# Boeing Alert Requirements Bulletin 747-53A2906 RB: No revision named

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- Title as filed: 747-53A2906 RB
- Pages: 23
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## Text

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### Page 1

Commercial 
Airplanes
747
Requirements Bulletin
ALERT
Number: 747-53A2906 RB
Original Issue: July 16, 2021
ATA System: 5300
SUBJECT: FUSELAGE STRUCTURE - Center Section - Crown Stringer Inspection and Repair
Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15
CFR 300-774). 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:
Copyright © 2021 Boeing.
Unpublished Work. All Rights Reserved.
Treatment of this document and its content is governed by contract with Boeing. Rights to use this document
are licensed on a per aircraft basis and such rights may not be transferable. For more information, contact The
Boeing Company.
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, KC-46, KDC-10, MD-10, MD-11, MD-80, MD-88, MD-90, P-8, Poseidon and
Boeing liveries 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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2.0

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Table of Contents
1. EFFECTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
A. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. CONCURRENT REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. APPROVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
B. Work Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
FIGURE 1: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND
STA 1000 - DETAILED INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
FIGURE 2: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - DETAILED INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
FIGURE 3: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND
STA 1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION . . 18
FIGURE 4: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION . . 21
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Commercial 
Airplanes
747
Requirements Bulletin
ALERT
Number: 747-53A2906 RB
Original Issue: July 16, 2021
ATA System: 5300
SUBJECT: FUSELAGE STRUCTURE - Center Section - Crown Stringer Inspection and Repair
THIS DOCUMENT 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 DOCUMENT
TO THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS DOCUMENT TO THE
NEW OWNER. THIS IS AN ENHANCED REQUIRED FOR COMPLIANCE DOCUMENT. THE BOEING
PROCESSES USED TO CREATE THE SERVICE BULLETIN (SB) AND THE REQUIREMENTS BULLETIN
(RB) ENSURE THAT THE INFORMATION BETWEEN "RC START" AND "RC END" IN THE SB ARE IDENTICAL
TO THE INFORMATION IN THE SAME SECTIONS (COMPLIANCE, WORK INSTRUCTIONS…) OF THE RB
WHICH THE SB REFERS TO AS THE RELATED DOCUMENT.
1. Effectivity
A. Airplanes
This bulletin is applicable to 747-8F Airplane(s), line number(s) 1420-1433, 1436-1438, 1441-1442,
1444-1445, 1447-1448, 1450, 1452, 1454-1455, 1457-1458, 1460-1465, 1467, 1469, 1471,
1473-1474, 1476, 1478-1479, 1481-1491, 1493, 1496, 1501-1502, 1504-1505, 1516, 1520-1522,
1526, 1528, 1530, 1532-1536, 1540-1574 in 1 Group(s). Where the effectivity is presented with
hyphens between line numbers, the airplane applicability means "through" and "inclusive", e.g.
line numbers 1-9 means line numbers 1 through 9 inclusive.
The Variable Numbers and Group Information for the applicable airplanes is given below.
NOTE: The Variable Number table below includes all affected airplanes up to Line Number 1571.
Affected airplanes after Line Number 1571 will be added to the service bulletin's
MyBoeingFleet.com (MBF) "get effectivity" result when they are added to the MBF Fleet
Profile Page.
DESCRIPTIONCONFIGURATIONGROUP
747-8F Airplanes.-1
Airplane Models:
747-8F
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GroupVariable Number
1RC501 - RC514
1RC521 - RC528
1RC531 - RC541
1RC546 - RC566
GroupVariable Number
1RC571 - RC582
1RC601 - RC610
1RC641 - RC644
1RC651 - RC652
GroupVariable Number
1RC661
1RC671 - RC674
1RC681 - RC696
1RC701
B. Spares Affected
None.
2. CONCURRENT REQUIREMENTS
None.
3. COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
Requirements Bulletin 747-53A2906 RB. The Airworthiness Directive will make the compliance tasks and
