# Boeing Alert Requirements Bulletin 757-57A0075 RB: No revision named

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- Title as filed: 757-57A0075 RB (1)
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### Page 1

Commercial 
Airplanes
757
Requirements Bulletin
ALERT
Number: 757-57A0075 RB
Original Issue: August 25, 2021
ATA System: 5710
SUBJECT: WINGS - Center Wing - Rear Spar on Lower Wing Skin - Inspection
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Unpublished Work.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,
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Table of Contents
1. EFFECTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
A. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. CONCURRENT REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. APPROVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
B. Work Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
FIGURE 1: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 1
SURFACE HFEC INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
FIGURE 2: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 2
DETAILED INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FIGURE 3: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
ULTRASONIC AND DETAIL INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . 26
FIGURE 4: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
DETAILED INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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Commercial 
Airplanes
757
Requirements Bulletin
ALERT
Number: 757-57A0075 RB
Original Issue: August 25, 2021
ATA System: 5710
SUBJECT: WINGS - Center Wing - Rear Spar on Lower Wing Skin - Inspection
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 757-200, 757-200CB, 757-200PF, 757-300 Airplane(s), line number(s)
1-1050 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.
DESCRIPTIONCONFIGURATIONGROUP
757-200, 757-200CB, 757-200PF, 757-300 Airplanes-1
Airplane Models:
757-200, 757-200CB, 757-200PF, 757-300
GroupVariable Number
1NA001 - NA028
1NA191 - NA199
1NA201 - NA239
1NA301 - NA305
1NA341 - NA352
1NA391 - NA399
GroupVariable Number
1NA401 - NA408
1NA441 - NA447
1NA501 - NA586
1NB001 - NB004
1NB021 - NB023
1NB036 - NB041
GroupVariable Number
1NB051 - NB053
1NB061 - NB073
1NB079
1NB131 - NB148
1NB161 - NB162
1NB166 - NB168
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GroupVariable Number
1NB201 - NB204
1NB221 - NB228
1NB230
1NB236
1NB239
1NB261 - NB267
1NB291 - NB299
1NB301 - NB302
1NB311 - NB312
1NB321 - NB331
1NB421 - NB438
1NB446
1NB451 - NB454
1NB501 - NB523
1NB561
1NB571
1NB581 - NB583
1NC001 - NC033
1NC041 - NC042
1NC051 - NC052
1NC056 - NC062
1NC066 - NC084
1NC091 - NC094
1NC151
1NC161
1NC901 - NC951
1NC971 - NC974
1ND001 - ND007
1ND011 - ND059
GroupVariable Number
1ND111 - ND113
1ND161 - ND199
1ND201 - ND203
1ND221 - ND225
1ND241 - ND248
1ND301 - ND322
1ND401
1ND891
1ND895
1NE001 - NE008
1NE011 - NE088
1NE091 - NE094
1NE141 - NE150
1NE161 - NE177
1NE201 - NE204
1NE301 - NE302
1NE311 - NE325
1NJ001 - NJ004
1NJ031 - NJ032
1NJ551 - NJ555
1NL001 - NL002
1NL006 - NL017
1NL101 - NL109
1NL141
1NL601 - NL616
1NN001 - NN002
1NN051 - NN052
1NP901 - NP904
1NS601 - NS616
GroupVariable Number
1NT001 - NT009
1NT201 - NT202
1NT231 - NT234
1NT237 - NT240
1NT242
1NT245 - NT248
1NT281 - NT289
1NT341 - NT347
1NT351 - NT360
1NT371 - NT373
1NT375 - NT379
1NT381 - NT386
1NT401 - NT409
1NT411 - NT412
1NT426 - NT427
1NT431 - NT432
1NT436 - NT438
1NT441 - NT442
1NT446
1NT701 - NT769
1NT791 - NT796
1NT861 - NT862
1NT881 - NT885
1NT901 - NT916
1NT971 - NT985
1NU031 - NU038
1NU701 - NU705
1NU721 - NU728
1NU731 - NU732
B. Spares Affected
None.
2. CONCURRENT REQUIREMENTS
None.
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3. COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
Requirements Bulletin 757-57A0075 RB. The Airworthiness Directive will make the compliance tasks and
times given in Requirements Bulletin 757-57A0075 RB mandatory.
Accomplish the required actions, based on the applicable conditions in Table 1, Table 2 and Table 3 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: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,000
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 757-
57A0075 RB.
Before 25,000
total flight cy-
cles.
OPTION 1: Do an exter-
nal High Frequency Eddy
Current (HFEC) inspec-
tion of the center wing
box lower skin and rear
spar lower chord for any
crack.
All Airplanes.
OPTION 2: Do an internal
detailed inspection of the
center wing box lower
skin and rear spar lower
chord for any crack.
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Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
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 DURING
OPTION 1 INSPECTION.
4,000 flight cycles.-CONDITION 1 ACTION
2 (OPTION 1): Repeat
external High Frequency
Eddy Current (HFEC) in-
spection of the center
wing box lower skin and
rear spar lower chord for
any crack at the unre-
paired areas.(a)(b)
-Within 4,000 flight cycles after the
most recent OPTION 1 inspection
was done.
CONDITION 1 ACTION
2 (OPTION 2): Do an in-
ternal detailed inspection
of the center wing box
lower skin and rear spar
lower chord for any crack
at the unrepaired ar-
eas.(a)(b)
4,000 flight cycles.-CONDITION 2 (OPTION
1): Repeat external High
Frequency Eddy Current
(HFEC) inspection of the
center wing box lower
skin and rear spar lower
chord for any crack.(a)(b)
CONDITION 2: NO
CRACK FOUND DURING
OPTION 1 INSPECTION.
-Within 4,000 flight cycles after the
most recent OPTION 1 inspection
was done.
CONDITION 2 (OPTION
2): Do an internal detailed
inspection of the center
wing box lower skin and
rear spar lower chord for
any crack.(a)(b)
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Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.CONDITION 3 (ACTION
1): Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 3: ANY
CRACK FOUND DURING
OPTION 2 INSPECTION.
-Within 6,000 flight cycles after the
most recent OPTION 2 inspection
was done.
CONDITION 3 ACTION
2 (OPTION 1): Do an ex-
ternal High Frequency
Eddy Current (HFEC) in-
spection of the center
wing box lower skin and
rear spar lower chord for
any crack at the unre-
