# Boeing Alert Service Bulletin 747-56A2012: Revision 1

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2011-0303; AD 2012-02-16 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Service Bulletin 747-56A2012](https://openairdocs.org/service-documents/boeing/747-56a2012.md)
- Title as filed: U.S. DOT/FAA - Service Bulletin
- Pages: 52
- PDF: https://openairdocs.org/files/sha256/16/8c/168c0186ed66dccf387ad82368c46c0140f638315ae6794d458c525b9729cf68
- Page: https://openairdocs.org/service-documents/boeing/747-56a2012/file/168c0186ed66

## Text

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### Page 1

Commercial 
Airplanes
747
Service Bulletin
Number: 747-56A2012
Original Issue: August 24, 2006
Revision 1: August 12, 2010
ATA System: 5611
SUBJECT: WINDOWS - Flight Compartment - Flight Compartment Windows - Inspection of Glass
No. 2 and No. 3 Windows for Cracks in the Fail-Safe Interlayer
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 © 2006 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Unpublished Work - All Rights Reserved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 ........................................ 2 0
B. Concurrent Requirements ...................................... 2 0
C. Reason ................................................ 2 0
D. Description .............................................. 2 2
E. Compliance .............................................. 2 3
F. Approval ............................................... 2 8
G. Manpower .............................................. 2 8
H. Weight and Balance Changes .................................... 2 9
I. Electrical Load Data ......................................... 2 9
J. References .............................................. 2 9
1. Existing Data: ......................................... 2 9
2. Data supplied with this Service Bulletin: ........................... 2 9
3. Installation Drawings Used in the Preparation of this Service Bulletin: ........... 3 0
K. Publications Affected ........................................ 3 0
L. Interchangeability and Intermixability of Parts ........................... 3 0
2. MATERIAL INFORMATION ........................................ 3 1
A. Material - Price and Availability ................................... 3 1
B. Industry Support Information .................................... 3 1
C. Parts Necessary For Each Airplane ................................. 3 1
1. Kits/Parts: ........................................... 3 1
2. Parts and Materials Supplied by the Operator: ........................ 3 1
3. Parts Modified and Reidentified: ............................... 3 2
4. Parts Removed and Not Replaced: .............................. 3 2
D. Parts Necessary to Change Spares ................................. 3 2
E. Special Tooling - Price and Availability ............................... 3 2
F. Special Tooling Necessary to do this Service Bulletin ....................... 3 2
3. ACCOMPLISHMENT INSTRUCTIONS .................................. 3 3
A. GENERAL INFORMATION ..................................... 3 3
B. WORK INSTRUCTIONS ....................................... 3 4
FIGURE 1: NO. 2 AND NO. 3 WINDOW IDENTIFICATION ....................... 3 6
FIGURE 2: 65B27042-( ) AND 65B27043-( ) SINGLE STRUCTURAL GLASS PANE  NO. 2 AND NO. 3
WINDOW DETAILED INSPECTION ............................. 4 0
FIGURE 3: 65B27046-( ) AND 65B27047-( ) SINGLE STRUCTURAL GLASS  PANE NO. 2 AND NO. 3
WINDOW DETAILED INSPECTION ............................. 4 6
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Commercial 
Airplanes
747
Service Bulletin
Revision Transmittal SheetNumber: 747-56A2012Original Issue: August 24, 2006
Revision 1: August 12, 2010
ATA System: 5611
SUBJECT: WINDOWS - Flight Compartment - Flight Compartment Windows - Inspection of Glass
No. 2 and No. 3 Windows for Cracks in the Fail-Safe Interlayer
This revision includes all pages of the service bulletin.
COMPLIANCE INFORMATION RELATED TO THIS REVISION
Federal Aviation Administration (FAA) Airworthiness Directive FAA AD 2007-15-10 is related to this service
bulletin.
No more work is necessary on airplanes changed as given in the original issue of this service bulletin. Continue
to do repeat inspections as given in Revision 1 until the new dual structural glass pane windows are installed
as given in Paragraph 1.E., Compliance.
No airplanes were added to the service bulletin effectivity; however, airplanes line number 1418 and on were
removed.
REASON FOR REVISION
This revision is sent to remove airplanes line number 1418 and on from the service bulletin effectivity and give
terminating action for the requirements of continued inspection as given in this service bulletin. The inspections
as given in this service bulletin are necessary on airplanes prior to line number 1418, which had single structural
glass pane windows that can have cracks in the internal fail-safe interlayer. The inspections as given in this
service bulletin are not necessary on airplanes line number 1418 and on, which have the new dual structural
glass pane windows installed in production. The installation of the new dual structural glass pane windows as
given in Revision 1 of this service bulletin is terminating action for the requirements of continued inspection as
given in this service bulletin.
These sections were changed:
1. Summary (Background and Action); Paragraph 1.C., Reason; and Paragraph 1.D., Description, were
changed to clarify the difference between the single structural and dual structural glass pane windows.
Correct names of different parts of the window assembly were added. Also added production incorporation
information of the new dual structural glass pane window.
2. In Summary (Effectivity) and Paragraph 1.A., Effectivity, airplanes line number 1418 and on were removed.
3. In Summary (Compliance), added a reference to AD 2007-15-10.
4. In Paragraph 1.D., Description, a note in reference to sending inspection program and results was deleted.
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5. In Paragraph 1.E., Compliance, updated compliance tables to show conditions that affect the new dual
structural glass pane windows, which is terminating action to the requirements of the continued inspection.
Also added a reference to AD 2007-15-10.
6. In Paragraph 1.F., Approval, an Alternative Method of Compliance statement to the requirements of AD
2007-15-10 was added.
7. In Paragraph 1.G., Manpower, the words "single structural glass pane" were added to the No. 2 and No. 3
window inspection task.
8. In Paragraph 1.J.1., Existing Data, references were updated.
9. In Paragraph 1.K., Publications Affected, affected publications and damage tolerance evaluation statement
were added.
10. In Paragraph 1.L., Interchangeability and Intermixability of Parts, statement was updated.
11. In Paragraph 2.C.2., Parts and Materials Supplied by the Operator, part information was updated.
12. In Paragraph 3.A., General Information, 747 minor models were removed from the reference to Structural
Repair Manual, Chapter 51. Also added a note.
13. In Paragraph 3.B., Work Instructions, updated PART 1 and PART 2 instructions that affect the new dual
structural glass pane windows. Added PART 3 to give window replacement instructions.
14. In Figure 1, notes were updated and added new dual structural glass pane window part numbers in the
step table.
15. In Figure 2 and Figure 3, updated the step tables to add and clarify inspection requirements of the windows.
Information Notice 747-56A2012 IN 01 and 02 were addressed.
16. In Summary Figure, Figure 2, and Figure 3, illustrations were updated to show text changes on part
description.
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
August 24, 2006Original Issue:
August 12, 2010Revision 1:
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Commercial 
Airplanes
747
Service Bulletin
SummaryNumber: 747-56A2012Original Issue: August 24, 2006
Revision 1: August 12, 2010
ATA System: 5611
SUBJECT: WINDOWS - Flight Compartment - Flight Compartment Windows - Inspection of Glass
No. 2 and No. 3 Windows for Cracks in the Fail-Safe Interlayer
CONCURRENT REQUIREMENTS
None.
BACKGROUND
Accomplishment of the inspection given in this service bulletin will make sure that no cracks are present in the
internal fail-safe interlayer of the No. 2 and No. 3 windows that use a single structural glass pane. Fail-safe
interlayer cracks can cause the affected windows to not be capable of carrying cabin pressurization loads if the
structural glass pane of the window becomes broken. This could result in loss of a window and rapid loss of
cabin pressure. Loss of a window can also cause crew communication difficulties or incapacitation of the crew.
The left No. 2 and No. 3 windows are the pilot's side windows. The right No. 2 and No. 3 windows are the
co-pilot's side windows.
