# Boeing Alert Service Bulletin 777-34A0191: Revision 1 - Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2014-0125; AD 2014-05-05 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Boeing Alert Service Bulletin 777-34A0191](https://openairdocs.org/service-documents/boeing/777-34a0191.md) - Title as filed: U.S. DOT/FAA - SB-777-34A0191-01 - Pages: 21 - PDF: https://openairdocs.org/files/sha256/aa/a8/aaa8bed6ba1d3426f6c01b9e823711d228e0334b24e35899cdfb33e1f8648dba - Page: https://openairdocs.org/service-documents/boeing/777-34a0191/file/aaa8bed6ba1d ## Text Some pages are OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 Commercial Airplanes 777 Service Bulletin ALERT Number: 777-34A0191 Original Issue: September 20, 2011 Revision 1: March 23, 2012 ATA System: 3433 SUBJECT: NAVIGATION - Radio Altimeter System - Radio Altimeter Transceiver Replacement 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all export laws. 9E991ECCN: BOEING PROPRIETARY, CONFIDENTIAL, AND/OR TRADE SECRET Copyright © 2011 The Boeing Company Unpublished Work - All Rights Reserved Boeing claims copyright in each page of this document only to the extent that the page contains copyrightable subject matter.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 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details.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: September 20, 2011 777-34A0191Revision 1: March 23, 2012 1 of 21 2.0 ### Page 2 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 2 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT BLANK PAGE ### Page 3 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 2 D. Description .............................................. 1 3 E. Compliance .............................................. 1 3 F. Approval ............................................... 1 3 G. Manpower .............................................. 1 3 H. Weight and Balance Changes .................................... 1 4 I. Electrical Load Data ......................................... 1 4 J. References .............................................. 1 4 1. Existing Data .......................................... 1 4 2. Data supplied with this Service Bulletin ............................ 1 4 3. Installation Drawings Used in the Preparation of this Service Bulletin ............ 1 4 K. Publications Affected ........................................ 1 5 L. Interchangeability and Intermixability of Parts ........................... 1 5 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 7 D. Parts Necessary to Change Spares ................................. 1 7 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: RADIO ALTIMETER TRANSCEIVER REPLACEMENT ................... 2 0 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 3 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 4 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 4 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT BLANK PAGE ### Page 5 Commercial Airplanes 777 Service Bulletin ALERT Revision Transmittal SheetNumber: 777-34A0191Original Issue: September 20, 2011 Revision 1: March 23, 2012 ATA System: 3433 SUBJECT: NAVIGATION - Radio Altimeter System - Radio Altimeter Transceiver Replacement This revision includes all pages of the service bulletin. COMPLIANCE INFORMATION RELATED TO THIS REVISION No more work is necessary on the airplanes changed in accordance with the original issue of this service bulletin. REASON FOR REVISION This revision is sent to add one airplane to the effectivity list of the original issue of this service bulletin. These sections were changed: 1. In PLANNING INFORMATION, Paragraph 1.A.1., airplane WE091 was added to the effectivities. 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 September 20, 2011Original Issue: March 23, 2012Revision 1: BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 5 of 21 ### Page 6 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 6 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT BLANK PAGE ### Page 7 Commercial Airplanes 777 Service Bulletin ALERT SummaryNumber: 777-34A0191Original Issue: September 20, 2011 Revision 1: March 23, 2012 ATA System: 3433 SUBJECT: NAVIGATION - Radio Altimeter System - Radio Altimeter Transceiver Replacement 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 gives instructions to replace the existing Radio Altimeter (RA) Transceivers with the upgraded units. The upgraded Radio Altimeter Transceivers have improved antenna monitoring capabilities for detecting antenna deterioration caused by the environmental conditions or damage to the antenna during antenna alteration which can result in breaks in the coaxial cables or damage to the coax connector. If the changes in this service bulletin are not done, incorrect Radio Altimeter output may be observed on the Primary Flight Displays (PFD). Some operators have reported inconsistent Radio Altimeter Transceiver outputs during the flight and on the ground. The antenna alteration at the antenna level can create micro cracks on the electrical grounding connection, damage the coax cables or the coax connector center pin contact. Any one of these damages to the antenna assembly can affect the Radio Altimeter system functionality. Boeing Service Related Problem 777-SRP-34-0120 is related to this service bulletin. Boeing Fleet Team Digest 777 FTD 34-10013 is related to this service bulletin. This