 17 3. Parts Modified and Reidentified:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4. Parts Removed and Not Replaced:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 D. Parts Necessary to Change Spares. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 E. Special Tooling - Price and Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 F. Special Tooling Necessary to do this Service Bulletin. . . . . . . . . . . . . . . . . . . . . . . 17 3. ACCOMPLISHMENT INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A. GENERAL INFORMATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. WORK INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE . 31 FIGURE 2: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1, W2281 WIRING CHANGE . 36 FIGURE 3: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 2, W2283 WIRING CHANGE . 38 FIGURE 4: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND ENGINE 2, RETURN ACCESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE . 42 FIGURE 6: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3, W2285 WIRING CHANGE . 47 FIGURE 7: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 4, W2287 WIRING CHANGE . 49 FIGURE 8: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND ENGINE 4, RETURN ACCESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 3 of 52 **BOEING SERVICE BULLETIN 747-78-2178**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 4 of 52 **BOEING SERVICE BULLETIN 747-78-2178**

BLANK PAGE

### Commercial **Airplanes** 

# 747 Service Bulletin **Revision Transmittal Sheet Number: 747-78-2178**  Original Issue: January 22, 2009 Revision 1: August 04, 2011 ATA System: 7834 **SUBJECT:** EXHAUST - Thrust Reverser Control System - Rolls Royce RB211-524 Powered Uncommanded Thrust Reverser Unlock Event, Change This revision includes all pages of the service bulletin. **COMPLIANCE INFORMATION RELATED TO THIS REVISION** No more work is necessary on the airplane(s) changed in accordance with the original issue of this service bulletin. **REASON FOR REVISION** As a part of a service bulletin validation program, this change was completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue before the release of Revision 1 of this service bulletin. The change completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue is equivalent to the release of Revision 1 of this service bulletin. Airplane RD142 has the configuration of a Group 1 airplane. This service bulletin revision is sent to provide operators with the changed service bulletin after the incorporation of the validation findings. During the modification, findings during testing led to a partial rewrite of the functional test to change the voltage check locations. A maintenance zone table has been added to the service bulletin. The Damage Tolerance Based Structural Inspections impact information was added. These sections were changed: 1. Summary Background, Validation Information added. 2. Paragrapgh 1.C, Reason, Validation Information added. 3. Paragrapgh 1.D, Maintenance Zones table added. 4. Paragrapgh 1.K, Publication Affected The Damage Tolerance Based Structural Inspections impact information added. 5. Section 2.C, Parts Necessary for Each Airplane, replaced several kit parts. 6. Paragrapgh 3.A, General Information, added information about lightweight and heavyweight intermix. 7. Paragrapgh 3.B, Work Instructions, added missing steps and changed voltage check location. 8. FIGURE 2, P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1, W2281 WIRING CHANGE, replaced kit parts with new parts.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 5 of 529. FIGURE 3, P252 PANEL - THRUST REVERSER CONTROL - ENGINE 2, W2283 WIRING CHANGE, replaced kit parts with new parts. 10. FIGURE 6, P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3, W2285 WIRING CHANGE, : 11. FIGURE 7, P253 PANEL - THRUST REVERSER CONTROL - ENGINE 4, W2287 WIRING CHANGE, : 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 22, 2009 Original Issue: August 04, 2011 Revision 1:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 6 of 52 **BOEING SERVICE BULLETIN 747-78-2178**

### Commercial **Airplanes** 

# 747 Service Bulletin **Summary Number: 747-78-2178**  Original Issue: January 22, 2009 Revision 1: August 04, 2011 ATA System: 7834 **SUBJECT:** EXHAUST - Thrust Reverser Control System - Rolls Royce RB211-524 Powered Uncommanded Thrust Reverser Unlock Event, Change **CONCURRENT REQUIREMENTS** Refer to Paragraph 1.B., Concurrent Requirements. **BACKGROUND** This service bulletin gives instructions to change the thrust reverser control logic in the P252 and the P253 panels. The change to the thrust reverser control logic will electrically isolate the number 2 and number 3 locking gear boxes from the air motor brake unlock proximity sensor. This change will prevent the gear box lock solenoids from receiving electrical power to unlock when the air motor brake proximity sensor senses an uncommanded brake disengagement. This is done by the removal of the air motor brake, release relay, from the thrust reverser control circuit. This change also installs a new unstow, time delay relay, for each engine. The position of the air motor brake, as sensed by the brake proximity sensor, will have no effect on the gear box unlock logic. If the change in this service bulletin is not done, then the number 2 locking gearbox can become unlocked with an associated air motor failure. One operator reported that during takeoff roll on an RB211-524 powered 747-400 airplane, the flight crew received the ENG 4 REV LIMTD EICAS status message and the ENG 4 REVERSER advisory and status messages. During climb, the cabin crew saw sparks from the exhaust of the number 4 engine. As a precaution, the flight crew shutdown the number 4 engine and proceeded with an uneventful air turn-back and landing. The event was found to be caused by a failure of the o-rings in the air motor switcher or shutoff solenoid valves because of overheating. This let the air motor shutoff valve open, which released the air motor brake. This, in the ground mode, energized the number 2 and number 3 thrust reverser gear box unlock solenoids and thereby unlocking the number 2 and number 3, gear boxes. As a part of a service bulletin validation program, this change was completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue before the release of Revision 1 of this service bulletin. The change completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue is equivalent to the release of Revision 1 of this service bulletin. Airplane RD142 has the configuration of a Group 1 airplane. Boeing Service Related Problem (SRP) 747-SRP-72-0029 is related to this service bulletin. **ACTION (PRR 85901-75S)** Remove power to the P252 and P253 panels and the thrust reverser systems. Get access to the P252 and P253 panels. Remove two existing relays and relay sockets from each panel. Add two new relays and relay sockets to each panel. Do the given wiring changes. Do continuity and voltage checks for each engine and the thrust reverser operational test. Return access.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 7 of 52**EFFECTIVITY** 747-200B/-200F/-300/SP airplanes powered by Rolls Royce RB211-524 engines with the lightweight thrust reversers. Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplanes. **COMPLIANCE** The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin mandatory. Federal Aviation Administration (FAA) Airworthiness Directive 2000-01-05 is related to service bulletin 747-78-2156. Service bulletin 747-78-2156 is related to this service bulletin. Boeing recommends that the change given in this service bulletin be done within 60 months after the date on this service bulletin. **INDUSTRY SUPPORT INFORMATION** Boeing warranty remedies are not available for the configuration changes given in this service bulletin. **MANPOWER Elapsed Hours**  **Total Task Hours Airplanes**  25 30 Group 1 **MATERIAL INFORMATION** Boeing Supplied Kits/Parts. Refer to Paragraph 2.A., Material - Price and Availability.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 8 of 52 **BOEING SERVICE BULLETIN 747-78-2178**