Affected airplanes may have No. 2 and No. 3 windows that are made from either acrylic or glass. The detailed
inspections in this service bulletin are required only for glass windows that use a single structural glass pane to
carry pressure loads. Airplanes prior to line number 1418 had single structural glass pane window, which can
have cracks in the internal fail-safe interlayer. Windows that use dual structural glass panes or acrylic panes do
not require inspections. Airplanes line number 1418 and on have No. 2 and No. 3 windows that use dual structural
glass panes, which are installed in production. For airplanes prior to line number 1418, installation of the new
dual structural glass pane windows is terminating action for the requirements of continued inspection as given
in this service bulletin.
There are two different, but interchangeable, designs for the No. 2 and No. 3 windows that use a single structural
glass pane. The 65B27042-( ) and 65B27043-( ) windows consist of an outer glass pane and a structural inner
glass pane, with a vinyl interlayer between them. The vinyl interlayer alone acts as the structural fail-safe load
path if the structural inner glass pane becomes broken. The 65B27046-( ) and 65B27047-( ) windows consist
of an outer glass pane and a structural inner glass pane, separated by an outboard urethane interlayer, a vinyl
interlayer, and an inboard urethane interlayer. The vinyl and inboard urethane interlayers act as the structural
fail-safe load path if the structural inner glass pane becomes broken.
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One operator told Boeing that a glass No. 3 window with 36,131 flight-hours and 5,607 flight-cycles departed
an airplane in-flight. Loss of the window resulted in rapid loss of cabin pressure, and an emergency landing was
performed. Investigation revealed that a crack was present in the fail-safe interlayer of the 65B27043-2 single
structural glass pane No. 3 window, along the inner edge of the window's aluminum edge insert. When the
structural inner glass pane cracked due to an electrical arcing event not associated with the interlayer cracking,
the interlayer was not able to support the airplane's cabin pressurization load and the window departed the
airplane. The remaining single structural glass pane No. 3 window and both single structural glass pane No. 2
windows of this airplane were inspected, and all were found to have cracks in the fail-safe interlayer.
Subsequent to this report, inspections accomplished by Boeing and some operators have found many additional
instances of fail-safe interlayer cracks in 65B27042-( ) and 65B27043-( ) single structural glass pane No. 2 and
No. 3 windows. In addition, several instances of inboard fail-safe interlayer cracks were found in 65B27046-( )
and 65B27047-( ) glass No. 2 and No. 3 windows.
Interlayer cracks are primarily caused by thermal stress due to the different thermal expansion properties of the
vinyl, glass, and window edging material. Moisture ingression into the window can also contribute to interlayer
cracks.
Accomplishment of the inspection in this service bulletin will ensure the structural integrity of the No. 2 and No.
3 windows that use a single structural glass pane.
Boeing Service Related Problem (SRP) 747-SRP-56-0016 is related to this service bulletin.
ACTION (PRR 85901-85S)
Get internal access to the No. 2 and No. 3 windows on both the left and right sides of the airplane. Identify the
windows (by part number) to determine if they are single structural glass pane, dual structural glass pane, or
acrylic windows. No additional inspections are necessary on the following No. 2 and No. 3 windows, unless the
windows are replaced with the single structural glass pane windows:
– 65B07639-( ) or 65B07640-( ) acrylic windows
– 141U4821-( ), 141U4831-( ), 141U4822-( ), or 141U4832-( ) dual structural glass pane windows
Do a detailed inspection for cracks or damage, particularly in the internal interlayers for the following No. 2 and
No. 3 windows that use single structural glass panes: 65B27042-( ), 65B27043-( ), 65B27046-( ), and 65B27047-(
). If no cracks or damage are found, do the inspection again at the time as given in this service bulletin. If any
cracks or damage as given in this service bulletin are found, replace the affected window before any more flights.
Do the inspection of all four windows again at the times as given in this service bulletin.
NOTE: Color photographs of typical No. 2 and No. 3 window damage can be found in Fleet Team Digest
Articles 747 FTD 56-05001 and 747-400 FTD 56-05001. These articles can be accessed through the
MyBoeingFleet website, or you may obtain copies from your local Boeing Field Service office.
As an alternative replace the single structural glass pane windows with dual structural glass pane windows.
Installation of the dual structural glass pane windows is terminating action for the requirements of continued
inspections as given in Paragraph 1.E., Compliance. Installation of the dual structural glass pane windows is
necessary at the time as given in Paragraph 1.E., Compliance.
EFFECTIVITY
747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F,
747SP, and 747SR airplanes. See Service Bulletin Paragraph 1.A.1 for effectivity.
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COMPLIANCE
See Service Bulletin Paragraph 1.E. for compliance information.
Federal Aviation Administration (FAA) Airworthiness Directive AD 2007-15-10 is related to this service bulletin.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the inspection or repair procedures given in this service bulletin.
MANPOWER
Elapsed HoursTotal Task-HoursTask
2.504.50Window Identification and Inspection
MATERIAL INFORMATION
Operator Supplied Parts.
Refer to Paragraph 2.A., Material - Price and Availability.
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BOEING SERVICE BULLETIN 747-56A2012
RIGHT WINDOW  -LEFT WINDOW
NO. 3  NO. 3
SEE  SEE
OUTER GLASS
PANE  VINYL  NO. 2  RIGHT WINDOW  LEFT WINDOW  NO. 2
FAIL-SAFE
INTERLAYER  SEE  SEE
STRUCTURAL  INNER
GLASS PANE
ALUMINUM
INSERT
HUMP
SEAL
- DO A DETAILED INSPECTION FOR
CRACKS IN THE FAIL-SAFE
INTERLAYER. IF CRACKS ARE
FOUND, REPLACE THE WINDOW.
PRESSURE
SEAL
FWD
EDGE MEMBER
TYPICAL SINGLE STRUCTURAL GLASS PANE
NO. 2 AND NO. 3 WINDOWS
U49986
Original Issue: August 24, 2006
Revision 1: August 12, 2010  747-56A2012
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Commercial 
Airplanes
747
Service Bulletin
Number: 747-56A2012
Original Issue: August 24, 2006
Revision 1: August 12, 2010
ATA System: 5611
SUBJECT: WINDOWS - Flight Compartment - Flight Compartment Windows - Inspection of Glass
No. 2 and No. 3 Windows for Cracks in the Fail-Safe Interlayer
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 85901-85S 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.
