# Boeing Requirements Bulletin 737-53A1375 RB: No revision named

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- Title as filed: 737-53A1375-00-- RB--
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### Page 1

Commercial 
Airplanes
737
Requirements Bulletin
ALERT
Number: 737-53A1375 RB
Original Issue: March 12, 2018
ATA System: 5313
SUBJECT: FUSELAGE - Body Station 303.9 Frame - Inspection of Frame Web and Doubler at
Stringer 16 Left
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 © 2018 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Unpublished Work.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.
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737-53A1375 RB
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3.0

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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
B. Work Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
FIGURE 1: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L  [Group 2, Configuration 2] . . . . . . . . . 15
FIGURE 2: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L  [Group 3, Configuration 2] . . . . . . . . . 18
FIGURE 3: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L  [Group 4, Configuration 2] . . . . . . . . . 21
FIGURE 4: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L  [Group 5] . . . . . . . . . . . . . . . . . . 24
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Commercial 
Airplanes
737
Requirements Bulletin
ALERT
Number: 737-53A1375 RB
Original Issue: March 12, 2018
ATA System: 5313
SUBJECT: FUSELAGE - Body Station 303.9 Frame - Inspection of Frame Web and Doubler at
Stringer 16 Left
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 737-100/200/200C/300/400/500 Airplanes, line numbers 1-3132.
DESCRIPTIONCONFIGURATIONGROUP
737-100/200/200C Airplanes, line numbers 1 thru 291.-1
737-200/300/400/500 Airplanes, line numbers 292 thru 2349 and
2351 thru 2437.
-2
Airplanes without any modification or repair installed on the STA
303.9 frame at S-16L.
1
Airplanes with doubler modification or repair installed in accordance
with SB 737-53A1197.
2
Airplanes with doubler modification or repair installed on STA 303.9
frame at S-16L that was not installed in accordance with SB
737-53A1197.
3
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DESCRIPTIONCONFIGURATIONGROUP
All 737-200C Airplanes.-3
Airplanes without any modification or repair installed on the STA
303.9 frame at S-16L.
1
Airplanes with doubler modification or repair installed in accordance
with SB 737-53A1197.
2
Airplanes with doubler modification or repair installed on STA 303.9
frame at S-16L that was not installed in accordance with SB
737-53A1197.
3
737-300/400/500 Airplanes, line numbers 2350 and 2438 thru 2765.-4
Airplanes without any modification or repair installed on the STA
303.9 frame at S-16L, or airplanes with a short doubler modification
or a short doubler repair installed in accordance with SB 737-53A1188
Original Issue or Revision 1.
1
Airplanes with a long doubler modification or a long doubler repair
installed in accordance with SB 737-53A1188 Revision 2 or Revision
3.
2
Airplanes with doubler modification or repair installed on STA 303.9
frame at S-16L that was not installed in accordance with SB
737-53A1188.
3
737-300/400/500 Airplanes, line numbers 2766 thru 3132.-5
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 737-53A1375 RB. The Airworthiness Directive will make the compliance tasks and
times given in Requirements Bulletin 737-53A1375 RB mandatory.
Accomplish the required actions, based on the applicable conditions in Tables 1 through 4, in accordance
with the 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 number or an OPTION number, do all of the ACTION
numbers for that CONDITION number or OPTION number.
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Group 1:
Boeing endorses the FAA rules related to Limit of Validity (LOV) and recommends immediate and permanent
removal from service of any airplanes upon reaching the LOV, whether or not it is operated under FAA
jurisdiction. As such, Boeing no longer provides maintenance instructions for airplanes that have accumulated
flight cycles beyond the LOV. Airplanes in Group 1 (line numbers 1-291) have accumulated flight cycles
beyond the LOV of the maintenance program. 14 CFR 121.1115 and 129.115 prohibit operation of an
airplane beyond its LOV.
Group 2-4, Configuration 1:
No work is necessary.
Group 2-3, Configuration 2:
Table 1: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 737-
53A1375 RB.
Within 15,000
flight cycles af-
ter the installa-
tion of the modi-
fication or repair
in accordance
with Boeing Ser-
vice Bulletin
(SB) 737-
53A1197.
Do surface HFEC inspec-
tions of the STA 303.9
frame web and doubler at
the stop fitting at S-16L
for any crack. (a)
All Airplanes
-Before further flight.CONDITION 1 (ACTION
1): Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 1: ANY
CRACK FOUND
4,500 flight cycles.-CONDITION 1 (ACTION
2): Repeat the surface
HFEC inspections of the
STA 303.9 frame web
and doubler at the stop
fitting at S-16L for any
crack. (a)
4,500 flight cycles.-Repeat the surface HFEC
inspections of the STA
303.9 frame web and
doubler at the stop fitting
at S-16L for any crack.
(a)
CONDITION 2: NO
CRACK FOUND
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Group 2-3, Configuration 2:
Table 1: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
(a) It is not required to do the inspections in accordance with Requirements Bulletin 737-53A1375 RB in areas
where an existing repair covers the inspection area and meets the following criteria:
1. The repair is installed after the Original Issue date of Requirements Bulletin 737-53A1375 RB.
2. The repair was approved by the Boeing Organization Designation Authorization (ODA) via an
FAA Form 8100-9 of which contains a repeat inspection program for the subject area.
Group 4, Configuration 2:
Table 2: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 737-
53A1375 RB.
Within 15,000
flight cycles af-
ter the installa-
tion of the modi-
fication or repair
in accordance
with Boeing Ser-
vice Bulletin
(SB) 737-
53A1188 Revi-
sion 2 or Revi-
sion 3.
Do surface HFEC inspec-
tions of the STA 303.9
frame web and doubler at
the stop fitting at S-16L
for any crack. (a)
All Airplanes
-Before further flight.CONDITION 1 (ACTION
1): Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 1: ANY
CRACK FOUND
12,000 flight cy-
cles.
-CONDITION 1 (ACTION
2): Repeat the surface
HFEC inspections of the
STA 303.9 frame web
and doubler at the stop
fitting at S-16L for any
crack. (a)
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Group 4, Configuration 2:
Table 2: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
12,000 flight cy-
cles.
-Repeat the surface HFEC
inspections of the STA
303.9 frame web and
doubler at the stop fitting
at S-16L for any crack.
(a)
CONDITION 2: NO
CRACK FOUND
(a) It is not required to do the inspections in accordance with Requirements Bulletin 737-53A1375 RB in areas
where an existing repair covers the inspection area and meets the following criteria:
1. The repair is installed after the Original Issue date of Requirements Bulletin 737-53A1375 RB.
2. The repair was approved by the Boeing Organization Designation Authorization (ODA) via an
FAA Form 8100-9 of which contains a repeat inspection program for the subject area.
Group 2-4, Configuration 3:
Table 3: Inspections of the Body Station (STA) 303.9 frame web and doubler at the stop fitting at stringer
16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 737-
53A1375 RB.
Before 15,000
total flight cy-
cles.
Contact The Boeing
Company for alternative
inspection instruction and
do the inspection and any
corrective actions as ap-
plicable.
All Airplanes
Group 5:
Table 4: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,500
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 737-
53A1375 RB.
Before 15,000
total flight cy-
cles.
Do surface HFEC inspec-
tions of the STA 303.9
frame web and doubler at
the stop fitting at S-16L
for any crack. (a)
All Airplanes
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Group 5:
Table 4: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9
frame web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.CONDITION 1 (ACTION
1): Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 1: ANY
CRACK FOUND
12,000 flight cy-
cles.
-CONDITION 1 (ACTION
2): Repeat the surface
HFEC inspections of the
STA 303.9 frame web
and doubler at the stop
fitting at S-16L for any
crack. (a)
12,000 flight cy-
cles.
-Repeat the surface HFEC
inspections of the STA
303.9 frame web and
doubler at the stop fitting
at S-16L for any crack.
(a)
CONDITION 2: NO
CRACK FOUND
(a) It is not required to do the inspections in accordance with Requirements Bulletin 737-53A1375 RB in areas
where an existing repair covers the inspection area and meets the following criteria:
1. The repair is installed after the Original Issue date of Requirements Bulletin 737-53A1375 RB.
2. The repair was approved by the Boeing Organization Designation Authorization (ODA) via an
FAA Form 8100-9 of which contains a repeat inspection program for the subject area.
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
Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved
airplanes listed in the service 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: 6. 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 737 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 737
Aircraft Maintenance Manual (AMM).
— Values for electrical maintenance tasks are included in Chapter 20 of
Standard Wiring Practices Manual (SWPM).
— Values for engine maintenance tasks are included in Chapter 70 of 737
Aircraft Maintenance Manual (AMM).
— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
7. Use the approved fastener, process and material substitutions in accordance with
SRM Chapter 51.
8. 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.
9. The instructions in the Work Instructions and the figures can include operation of
tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated Tool and
Equipment Manual, and the Special Tool and Ground Handling Drawing Index contain
data on versions of the tools or test equipment that you can use. It is permitted to
use replaced tools. It is not permitted to use superseded tools.
10. 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.
11. 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.
12. 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 number or an
OPTION number, do all of the ACTION numbers for that CONDITION number or
OPTION number.
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### Page 12