paired areas.(a)(b)
6,000 flight cycles.-CONDITION 3 ACTION
2 (OPTION 2): Repeat
internal detailed inspec-
tion of the center wing
box lower skin and rear
spar lower chord for any
crack at the unrepaired
areas.(a)(b)
-Within 6,000 flight cycles after the
most recent OPTION 2 inspection
was done.
CONDITION 4 (OPTION
1): Do an external High
Frequency Eddy Current
(HFEC) inspection of the
center wing box lower
skin and rear spar lower
chord for any crack.(a)(b)
CONDITION 4: NO
CRACK FOUND DURING
OPTION 2 INSPECTION.
6,000 flight cycles.-CONDITION 4 (OPTION
2): Repeat internal de-
tailed inspection of the
center wing box lower
skin and rear spar lower
chord for any crack.(a)(b)
(a) After the accomplishment of this OPTION, it is acceptable to change the repeat action from this OPTION
to any other OPTION under this CONDITION.
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Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
(b) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-57A0075
RB and installed after the original issue date of Requirements Bulletin 757-57A0075 RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA) via a
FAA Form 8100-9.
Table 2: Internal Ultrasonic Inspection of the Center Wing Box Lower Chord and Detailed Inspection of
the Lower Skin at the Rear Spar
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
Later)
ActionCondition
-Within 4,000 flight
cycles after the
original issue date
of Requirements
Bulletin 757-
57A0075 RB.
The compliance times
given in 1., 2., and 3.,
whichever occurs first:
1. Before
120,000 total
flight hours.
2. Before
50,000 total
flight cycles.
3. Before the
result of
80000-(0.5 X
TFH) - TFC
is less than
or equal to
zero.
TFC = Total Flight Cy-
cles
Do an internal ultra-
sonic inspection of the
center wing box lower
chord and detailed in-
spection of the lower
skin at the rear spar
for any crack.
All Airplanes.
TFH = Total Flight
Hours
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Table 2: Internal Ultrasonic Inspection of the Center Wing Box Lower Chord and Detailed Inspection of
the Lower Skin at the Rear Spar
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever Occurs
Later)
ActionCondition
-Before further flight.CONDITION 5 (AC-
TION 1): Contact The
Boeing Company for
repair instructions and
do the repair.
CONDITION 5: ANY
CRACK FOUND.
12,000 flight cy-
cles.
-CONDITION 5 (AC-
TION 2): Repeat inter-
nal ultrasonic inspec-
tion of the center wing
box lower chord and
detailed inspection of
the lower skin at the
rear spar for any
crack at the unre-
paired areas.(a)
12,000 flight cy-
cles.
-CONDITION 2: Re-
peat internal ultrason-
ic inspection of the
center wing box lower
chord and detailed in-
spection of the lower
skin at the rear spar
for any crack.(a)
CONDITION 6: NO
CRACK FOUND.
(a) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-57A0075
RB and installed after the original issue date of Requirements Bulletin 757-57A0075 RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA) via a
FAA Form 8100-9.
Table 3: Internal Detailed Inspection of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Within 4,000
flight cycles af-
ter the original
issue date of
Requirements
Bulletin 757-
57A0075 RB.
Before 50,000
total flight cy-
cles.
Do an internal detailed
inspection of the center
wing box lower skin and
rear spar lower chord for
any crack.
All Airplanes.
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Table 3: Internal Detailed Inspection of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Repeat Interval
(Not to Exceed)
Compliance Time (Whichever
Occurs Later)
ActionCondition
-Before further flight.CONDITION 7 (ACTION
1): Contact The Boeing
Company for repair in-
structions and do the re-
pair.
CONDITION 7: ANY
CRACK FOUND.
12,000 flight cy-
cles.
-CONDITION 7 (ACTION
2): Repeat internal de-
tailed inspection of the
center wing box lower
skin and rear spar lower
chord for any crack at the
unrepaired areas.(a)
12,000 flight cy-
cles.
-CONDITION 2: Repeat
internal detailed inspec-
tion of the center wing
box lower skin and rear
spar lower chord for any
crack.(a)
CONDITION 8: NO
CRACK FOUND.
(a) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-57A0075
RB and installed after the original issue date of Requirements Bulletin 757-57A0075 RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA) via a
FAA Form 8100-9.
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 757-SL-51-022, 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 757 Structural Repair Manual,
Chapter 51.
— Values for airframe maintenance tasks are included in Chapter 20 of 757
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 757
Aircraft Maintenance Manual (AMM).
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— Non-standard torque values for maintenance tasks are included in the
applicable installation step.
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
1. Requirements.
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Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
Do PART 1: GET ACCESS
FOR EXTERNAL INSPEC-
TION.
-OPTION 1:
Do an external High Frequen-
cy Eddy Current (HFEC) in-
spection of the center wing
box lower skin and rear spar
lower chord for any crack.
All airplanes.
-FIGURE 1
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-OPTION 2:
Do an internal detailed inspec-
tion of the center wing box
lower skin and rear spar low-
er chord for any crack. -FIGURE 2
Do PART 3: CLOSE AC-
CESS FOR EXTERNAL IN-
SPECTION.
-CONDITION 1 (ACTION 1):
Contact The Boeing Compa-
ny for repair instructions and
do the repair.
CONDITION 1: ANY
CRACK FOUND DUR-
ING OPTION 1 IN-
SPECTION.
Do PART 1: GET ACCESS
FOR EXTERNAL INSPEC-
TION.
-CONDITION 1 (ACTION 2)
(OPTION 1):
Repeat external High Fre-
quency Eddy Current (HFEC)
inspection of the center wing
box lower skin and rear spar
lower chord for any crack at
unrepaired areas.(a)(b)
-FIGURE 1
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-CONDITION 1 (ACTION 2)
(OPTION 2):
Do an internal detailed inspec-
tion of the center wing box
lower skin and rear spar low-
er chord for any crack at the
unrepaired areas.(a)(b)
-FIGURE 2
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 16

Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
Do PART 3: CLOSE AC-
CESS FOR EXTERNAL IN-
SPECTION.
-CONDITION 2 (OPTION 1):
Repeat external High Fre-
quency Eddy Current (HFEC)
inspection of the center wing
box lower skin and rear spar
lower chord for any crack.
(a)(b)
CONDITION 2: NO
CRACK FOUND DUR-
ING OPTION 1 IN-
SPECTION. Do PART 1: GET ACCESS
FOR EXTERNAL INSPEC-
TION.
-
-FIGURE 1
Do PART 3: CLOSE AC-
CESS FOR EXTERNAL IN-
SPECTION.
-CONDITION 2 (OPTION 2):
Do an internal detailed inspec-
tion of the center wing box
lower skin and rear spar low-
er chord for any crack.(a)(b) Do PART 2: GET ACCESSFOR INTERNAL INSPEC-
TION.
-
-FIGURE 2
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-CONDITION 3 (ACTION 1):
Contact The Boeing Compa-
ny for repair instructions and
do the repair.
CONDITION 3: ANY
CRACK FOUND DUR-
ING OPTION 2 IN-
SPECTION.
Do PART 1: GET ACCESS
FOR EXTERNAL INSPEC-
TION.
-CONDITION 3 (ACTION 2)
(OPTION 1):
Do an external High Frequen-
cy Eddy Current (HFEC) in-
spection of the center wing
box lower skin and rear spar
lower chord for any crack at
unrepaired areas.(a)(b)
-FIGURE 1
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-CONDITION 3 (ACTION 2)
(OPTION 2):
Repeat internal detailed in-
spection of the center wing
box lower skin and rear spar
lower chord for any crack at
the unrepaired areas.(a)(b)
-FIGURE 2
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 17