DESCRIPTIONCONFIGURATIONGROUP
747 airplanes line number 1 through 1417.-1
Airplane Models:
747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400,
747-400D, 747-400F, 747SP, 747SR
GroupVariable Number
1RA001 - RA034
1RA101 - RA115
1RA161 - RA164
1RA201 - RA203
1RA216 - RA217
1RA245 - RA246
1RA251 - RA266
1RA301 - RA318
1RA351 - RA360
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GroupVariable Number
1RA369 - RA373
1RA401 - RA418
1RA501 - RA502
1RA521 - RA528
1RA532 - RA548
1RA551 - RA552
1RA559 - RA561
1RA581 - RA582
1RA585
1RA601 - RA602
1RA631 - RA635
1RA651 - RA652
1RA671 - RA677
1RA701 - RA702
1RA721 - RA731
1RA741 - RA745
1RA749 - RA750
1RA761 - RA762
1RA781 - RA784
1RA901 - RA916
1RB001 - RB016
1RB041 - RB044
1RB071 - RB075
1RB101 - RB102
1RB411 - RB413
1RB421
1RB601 - RB607
1RB681 - RB697
1RB711
1RB721 - RB723
1RB741 - RB748
1RD001 - RD004
1RD021 - RD022
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GroupVariable Number
1RD041 - RD059
1RD071 - RD072
1RD081 - RD083
1RD091 - RD092
1RD101 - RD104
1RD121 - RD127
1RD131 - RD144
1RD166 - RD167
1RD171 - RD172
1RD181 - RD183
1RD201 - RD204
1RD221 - RD227
1RD231 - RD235
1RD241 - RD243
1RD251 - RD262
1RD271 - RD272
1RD291 - RD292
1RD301 - RD302
1RD311
1RD351 - RD358
1RD361 - RD366
1RD381 - RD383
1RD411 - RD414
1RD421 - RD426
1RD431 - RD435
1RD441 - RD442
1RD451 - RD456
1RD461
1RD471 - RD475
1RD513 - RD519
1RD531 - RD533
1RD551
1RD561
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GroupVariable Number
1RD571
1RD581 - RD583
1RD591 - RD593
1RD601 - RD607
1RD621 - RD623
1RD641 - RD649
1RD651 - RD659
1RD661
1RD671
1RD681 - RD682
1RD691 - RD692
1RD701 - RD702
1RD721 - RD722
1RD741 - RD742
1RD751 - RD755
1RD761
1RD771 - RD775
1RD781 - RD783
1RD791 - RD792
1RE001
1RF001 - RF006
1RG001 - RG009
1RG091
1RG095
1RG101 - RG104
1RG121 - RG126
1RG141 - RG142
1RG161 - RG164
1RG171 - RG174
1RG191 - RG193
1RG211 - RG213
1RG221 - RG222
1RH101 - RH102
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GroupVariable Number
1RH111 - RH112
1RH121 - RH122
1RJ131 - RJ133
1RJ151 - RJ152
1RJ301 - RJ303
1RJ321 - RJ322
1RJ331 - RJ333
1RL401 - RL403
1RL411 - RL436
1RL451 - RL456
1RL461 - RL462
1RL471 - RL479
1RL481
1RL491 - RL492
1RL501 - RL502
1RL511 - RL516
1RL521 - RL522
1RL531 - RL534
1RL551
1RL561 - RL568
1RL571
1RL576 - RL577
1RL579
1RL581 - RL586
1RL651 - RL655
1RL671 - RL675
1RL681 - RL684
1RL751 - RL752
1RM001 - RM007
1RM010 - RM013
1RM021 - RM024
1RM026 - RM030
1RM036 - RM045
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GroupVariable Number
1RM051 - RM053
1RM071
1RM081 - RM084
1RM091
1RM096 - RM097
1RM116 - RM117
1RM126 - RM132
1RM136 - RM147
1RM156 - RM158
1RM166 - RM177
1RM191 - RM192
1RM231 - RM233
1RM241 - RM246
1RM261 - RM264
1RM316 - RM318
1RM331 - RM333
1RM341
1RM351 - RM355
1RM366 - RM367
1RM401 - RM403
1RM426
1RM431
1RM441 - RM443
1RM445
1RM801 - RM803
1RM811 - RM813
1RM851 - RM859
1RM861 - RM863
1RM871 - RM899
1RM901 - RM906
1RM911
1RR001 - RR005
1RR021 - RR025
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GroupVariable Number
1RR031
1RR201 - RR206
1RR221 - RR226
1RR261 - RR267
1RR301 - RR310
1RR331 - RR332
1RR336
1RR341 - RR345
1RR361 - RR362
1RR421 - RR422
1RR431 - RR432
1RR441 - RR442
1RR451
1RR501 - RR504
1RR521 - RR522
1RR526
1RR531
1RR551 - RR556
1RR561
1RR566
1RR701
1RR721 - RR724
1RR746 - RR748
1RR851 - RR856
1RR861 - RR862
1RR951 - RR952
1RS001 - RS002
1RS201
1RS211 - RS212
1RS221 - RS222
1RS231 - RS241
1RS251 - RS259
1RS263
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GroupVariable Number
1RS265 - RS268
1RS271 - RS276
1RS291 - RS292
1RS301 - RS306
1RS311 - RS320
1RS331 - RS333
1RS341 - RS342
1RS699
1RS701 - RS703
1RS711 - RS713
1RS721 - RS722
1RS731 - RS732
1RS741 - RS743
1RS751 - RS752
1RS761 - RS762
1RS771
1RS781 - RS782
1RS786
1RT001 - RT014
1RT021 - RT022
1RT031 - RT035
1RT041 - RT047
1RT061
1RT071 - RT075
1RT101 - RT103
1RT121
1RT131 - RT137
1RT151 - RT152
1RT161 - RT168
1RT401 - RT412
1RT431 - RT447
1RT451 - RT469
1RT471 - RT499
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GroupVariable Number
1RT501 - RT535
1RT551 - RT568
1RT571 - RT591
1RT601 - RT657
1RT671 - RT673
1RT681 - RT682
1RT691 - RT699
1RT701 - RT704
1RT711 - RT717
1RT741 - RT757
1RT776 - RT777
1RT781 - RT784
1RT801 - RT803
1RT811 - RT814
1RT831 - RT837
1RT861 - RT864
1RT876 - RT880
1RT931 - RT932
1RT945 - RT949
1RT951 - RT955
1RT966 - RT967
1RU001 - RU006
1RU016 - RU017
1RU031 - RU032
1RU051 - RU052
1RU059 - RU062
1RU081 - RU083
1RU101 - RU102
1RU121 - RU132
1RU801 - RU809
1RU831 - RU841
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2. Spares Affected
None.
B. Concurrent Requirements
None.
C. Reason
Accomplishment of the inspection given in this service bulletin will make sure that no cracks are present
in the internal fail-safe interlayer of the No. 2 and No. 3 windows that use a single structural glass pane.
Fail-safe interlayer cracks can cause the affected windows to not be capable of carrying cabin
pressurization loads if the structural glass pane of the window becomes broken. This could result in
loss of a window and rapid loss of cabin pressure. Loss of a window can also cause crew communication
difficulties or incapacitation of the crew.
The left No. 2 and No. 3 windows are the pilot's side windows. The right No. 2 and No. 3 windows are
the co-pilot's side windows.
Affected airplanes may have No. 2 and No. 3 windows that are made from either acrylic or glass. The
detailed inspections in this service bulletin are required only for glass windows that use a single structural
glass pane to carry pressure loads. Airplanes prior to line number 1418 had single structural glass
pane window, which can have cracks in the internal fail-safe interlayer. Windows that use dual structural
glass panes or acrylic panes do not require inspections. Airplanes line number 1418 and on have No.
2 and No. 3 windows that use dual structural glass panes, which are installed in production. For airplanes
prior to line number 1418, installation of the new dual structural glass pane windows is terminating
action for the requirements of continued inspection as given in this service bulletin.
There are two different, but interchangeable, designs for the No. 2 and No. 3 windows that use a single
structural glass pane:
— The 65B27042-( ) and 65B27043-( ) windows consist of an outer glass pane and a structural inner
glass pane, with a vinyl interlayer between them. The vinyl interlayer alone acts as the structural
fail-safe load path if the structural inner glass pane becomes broken.
— The 65B27046-( ) and 65B27047-( ) windows consist of an outer glass pane and a structural inner
glass pane, separated by an outboard urethane interlayer, a vinyl interlayer, and an inboard
urethane interlayer. The vinyl and inboard urethane interlayers act as the structural fail-safe load
path if the structural inner glass pane becomes broken.
In No. 2 and No. 3 windows that use dual structural glass panes or acrylic panes, the second pane,
not vinyl interlayer, acts as the structural fail-safe element.
One operator told Boeing that a glass No. 3 window with 36,131 flight-hours and 5,607 flight-cycles
departed an airplane in-flight. Loss of the window resulted in rapid loss of cabin pressure, and an
emergency landing was performed. Investigation revealed that a crack was present in the fail-safe
interlayer of the 65B27043-2 single structural glass pane No. 3 window, along the inner edge of the
window's aluminum edge insert. When the structural inner glass pane cracked due to an electrical
arcing event not associated with the interlayer cracking, the interlayer was not able to support the
airplane's cabin pressurization load and the window departed the airplane. The remaining single
structural glass pane No. 3 window and both single structural glass pane No. 2 windows of this airplane
were inspected, and all were found to have cracks in the fail-safe interlayer.
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Subsequent to this report, inspections accomplished by Boeing and some operators have found many
additional instances of fail-safe interlayer cracks in 65B27042-( ) and 65B27043-( ) single structural
glass pane No. 2 and No. 3 windows. In addition, several instances of inboard fail-safe interlayer cracks
were found in 65B27046-( ) and 65B27047-( ) single structural glass pane No. 2 and No. 3 windows.