13. 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.
14. 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.
B. WORK INSTRUCTIONS
Actions Required for Compliance:
1. Requirements
Group 1:
Boeing endorses the FAA rules related to Limit of Validity (LOV) and recommends immediate and
permanent removal from service of any airplanes upon reaching the LOV, whether or not it is
operated under FAA jurisdiction. As such, Boeing no longer provides maintenance instructions for
airplanes that have accumulated flight cycles beyond the LOV. Airplanes in Group 1 (line numbers
1-291) have accumulated flight cycles beyond the LOV of the maintenance program. 14 CFR
121.1115 and 129.115 prohibit operation of an airplane beyond its LOV.
Group 2-4, Configuration 1:
No work is necessary.
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### Page 13

Group 2-4, Configuration 2; Group 5:
Table 1: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9 frame
web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Refer to the listed proce-
dures in SB 737-53A1375
Original Issue or later ap-
proved revisions as an
accepted procedure:
Method of ComplianceActionCondition
PART 1: OPEN ACCESS-Do surface HFEC inspections
of the STA 303.9 frame web and
doubler at the stop fitting at S-
16L for any crack. (a)
All Airplanes
-FIGURE 1Group 2, Con-
figuration 2
-FIGURE 2Group 3, Con-
figuration 2
-FIGURE 3Group 4, Con-
figuration 2
-FIGURE 4Group 5
PART 2: CLOSE ACCESS-
--CONDITION 1 (ACTION 1):
Contact The Boeing Company
for repair instructions and do the
repair.
CONDITION 1:
ANY CRACK
FOUND
PART 1: OPEN ACCESS-CONDITION 1 (ACTION 2):
Repeat the surface HFEC in-
spections of the STA 303.9
frame web and doubler at the
stop fitting at S-16L for any
crack. (a)
-FIGURE 1Group 2, Con-
figuration 2
-FIGURE 2Group 3, Con-
figuration 2
-FIGURE 3Group 4, Con-
figuration 2
-FIGURE 4Group 5
PART 2: CLOSE ACCESS-
PART 1: OPEN ACCESS-Repeat the surface HFEC in-
spections of the STA 303.9
frame web and doubler at the
stop fitting at S-16L for any
crack. (a)
CONDITION 2: NO
CRACK FOUND -FIGURE 1Group 2, Con-
figuration 2
-FIGURE 2Group 3, Con-
figuration 2
-FIGURE 3Group 4, Con-
figuration 2
-FIGURE 4Group 5
PART 2: CLOSE ACCESS-
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### Page 14