times given in Requirements Bulletin 747-53A2906 RB mandatory.
Accomplish the required action(s), based on the applicable conditions in Table 1 and Table 2 in accordance
with Accomplishment Instructions.
When more than one OPTION is given for a CONDITION, do only one of the OPTION numbers. When
more than one ACTION is given for a CONDITION or an OPTION, do all of the ACTION numbers for that
CONDITION or OPTION.
Table 1: Crown Stringers Detailed Inspection for Any Crack
Repeat Interval
(Not to Exceed)
Boeing Recommended Compli-
ance Time (Whichever Occurs
Later)
ActionCondition
-Within 3,600
flight cycles or
36 months after
the original is-
sue date of Re-
quirements Bul-
letin 747-
53A2906 RB,
whichever oc-
curs first.
Before 9,600 to-
tal flights cycles.
Do a detailed inspection of the
left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
All Airplanes.
9,600 flight cycles.-Repeat the detailed inspection
of the left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
CONDITION 1: NO
CRACK FOUND.
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Table 1: Crown Stringers Detailed Inspection for Any Crack
Repeat Interval
(Not to Exceed)
Boeing Recommended Compli-
ance Time (Whichever Occurs
Later)
ActionCondition
-Before further flight.CONDITION 2 (ACTION 1):CONDITION 2: ANY
CRACK FOUND. Repair in accordance with
Structural Repair Manual
(SRM) 747-8F SRM 53-20-03.
9,600 flight cycles.-CONDITION 2 (ACTION 2):
Repeat the detailed inspection
of the left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
At the times specified in Table 2.CONDITION 2 (ACTION 3): Do
the actions specified in Table
2.
Table 2: Crown Stringers Surface High Frequency Eddy Current (HFEC) Inspection for Any Crack at
Repaired Areas
Repeat Interval
(Not to Exceed)
Boeing Recommended Compli-
ance Time (Whichever Occurs
Later)
ActionCondition
-Within 3,600
flight cycles or
36 months after
the original is-
sue date of Re-
quirements Bul-
letin 747-
53A2906 RB,
whichever oc-
curs first.
Before 9,600 to-
tal flights cycles.
Do a surface High Frequency
Eddy Current (HFEC) inspec-
tion of the left and right side
crown stringers located at S-7,
S-8, S-9, S-10, S-11, and S-12
between STA 740 and STA
1000 for any crack at repaired
areas. (a)
Airplanes with re-
pair(s) not done in ac-
cordance with 747-
53A2906 RB. (a)
-Within 9,600 flight cycles after re-
pair.
Do a surface HFEC inspection
of the left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack at repaired areas.
(a)
Airplanes with re-
pair(s) done in accor-
dance with 747-
53A2906 RB. (a)
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Table 2: Crown Stringers Surface High Frequency Eddy Current (HFEC) Inspection for Any Crack at
Repaired Areas
Repeat Interval
(Not to Exceed)
Boeing Recommended Compli-
ance Time (Whichever Occurs
Later)
ActionCondition
9,600 flight cycles.-Repeat the surface HFEC in-
spection of the left and right
side crown stringers located at
S-7, S-8, S-9, S-10, S-11, and
S-12 between STA 740 and
STA 1000 for any crack at re-
paired areas. (a)
CONDITION 1: NO
CRACK FOUND.
-Before further flight.CONDITION 2 (ACTION 1):CONDITION 2: ANY
CRACK FOUND. Repair in accordance with
Structural Repair Manual
(SRM) 747-8F SRM 53-20-03.
9,600 flight cycles.-CONDITION 2 (ACTION 2):
Repeat the surface HFEC in-
spection of the left and right
side crown stringers located at
S-7, S-8, S-9, S-10, S-11, and
S-12 between STA 740 and
STA 1000 for any crack at re-
paired areas. (a)
(a) A repaired area includes Structural Repair Manual (SRM) repairs, Boeing approved unpublished repairs,
or rework accomplished during production identified in the Significant Rework Log (SRL) provided with
each individual aircraft at delivery.
4. APPROVAL
This Requirements Bulletin was examined by the Federal Aviation Administration (FAA). The changes
specified in this document comply with the applicable regulations and are FAA approved, as well as European
Union Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in this Requirements Bulletin effectivity. This document and its approval were based on the
airplane in its original Boeing delivery configuration or as modified by other Boeing changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also affected by
this Requirements Bulletin, the operator is responsible for obtaining appropriate regulatory agency approval