Interlayer cracks are primarily caused by thermal stress due to the different thermal expansion properties
of the vinyl, glass, and window edging material. Moisture ingression into the window can also contribute
to interlayer cracks.
Accomplishment of the inspection in this service bulletin will ensure the structural integrity of the No.
2 and No. 3 windows that use a single structural glass pane.
Revision 1 is sent to remove airplanes line number 1418 and on from the service bulletin effectivity
and give terminating action for the requirements of continued inspection as given in this service bulletin.
The inspections as given in this service bulletin are necessary on airplanes prior to line number 1418,
which had single structural glass pane windows that can have cracks in the internal fail-safe interlayer.
The inspections as given in this service bulletin are not necessary on airplanes line number 1418 and
on, which have the new dual structural glass pane windows installed in production. The installation of
the new dual structural glass pane windows as given in Revision 1 of this service bulletin is terminating
action for the requirements of continued inspection as given in this service bulletin.
These sections were changed:
1. Summary (Background and Action); Paragraph 1.C., Reason; and Paragraph 1.D., Description,
were changed to clarify the difference between the single structural and dual structural glass pane
windows. Correct names of different parts of the window assembly were added. Also added
production incorporation information of the new dual structural glass pane window.
2. In Summary (Effectivity) and Paragraph 1.A., Effectivity, airplanes line number 1418 and on were
removed.
3. In Summary (Compliance), added a reference to AD 2007-15-10.
4. In Paragraph 1.D., Description, a note in reference to sending inspection program and results was
deleted.
5. In Paragraph 1.E., Compliance, updated compliance tables to show conditions that affect the new
dual structural glass pane windows, which is terminating action to the requirements of the continued
inspection. Also added a reference to AD 2007-15-10.
6. In Paragraph 1.F., Approval, an Alternative Method of Compliance statement to the requirements
of AD 2007-15-10 was added.
7. In Paragraph 1.G., Manpower, the words "single structural glass pane" were added to the No. 2
and No. 3 window inspection task.
8. In Paragraph 1.J.1., Existing Data, references were updated.
9. In Paragraph 1.K., Publications Affected, affected publications and damage tolerance evaluation
statement were added.
10. In Paragraph 1.L., Interchangeability and Intermixability of Parts, statement was updated.
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11. In Paragraph 2.C.2., Parts and Materials Supplied by the Operator, part information was updated.
12. In Paragraph 3.A., General Information, 747 minor models were removed from the reference to
Structural Repair Manual, Chapter 51. Also added a note.
13. In Paragraph 3.B., Work Instructions, updated PART 1 and PART 2 instructions that affect the
new dual structural glass pane windows. Added PART 3 to give window replacement instructions.
14. In Figure 1, notes were updated and added new dual structural glass pane window part numbers
in the step table.
15. In Figure 2 and Figure 3, updated the step tables to add and clarify inspection requirements of the
windows. Information Notice 747-56A2012 IN 01 and 02 were addressed.
16. In Summary Figure, Figure 2, and Figure 3, illustrations were updated to show text changes on
part description.
Boeing Service Related Problem (SRP) 747-SRP-56-0016 is related to this service bulletin.
D. Description
Get internal access to the No. 2 and No. 3 windows on both the left and right sides of the airplane.
Identify the windows (by part number) to determine if they are single structural glass pane, dual structural
glass pane, or acrylic windows. No additional inspections are necessary on the following No. 2 and
No. 3 windows, unless the windows are replaced with the single structural glass pane windows:
– 65B07639-( ) or 65B07640-( ) acrylic windows
– 141U4821-( ), 141U4831-( ), 141U4822-( ), or 141U4832-( ) dual structural glass pane windows
Do a detailed inspection for cracks or damage, particularly in the internal interlayers for the following
No. 2 and No. 3 windows that use single structural glass panes: 65B27042-( ), 65B27043-( ), 65B27046-(
), and 65B27047-( ). If no cracks or damage are found, do the inspection again at the time as given in
this service bulletin. If any cracks or damage as given in this service bulletin are found, replace the
affected window before any more flights. Do the inspection of all four windows again at the times as
given in this service bulletin.
NOTE: Color photographs of typical No. 2 and No. 3 window damage can be found in Fleet Team
Digest Articles 747 FTD 56-05001 and 747-400 FTD 56-05001. These articles can be accessed
through the MyBoeingFleet website, or you may obtain copies from your local Boeing Field
Service office.
As an alternative replace the single structural glass pane windows with dual structural glass pane
windows. Installation of the dual structural glass pane windows is terminating action for the requirements
of continued inspections as given in Paragraph 1.E., Compliance. Installation of the dual structural
glass pane windows is necessary at the time as given in Paragraph 1.E., Compliance.
Revision 1 - No more work is necessary on airplanes changed as given in the original issue of this
service bulletin. Continue to do repeat inspections as given in Revision 1 until the new dual structural
glass pane windows are installed as given in Paragraph 1.E., Compliance.
The work in this service bulletin is done in the maintenance zone(s) given below.
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Affected Maintenance Zones
ZoneModel
221, 222747-100, 747-100B, 747-100B
SUD, 747-200B, 747-200C,
747-200F, 747-300, 747-400,
747-400D, 747-400F, 747SP,
747SR
E. Compliance
Table 1: No. 2 and No. 3 Window Identification
Compliance Time (Whichever Occurs First)ActionCondition
Within 2 years after
the original issue
date of this service
bulletin.
Within 5,500 flight-hours after
the window was installed or
1,000 flight-hours after the
original issue date of this ser-
vice bulletin, whichever occurs
later. (b)
Do Window Identification as
given in PART 1 of Paragraph
3.B., Work Instructions. (a)
All airplanes
Refer to Table 2Refer to Table 2Do detailed inspections as
shown in Table 2.
65B27042-( ) or
65B27043-( ) single
structural glass pane
windows found or in-
stalled
Refer to Table 3Refer to Table 3Do detailed inspections as
shown in Table 3.
65B27046-( ) or
65B27047-( ) single
structural glass pane
windows found or in-
stalled
--No further action required for
that window position. (c)
65B07639-( ) or
65B07640-( ) acrylic
windows found or in-
stalled
--No further action required for
that window position. (c)
141U4821-( ),
141U4822-( ),
141U4831-( ), or
141U4832-( ) dual struc-
tural glass pane win-
dows found or installed
(a) Instead of inspecting the windows for identification, a review of maintenance records is acceptable if the
part number of the window can be positively determined from that review.
(b) If the number of flight-hours since the window was installed is not known, you must assume that the
window is beyond the 5,500 flight-hour limit.
(c) If the window is later replaced, refer to the applicable condition in this table for subsequent inspection
requirements of the replacement window.
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Table 2: Detailed Inspections for 65B27042-( ) and 65B27043-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
-Within 2 years
after the origi-
nal issue date
of this service
bulletin.
Within 5,500 flight-hours
after the window was in-
stalled or 1,000 flight-hours
after the original issue date
of this service bulletin,
whichever occurs later. (a)
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27042-( ) or
65B27043-( ) Sin-
gle Structural
Glass Pane No. 2
and No. 3 Win-
dows.
AND
-Within 6 years of the Revision 1 date of this
service bulletin.
Replace the window with
141U4821-( ), 141U4822-
( ), 141U4831-( ), and/or
141U4832-( ) dual struc-
tural glass pane windows
as given in PART 3 of
Paragraph 3.B., Work In-
structions.
--No further action required
for that window position.
(c) (d)
141U4821-( ),
141U4822-( ),
141U4831-( ),
and/or 141U4832-
( ) dual structural
glass pane re-
placement win-
dows installed.
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Table 2: Detailed Inspections for 65B27042-( ) and 65B27043-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
3,000 flight-hours
or 3 years,
whichever occurs
first.
Within 3,000 flight-hours or 3 years of the
initial inspection, whichever occurs first.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
No window cracks
or damage found.
-Before further flight.Replace the window as
given in PART 3 of Para-
graph 3.B., Work Instruc-
tions. (c)
Window cracks or
damage found.
3,000 flight-hours
or 3 years,
whichever occurs
first.