Table 1: External or Internal Inspections of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-CONDITION 4 (OPTION 1):
Do an external High Frequen-
cy Eddy Current (HFEC) in-
spection of the center wing
box lower skin and rear spar
lower chord for any
crack.(a)(b)
CONDITION 4: NO
CRACK FOUND DUR-
ING OPTION 2 IN-
SPECTION. Do PART 1: GET ACCESS
FOR EXTERNAL INSPEC-
TION.
-
-FIGURE 1
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-CONDITION 4 (OPTION 2):
Repeat internal detailed in-
spection of the center wing
box lower skin and rear spar
lower chord for any
crack.(a)(b)
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-
-FIGURE 2
(a) After the accomplishment of this OPTION, it is acceptable to change the repeat action from this OPTION
to any other OPTION under this CONDITION.
(b) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-
57A0075 RB and installed after the original issue date of Requirements Bulletin 757-57A0075
RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA)
via a FAA Form 8100-9.
Table 2: Internal Ultrasonic Inspections of the Center Wing Box Lower Chord and Detailed Inspection
of the Lower Skin at the Rear Spar
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-Do an internal ultrasonic in-
spection of the center wing
box lower chord and detailed
inspection of the lower skin
at the rear spar for any crack.
All airplanes.
-FIGURE 3
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 18

Table 2: Internal Ultrasonic Inspections of the Center Wing Box Lower Chord and Detailed Inspection
of the Lower Skin at the Rear Spar
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
--CONDITION 5 (ACTION 1):CONDITION 5: ANY
CRACK FOUND. Contact The Boeing Compa-
ny for repair instructions and
do the repair.
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-CONDITION 5 (ACTION 2):
Repeat internal ultrasonic in-
spection of the center wing
box lower chord and detailed
inspection of the lower skin
at the rear spar for any crack
at the unrepaired areas.(a)
-FIGURE 3
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION
-Repeat internal ultrasonic in-
spection of the center wing
box lower chord and detailed
inspection of the lower skin
at the rear spar for any crack.
(a)
CONDITION 6: NO
CRACK FOUND.
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-
-FIGURE 3
(a) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-
57A0075 RB and installed after the original issue date of Requirements Bulletin 757-57A0075
RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA)
via a FAA Form 8100-9.
Table 3: Internal Detailed Inspection of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-Do an internal detailed inspec-
tion of the center wing box
lower skin and rear spar low-
er chord for any crack.
All airplanes.
-FIGURE 4
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 19