before incorporating this Requirements Bulletin.
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5.    ACCOMPLISHMENT INSTRUCTIONS
A. GENERAL INFORMATION
NOTE: 1. This is an Enhanced Required for Compliance document. There will be a separate
Service Bulletin (SB) and a separate Requirements Bulletin (RB). If an RB is mandated
by an Airworthiness Directive (AD), then all applicable requirements specified in the
RB must be done. For the related SB, some locations are marked RC Start and RC
End to identify the requirements that are restated from the RB. For the related SB,
the areas between RC Start and RC End, including sub-steps and any figures
identified between RC Start and RC End, must be done to comply with the AD.
Therefore, an Alternative Method of Compliance (AMOC) is required for any deviations
to steps between RC Start and RC End, including substeps and identified figures.
For the related SB, the steps not between RC Start and RC End may be deviated
from using accepted methods in accordance with the operator's maintenance or
inspection program without obtaining approval of an AMOC; this is provided that the
steps between RC Start and RC End, including sub-steps and identified figures, can
still be done as specified, and the airplane can be put back in an airworthy condition.
Figures not required for compliance are omitted from the RB.
2. This is an Enhanced Required for Compliance document. The Boeing processes
used to create the Service Bulletin (SB) and the Requirements Bulletin (RB) ensure
that the information between "RC Start" and "RC End" in the SB are identical to the
information in the same sections (Compliance, Work Instructions...) of the RB which
the SB refers to as the related document.
3. The compliance times for the actions in WORK INSTRUCTIONS are in Compliance.
4. Boeing Service Letter 747-SL-51-048, Damage Reporting and Repair Plan/Design
Guidelines, is an acceptable procedure to request information from Boeing for
additional structural repair instructions. The Service Letter describes what information
must be provided to Boeing before a structural repair can be provided.
5. Unless shown differently, these dimensions and tolerances are used:
– Linear dimensions are in inches
– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus
or minus 0.03 inch
– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch
– Angular tolerance is plus or minus 2 degrees
– Hole dimensions for standard solid rivets and fasteners are in Structural Repair
Manual (SRM) Chapter 51
– Torque Values:
— Values for structural fasteners are given in 747 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 747
Aircraft Maintenance Manual (AMM).
— Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
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6. 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.
7. Where the work instructions include installation of a kept part, a new or serviceable
part with the same part number can be installed as an alternative to the kept part.
8. If it is necessary to remove more parts for access, you can remove those parts. If
you can get access without removing identified parts, it is not necessary to remove
all of the identified parts. Jacking and shoring limitations must be observed.
9. Use the approved fastener, process and material substitutions in accordance with
SRM Chapter 51.
10. A Detailed Inspection is defined as: An intensive examination of a specific item,
installation or assembly to detect damage, failure or irregularity. This could include
tactile assessment in which a component or assembly can be checked for
tightness/security. Available lighting is normally supplemented with a direct source
of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors
and magnifying lenses may be necessary. Surface cleaning and elaborate access
procedures may be required.
11. When more than one OPTION is given for a CONDITION, do only one of the OPTION
numbers. When more than one ACTION is given for a CONDITION or an OPTION,
do all of the ACTION numbers for that CONDITION or OPTION.
B. WORK INSTRUCTIONS
Actions Required for Compliance
1. Requirements
Table 1: Crown Stringers Detailed Inspection for Any Crack
Refer to the listed
procedures in SB
747-53A2906