Within 5,500 flight-hours after the window
was installed.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27042-( )
and/or 65B27043-
( ) single struc-
tural glass pane
replacement win-
dows that are
new or have zero
flight hours.
3,000 flight-hours
or 3 years,
whichever occurs
first.
Before installation.Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27042-( )
and/or 65B27043-
( ) single struc-
tural glass pane
replacement win-
dows that are not
new or have un-
known flight
hours.
7,500 flight-hours
or 5 years,
whichever occurs
first.
Within 22,000 flight-hours after the window
was installed.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27046-( )
and/or 65B27047-
( ) single struc-
tural glass pane
replacement win-
dows that are
new or have zero
flight hours.
7,500 flight-hours
or 5 years,
whichever occurs
first.
Before installation.Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27046-( )
and/or 65B27047-
( ) single struc-
tural glass pane
replacement win-
dows that are not
new or have un-
known flight
hours.
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Table 2: Detailed Inspections for 65B27042-( ) and 65B27043-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
(a) If the number of flight-hours since the window was installed is not known, you must assume that the
window is beyond the 5,500 flight-hour limit.
(b) The detailed inspection of single structural glass pane windows is only applicable within 6 years after the
Revision 1 date of this service bulletin.
(c) Installation of 141U4821-( ), 141U4822-( ), 141U4831-( ), and/or 141U4832-( ) dual structural glass pane
windows is terminating action for the continued inspections as given in this service bulletin and is necessary
within 6 years after the Revision 1 date of this service bulletin.
(d) If the window is later replaced, refer to the applicable condition in this table for subsequent inspection
requirements of the replacement window.
Table 3: Detailed Inspections for 65B27046-( ) and 65B27047-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
-Within 3 years
after the origi-
nal issue date
of this service
bulletin.
Within 22,000 flight-hours
after the window was in-
stalled or 1,000 flight-
hours after the original is-
sue date of this service
bulletin, whichever occurs
later. (a)
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27046-( ) or
65B27047-( ) Sin-
gle Structural
Glass Pane No. 2
and No. 3 Win-
dows.
AND
-Within 6 years of the Revision 1 date of this
service bulletin.
Replace the window with
141U4821-( ), 141U4822-
( ), 141U4831-( ), and/or
141U4832-( ) dual struc-
tural glass pane windows
as given in PART 3 of
Paragraph 3.B., Work In-
structions.
--No further action required
for that window position.
(c) (d)
141U4821-( ),
141U4822-( ),
141U4831-( ),
and/or 141U4832-
( ) dual structural
glass pane re-
placement win-
dows installed.
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Table 3: Detailed Inspections for 65B27046-( ) and 65B27047-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
7,500 flight-hours
or 5 years,
whichever occurs
first.
Within 7,500 flight-hours or 5 years of the
initial inspection, whichever occurs first.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
No window cracks
or damage found.
-Before further flight.Replace the window as
given in PART 3 of Para-
graph 3.B., Work Instruc-
tions. (c)
Window cracks or
damage found.
3,000 flight-hours
or 3 years,
whichever occurs
first.
Within 5,500 flight-hours after the window
was installed.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27042-( )
and/or 65B27043-
( ) single struc-
tural glass pane
replacement win-
dows that are
new or have zero
flight hours.
3,000 flight-hours
or 3 years,
whichever occurs
first.
Before installation.Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27042-( )
and/or 65B27043-
( ) single struc-
tural glass pane
replacement win-
dows that are not
new or have un-
known flight
hours.
7,500 flight-hours
or 5 years,
whichever occurs
first.
Within 22,000 flight-hours after the window
was installed.
Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27046-( )
and/or 65B27047-
( ) single struc-
tural glass pane
replacement win-
dows that are
new or have zero
flight hours.
7,500 flight-hours
or 5 years,
whichever occurs
first.
Before installation.Do a detailed inspection of
the windows as given in
PART 2 of Paragraph 3.B.,
Work Instructions. (b) (c)
65B27046-( )
and/or 65B27047-
( ) single struc-
tural glass pane
replacement win-
dows that are not
new or have un-
known flight
hours.
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Table 3: Detailed Inspections for 65B27046-( ) and 65B27047-( ) Single Structural Glass Pane No. 2 and
No. 3 Windows
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
First)
ActionCondition
(a) If the number of flight-hours since the window was installed is not known, you must assume that the
window is beyond the 22,000 flight-hour limit.
(b) The detailed inspection of single structural glass pane windows is only applicable within 6 years after
the Revision 1 date of this service bulletin.
(c) Installation of 141U4821-( ), 141U4822-( ), 141U4831-( ), and/or 141U4832-( ) dual structural glass pane
windows is terminating action for the continued inspections as given in this service bulletin and is neces-
sary within 6 years after the Revision 1 date of this service bulletin.
(d) If the window is later replaced, refer to the applicable condition in this table for subsequent inspection
requirements of the replacement window.
Federal Aviation Administration (FAA) Airworthiness Directive AD 2007-15-10 is related to 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.
The Manager of the FAA Seattle Aircraft Certification office (ACO) approves the applicability under
paragraph 1.A., "Effectivity" of Service Bulletin 747-56A2012, Revision 1, as an AMOC to the applicability
required by paragraph (c) of AD 2007-15-10. In addition, the Manager of the FAA Seattle ACO approves
the inspections, investigative and corrective actions with the corresponding compliance times specified
in Tables 1 through 3, under paragraph 1.E., “Compliance," of Service Bulletin 747-56A2012, Revision
1, as an AMOC to the inspection, investigative and corrective actions with the corresponding compliance
times specified in Table 1 through 3, under paragraph 1.E., “Compliance," of Service Bulletin
747-56A2012, dated August 24, 2006, required by paragraphs (f) and (g) of AD 2007-15-10. When this
service bulletin specifies contacting Boeing for repair instructions, the repair instructions must be
approved by the FAA in accordance with paragraph (h) of the AD. All provisions of AD 2007-15-10 that
are not specifically referenced in this paragraph remain fully applicable and must be complied with.
G. Manpower
The table below shows an estimate of the task-hours necessary to do this inspection 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:
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— 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.
Elapsed HoursTask-HoursNumber of
Persons
Task
0.250.251Open Access
1.753.502Identify the No. 2 and No. 3 Windows,
Left and Right (Figure 1)
0.250.502Inspect the Single Structural Glass
Pane No. 2 and No. 3 Windows, Left
and Right (Figure 2 or Figure 3)
0.250.251Close Access
2.504.50TOTAL FOR EACH AIRPLANE
NOTE: More time will be required for window replacement if damage is found.
H. Weight and Balance Changes
None.
I. Electrical Load Data
747-400: Not changed.
All other 747: Not applicable.
J. References
1. Existing Data:
a. Service Related Problem (SRP) 747-SRP-56-0016
b. Engineering Change Memo PRR 85901-85S
c. Federal Aviation Administration (FAA) Airworthiness Directive AD 2007-15-10
d. 747-100/200/300 Aircraft Maintenance Manual (AMM) 25-13-03, 25-15-02, 56-11-00, 56-11-02
e. 747-400 Aircraft Maintenance Manual (AMM) 25-13-03, 25-15-02, 56-11-00, 56-11-02
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
Window Instl - Control Cab No. 2141U0001
Window Instl - Control Cab No. 3141U0002
These drawings were used to prepare this service bulletin. These drawings are not necessary to
make the specified changes, and are not supplied with this service bulletin. These drawings may
not be applicable to all airplane configurations or operators.
K. Publications Affected
1. Publications:
Chapter-SectionPublication
56-11747-100/200/300 Illustrated Parts Catalog
56-11747-400 Illustrated Parts Catalog
56-11747-400LCF Illustrated Parts Catalog
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
Refer to Paragraph 2.C., Parts Necessary for Each Airplane, for interchangeability and intermixability
information.
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2.    MATERIAL INFORMATION
A. Material - Price and Availability
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.