### Commercial **Airplanes** 

# 747 Service Bulletin **Number: 747-78-2178** Original Issue: January 22, 2009 Revision 1: August 04, 2011 ATA System: 7834 **SUBJECT:** EXHAUST - Thrust Reverser Control System - Rolls Royce RB211-524 Powered Uncommanded Thrust Reverser Unlock Event, Change **1. PLANNING INFORMATION A. Effectivity**  1. Airplanes This service bulletin is for the airplanes shown below. An equivalent change is on subsequent production airplanes. Refer to PRR 85901-75S for data about this change. Refer to Service Bulletin Index Document D6-30300 Part 3 for Airplane Variable Number, Line Number, and Serial Number data. **DESCRIPTION CONFIGURATION**  **GROUP** 747-200/-300/SP airplanes powered by Rolls Royce RB211-524 engines with the light weight thrust reversers. - 1

Airplane Models: 747-200B, 747-200F, 747-300, 747SP **Group Variable Number**  1 RB411 - RB413 1 RD131 - RD132 1 RD135 - RD138 1 RD141 - RD144 1 RD311 1 RD356 - RD358 1 RD471 - RD475 1 RH101 - RH102 1 RR441 - RR442

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 9 of 52**Group Variable Number**  1 RR526 1 RR531 1 RS271 - RS276 1 RS301 - RS306 1 RS311 - RS320 2. Spares Affected None. **B. Concurrent Requirements** The service bulletin listed below must be done before or at the same time as this service bulletin: **Description Service Bulletin**  **Company** Gives the instruction to install an additional locking system on the thrust reversers. 747-78-2156, Original Issue or Revision 1 Boeing

**C. Reason** This service bulletin gives instructions to change the thrust reverser control logic in the P252 and the P253 panels. The change to the thrust reverser control logic will electrically isolate the number 2 and number 3 locking gear boxes from the air motor brake, unlock proximity sensor. This change will prevent the gear box lock solenoids from receiving electrical power to unlock when the air motor brake proximity sensor senses an uncommanded brake disengagement. This is done by the removal of the air motor brake, release relay, from the thrust reverser control circuit. This change also installs a new unstow, time delay relay, for each engine. The position of the air motor brake, as sensed by the brake proximity sensor, will have no effect on the gear box unlock logic. If the change in this service bulletin is not done, then the number 2 locking gearbox can become unlocked with an associated air motor failure. One operator reported that during takeoff roll on an RB211-524 powered 747-400 airplane, the flight crew received the ENG 4 REV LIMTD EICAS status message and the ENG 4 REVERSER advisory and status messages. During climb, the cabin crew saw sparks from the exhaust of the number 4 engine. As a precaution, the flight crew shutdown the number 4 engine and proceeded with an uneventful air turn-back and landing. The event was found to be caused by a failure of the o-rings in the air motor switcher or shutoff solenoid valves because of overheating. This let the air motor shutoff valve open, which released the air motor brake. This, in the ground mode, energized the number 2 and number 3 thrust reverser gear box unlock solenoids and thereby unlocking the number 2 and number 3, gear boxes. As a part of a service bulletin validation program, this change was completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue before the release of Revision 1 of this service bulletin. The change completed on airplane RD142 by Service Bulletin 747-78-2178 Original Issue is equivalent to the release of Revision 1 of this service bulletin. Airplane RD142 has the configuration of a Group 1 airplane.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 10 of 52 **BOEING SERVICE BULLETIN 747-78-2178**Revision 1 is sent to provide operators with the changed service bulletin after the incorporation of the validation findings. During the modification, findings during testing led to a partial rewrite of the functional test to change the voltage check locations. A maintenance zone table has been added to the service bulletin. The Damage Tolerance Based Structural Inspections impact information was added. Boeing Service Related Problem (SRP) 747-SRP-72-0029 is related to this service bulletin. **D. Description** Remove power to the P252 and P253 panels and the thrust reverser systems. Get access to the P252 and P253 panels. Remove two existing relays and relay sockets from each panel. Add two new relays and relay sockets to each panel. Do the given wiring changes. Do continuity and voltage checks for each engine and the thrust reverser operational test. Return access. No more work is necessary on the airplane(s) 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 Zone**  **Model** 115, 116, 117, 118 747-200B, 747-200F, 747-300, 747SP **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. Federal Aviation Administration (FAA) Airworthiness Directive 2000-01-05 is related to service bulletin 747-78-2156. Service bulletin 747-78-2156 is related to this service bulletin. Boeing recommends that the change given in this service bulletin be done within 60 months after the date on 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 11 of 52 **BOEING SERVICE BULLETIN 747-78-2178**In addition, the Manager of the FAA Seattle Aircraft Certification Office approves the action (i.e. inspection or modification) defined in this service bulletin as an alternative method of compliance to the requirements of paragraph (c) of FAA AD 2000-01-05. All provisions of FAA AD 2000-01-05 that are not specifically referenced in the above statement remain fully applicable and must be complied with. **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 examine the work — Time to cure the materials — Time to make the parts — Time to find the tools. This estimate does not include the task-hour data given in the service bulletins in Paragraph 1.B., Concurrent Requirements. **Elapsed Hours Task-Hours**  **Number of Per- sons**  **Task**
0.25 0.25 1 Open Access 1.0 1.0 1 Figure 1 4.25 4.25 1 Figure 2 4.25 4.25 1 Figure 3 0.25 0.25 1 Figure 4 1.0 1.0 1 Figure 5 4.25 4.25 1 Figure 6 4.25 4.25 1 Figure 7 0.25 0.25 1 Figure 8 0.25 0.25 1 Close Access 5 10 2 Continuity Checks and Functional Tests 25 30 TOTAL FOR EACH AIRPLANE **H. Weight and Balance Changes Change in Moment**  **(Pound-Inches) Change in Weight**  **(Pounds) Airplane** 
+315.0 +0.9 747-200, 747-300 +495.0 +0.9 747 SP