Original Issue or
later approved re-
visions as an ac-
cepted proce-
dure.
Method of ComplianceActionCondition
Do PART 1: OPEN
ACCESS.
-Do a detailed inspection of the
left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
All Airplanes.
-LEFT SIDE: FIGURE 1
and
RIGHT SIDE: FIGURE 2.
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Table 1: Crown Stringers Detailed Inspection for Any Crack
Refer to the listed
procedures in SB
747-53A2906
Original Issue or
later approved re-
visions as an ac-
cepted proce-
dure.
Method of ComplianceActionCondition
Do PART 2:
CLOSE ACCESS.
-Repeat the detailed inspection
of the left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
CONDITION 1: NO
CRACK FOUND.
-LEFT SIDE: FIGURE 1
and
RIGHT SIDE: FIGURE 2.
-747-8F SRM 53-20-03-2R-1 orCONDITION 2 (ACTION 1):CONDITION 2: ANY
CRACK FOUND. 747-8F SRM 53-20-03-2R-2 orRepair in accordance with
Structural Repair Manual
(SRM) 747-8F SRM 53-20-03.
747-8F SRM 53-20-03-2R-3 or
747-8F SRM 53-20-03-2R-4.
Do PART 2:
CLOSE ACCESS
-
-LEFT SIDE: FIGURE 1CONDITION 2 (ACTION 2):
andRepeat the detailed inspection
of the left and right side crown
stringers located at S-7, S-8,
S-9, S-10, S-11, and S-12 be-
tween STA 740 and STA 1000
for any crack.
RIGHT SIDE: FIGURE 2.
--CONDITION 2 (ACTION 3):
Do the actions specified in Ta-
ble 2.
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Table 2: Crown Stringers Surface High Frequency Eddy Current (HFEC) Inspection for Any Crack at
Repaired Areas
Refer to the listed
procedures in SB
747-53A2906
Original Issue or
later approved re-
visions as an ac-
cepted proce-
dure.
Method of ComplianceActionCondition
Do PART 1: OPEN
ACCESS.
-Do a surface High Frequency
Eddy Current (HFEC) inspec-
tion at repaired areas of the left
and right side crown stringers
located at S-7, S-8, S-9, S-10,
S-11, and S-12 between STA
740 and STA 1000 for any
crack. (a)
Airplanes with re-
pair(s) not done in ac-
cordance with 747-
53A2906 RB.(a) -LEFT SIDE: FIGURE 3and
RIGHT SIDE: FIGURE 4.
Do PART 1: OPEN
ACCESS.
-Do a surface HFEC inspection
at repaired areas of the left
and right side crown stringers
located at S-7, S-8, S-9, S-10,
S-11, and S-12 between STA
740 and STA 1000 for any
crack. (a)
Airplanes with re-
pair(s) done in accor-
dance with 747-
53A2906 RB.(a) -LEFT SIDE: FIGURE 3and
RIGHT SIDE: FIGURE 4.
Do PART 2:
CLOSE ACCESS.
-Repeat the surface HFEC in-
spection of the left and right
side crown stringers located at
S-7, S-8, S-9, S-10, S-11, and
S-12 between STA 740 and
STA 1000 for any crack at re-
paired areas. (a)
CONDITION 1: NO
CRACK FOUND.
-LEFT SIDE: FIGURE 3
and
RIGHT SIDE: FIGURE 4.
-747-8F SRM 53-20-03-2R-1 orCONDITION 2 (ACTION 1):CONDITION 2: ANY
CRACK FOUND. 747-8F SRM 53-20-03-2R-2 orRepair in accordance with
Structural Repair Manual
(SRM) 747-8F SRM 53-20-03.
747-8F SRM 53-20-03-2R-3 or
747-8F SRM 53-20-03-2R-4.
Do PART 2:
CLOSE ACCESS.
-
-LEFT SIDE: FIGURE 3CONDITION 2 (ACTION 2):
andRepeat the surface HFEC in-
spection of the left and right
side crown stringers located at
S-7, S-8, S-9, S-10, S-11, and
S-12 between STA 740 and
STA 1000 for any crack at re-
paired areas. (a)
RIGHT SIDE: FIGURE 4.
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Table 2: Crown Stringers Surface High Frequency Eddy Current (HFEC) Inspection for Any Crack at
Repaired Areas
Refer to the listed
procedures in SB
747-53A2906
Original Issue or
later approved re-
visions as an ac-
cepted proce-
dure.
Method of ComplianceActionCondition
(a) A repaired area includes Structural Repair Manual (SRM) repairs, Boeing approved unpublished repairs,
or rework accomplished during production identified in the Significant Rework Log (SRL) provided with
each individual aircraft at delivery.
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### Page 14 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
STA
STA  , 1000
740  ~S-7L  STA
740
S-12L  ·—S-7L
₴—S-8L  ₴—S-9L  →S-10L
3-S-11L  / S-12L
STA
1000
VIEW LOOKING UP AND OUTBOARD
(TYPICAL)
STRINGER 1  TYPICAL CRACK  LOCATION
• B
FRAME  SKIN  FRAME
INSPECTION AREA  STRINGER SECTION INSPECTION AREA
(TYPICAL)  2959876
A-A
FIGURE 1: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND STA
1000 - DETAILED INSPECTION
(SHEET 1 OF 2)
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### Page 15