table is provided to operators for planning purposes only. Refer to the applicable sections for more information. ReferenceAffectedPlanning Data Paragraph 1.A.2., Spares AffectedYesSpares Affected Paragraph 1.E., ComplianceNoAD Related Paragraph 1.H., Weight and Balance ChangesNoWeight and Balance Change Paragraph 1.I., Electrical Load DataNoElectrical Load Changed Paragraph 1.K., Publications AffectedYesPublications Affected BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 7 of 21 ### Page 8 ReferenceAffectedPlanning Data Paragraph 1.K., Publications AffectedNoAirplane Flight Operations Affected (Flight Crew Operations Manual and/or FAA Approved Air- plane Flight Manual) Paragraph 2.C.1., Kits/PartsNoKits/Parts Required Paragraph 2.C.2., Parts and Materials Supplied by the Operator YesOperator Supplied Material Paragraph 2.F., Special Tooling Necessary to do this Service Bulletin NoSpecial Tooling Required ACTION (PRR 62777-85S) 1. Gain access to the E5 rack in the forward cargo compartment. 2. Replace the Radio Altimeter (RA) Transceivers. 3. Do Installation Test. EFFECTIVITY 777-200, 777-200LR, 777-300, 777-300ER, and 777F Airplane(s). Refer to Paragraph 1.A.1., Airplanes, for the list of affected airplane(s). COMPLIANCE Boeing recommends that the changes given in this service bulletin be done within 24 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 1.651.65All MATERIAL INFORMATION Operator Supplied Parts/Materials. Refer to Paragraph 2.A., Material - Price and Availability. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 8 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 9 (OCR) BOEING SERVICE BULLETIN 777-34A0191 ALERT ALERT E5 RACK (FORWARD CARGO COMPARTMENT) REPLACE RADIO ALTIMETER (RA) E TRANSCEIVERS (XCVR) RIGHT RA XCVR (E5-2) CENTER RA XCVR (E5-3) LEFT RA XCVR (E5-4) ^ FWD ELECTRONIC EQUIPMENT RACK, E5- 2095348 FORWARD CARGO COMPARTMENT Original Issue: September 20, 2011 Revision 1: March 23, 2012 777-34A0191 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. 9 of 21 ### Page 10 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 10 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT BLANK PAGE ### Page 11 Commercial Airplanes 777 Service Bulletin ALERT Number: 777-34A0191 Original Issue: September 20, 2011 Revision 1: March 23, 2012 ATA System: 3433 SUBJECT: NAVIGATION - Radio Altimeter System - Radio Altimeter Transceiver Replacement 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 This service bulletin is for the airplane(s) shown below. Refer to PRR 62777-85S for data about this change. Refer to Service Bulletin Index D624W001 Part 3 for Airplane Variable Number, Line Number, and Serial Number data. DESCRIPTIONCONFIGURATIONGROUP Replace existing Radio Altimeter Transceivers with 9599-607-19996 part number -1 Airplane Models: 777-200, 777-200LR, 777-300, 777-300ER, 777F GroupVariable Number 1WA196 - WA198 1WB101 - WB106 1WB161 - WB177 1WB306 - WB307 1WB631 - WB638 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 11 of 21 ### Page 12 GroupVariable Number 1WB646 - WB649 1WC111 - WC120 1WC581 1WD046 - WD055 1WD581 - WD599 1WD606 - WD609 1WD621 - WD632 1WD671 - WD677 1WD846 - WD862 1WD921 - WD922 1WE091 1WF031 - WF032 1WF131 2. Spares Affected Examine your spares supply for the parts or components identified in Paragraph 2.C., Parts Necessary for Each Airplane. If any parts or components are found, refer to Paragraph 2.C. for the recommended use. B. Concurrent Requirements None. C. Reason This service bulletin gives instructions to replace the existing Radio Altimeter (RA) Transceivers with the upgraded units. The upgraded Radio Altimeter Transceivers have improved antenna monitoring capabilities for detecting antenna deterioration caused by the environmental conditions or damage to the antenna during antenna alteration which can result in breaks in the coaxial cables or damage to the coax connector. If the changes in this service bulletin are not done, incorrect Radio Altimeter output may be observed on the Primary Flight Displays (PFD). Some operators have reported inconsistent Radio Altimeter Transceiver outputs during the flight and on the ground. The antenna alteration at the antenna level can create micro cracks on the electrical grounding connection, damage the coax cables or the coax connector center pin contact. Any one of these damages to the antenna assembly can affect the Radio Altimeter system functionality. Boeing Service Related Problem 777-SRP-34-0120 is related to this service bulletin. Boeing Fleet Team Digest 777 FTD 34-10013 is relate to this service bulletin. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 12 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 13 Revision 1 is sent to add WE091 to the effectivity list of the airplanes in the original issue of this service bulletin. D. Description 1. Gain access to the E5 rack in the forward cargo compartment. 2. Replace the Radio Altimeter (RA) Transceivers. 3. Do Installation Test. 