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 12 of 52 **BOEING SERVICE BULLETIN 747-78-2178 I. Electrical Load Data**  Not applicable. **J. References** 1. Existing Data: a. Engineering Change Memo PRR 85901-75S b. 747-100/200/300 Aircraft Maintenance Manual (AMM) 24-22-00, 36-00-00, 78-30-00, 78-30-01 c. 747 Wiring Diagram 78-34-12, 78-34-22, 78-34-32, 78-34-42 d. Standard Wiring Practices Manual SWPM 20-00-13, 20-10-11, 20-10-12, 20-10-19, 20-61-11, 20-81-12, 20-81-22, 20-90-11, 20-90-15 e. Standard Overhaul Practices Manual (SOPM) 20-50-05, 20-50-10 f. Service Related Problem (SRP) 747-SRP-72-0029 g. Boeing Service Bulletin 747-78-2156 h. Federal Aviation Administration (FAA) Airworthiness Directive 2000-01-05 i. Boeing Drawing 012W6100 2. Data supplied with this Service Bulletin: None. 3. Installation Drawings Used in the Preparation of this Service Bulletin: None. **K. Publications Affected** 1. Publications: **Chapter-Section Publication**  78-34-12, 78-34-22, 78-34-32, 78-34-42 747 Wiring Diagram 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 13 of 52 **BOEING SERVICE BULLETIN 747-78-2178 Chapter-Section**  **Publication** 78-34-12, 78-34-22, 78-34-32, 78-34-42 747 Wiring Diagram Manual **L. Interchangeability and Intermixability of Parts** Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 14 of 52 **BOEING SERVICE BULLETIN 747-78-2178 2. MATERIAL INFORMATION**  **A. Material - Price and Availability** Boeing can supply the kits shown in Paragraph 2.C., Parts Necessary For Each Airplane. If there is a limit to the quantity (QTY) of available kits, a supply sequence is given by Spares. More kits become available as shown in the Reorder Lead Time (ROLT). ROLT is calculated from the date Boeing gets the purchase order. The kits are subject to the terms and conditions of the Boeing standard purchase order acknowledgment. After the Unit Price date, new price and ROLT data is applicable. 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. Spares Customer Support - MC 36-65 Boeing Spares Department P.O. Box 3707 Seattle, Washington 98124-2207 USA **Unit Price thru Apr 30, 2008**  **ROLT (Weeks)**  **QTY Date**  **Name Kit Number**  $4,289 22 1 November 8, 2007 Top Kit 015U1820-3 **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: **NOTE:**One top kit and the items shown in Paragraph 2.C.2., Parts and Materials Supplied by the Operator, are necessary for each airplane. To get the kits/parts shown below, refer to Paragraph 2.A., Material - Price and Availability. **Kit 015U1820-3 Notes**  **Name QTY**  **New Part Number -3**  TOP KIT - RR Powered 747 Uncommanded Thrust Reverser Unlock Events - 015U1820-3 LACING TAPE - WHITE (135C) 100 FT 1 289T9001-91 ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 1 (W2281) 1 61B20562-101

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 15 of 52 **BOEING SERVICE BULLETIN 747-78-2178 Kit 015U1820-3**  **Notes Name**  **QTY New Part Number**  **-3** ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 2 (W2283) 1 61B20562-102
ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 3 (W2285) 1 61B20562-103
ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 4 (W2287) 1 61B20562-104 TAPE, ID 4 BACT19J2 TIME DELAY RELAY 4 TDH-8120-1001
**Wire Kit 61B20562 Notes**  **Name QTY**  **New Part Number -101**  **-102 -103**  **-104** WIRE KIT - ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 1 (W2281) - . . . 61B20562-101

WIRE KIT - ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 2 (W2283) . - . . 61B20562-102

WIRE KIT - ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 3 (W2285) . . - . 61B20562-103

WIRE KIT - ROLLS ROYCE POWERED 747 UNCOMMANDED THRUST REVERSER UNLOCK ENG 4 (W2287) . . . - 61B20562-104

WIRE CUT & CODE 1

. . . 61B20562-101W WIRE CUT & CODE

. 1

. . 61B20562-102W WIRE CUT & CODE

. . 1

. 61B20562-103W WIRE CUT & CODE

. . . 1 61B20562-104W I.D. TAPE 1

. . . 61B20562-10101 I.D. TAPE

. 1

. . 61B20562-10201 I.D. TAPE

. . 1

. 61B20562-10301 I.D. TAPE

. . . 1 61B20562-10401 (a) CONTACT, SOCKET 3 3 3 3 BACC47CP1 (a) CONTACT, PIN 7 7 7 7 M39029/11-145 (a) CONTACT, SOCKET 7 7 7 7 BACC47DJ1

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 16 of 52 **BOEING SERVICE BULLETIN 747-78-2178 Wire Kit 61B20562**  **Notes Name**  **QTY New Part Number**  **-101 -102**  **-103 -104**  (a) SLEEVE, SOLDER (HEAT SHRINK) 3 3 3 3 BACS13CT2C (a) SLEEVE, SOLDER (HEAT SHRINK) 2 2 2 2 BACS13CT3N RELAY SOCKET 1 1 1 1 BACS16W5A (a) CONTACT, PIN, SIZE 20 4 4 4 4 S280W555-920 (a) There are more parts than are necessary. 2. Parts and Materials Supplied by the Operator: None. 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.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 17 of 52 **BOEING SERVICE BULLETIN 747-78-2178**BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 18 of 52 **BOEING SERVICE BULLETIN 747-78-2178**