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 figure.
More DataQtyIdentificationNameTaskStep
(a)1S-7L, BETWEEN STA
740 AND STA 1000
STRINGERInspect1
(a)1S-8L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-9L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-10L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-11L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-12L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a) Do a detailed inspection of the crown stringer for any crack.
FIGURE 1: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND STA
1000 - DETAILED INSPECTION
(SHEET 2 OF 2)
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### Page 16 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
STA
STA  740  S-7R  1000,  STA  740
S-8R -  S-7R _  S-12R
S-9R.
S-10R_
S-11R~
S-12R _
STA
1000
VIEW LOOKING UP AND OUTBOARD
(TYPICAL)
TYPICAL CRACK  LOCATION  1) STRINGER
FRAME  SKIN  FRAME
INSPECTION AREA  STRINGER SECTION INSPECTION AREA
(TYPICAL)  2959883
A-A
FIGURE 2: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - DETAILED INSPECTION
(SHEET 1 OF 2)
Original Issue: July 16, 2021
Export Controlled ECCN: 9E991  747-53A2906 RB
Copyright © Unpublished
Work - See page 1 for details.  16 of 23

### Page 17

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 figure.
More DataQtyIdentificationNameTaskStep
(a)1S-7R, BETWEEN STA
740 AND STA 1000
STRINGERInspect1
(a)1S-8R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-9R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-10R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-11R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)1S-12R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a) Do a detailed inspection of the crown stringer for any crack.
FIGURE 2: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - DETAILED INSPECTION
(SHEET 2 OF 2)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 16, 2021
747-53A2906 RB
17 of 23
REQUIREMENTS BULLETIN 747-53A2906
ALERTALERT

### Page 18 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
STA
STA  1000
740  S-7L  STA
740
• S-12L
→—S-8L  →—S-10L  ,—S-9L
3S-11L  - S-12L
STA
1000
VIEW LOOKING UP AND OUTBOARD
(TYPICAL)
FRAME  • STRINGER CLIP
(TYPICAL)  SKIN (TYPICAL) (TYPICAL)
STA  STA
1000  741
REPAIR
FWD  STRINGER  (TYPICAL)  HAT SECTION  STRINGER  SECTION
SPLICE
A-A
2967845
FIGURE 3: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND STA
1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 1 OF 3)
Original Issue: July 16, 2021
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.