Table 3: Internal Detailed Inspection of the Center Wing Box Lower Skin and Rear Spar Lower Chord
Refer to the listed proce-
dures in SB 757-57A0075
Original Issue or later ap-
proved revisions as an ac-
cepted procedure
Method of ComplianceActionCondition
--CONDITION 7 (ACTION 1):CONDITION 7: ANY
CRACK FOUND. Contact The Boeing Compa-
ny for repair instructions and
do the repair.
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-CONDITION 7 (ACTION 2):
Repeat internal detailed in-
spection of the center wing
box lower skin and rear spar
lower chord for any crack at
unrepaired areas.(a)
-FIGURE 4
Do PART 4: CLOSE AC-
CESS FOR INTERNAL IN-
SPECTION.
-Repeat internal detailed in-
spection of the center wing
box lower skin and rear spar
lower chord for any crack. (a)
CONDITION 8: NO
CRACK FOUND.
Do PART 2: GET ACCESS
FOR INTERNAL INSPEC-
TION.
-
-FIGURE 4
(a) It is not required to do the inspection in areas where a repair covers the affected inspection area if the
repair meets the conditions that follow:
1. The repair is the corrective action to the crack condition identified in Requirements Bulletin 757-
57A0075 RB and installed after the original issue date of Requirements Bulletin 757-57A0075
RB.
2. The installed repair was approved by the Boeing Organization Designation Authorization (ODA)
via a FAA Form 8100-9.
Export Controlled ECCN: 9E991
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Work - See page 1 for details.
Original Issue: August 25, 2021
757-57A0075 RB
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 20 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
RBBL
70.50
52.80  RBBL  1040  STA
RBBI
38.7
RBBL
7.39
B
LBBL
52.80
2958324
FIGURE 1: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 1 SURFACE
HFEC INSPECTION
(SHEET 1 OF 3)
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Work - See page 1 for details.  20 of 32

### Page 21 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
REAR SPAR
LBBL  31.78  LBBL  LBBL  16.49
38.70  LBBL
TO THE MIDDLE  24.80  TO THE EDGE
OF STIFFENER  OF STIFFENER  LBBL  BBL
(LBBL 38.70)  (LBBL 7.39)  7.39  0.0
SINBD
(VIEW LOOKING FORWARD)
REAR SPAR
* +
RBBL  RBBL  RBBL
16.49  31.78  38.70
BBL  O.0  7.39  RBBL  TO THE EDGE  (RBBL 7.39)  OF STIFFENER  24.80  RBBL  (RBBL 38.70)  TO THE MIDDLE  OF STIFFENER
INBD
(VIEW LOOKING FORWARD)
/ HFEC INSPECTION AREA  2958325
FIGURE 1: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 1 SURFACE
HFEC INSPECTION
(SHEET 2 OF 3)
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### Page 22

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for this figure.
More DataQtyIdentificationNameTaskStep
(a)1-LOWER SKINInspect1
(b)1-LOWER CHORDInspect2
(a) Do an external surface HFEC inspection on the edge of lower skin at the rear spar for any crack in accor-
dance with 757 NDT Manual Part 6, 51-00-01 or 757 NDT Manual Part 6, 51-00-19.
(b) Do an external surface HFEC inspection on the edge of the rear spar lower chord for any crack in accor-
dance with 757 NDT Manual Part 6, 51-00-01 or 757 NDT Manual Part 6, 51-00-19 as an accepted pro-
cedure.
FIGURE 1: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 1 SURFACE
HFEC INSPECTION
(SHEET 3 OF 3)
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 23 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
>
RBBL
70.5  STA
LBBL  , 1040
LBBL 45.55
38.70
BBL  24.80
0.0
LBBL
7.39
ABBI
7.39
RBBL 24.8L
38.70
RBBL
45.55
RBBL
70.5
2958327
FIGURE 2: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 2 DETAILED
INSPECTION
(SHEET 1 OF 3)
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Work - See page 1 for details.  23 of 32

### Page 24 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
LBBL
38.70
BBL  LBBL  LBBL  LBBL  LBBL
0.00  7.50  16.49  STIFFENER  24.80  31.78  WEB  LOWER  CHORD
+
RADIUS  FITTING  13.50
FILLER  TO EDGE OF  LOWER  13.00
FITTING  SKIN
2.25
2.00
CONSTANT
(VIEW LOOKING DOWN)
RBBL
38.70
RBBL  RBBL  RBBL  RBBL  BBL
LOWER  CHORD  WEB  31.78  24.80  STIFFENER  16.49  7.50  0.00
+
FITTING
13.50  13.00  LOWEF  TO EDGE OF  FITTING  FILLER  RADIUS
2.25
2.00
CONSTANT
(VIEW LOOKING DOWN)
DETAILED INSPECTION AREA  2958329
FIGURE 2: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 2 DETAILED
INSPECTION
(SHEET 2 OF 3)
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### Page 25