BLANK PAGE**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. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for definition of the acronyms. 2. Obey all of the warnings and cautions given in the specified manual sections. 3. Unless shown differently, these dimensions and tolerances are used: — Linear dimensions are in inches — Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch. — Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch — Angular tolerance is plus or minus 2 degrees — Hole dimensions for standard solid rivets are given in 747 Structural Repair Manual, Chapter 51 — Torque limits to tighten nuts and bolts are given in 747 Structural Repair Manual, Chapter 51. 4. For approved fastener and process material substitutions, refer to 747 Structural Repair Manual, Chapter 51, Alternate fasteners are given in 747 Structural Repair Manual Chapter 51 and Boeing Drawing 012W6100. 5. Refer to the Boeing Standard Wiring Practices Manuals SWPM 20-10-11, SWPM 20-10-12 and SWPM 20-10-19 for the wire installation procedures. 6. If the length of fasteners specified in this service bulletin do not meet the installation standards, fasteners of the same specification, or an approved substitute, one grip length longer or shorter may be used. 7. These work instructions refer to procedures included on 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. 8. Because intermix of lightweight and heavyweight thrust reversers is allowed on the same aircraft, the aircraft wiring for the lightweight configuration should be changed even though a heavyweight thrust reverser is installed, since there is the capability for a lightweight reverser to be installed on the plane. The functional test should pass even if a heavyweight thrust reverser is installed. When the heavyweight thrust reverser is replaced with a lightweight thrust reverser, the operator must successfully complete the functional test in this service bulletin for that engine prior to dispatch or lock out the reverser per the Master Minimum Equipment List (MMEL) until the functional test in this service bulletin is successfully completed.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 19 of 52 **BOEING SERVICE BULLETIN 747-78-2178 B. WORK INSTRUCTIONS**  1. Open these circuit breakers on the P6 and P12 panels. Install safety tags. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 1 C10934 T/R LOCK CONT ENG 2 C10935 **P12 Overhead Circuit Breaker Panel Name**  **Circuit Breaker Number** T/R IND ENG 1 C00405 T/R CONT ENG 1 C01703 T/R IND ENG 2 C00402 T/R CONT ENG 2 C01704 2. Get access to the P252 Panel. Remove two relays and relay sockets, and install two relays and relay sockets, as given in Figure 1. • R8965 - Relay, Thrust Reverser Unstowed Engine 1 • R8966 - Relay, Thrust Reverser Unstowed Engine 2 3. Do the W2281 wiring changes in the P252 Panel, as given in Figure 2. 4. Do the W2283 wiring changes in the P252 Panel, as given in Figure 3. 5. Open these circuit breakers on the P6 and P12 panels. Install safety tags. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 3 C10936 T/R LOCK CONT ENG 4 C10937 **P12 Overhead Circuit Breaker Panel Name**  **Circuit Breaker Number** T/R IND ENG 3 C00403 T/R CONT ENG 3 C01442 T/R IND ENG 4 C00404 T/R CONT ENG 4 C01441