Group 2-4, Configuration 2; Group 5:
Table 1: Surface High Frequency Eddy Current (HFEC) inspections of the Body Station (STA) 303.9 frame
web and doubler at the stop fitting at stringer 16 left (S-16L) for any crack
Refer to the listed proce-
dures in SB 737-53A1375
Original Issue or later ap-
proved revisions as an
accepted procedure:
Method of ComplianceActionCondition
(a) It is not required to do the inspections in accordance with Requirements Bulletin 737-53A1375 RB in areas
where an existing repair covers the inspection area and meets the following criteria:
1. The repair is installed after Original Issue date of Requirements Bulletin 737-53A1375 RB.
2. The repair is approved by the Boeing Organization Designation Authorization (ODA) via an FAA
Form 8100-9 of which contains a repeat inspection program for the subject area.
Group 2-4, Configuration 3:
Table 2: Inspections of the Body Station (STA) 303.9 frame web and doubler at the stop fitting at stringer
16 left (S-16L) for any crack
Refer to the listed proce-
dures in SB 737-53A1375
Original Issue or later ap-
proved revisions as an
accepted procedure:
Method of ComplianceActionCondition
PART 1: OPEN ACCESS-Contact The Boeing Company
for alternative inspection instruc-
tion and do the inspection and
any corrective actions as appli-
cable.
All Airplanes
--
PART 2: CLOSE ACCESS-
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### Page 15 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
This Figure applies only to: Group 2, Configuration 2.
STA
303.9
STA
FRAME  303.9
WEB  INNER CHORD
DOUBLER
S-16L
WL <
208
STOP FITTING
INNER CHORD
WL
208 -
2791587
FIGURE 1: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 1 OF 3)
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### Page 16 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
UPPER FRAME  DOUBLER  INNER CHORD
• STRAP
INNER CHORD
S-16L
STOP FITTING
INBD  CRACK
(TYPICAL)
A-A
INNER CHORD  2 FRAME
WEB  CLIP
STRAP
SPLICE CHORD
INNER CHORD
S-16L
CRACK
(TYPICAL)
INBD
INSPECTION AREA
B-B  2791589
FIGURE 1: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 2 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  16 of 26

### Page 17

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--DOUBLERInspect1
(b)--FRAME WEBInspect2
(a) Do a surface High Frequency Eddy Current (HFEC) inspection of the doubler along the edges of the stop
fitting, the strap and the cutout for any crack in accordance with 737 NDT Manual Part 6, 51-00-00, Pro-
cedure 4 or Procedure 23.
(b) Do a surface HFEC inspection of the frame web along the edges of the clip, the cutout and the inner
chords, and around the adjacent fasteners for any crack in accordance with 737 NDT Manual Part 6, 51-
00-00, Procedure 4 or Procedure 23.
FIGURE 1: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: March 12, 2018
737-53A1375 RB
17 of 26
REQUIREMENTS BULLETIN 737-53A1375
ALERTALERT

### Page 18 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
This Figure applies only to: Group 3, Configuration 2.
STA
303.9
STA
303.9
FRAME
WEB
INNER CHORD
DOUBLER
S-16L _  WL <
208
STOP FITTING
INNER CHORD
WL
208 -
2791593
FIGURE 2: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 1 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  18 of 26

### Page 19 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
UPPER FRAME  DOUBLER  INNER CHORD
• STRAP
INNER CHORD
S-16L
STOP FITTING
INBD  CRACK
(TYPICAL)
A-A
INNER CHORD  2 FRAME  WEB  CLIP
STRAP
SPLICE CHORD
INNER CHORD
S-16L
CRACK
(TYPICAL)
INBD
INSPECTION AREA
B-B  2791594
FIGURE 2: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 2 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  19 of 26