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 122, 211, 212777-200, 777-200LR, 777-300, 777-300ER, 777F E. Compliance Boeing recommends that the changes given in this service bulletin be done within 24 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 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 13 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 14  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. Elapsed HoursTask HoursNumber of PersonsTask 0.250.251Open Access 0.900.901Figure 1 0.250.251RA Installation tests 0.250.251Close Access 1.651.65TOTAL FOR EACH AIRPLANE H. Weight and Balance Changes None. I. Electrical Load Data Not changed. J. References 1. Existing Data a. Engineering Change Memo PRR 62777-85S b. Service Related Problem (SRP) 777-SRP-34-0120 c. Fleet Team Digest (FTD) 777 FTD 34-10013 d. 777 Maintenance Manual (AMM) Subject 777 AMM 34-33-01 e. THALES SB ERT-550-34-04 2. Data supplied with this Service Bulletin None. 3. Installation Drawings Used in the Preparation of this Service Bulletin TitleDrawing Number EQUIPMENT INSTL - E5 RACK284W1205 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 14 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 15 The table above lists applicable drawings used to prepare this service bulletin. The drawings are not necessary to make the specified changes, and are not supplied with this service bulletin. The drawings may not be applicable to all airplane configurations or operators. K. Publications Affected 1. Publications: Chapter-SectionPublication 34-33777 Aircraft Maintenance Manual EQUIPMENT LIST777 Wiring Diagram Manual 34-33, 25-17777 Illustrated Parts Catalog 34-32Component Maintenance 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. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 15 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 16 BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 16 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT BLANK PAGE ### Page 17 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 . Refer to THALES SB ERT-550-34-04 for price and upgrade kit availability. 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 NotesExisting Part NumberNameQTYPart Number / Specification (a) (b) (c)9599-607-19991 or 9599- 607-19992 or 9599-607- 19993 Radio Altimeter Transceiver39599-607-19996 (a) The existing/installed Radio Altimeter Transceivers have one of the part numbers mentioned in the "Existing Part Number" column. (b) You can use the existing Radio Altimeter Transceivers to upgrade to 9599-607-19996 part number. Refer to THALES SB ERT-550-34-04 for the information on how to upgrade the existing Radio Altimeter Transceivers to 9599-607-19996 part number. (c) 9599-607-19991 and 9599-607-19992 units must first be converted to 9599-607-19993 part number before they can be upgraded to 9599-607-19996 part number. Refer to the "Concurrent Requirements" section of THALES SB ERT-550-34-04 for this information. 3. Parts Modified and Reidentified None. 4. Parts Removed and Not Replaced None D. Parts Necessary to Change Spares To get the parts shown below, refer to Paragraph 2.A., Material - Price and Availability. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 17 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 18 QTYNamePart Number -Radio Altimeter Transceiver 9599-607-19996 (a) (a) Refer to THALES SB ERT-550-34-04 for the information on how to upgrade the existing RAs to 9599-607-19996 part number. 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: September 20, 2011 777-34A0191Revision 1: March 23, 2012 18 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 19 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. These work instructions refer to procedures included in other Boeing documents. When the words "refer to" are used and the operator has an accepted alternative procedure, the accepted alternative procedure can be used. When the words "in accordance with" are included in the instruction, the procedure in the Boeing document must be used. B. WORK INSTRUCTIONS 1. Get access to Electronic Equipment Rack E5 in the Forward Cargo Compartment. 2. Replace the Radio Altimeter (RA) Transceivers in accordance with FIGURE 1. 3. Do installation test. Refer to 777 AMM 34-33-01 as an accepted procedure. 4. Put the airplane back to a serviceable condition. BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1: March 23, 2012 19 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT ### Page 20 (OCR) BOEING SERVICE BULLETIN 777-34A0191 ALERT ALERT CARGO COMPARTMENT) E5 RACK (FORWARD RIGHT RA XCVR (E5-2) CENTER RA XCVR (E5-3) LEFT RA XCVR (E5-4) FWD ELECTRONIC EQUIPMENT RACK, E5- 2095352 FORWARD CARGO COMPARTMENT FIGURE 1: RADIO ALTIMETER TRANSCEIVER REPLACEMENT (SHEET 1 OF 2) Original Issue: September 20, 2011 Revision 1 March 23, 2012 BOEING PROPRIETARY - 777-34A0191 Copyright © Unpublished Work - See page 1 for details. 20 of 21 ### Page 21 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 this figure. More DataQtyIdentificationNameTaskStep (a)39599-607-19991 OR 9599-607-19992 OR 9599-607-19993 RADIO ALTIMETER TRANSCEIVER Remove1 (b)39599-607-19996RADIO ALTIMETER TRANSCEIVER Install (Changed)2 (a) Refer to 777 AMM 34-33-01 as an accepted procedure. The existing/installed Radio Altimeter Transceivers have one of the following 9599-607-19991, 9599-607-19992 or 9599-607-19993 part numbers. (b) Refer to 777 AMM 34-33-01 as an accepted procedure. FIGURE 1: RADIO ALTIMETER TRANSCEIVER REPLACEMENT (SHEET 2 OF 2) BOEING PROPRIETARY - Copyright © Unpublished Work - See page 1 for details. Original Issue: September 20, 2011 777-34A0191Revision 1 March 23, 2012 21 of 21 BOEING SERVICE BULLETIN 777-34A0191 ALERTALERT --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. 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