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 20 of 52 **BOEING SERVICE BULLETIN 747-78-2178**6. Get access to the P253 Panel. Remove two relays and relay sockets, and install two relays and relay sockets, as given in Figure 5. • R8967 - Relay, Thrust Reverser Unstowed Engine 3 • R8968 - Relay, Thrust Reverser Unstowed Engine 4 7. Do the W2285 wiring changes in the P253 Panel, as given in Figure 6. 8. Do the W2287 wiring changes in the P253 Panel, as given in Figure 7. 9. Close these circuit breakers on the P6 and P12 panels. Remove the safety tags. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number**T/R LOCK CONT ENG 1 C10934 T/R LOCK CONT ENG 2 C10935 T/R LOCK CONT ENG 3 C10936 T/R LOCK CONT ENG 4 C10937 **P12 Overhead Circuit Breaker Panel Name**  **Circuit Breaker Number** T/R IND ENG 1 C00405 T/R CONT ENG 1 C01703 T/R IND ENG 2 C00402 T/R CONT ENG 2 C01704 T/R IND ENG 3 C00403 T/R CONT ENG 3 C01442 T/R IND ENG 4 C00404 T/R CONT ENG 4 C01441 10. Do the following continuity and voltage check for Engine #1. a. Make sure that there is electrical power applied to the airplane. Refer to 747-100/200/300 AMM 24-22-00, as an accepted procedure. b. Open this circuit breaker on the P6 Panel and install a safety tag.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 21 of 52 **BOEING SERVICE BULLETIN 747-78-2178 P6 Main Power Distribution Panel**  **Name Circuit Breaker Number**  T/R LOCK CONT ENG 1 C10934 c. Disconnect the connector D17821P from the P252 Panel. d. Remove the relays R8021, R8685 and R8965 from the P252 Panel. e. Do a wiring continuity check to make sure there is continuity (less than 7.5 ohms) between the connector pins given in the table below. All continuity check locations are in the P252 Panel except as noted. **Pin # TO**  **Pin # FROM**  17 D17820 33 D17821J B1 DR8965 33 D17821J B2 DR8965 6 D17821J C1 DR8965 B2 DR8021 X1 DR8965 30 D17821J A2 DR8685 30 D17821J B1 DR8021 30 D17821J X1 DR8021 30 D17821J X1 DR8685 22 D17821J A1 DR8685 22 D17821J f. Do a wiring continuity check to make sure there is NOT continuity between the connector pins given in the table below. All continuity checks are in the P252 Panel. **Pin # TO**  **Pin # FROM**  B2 DR8021 33 D17821J B1 DR8021 6 D17821J X1 DR8021 22 D17821J X1 DR8021 X1 DR8685 X1 DR8021 A1 DR8965 g. Connect the connector D17821P to the P252 panel. h. Install the relays R8021, R8685 and R8965 from the P252 Panel. i. Make sure the applicable thrust reverser is fully stowed.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 22 of 52 **BOEING SERVICE BULLETIN 747-78-2178**j. Make sure pneumatic pressure is not applied to the airplane. To remove pneumatic pressure refer to 747-100/200/300 AMM 36-00-00, as an accepted procedure. k. Release the air motor brake. Pull the air motor brake manual release handle forward and rotate counterclockwise to lock in the released position. l. Set the air motor manual override switch to CLOSED. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. m. Close this circuit breaker on the P6 Panel and remove the safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number**T/R LOCK CONT ENG 1 C10934 n. Measure these voltages: (1) Make sure that there are 0 - 1.5 volts between terminal block TBD17, position Z7, and a ground in the P252 panel. (2) Make sure that there are more than 24 volts between pin number 1 and pin number 2 at connector DV225 (Gear Box Lock Solenoid Number 3). o. Manually drive the thrust reverser cowl approximately 2 inches in the deploy direction. p. Measure this voltage: (1) Make sure that there are more than 24 volts between terminal block TBD17, position Z7, and a ground in the P252 panel. q. Manually drive the thrust reverser cowl to the fully stowed and locked position. Then after 1 second, measure this voltage: (1) Make sure that there are 0 - 1.5 volts between terminal block TBD17, position Z7, and a ground in the P252 panel. r. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 1 C10934 s. Unlock the gear boxes and manually stow the thrust reverser. t. Manually engage the air motor brake. Pull the air motor brake manual release handle forward and rotate clockwise to lock in the engaged position. u. Set the air motor manual override switch to OPEN.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 23 of 52 **BOEING SERVICE BULLETIN 747-78-2178**11. Do the following continuity and voltage check for Engine #2. a. Make sure that there is electrical power applied to the airplane. Refer to 747-100/200/300 AMM 24-22-00, as an accepted procedure. b. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 2 C10935 c. Disconnect the connector D17824P from the P252 Panel. d. Remove the relays R8022, R8686 and R8966 from the P252 Panel. e. Do a wiring continuity check to make sure there is continuity (less than 7.5 ohms) between the connector pins given in the table below. All continuity check locations are in the P252 Panel except as noted. **Pin # TO**  **Pin # FROM**  17 D17823 33 D17824J B1 DR8966 33 D17824J B2 DR8966 6 D17824J C1 DR8966 B2 DR8022 X1 DR8966 30 D17824J A2 DR8686 30 D17824J B1 DR8022 30 D17824J X1 DR8022 30 D17824J X1 DR8686 22 D17824J A1 DR8686 22 D17824J f. Do a wiring continuity check to make sure there is NOT continuity between the connector pins given in the table below. All continuity checks are in the P252 Panel. **Pin # TO**  **Pin # FROM**  B2 DR8022 33 D17824J B1 DR8022 6 D17824J X1 DR8022 22 D17824J X1 DR8022 X1 DR8686 X1 DR8022 A1 DR8966

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 24 of 52 **BOEING SERVICE BULLETIN 747-78-2178**g. Connect the connector D17824P to the P252 panel. h. Install relays R8022, R8686 and R8966. i. Make sure the applicable thrust reverser is fully stowed. j. Make sure pneumatic pressure is not applied to the airplane. To remove pneumatic pressure refer to 747-100/200/300 AMM 36-00-00, as an accepted procedure. k. Release the air motor brake. Pull the air motor brake manual release handle forward and rotate counterclockwise to lock in the released position. l. Set the air motor manual override switch to CLOSED. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. m. Close this circuit breaker on the P6 Panel and remove the safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 2 C10935 n. Measure these voltages: (1) Make sure that there are 0 - 1.5 volts between terminal block TBD18, position Z7, and a ground in the P252 panel. (2) Make sure that there are more than 24 volts between pin number 1 and pin number 2 at connector DV225 (Gear Box Lock Solenoid Number 3). o. Manually drive the thrust reverser cowl approximately 2 inches in the deploy direction. p. Measure this voltage: (1) Make sure that there are more than 24 volts between terminal block TBD18, position Z7, and a ground in the P252 panel. q. Manually drive the thrust reverser cowl to the fully stowed and locked position. Then after 1 second, measure this voltage: (1) Make sure that there are 0 - 1.5 volts between terminal block TBD18, position Z7, and a ground in the P252 panel. r. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 2 C10935

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 25 of 52 **BOEING SERVICE BULLETIN 747-78-2178**s. Unlock the gear boxes and manually stow the thrust reverser. t. Manually engage the air motor brake. Pull the air motor brake manual release handle forward and rotate clockwise to lock in the engaged position. u. Set the air motor manual override switch to OPEN. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. 12. Close access to the P252 Panel, as given in Figure 4. 13. Do the following continuity and voltage check for Engine #3. a. Make sure that there is electrical power applied to the airplane. Refer to 747-100/200/300 AMM 24-22-00, as an accepted procedure. b. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 3 C10936 c. Disconnect the connector D17827P from the P253 Panel. d. Remove the relays R8023, R8687 and R8967 from the P253 Panel. e. Do a wiring continuity check to make sure there is continuity (less than 7.5 ohms) between the connector pins given in the table below. All continuity check locations are in the P253 Panel except as noted. **Pin # TO**  **Pin # FROM**  17 D17826 33 D17827J B1 DR8967 33 D17827J B2 DR8967 6 D17827J C1 DR8967 B2 DR8023 X1 DR8967 30 D17827J A2 DR8687 30 D17827J B1 DR8023 30 D17827J X1 DR8023 30 D17827J X1 DR8687 22 D17827J A1 DR8687 22 D17827J f. Do a wiring continuity check to make sure there is NOT continuity between the connector pins given in the table below. All continuity checks are in the P253 Panel.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 26 of 52 **BOEING SERVICE BULLETIN 747-78-2178 Pin #**  **TO Pin #**  **FROM** B2 DR8023 33 D17827J B1 DR8023 6 D17827J X1 DR8023 22 D17827J X1 DR8023 X1 DR8687 X1 DR8023 A1 DR8967 g. Connect the connector D17827P to the P253 panel. h. Install relays R8023, R8687 and R8967. i. Make sure the applicable thrust reverser is fully stowed. j. Make sure pneumatic pressure is not applied to the airplane. To remove pneumatic pressure refer to 747-100/200/300 AMM 36-00-00, as an accepted procedure. k. Release the air motor brake. Pull the air motor brake manual release handle forward and rotate counterclockwise to lock in the released position. l. Set the air motor manual override switch to CLOSED. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. m. Close this circuit breaker on the P6 Panel and remove the safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 3 C10936 n. Measure these voltages: (1) Make sure that there is 0 - 1.5 volts between terminal block TBD19, position Z7, and a ground in the P253 panel. (2) Make sure that there are more than 24 volts between pin number 1 and pin number 2 at connector DV225 (Gear Box Lock Solenoid Number 3). o. Manually drive the thrust reverser cowl approximately 2 inches in the deploy direction. p. Measure this voltage: (1) Make sure that there is more than 24 volts between terminal block TBD19, position Z7, and a ground in the P253 panel. q. Manually drive the thrust reverser cowl to the fully stowed and locked position. Then after 1 second, measure this voltage:

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 27 of 52 **BOEING SERVICE BULLETIN 747-78-2178**(1) Make sure that there is 0 - 1.5 volts between terminal block TBD19, position Z7, and a ground in the P253 panel. r. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 3 C10936 s. Unlock the gear boxes and manually stow the thrust reverser. t. Manually engage the air motor brake. Pull the air motor brake manual release handle forward and rotate clockwise to lock in the engaged position. u. Set the air motor manual override switch to OPEN. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. 14. Do the following continuity and voltage check for Engine #4. a. Make sure that there is electrical power applied to the airplane. Refer to 747-100/200/300 AMM 24-22-00, as an accepted procedure. b. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 4 C10937 c. Disconnect the connector D17830P from the P253 Panel. d. Remove the relays R8024, R8688 and R8968 from the P253 Panel. e. Do a wiring continuity check to make sure there is continuity (less than 7.5 ohms) between the connector pins given in the table below. All continuity check locations are in the P253 Panel except as noted. **Pin # TO**  **Pin # FROM**  17 D17829 33 D17830J B1 DR8968 33 D17830J B2 DR8968 6 D17830J C1 DR8968 B2 DR8024 X1 DR8968 30 D17830J A2 DR8688 30 D17830J B1 DR8024 30 D17830J

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 28 of 52 **BOEING SERVICE BULLETIN 747-78-2178 Pin #**  **TO Pin #**  **FROM** X1 DR8024 30 D17830J X1 DR8688 22 D17830J A1 DR8688 22 D17830J f. Do a wiring continuity check to make sure there is NOT continuity between the connector pins given in the table below. All continuity checks are in the P253 Panel. **Pin # TO**  **Pin # FROM**  B2 DR8024 33 D17830J B1 DR8024 6 D17830J X1 DR8024 22 D17830J X1 DR8024 X1 DR8688 X1 DR8024 A1 DR8968 g. Connect the connector D17830P to the P253 panel. h. Install relays R8024, R8688 and R8968. i. Make sure the applicable thrust reverser is fully stowed. j. Make sure pneumatic pressure is not applied to the airplane. To remove pneumatic pressure refer to 747-100/200/300 AMM 36-00-00, as an accepted procedure. k. Release the air motor brake. Pull the air motor brake manual release handle forward and rotate counterclockwise to lock in the released position. l. Set the air motor manual override switch to CLOSED. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. m. Close this circuit breaker on the P6 Panel and remove the safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 4 C10937 n. Measure these voltages: (1) Make sure that there is 0 - 1.5 volts between terminal block TBD20, position Z7, and a ground in the P253 panel. (2) Make sure that there are more than 24 volts between pin number 1 and pin number 2 at connector DV225 (Gear Box Lock Solenoid Number 3). o. Manually drive the thrust reverser cowl approximately 2 inches in the deploy direction.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 29 of 52 **BOEING SERVICE BULLETIN 747-78-2178**p. Measure this voltage: (1) Make sure that there is more than 24 volts between terminal block TBD20, position Z7, and a ground in the P253 panel. q. Manually drive the thrust reverser cowl to the fully stowed and locked position. Then after 1 second, measure this voltage: (1) Make sure that there is 0 - 1.5 volts between terminal block TBD20, position Z7, and a ground in the P253 panel. r. Open this circuit breaker on the P6 Panel and install a safety tag. **P6 Main Power Distribution Panel Name**  **Circuit Breaker Number** T/R LOCK CONT ENG 4 C10937 s. Unlock the gear boxes and manually stow the thrust reverser. t. Manually engage the air motor brake. Pull the air motor brake manual release handle forward and rotate clockwise to lock in the engaged position. u. Set the air motor manual override switch to OPEN. Refer to 747-100/200/300 AMM 78-30-01, as an accepted procedure. 15. Return access to the P253 Panel, as given in Figure 8. 16. Do the Thrust Reverser Operational Test as given in 747-100/200/300 AMM 78-30-00. 17. Put the airplane back to a serviceable condition.