### Page 20

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--DOUBLERInspect1
(b)--FRAME WEBInspect2
(a) Do a surface High Frequency Eddy Current (HFEC) inspection of the doubler along the edges of the stop
fitting, the strap and the cutout for any crack in accordance with 737 NDT Manual Part 6, 51-00-00, Pro-
cedure 4 or Procedure 23.
(b) Do a surface HFEC inspection of the frame web along the edges of the clip, the cutout and the inner
chords, and around the adjacent fasteners for any crack in accordance with 737 NDT Manual Part 6, 51-
00-00, Procedure 4 or Procedure 23.
FIGURE 2: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: March 12, 2018
737-53A1375 RB
20 of 26
REQUIREMENTS BULLETIN 737-53A1375
ALERTALERT

### Page 21 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
This Figure applies only to: Group 4, Configuration 2.
STA
303.9
S-15L  STA
303.9
DOUBLER
STOP FITTING  - S-16L  WL <
208
INNER CHORD
FRAME
WEB
WL
208
2791597
FIGURE 3: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 1 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  21 of 26

### Page 22 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
INNER CHORD
„STRAP
DOUBLER
RADIUS
FILLER
S-16L
110
STOP FITTING
INBD  CRACK
(TYPICAL)
A-A
INNER CHORD  FRAME
WEB
STRAP,
_ CLIP
S-16L
CRACK  OUTER CHORD
(TYPICAL)
INSPECTION AREA  INBD
B-B  2791599
FIGURE 3: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 2 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  22 of 26

### Page 23

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--DOUBLERInspect1
(b)--FRAME WEBInspect2
(a) Do a surface High Frequency Eddy Current (HFEC) inspection of the doubler along the edges of the stop
fitting, the cutout and the radius filler for any crack in accordance with 737 NDT Manual Part 6, 51-00-00,
Procedure 4 or Procedure 23.
(b) Do a surface HFEC inspection of the frame web along the edges of the clip, the cutout, the inner and
outer chord, and around the adjacent fasteners for any crack in accordance with 737 NDT Manual Part
6, 51-00-00, Procedure 4 or Procedure 23.
FIGURE 3: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: March 12, 2018
737-53A1375 RB
23 of 26
REQUIREMENTS BULLETIN 737-53A1375
ALERTALERT

### Page 24 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
This Figure applies only to: Group 5.
STA
303.9
_ S-15L
STA
303.9
DOUBLER
_ S-16L
STOP FITTING
WL /
208
INNER
FRAME  CHORD
WEB
WL
208
2791676
FIGURE 4: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 1 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  24 of 26

### Page 25 (OCR)

REQUIREMENTS BULLETIN 737-53A1375
ALERT  ALERT
INNER CHORD
STRAP
DOUBLER
S-16L-
STOP FITTING  INBD  CRACK
(TYPICAL)
A-A
INNER CHORD  FRAME
WEB
STRAP,
_CLIP
S-16L
CRACK  OUTER CHORD
(TYPICAL)
INSPECTION AREA  INBD
B-B  2791677
FIGURE 4: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 2 OF 3)
Original Issue: March 12, 2018
Export Controlled ECCN: 9E991  737-53A1375 RB
Copyright © Unpublished
Work - See page 1 for details.  25 of 26

### Page 26

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.
More DataQtyIdentificationNameTaskStep
(a)--DOUBLERInspect1
(b)--FRAME WEBInspect2
(a) Do a surface High Frequency Eddy Current (HFEC) inspection of the doubler along the edges of the stop
fitting and the cutout for any crack in accordance with 737 NDT Manual Part 6, 51-00-00, Procedure 4 or
Procedure 23.
(b) Do a surface HFEC inspection of the frame web along the edges of the clip, the cutout, the inner and
outer chord, and around the adjacent fasteners for any crack in accordance with 737 NDT Manual Part
6, 51-00-00, Procedure 4 or Procedure 23.
FIGURE 4: LEFT SIDE - STA 303.9 FRAME - SURFACE HFEC INSPECTIONS OF FRAME WEB AND
DOUBLER AT THE STOP FITTING AT S-16L
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: March 12, 2018
737-53A1375 RB
26 of 26
REQUIREMENTS BULLETIN 737-53A1375
ALERTALERT

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