B. Industry Support Information
Boeing warranty remedies are not available for the inspection or repair procedures 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 Number
(b) (c)
NameQTYPart Number
(a)
-65B27042-1 or 65B27046-
1
Glass No. 2 Window Assembly - Left
Side (Manufactured by GKN)
1141U4821-11
-65B27042-1 or 65B27046-
1
Glass No. 2 Window Assembly - Left
Side (Manufactured by PPG)
1141U4822-11
-65B27042-2 or 65B27046-
2
Glass No. 2 Window Assembly -
Right Side (Manufactured by GKN)
1141U4821-12
-65B27042-2 or 65B27046-
2
Glass No. 2 Window Assembly -
Right Side (Manufactured by PPG)
1141U4822-12
-65B27043-1 or 65B27047-
1
Glass No. 3 Window Assembly - Left
Side (Manufactured by GKN)
1141U4831-1
-65B27043-1 or 65B27047-
1
Glass No. 3 Window Assembly - Left
Side (Manufactured by PPG)
1141U4832-11
-65B27043-2 or 65B27047-
2
Glass No. 3 Window Assembly -
Right Side (Manufactured by GKN)
1141U4831-2
-65B27043-2 or 65B27047-
2
Glass No. 3 Window Assembly -
Right Side (Manufactured by PPG)
1141U4832-12
(a) This new part is used in production. The installation of the new part is necessary at the time as given
in Paragraph 1.E., Compliance.
(b) You can not use the existing part to replace the new part.
(c) You can continue to use the existing part until the time as given in Paragraph 1.E., Compliance. If you
use the existing part, repeat inspections are necessary at the times as given Paragraph 1.E., Compliance.
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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.
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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. 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.
— Angular tolerance is plus or minus 2 degrees
— Torque limits to tighten nuts and bolts are given in 747 Structural Repair Manual,
Chapter 51.
4. A Detailed Inspection is defined as: An intensive examination of a specific item,
installation, or assembly to detect damage, failure, or irregularity. Available lighting
is normally supplemented with a direct source of good lighting at an intensity deemed
appropriate. Inspection aids such as mirrors magnifying lenses, etc. may be
necessary. Surface cleaning and elaborate procedures may be required.
5. If the inspection is to be done in bright daylight conditions, Boeing recommends use
of a high power LED flashlight to find fail-safe interlayer cracks.
6. 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.
7. To avoid unscheduled removal of the airplane from service for window replacement,
Boeing recommends that operators have replacement window assemblies available
before window inspections begin.
8. This service bulletin contains instructions to remove and keep parts for installation.
However, before installation of any removed and kept part, the part must be in a
serviceable condition. Replacement of the removed and kept part with a new or
serviceable part of the same part number/specification is an acceptable alternative
unless otherwise stated in the service bulletin instructions.
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B. WORK INSTRUCTIONS
PART 1 - WINDOW IDENTIFICATION
1. Get internal access to the flight deck windows and identify the No. 2 and No. 3 windows as given
in Figure 1.
2. If any of the following windows are found or installed, put the airplane back to a serviceable
condition:
– 65B07639-( ) or 65B07640-( ) acrylic windows
– 141U4821-( ), 141U4822-( ), 141U4831-( ), or 141U4832-( ) dual structural glass pane windows
No additional inspections are required on these windows.
3. If any glass 65B27042-( ), 65B27043-( ), 65B27046-( ), or 65B27047-( ) windows are found or
installed, put the airplane back to a serviceable condition.
PART 2 - WINDOW INSPECTION
1. Get internal access and prepare to inspect the No. 2 and No. 3 flight deck windows. Refer to
747-100/200/300 AMM 56-11-00 or 747-400 AMM 56-11-00 as an accepted procedure.
NOTE: If internal inspections are not adequate to determine the condition of the windows, also
do external inspections.
2. Do a detailed inspection of 65B27042-( ) and 65B27043-( ) single structural glass pane No. 2 and
No. 3 windows (left and right sides) as given in Figure 2.
3. Do a detailed inspection of 65B27046-( ) and 65B27047-( ) single structural glass pane No. 2 and
No. 3 windows (left and right sides) as given in Figure 3.
4. If any of the following cracks or damage are found, replace the affected window as given in PART
3:
a. The window has cracks in any fail-safe interlayer.
b. The window has cracks in a glass pane.
c. The window has chips in a structural glass pane.
d. The window shows any indications of arcing.
Arcing usually occurs near the window bus bars. Heat damage caused by arcing can be
identified by brown or black burn marks in the internal interlayer.
e. The window has any non-clear damage. Non-clear damage may indicate a degradation of
the structural capability of the window and may hinder inspection for other damage such as
fail-safe interlayer cracks or electrical arcing.
5. If no cracks or damage are found, put the airplane back to a serviceable condition. Do the
inspections as given in PART 2 again at the times as given in Paragraph 1.E., Compliance.
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NOTE: As an alternative to repeat inspections, replace the single structural glass pane windows
with the dual structural glass pane windows as given in PART 3. Installation of the dual
structural glass pane windows is terminating action for the requirements of continued
inspection as given in this service bulletin and necessary at the time as given in Paragraph
1.E., Compliance.
PART 3 - WINDOW REPLACEMENT
1. Option 1:
a. Replace single structural glass pane No. 2 and/or No. 3 windows with 65B27042-( ), 65B27043-(
), 65B27046-( ) and/or 65B27047-( ) single structural glass pane No. 2. and/or No. 3 windows
as applicable. Refer to 747-100/200/300 AMM 56-11-02 or 747-400 AMM 56-11-02 as an
accepted procedure for the window replacement.
NOTE: 65B27042-( ) and 65B27046-( ) single structural glass pane No. 2. windows are
interchangeable.
65B27043-( ) and 65B27047-( ) single structural glass pane No. 3. windows are
interchangeable.
b. Do the inspections given in PART 2 again at the times as given in Paragraph 1.E., Compliance.
2. Option 2:
a. Replace 65B27042-( ) and/or 65B27046-( ) single structural glass pane No. 2 windows with
141U4821-( ) and/or 141U4822-( ) dual structural glass pane No. 2 windows. Refer to
747-100/200/300 AMM 56-11-02 or 747-400 AMM 56-11-02 as an accepted procedure for
the window replacement.
b. Replace 65B27043-( ) and/or 65B27047-( ) single structural glass pane No. 3 windows with
141U4831-( ) and/or 141U4832-( ) dual structural glass pane No. 3 windows. Refer to
747-100/200/300 AMM 56-11-02 or 747-400 AMM 56-11-02 as an accepted procedure for
the window replacement.
c. No more inspections are necessary as given in this service bulletin for the dual structural glass
pane No. 2 and No. 3 windows.
3. Put the airplane back to a serviceable condition.
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BOEING SERVICE BULLETIN 747-56A2012
SEE
LEFT NO. 3 WINDOW
RIGHT NO. 3 WINDOW
LEFT NO. 2 WINDOW
RIGHT NO. 2 WINDOW
SEE
SEE
747-400 FLIGHT DECK SHOWN
FIGURE 1: NO. 2 AND NO. 3 WINDOW IDENTIFICATION
(SHEET 1 OF 4)
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### Page 37 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
SUNVISOR  TRACK  114 PADS  \ CRASH  11 MOLDING  UPPER
SUNSHADE 3) 12
5 10
- NO. 2 WINDOW
MOLDING
NO. 3 WINDOW 6)
NO. 1
SUNSHADE  WINDOW  →→ FWD
AIR DISTRIBUTION
DUCT  NO. 2 AND NO. 3 WINDOWS
(LEFT SIDE)  INBD
UPPER  CRASH,
MOLDING  PADS  SUNVISOR
TRACK  12) SUNSHADE
(10
NO. 2 WINDOW (8)
MOLDING
1 NO. 3 WINDOW
NO.
WINDOW
SUNSHADE  *AIR DISTRIBUTION DUCT
FWD  NO. 2 AND NO. 3 WINDOWS
(RIGHT SIDE)
INBD  U50126
FIGURE 1: NO. 2 AND NO. 3 WINDOW IDENTIFICATION
(SHEET 2 OF 4)
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### Page 38

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.
NOTE: The window part number can be found on the manufacturer's nameplate, which should be
located along the upper edge of the window, on the inboard surface of the window or window
edging.
1.