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1: August 04, 2011 30 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE**  **(SHEET 1 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 31 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE**  **(SHEET 2 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 32 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE**  **(SHEET 3 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 33 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each airplane. The parts necessary to do this figure are found in Top Kit 015U1820-3, wire kit 61B20562-101 and wire kit 61B20562-102. **NOTE:**The relay panel assemblies that hold the relays must not be installed when this figure is completed, because there are wiring changes done behind these panels. The return access to the P252 Panel will do this work in a separate figure. **MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP** 

- 1
- P252 Panel Access 1

- 1
- P252 Panel Door Open 2

- 1
- Relay (R1269) Remove 3

- 4
- Screws Remove/Keep 4 to get access to remove the relay socket. Support the relay panel as necessary to not put strain on the wire bundle. 1
- Panel Assembly Move 5

(a) 1
- Relay Socket Remove 6 (a) (b) 1 BACS16W5A Relay Socket Install (New) 7 (b) 1 TDH-8120-1001 Relay (R8965) Install (New) 8 with relay number R1269. 1
- I.D. Tape Remove 9 below the new relay. Refer toSOPM 20-50-05, as an accepted procedure. 1 BACT19J2 I.D. Tape Install (New) 10
to the I.D. Tape. Refer toSOPM 20-50-10, as an accepted procedure. 1 R8965 Relay Number Apply 11

- 1
- Relay (R1270) Remove 12

- 4
- Screws Remove/Keep 13 to get access to remove a relay socket. Support the relay panel as necessary to not put strain on the wire bundle. 1
- Panel Assembly Move 14

(a) 1
- Relay Socket Remove 15 (a) (b) 1 BACS16W5A Relay Socket Install (New) 16 (b) 1 TDH-8120-1001 Relay (R8966) Install (New) 17 with relay number R1270. 1
- I.D. Tape Remove 18

**FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE (SHEET 4 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 34 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** below the new relay. Refer toSOPM 20-50-05, as an accepted procedure. 1 BACT19J2 I.D. Tape Install (New) 19
to the I.D. Tape. Refer toSOPM 20-50-10, as an accepted procedure. 1 R8966 Relay Number Apply 20
The wires that are disconnected to remove the relay socket will not be put back into the new relay socket at this time. These wires are changed in a separate figure in this service bulletin. (a) The fasteners necessary to install the relay socket and the relay are provided with the new relay socket. Refer to SWPM 20-81-22, as an accepted procedure. (b)

**FIGURE 1: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND 2, RELAY CHANGE (SHEET 5 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 35 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure. The parts necessary to do this figure are found in wire kit 61B20562-101 and Top Kit 015U1820-3.

**FIGURE 2: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1, W2281 WIRING CHANGE (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 36 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME FLAG**  **NOTE** Refer to SWPM 20-61-11, as an accepted procedure. 2 BACC47CP1 CONTACT, SOCKET 1 Refer to SWPM 20-81-12, as an accepted procedure. 6 BACC47DJ1 CONTACT, SOCKET 2 Refer to SWPM 20-90-15, as an accepted procedure. 3 S280W555-920 CONTACT 3

- 2 BACS13CT2C SLEEVE, SOLDER 4

- 1 BACS13CT3N SLEEVE, SOLDER 5 Refer to SWPM 20-90-11, as an accepted procedure. 6 M39029/11-145 CONTACT, PIN 6
DR8965 M/W R8965 1 61B20562-10101 I.D. TAPE 7 BMS 13-54, Color White. Operator can use an equivalent material. Refer to SWPM 20-10-19, as an accepted procedure. - 289T9001-91 LACING TAPE 8

**WIRE INFORMATION TABLE FOR 61B20562-101W CUT LENGTH (inches)**  **TYPE CODE MATERIAL SPECIFICATION**  **WIRE NUMBER** 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-098-20 30 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-099-20 24 PQ BMS 13-48, TYPE 3, CLASS 1, AWG 20 W2281-147-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-148-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-149-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-150-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2281-151-20

**FIGURE 2: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1, W2281 WIRING CHANGE (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 37 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure. The parts necessary to do this figure are found in wire kit 61B20562-102 and Top Kit 015U1820-3.

**FIGURE 3: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 2, W2283 WIRING CHANGE (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 38 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME FLAG**  **NOTE** Refer to SWPM 20-61-11, as an accepted procedure. 2 BACC47CP1 CONTACT, SOCKET 1 Refer to SWPM 20-81-12, as an accepted procedure. 6 BACC47DJ1 CONTACT, SOCKET 2 Refer to SWPM 20-90-15, as an accepted procedure. 3 S280W555-920 CONTACT 3

- 2 BACS13CT2C SLEEVE, SOLDER 4

- 1 BACS13CT3N SLEEVE, SOLDER 5 Refer to SWPM 20-90-11, as an accepted procedure. 6 M39029/11-145 CONTACT, PIN 6
DR8966 M/W R8966 1 61B20562-10201 I.D. TAPE 7 BMS 13-54, Color White. Operators can use an equivalent material. Refer to SWPM 20-10-19, as an accepted procedure. - 289T9001-91 LACING TAPE 8

**WIRE INFORMATION TABLE FOR 61B20562-102W CUT LENGTH (inches)**  **TYPE CODE MATERIAL SPECIFICATION**  **WIRE NUMBER** 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-098-20 30 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-099-20 24 PQ BMS 13-48, TYPE 3, CLASS 1, AWG 20 W2283-147-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-148-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-149-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-150-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2283-151-20

**FIGURE 3: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 2, W2283 WIRING CHANGE (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 39 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each airplane.

**FIGURE 4: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND ENGINE 2, RETURN ACCESS (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 40 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** back to their initial position. 2
- Panel Assembly Put 1

- 8
- Screws Install (Kept) 2

- 1
- P252 Panel Door Close 3

**FIGURE 4: P252 PANEL - THRUST REVERSER CONTROL - ENGINE 1 AND ENGINE 2, RETURN ACCESS (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 41 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE**  **(SHEET 1 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 42 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE**  **(SHEET 2 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 43 of 52 **BOEING SERVICE BULLETIN 747-78-2178 FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE**  **(SHEET 3 OF 5)**

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 44 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each airplane. The parts necessary to do this figure are found in Top Kit 015U1820-3, wire kit 61B20562-103 and wire kit 61B20562-104. **NOTE:**The relay panel assemblies that hold the relays must not be installed when this figure is completed, because there are wiring changes done behind these panels. The return access to the P253 Panel will do this work in a separate figure. **MORE DATA QTY**  **IDENTIFICATION NAME**  **TASK STEP** 