### Page 19 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
FRAME
STRINGER CLIP  CUT  (TYPICAL)
(TYPICAL)  BETWEEN
FRAMES
STRINGER  HAT SECTION  O  REPAIR
SPLICE  STRINGER
(TYPICAL)  SECTION
1.0 INCH  •1.0 INCH
SKIN MINIMUM  MINIMUM
FWD
B-B
HAT SECTION SPLICE
STRINGER OF
1) REPAIF
STRINGER
SECTION
SKIN
• INSPECTION AREA
C-C  2967847
FIGURE 3: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND STA
1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 2 OF 3)
Original Issue: July 16, 2021
Export Controlled ECCN: 9E991  747-53A2906 RB
Copyright © Unpublished
Work - See page 1 for details.  19 of 23

### Page 20

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 figure.
More DataQtyIdentificationNameTaskStep
(a)(b)1S-7L, BETWEEN STA
740 AND STA 1000
STRINGERInspect1
(a)(b)1S-8L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-9L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-10L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-11L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-12L, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a) Do a Surface High Frequency Eddy Current (HFEC) inspection of the crown stringer for any crack at re-
paired areas in accordance with 747 NDT Manual Part 6, 51-00-00, Procedure 4 or 23.
(b) A repaired area includes Structural Repair Manual (SRM) repairs, Boeing approved unpublished repairs,
or rework accomplished during production identified in the Significant Rework Log (SRL) provided with
each individual aircraft at delivery.
FIGURE 3: LEFT SIDE FUSELAGE - CROWN STRINGER AT S-7L TO S-12L BETWEEN STA 740 AND STA
1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 16, 2021
747-53A2906 RB
20 of 23
REQUIREMENTS BULLETIN 747-53A2906
ALERTALERT

### Page 21 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
STA
1000  STA
STA  S-7R.  740
740
S-TR -  S-12R•
S-10R
S-11R ~
S-12R~
STA
1000
VIEW LOOKING UP AND OUTBOARD
(TYPICAL)
STRINGER CLIP  FRAME
(TYPICAL)  SKIN (TYPICAL)  (TYPICAL)
STA  STA
741  1000
B
REPAIR  •WD
STRINGER  STRINGER
SECTION  HAT SECTION  (TYPICAL)
SPLICE
A-A
2967854
FIGURE 4: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 1 OF 3)
Original Issue: July 16, 2021
Export Controlled ECCN: 9E991  747-53A2906 RB
Copyright © Unpublished
Work - See page 1 for details.  21 of 23

### Page 22 (OCR)

REQUIREMENTS BULLETIN 747-53A2906
ALERT  ALERT
FRAME  • STRINGER CLIP
(TYPICAL)  CUT  → (TYPICAL)
BETWEEN
FRAMES
REPAIR  HAT SECTION  STRINGER
STRINGER  SPLICE
SECTION  (TYPICAL)
1.0 INCH-  1.0 INCH
MINIMUM  MINIMUM  SKIN
FWD
B-B
HAT SECTION SPLICE
OSERAGEROR
STRINGER
SECTION
SKIN
INSPECTION AREA
C-C  2967859
FIGURE 4: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 2 OF 3)
Original Issue: July 16, 2021
Export Controlled ECCN: 9E991  747-53A2906 RB
Copyright © Unpublished
Work - See page 1 for details.  22 of 23

### Page 23

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 figure.
More DataQtyIdentificationNameTaskStep
(a)(b)1S-7R, BETWEEN STA
740 AND STA 1000
STRINGERInspect1
(a)(b)1S-8R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-9R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-10R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-11R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a)(b)1S-12R, BETWEEN STA
740 AND STA 1000
STRINGERInspect
(a) Do a Surface High Frequency Eddy Current (HFEC) inspection of the crown stringer for any crack at re-
paired areas in accordance with 747 NDT Manual Part 6, 51-00-00, Procedure 4 or 23.
(b) A repaired area includes Structural Repair Manual (SRM) repairs, Boeing approved unpublished repairs,
or rework accomplished during production identified in the Significant Rework Log (SRL) provided with
each individual aircraft at delivery.
FIGURE 4: RIGHT SIDE FUSELAGE - CROWN STRINGER AT S-7R TO S-12R BETWEEN STA 740 AND
STA 1000 - SURFACE HIGH FREQUENCY EDDY CURRENT (HFEC) INSPECTION
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: July 16, 2021
747-53A2906 RB
23 of 23
REQUIREMENTS BULLETIN 747-53A2906
ALERTALERT

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