2. If the window part number cannot be found, the following may be used to help distinguish
between the different windows:
— Acrylic windows (Part Number 65B07639-( ) and 65B07640-( ) ) do not have a window
edging or metal insert as is found on the single structural glass pane windows (Part
Number 65B027042-( ), 65B27043-( ), 65B27046-( ), and 65B27046-( ) ) and dual structural
glass pane windows (Part Number 141U4821-( ), 141U4822-( ), 141U4831-(), and
141U4832-( ) ).
— Dual structural glass pane windows have wire grid temperature sensors embedded in
the interlayer between glass panes. For No. 2 windows, these sensors are located along
the forward edge; and for No. 3 windows, these sensors are located along the aft edge.
— On acrylic windows, one of the thermal sensors is recessed into the inner ply. On single
and dual structural glass pane windows, both thermal sensors are surface mounted.
— On single and dual structural glass pane windows, there will be a small surface mounted
plastic ring around one of the thermal sensors to hold it in place. The plastic ring is not
used on acrylic windows.
— The 65B27042-( ) and 65B27043-( ) single structural glass pane windows have internal
tape that is visible around the periphery of the window. The internal tape is nearly
transparent, but may include visible wrinkles, particularly in the corners of the windows.
The internal tape does not exist on; 65B27046-( ) and 65B27047-( ) single structural glass
pane windows; 65B07639-( ) and 65B07640-( ) acrylic windows; 141U4821-( ),
141U4822-(), 141U4831-( ), and 141U4832-( ) dual structural glass pane windows.
MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
Refer to 747-100/200/300
AMM 25-15-02 or 747-400
AMM 25-15-02 as accepted
procedures.
4-Crash PadsRemove / Keep1
Refer to 747-100/200/300
AMM 25-13-03 or 747-400
AMM 25-13-03 as accepted
procedures.
2-Visor TrackRemove / Keep2
-2-No. 3 Window Sun-
shade
Remove / Keep3
Common to the No. 1, No.
2, and No. 3 windows.
2-Upper MoldingRemove / Keep4
-2-Sidewall LiningRemove / Keep5
FIGURE 1: NO. 2 AND NO. 3 WINDOW IDENTIFICATION
(SHEET 3 OF 4)
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### Page 39

MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
of Left No. 3 Window165B27043-1 or
65B27047-1 or
65B07640-1 or
65B07640-19 or
141U4831-1 or
141U4832-11 (a)
Part NumberRecord6
of Left No. 2 Window165B27042-1 or
65B27046-1 or
65B07639-1 or
65B07639-19 or
141U4821-11 or
141U4822-11 (b)
Part NumberRecord7
of Right No. 2 Window165B27042-2 or
65B27046-2 or
65B07639-2 or
65B07639-20 or
141U4821-12 or
141U4822-12 (c)
Part NumberRecord8
of Right No. 3 Window165B27043-2 or
65B27047-2 or
65B07640-2 or
65B07640-20 or
141U4831-2 or
141U4832-12 (d)
Part NumberRecord9
-2-Sidewall Lining (Kept)Install10
-2-Upper Molding (Kept)Install11
-2-No. 3 Window Sun-
shade (Kept)
Install12
Refer to 747-100/200/300
AMM 25-13-03 or 747-400
AMM 25-13-03 as accepted
procedures.
2-Visor Track (Kept)Install13
Refer to 747-100/200/300
AMM 25-15-02 or 747-400
AMM 25-15-02 as accepted
procedures.
4-Crash Pads (Kept)Install14
(a) If the window cannot be identified, assume the part number is 65B27043-1.
(b) If the window cannot be identified, assume the part number is 65B27042-1.
(c) If the window cannot be identified, assume the part number is 65B27042-2.
(d) If the window cannot be identified, assume the part number is 65B27043-2.
FIGURE 1: NO. 2 AND NO. 3 WINDOW IDENTIFICATION
(SHEET 4 OF 4)
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### Page 40 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
SEE
LEFT NO. 3 WINDOW
RIGHT NO. 3 WINDOW
LEFT NO. 2 WINDOW
RIGHT NO. 2 WINDOW
SEE
SEE
747-400 FLIGHT DECK SHOWN
U50165
FIGURE 2: 65B27042-() AND 65B27043-() SINGLE STRUCTURAL GLASS PANE NO.2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 1 OF 6)
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### Page 41 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
CRASH
FIBERGLASS INTERIOR  PADS
LINING OR VERTICAL
SIDEWALL LINING AT  SEE  BUS BARS
THE AFT EDGE OF THE
WINDOW  BUS BAR
2) NO. 2 WINDOW
BUS BAR
NO. 3 WINDOW
NO. 1
SEE  SEE  WINDOW
> FWD
NO. 2 AND NO. 3 WINDOWS
(LEFT SIDE)
INBD
CRASH
PADS  BUS BARS SEE
FIBERGLASS INTERIOR
LINING OR VERTICAL
SIDEWALL LINING AT
NO. 2 WINDOW  THE AFT EDGE OF THE
WINDOW
BUS BAR
• BUS BAR
4 NO. 3 WINDOW
NO. 1
WINDOW
FWD  SEE  NO. 2 AND NO. 3 WINDOWS  SEE
(RIGHT SIDE)
INBD  U50159
FIGURE 2: 65B27042-() AND 65B27043-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 2 OF 6)
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### Page 42 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
OUTER GLASS
PANE
VINYL
FAIL-SAFE
INTERLAYER
STRUCTURAL INNER
GLASS PANE
ALUMINUM
INSERT
HUMP
SEAL
INTERLAYER CRACK  TYPICAL FAIL-SAFE
PRESSURE
SEAL
- WD
EDGE MEMBER
TYPICAL NO. 2 AND NO. 3 WINDOWS
A—A  U50188
• FIGURE 2: 65B27042-() AND 65B27043-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 3 OF 6)
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### Page 43 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
VINYL CRACK ALONG
CORNER OF METAL
INSERT
ALUMINUM
TAPE  INSERT
EDGE
VINYL CRACK ALONG
TAPE EDGE
POWER
TERMINAL
BLOCK
BOLT HOLE
TYPICAL NO. 2 AND NO. 3 WINDOWS
PEEL CHIP
(INTERNAL SURFACE)
INNER GLASS
PANE
VINYL
INTERLAYER
OUTER GLASS
PANE
V-SHAPED CHIPS
(EXTERNAL SURFACE)
TYPICAL NO. 2 AND NO. 3 WINDOWS
U56699
_ FIGURE 2: 65B27042-() AND 65B27043-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 4 OF 6)
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### Page 44 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
BUS BAR
BUS BAR
SEE
TYPICAL NO.2 AND NO.3 WINDOWS
HEATING
FILM
ARCING
ARCING ALONG
BUS BAR
BUS BAR
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
STEP  TASK  NAME  IDENTIFICATION  QTY  MORE DATA
Inspect  Left No. 3 Window  1  (a) (b) (c) (d)
_ FIGURE 2: 65B27042-() AND 65B27043-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 5 OF 6)
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### Page 45

MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
(a) (b) (c) (d)1-Left No. 2 WindowInspect2
(a) (b) (c) (d)1-Right No. 2 WindowInspect3
(a) (b) (c) (d)1-Right No. 3 WindowInspect4
(a) Do an internal detailed inspection of the flight deck window for the following cracks or damage: fail-safe
interlayer cracks, glass pane cracks and chips, and indications of arcing. An optional external detailed
inspection of the flight deck window for the damage may be necessary if the existing window conditions
do not allow complete inspection from the inside of the flight deck. Any non-clear damage should be noted
that may hinder inspection of the damage.
(b) Inspect the window for vinyl fail-safe interlayer cracks along the metal edge insert and along the edge of
the release tape. Vinyl fail-safe interlayer cracks can be at any location in the window, but are usually
found along the metal edge insert and along the edge of the release tape.