- 1
- P253 Panel Access 1

- 1
- P253 Panel Door Open 2

- 1
- Relay (R1271) Remove 3

- 4
- Screws Remove/Keep 4 to get access to remove therelay socket. Support the relay panel as necessary to not put strain on the wire bundle. 1
- Panel Assembly Move 5

(a) 1
- Relay Socket Remove 6 (a) (b) 1 BACS16W5A Relay Socket Install (New) 7 (b) 1 TDH-8120-1001 Relay (R8967) Install (New) 8 with relay number R1271. 1
- I.D. Tape Remove 9 below the new relay. Refer to SOPM 20-50-05 1 BACT19J2 I.D. Tape Install (New) 10 to the I.D. Tape. Refer toSOPM 20-50-10, as an accepted procedure. 1 R8967 Relay Number Apply 11

- 1
- Relay (R1272) Remove 12

- 4
- Screws Remove/Keep 13 to get access to remove a relay socket. Support the relay panel as necessary to not put strain on the wire bundle. 1
- Panel Assembly Move 14

(a) 1
- Relay Socket Remove 15 (a) (b) 1 BACS16W5A Relay Socket Install (New) 16 (b) 1 TDH-8120-1001 Relay (R8968) Install (New) 17 with relay number R1272. 1
- I.D. Tape Remove 18 below the new relay. Refer toSOPM 20-50-05, as an accepted procedure. 1 BACT19J2 I.D. Tape Install (New) 19

**FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE (SHEET 4 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 45 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** to the I.D. Tape. Refer toSOPM 20-50-10, as an accepted procedure. 1 R8968 Relay Number Apply 20
The wires that are disconnected to remove the relay socket will not be put back into the new relay socket at this time. These wires are changed in a separate figure in this service bulletin. (a) The fasteners necessary to install the relay socket and the relay are provided with the new relay socket. Refer to SWPM 20-81-22, as an accepted procedure. (b)

**FIGURE 5: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND 4, RELAY CHANGE (SHEET 5 OF 5)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 46 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure. The parts necessary to do this figure are found in wire kit 61B20562-103 and Top Kit 015U1820-3.

**FIGURE 6: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3, W2285 WIRING CHANGE (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 47 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME FLAG**  **NOTE** Refer to SWPM 20-61-11, as an accepted procedure. 2 BACC47CP1 CONTACT, SOCKET 1 Refer to SWPM 20-81-12, as an accepted procedure. 6 BACC47DJ1 CONTACT, SOCKET 2 Refer to SWPM 20-90-15, as an accepted procedure. 3 S280W555-920 CONTACT 3

- 2 BACS13CT2C SLEEVE, SOLDER 4

- 1 BACS13CT3N SLEEVE, SOLDER 5 Refer to SWPM 20-90-11, as an accepted procedure. 6 M39029/11-145 CONTACT, PIN 6
DR8967 M/W R8967 1 61B20562-10301 I.D. TAPE 7 BMS 13-54, Color White. Operator can use an equivalent material. Refer toSWPM 20-10-19, as an accepted procedure. - 289T9001-91 LACING TAPE 8

**WIRE INFORMATION TABLE FOR 61B20562-103W CUT LENGTH (inches)**  **TYPE CODE MATERIAL SPECIFICATION**  **WIRE NUMBER** 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-098-20 30 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-099-20 24 PQ BMS 13-48, TYPE 3, CLASS 1, AWG 20 W2285-147-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-148-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-149-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-150-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2285-151-20

**FIGURE 6: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3, W2285 WIRING CHANGE (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 48 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The flag note numbers shown below agree with the numbers shown in the flag symbols in the figure. The parts necessary to do this figure are found in wire kit 61B20562-104 and Top Kit 015U1820-3.

**FIGURE 7: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 4, W2287 WIRING CHANGE (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 49 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME FLAG**  **NOTE** Refer to SWPM 20-61-11, as an accepted procedure. 2 BACC47CP1 CONTACT, SOCKET 1 Refer to SWPM 20-81-12, as an accepted procedure. 6 BACC47DJ1 CONTACT, SOCKET 2 Refer to SWPM 20-90-15, as an accepted procedure. 3 S280W555-920 CONTACT 3

- 2 BACS13CT2C SLEEVE, SOLDER 4

- 1 BACS13CT3N SLEEVE, SOLDER 5 Refer to SWPM 20-90-11, as an accepted procedure. 6 M39029/11-145 CONTACT, PIN 6
DR8968 M/W R8968 1 61B20562-10401 I.D. TAPE 7 BMS 13-54, Color White. Operator can use an equivalent material. Refer toSWPM 20-10-19, as an accepted procedure. - 289T9001-91 LACING TAPE 8

**WIRE INFORMATION TABLE FOR 61B20562-104W CUT LENGTH (inches)**  **TYPE CODE MATERIAL SPECIFICATION**  **WIRE NUMBER** 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-098-20 30 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-099-20 24 PQ BMS 13-48, TYPE 3, CLASS 1, AWG 20 W2287-147-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-148-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-149-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-150-20 24 PA BMS 13-48, TYPE 10, CLASS 1, AWG 20 W2287-151-20

**FIGURE 7: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 4, W2287 WIRING CHANGE (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 50 of 52 **BOEING SERVICE BULLETIN 747-78-2178**The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY numbers shown below are the number of parts necessary for each airplane.

**FIGURE 8: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND ENGINE 4, RETURN ACCESS (SHEET 1 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 51 of 52 **BOEING SERVICE BULLETIN 747-78-2178 MORE DATA**  **QTY IDENTIFICATION**  **NAME TASK**  **STEP** back to their initial position. 2
- Panel Assembly Put 1

- 8
- Screws Install (Kept) 2

- 1
- P253 Panel Door Close 3

**FIGURE 8: P253 PANEL - THRUST REVERSER CONTROL - ENGINE 3 AND ENGINE 4, RETURN ACCESS (SHEET 2 OF 2)** 

BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: January 22, 2009 747-78-2178 Revision 1 August 04, 2011 52 of 52 **BOEING SERVICE BULLETIN 747-78-2178**