(c) Inspect the window for glass pane cracks and chips. There are many types of chips but pay particular
attention to "V" shaped chips and peel chips. "V" shaped chips occur on the external surface of the glass
pane and have a sharp narrow "V" where the depth is equal to or larger than the width. Peel chips occur
on the internal surface of the glass pane and these areas have a curved, rough grained shape, and are
easily seen in reflected light. The area of the peel chips can have small glass flakes, usually white, and
view through the window will distort through the rough surface of the chip. Peel chips start very small but
can continue to grow with the continued use of the airplane.
(d) Inspect the window for any indications of arcing. An arc can occur due to an electrical discharge or short
circuit across a wire, bus bar, conductive heating film or other internal window components. Arcs usually
occur near the window bus bars, and are typically the result of moisture ingress. The heat from an arc
can cause dark brown or black burn marks on the bus bar and in the interlayer. Arcs in the heating film
away from the bus bar can occur as a jagged line.
The flag note number shown below agrees with the number shown in the flag symbols in the figure.
MORE DATAFLAG
NOTE
Color photographs of typical single structural glass pane No. 2 and No. 3 window damage can
be found in Fleet Team Digest Articles 747 FTD 56-05001 and 747-400 FTD 56-05001. These
articles can be accessed through the MyBoeingFleet website, or you may obtain copies from
your local Boeing Field Service office.
1
FIGURE 2: 65B27042-( ) AND 65B27043-( ) SINGLE STRUCTURAL GLASS PANE  NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 6 OF 6)
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### Page 46 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
SEE
LEFT NO. 3 WINDOW
RIGHT NO. 3 WINDOW
LEFT NO. 2 WINDOW
RIGHT NO. 2 WINDOW
SEE
SEE
747-400 FLIGHT DECK SHOWN
U54208
FIGURE 3: 65B27046-() AND 65B27047-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 1 OF 7)
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### Page 47 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
CRASH
FIBERGLASS INTERIOR
PADS
LINING OR VERTICAL  BUS BARS
SIDEWALL LINING AT
THE AFT EDGE OF THE
WINDOW
2) NO. 2 WINDOW
BUS BAR  BUS BAR
NO. 3 WINDOW
SEE
SEE
NO. 1
WINDOW
SEE
• FWD
NO. 2 AND NO. 3 WINDOWS
(LEFT SIDE)
INBD
CRASH
PADS
BUS BARS
FIBERGLASS INTERIOR
LINING OR VERTICAL
SIDEWALL LINING AT
NO. 2 WINDOW 3  THE AFT EDGE OF THE
WINDOW
BUS BAR  BUS BAR
4 NO. 3 WINDOW
SEE R
NO. 1  SEE
WINDOW
SEE
FWD  NO. 2 AND NO. 3 WINDOWS
(RIGHT SIDE)
INBD
FIGURE 3: 65B27046-() AND 65B27047-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 2 OF 7)
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### Page 48 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
INBOARD URETHANE
FAIL-SAFE
INTERLAYER
VINYL
FAIL-SAFE
INTERLAYER
OUTER GLASS
PANE
STRUCTURAL INNER
OUTBOARD  / GLASS PANE
URETHANE
INTERLAYER
TYPICAL URETHANE
INTERLAYER CRACKS
INSERT
EDGE SEAL
PRESSURE
SEAL
FWD
EDGE MEMBER
TYPICAL NO. 2 AND NO. 3 WINDOWS
A-A
_ FIGURE 3: 65B27046-() AND 65B27047-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 3 OF 7)
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### Page 49 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
- POWER
TERMINAL
- BOLT HOLE
(TYPICAL)
TYPICAL INBOARD URETHANE
FAIL-SAFE INTERLAYER CRACKS
TYPICAL NO. 2 AND NO. 3 WINDOW
U56949
| FIGURE 3: 65B27046-() AND 65B27047-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 4 OF 7)
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### Page 50

FIGURE 3: 65B27046-( ) AND 65B27047-( ) SINGLE STRUCTURAL GLASS  PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 5 OF 7)
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### Page 51 (OCR)

BOEING SERVICE BULLETIN 747-56A2012
BUS BAR
→ SEE H
BUS BAR
SEE
TYPICAL NO.2 AND NO.3 WINDOWS
HEATING
FILM
ARCING
ARCING ALONG
BUS BAR
BUS BAR
(н)
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
STEP  TASK  NAME  IDENTIFICATION  QTY  MORE DATA
Inspect  Left No. 3 Window  1  (a) (b) (c) (d) (e)
• FIGURE 3: 65B27046-() AND 65B27047-() SINGLE STRUCTURAL GLASS PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 6 OF 7)
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### Page 52

MORE DATAQTYIDENTIFICATIONNAMETASKSTEP
(a) (b) (c) (d) (e)1-Left No. 2 WindowInspect2
(a) (b) (c) (d) (e)1-Right No. 2 WindowInspect3
(a) (b) (c) (d) (e)1-Right No. 3 WindowInspect4
(a) Do an internal detailed inspection of the flight deck window for the following cracks or damage: fail-safe
interlayer cracks, glass pane cracks and chips, and indications of arcing. An optional external detailed
inspection of the flight deck window for the damage may be necessary if the existing window conditions
do not allow complete inspection from the inside of the flight deck. Any non-clear damage should be noted
that may hinder inspection of the damage.
(b) Inspect the window for fail-safe interlayer cracks along the metal edge insert. Fail-safe interlayer cracks
can be at any location in the window, but are usually found along the metal edge insert. As of the issue
date of this service bulletin, on 65B27046-( ) and 65B27047-( ) single structural glass pane No. 2 and No.
3 windows cracks have only been found in the inboard urethane fail-safe interlayer. No cracks have been
found in the vinyl fail-safe interlayer. The inboard urethane fail-safe interlayer cracks that have been found
do not run parallel to the edges of the window. Instead, they appear to be in random in directions close
to the window attachment bolt holes. Inboard urethane fail-safe interlayer cracks are frequently accompanied
by white or yellow discoloration of the urethane.
(c) On 65B27046-( ) and 65B27047-( ) single structural glass pane No. 2 and No. 3 windows, the outboard
urethane interlayer is considered to be non-structural. This layer is 0.02 inch thick and is located adjacent
to the outer glass pane. White or yellow discoloration and cracking in this layer is considered to be accept-
able, as long as the pilot's vision is not obscured.
(d) Inspect the window for glass pane cracks and chips. There are many types of chips but pay particular
attention to "V" shaped chips and peel chips. "V" shaped chips occur on the external surface of the glass
pane and have a sharp narrow "V" where the depth is equal to or larger than the width. "V" shaped chips
occur on the external surface of the glass pane and have a sharp narrow "V" where the depth is equal to
or larger than the width. Peel chips occur on the internal surface of the glass pane and these areas have
a curved, rough grained shape, and are easily seen in reflected light. The area of the peel chips can have
small glass flakes, usually white, and view through the window will distort through the rough surface of
the chip. Peel chips start very small but can continue to grow with the continued use of the airplane.
(e) Inspect the window for any indications of arcing. An arc can occur due to an electrical discharge or short
circuit across a wire, bus bar, conductive heating film or other internal window components. Arcs usually
occur near the window bus bars, and are typically the result of moisture ingress. The heat from an arc
can cause dark brown or black burn marks on the bus bar and in the interlayer. Arcs in the heating film
away from the bus bar can occur as a jagged line.
The flag note number shown below agrees with the number shown in the flag symbols in the figure.
MORE DATAFLAG
NOTE
Color photographs of typical single structural glass pane No. 2 and No. 3 window damage can
be found in Fleet Team Digest Articles 747 FTD 56-05001 and 747-400 FTD 56-05001. These
articles can be accessed through the MyBoeingFleet website, or you may obtain copies from
your local Boeing Field Service office.
1
FIGURE 3: 65B27046-( ) AND 65B27047-( ) SINGLE STRUCTURAL GLASS  PANE NO. 2 AND NO. 3 WINDOW
DETAILED INSPECTION
(SHEET 7 OF 7)
BOEING PROPRIETARY -
Copyright © Unpublished Work - See page 1 for details.
Original Issue: August 24, 2006
747-56A2012Revision 1 August 12, 2010
52 of 52
BOEING SERVICE BULLETIN 747-56A2012

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