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for this figure.
More DataQtyIdentificationNameTaskStep
(a)--SEALANTRemove1
(b)1-LOWER SKINInspect2
(c)1-LOWER CHORDInspect
(d)-BMS 5-45FUEL TANK SEALANTApply3
(d)-BMS 5-168FAST CURE FUEL
TANK SEALANT
Apply
(a) Remove any sealant from the lower skin or lower chord inspection area. Refer to 757-200 SRM 51-80-
01, 757-200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01 as an accepted
procedure.
(b) Do an internal detailed inspection of lower skin at the rear spar for any crack.
(c) Do an internal detailed inspection of the rear spar lower chord for any crack.
(d) In areas where the sealant was removed, apply sealant in accordance with 757-200 SRM 51-80-01, 757-
200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01.
FIGURE 2: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - OPTION 2 DETAILED
INSPECTION
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
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REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 26 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
RBBL
70.5  STA
LBBL 45.55  38.70  LBBL  1040
BBL  0.0  LBBL  24.80
7.39
RBBL
7.39
RBBI
RBBL
70.5
2958333
FIGURE 3: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
ULTRASONIC AND DETAIL INSPECTION
(SHEET 1 OF 4)
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Work - See page 1 for details.  26 of 32

### Page 27 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
3 4
BBL  RADIUS  LBBL  2.25  LBBI  LBBL  LBBL  LBBL
0.00  FILLER  7.50  2.00  CONSTANT  16.49  STIFFENER  24.80  31.78  WEB  38.70
+  +  + +  +  +
+
(2) 4  LOWER
CHORD  LOWER
SKIN
0.60  0.60
0.35  0.35
FITTING
EDGE OF  EDGE OF  (VIEW LOOKING DOWN)
FITTING  FITTING
(1)3
RBBL  WEB  RBBL  RBBL  RBBL  2.25  RBBL  RADIUS  BBL
38.70  31.78  24.80  16.49  2.00  7.50  FILLER  0.00
CONSTANT
+ +  +  +
+  +
+  + +  +  +  +  +
LOWER  LOWER  (4>
SKIN
0.60  0.60
0.35  0.35
FITTING
(VIEW LOOKING DOWN)  EDGE OF  EDGE OF
FITTING  FITTING
A
DETAILED INSPECTION AREA
A UT INSPECTION AREA  2958335
FIGURE 3: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
ULTRASONIC AND DETAIL INSPECTION
(SHEET 2 OF 4)
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Work - See page 1 for details.  27 of 32

### Page 28

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for this figure.
More DataQtyIdentificationNameTaskStep
(a)--SEALANTRemove1
(b)1-LOWER SKINInspect2
(c)1-LOWER CHORDInspect3
(d)-BMS 5-45FUEL TANK SEALANTApply4
(d)-BMS 5-168FAST CURE FUEL
TANK SEALANT
Apply
(a) Remove any sealant from the lower skin or lower chord inspection area. Refer to 757-200 SRM 51-80-
01, 757-200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01 as an accepted
procedure.
(b) Do an internal detailed inspection of the lower skin at the rear spar for any crack.
FIGURE 3: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
ULTRASONIC AND DETAIL INSPECTION
(SHEET 3 OF 4)
Export Controlled ECCN: 9E991
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Work - See page 1 for details.
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757-57A0075 RB
28 of 32
REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 29

More DataQtyIdentificationNameTaskStep
(c) Do an internal ultrasonic inspection of the center wing box rear spar lower chord for any crack in accordance
with 757 NDT Manual Part 4 57-10-01.
(d) In areas where the sealant was removed, apply sealant in accordance with 757-200 SRM 51-80-01, 757-
200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01.
FIGURE 3: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL
ULTRASONIC AND DETAIL INSPECTION
(SHEET 4 OF 4)
Export Controlled ECCN: 9E991
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Original Issue: August 25, 2021
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29 of 32
REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

### Page 30 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
RBBL
70.5  STA
LBBL 45.55  38.70  LBBL  1040
BBL  0.0  LBBL  24.80
LBBL
7.39
RBBL
7.39
RBBL
RBBL  24.80
RBBL
45.55
RBBL
70.5
2958337
FIGURE 4: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL DETAILED
INSPECTION
(SHEET 1 OF 3)
Original Issue: August 25, 2021
Export Controlled ECCN: 9E991  757-57A0075 RB
Copyright © Unpublished
Work - See page 1 for details.  30 of 32

### Page 31 (OCR)

REQUIREMENTS BULLETIN 757-57A0075
ALERT  ALERT
RBBL  WEB  RBBL  BELA T  LBBL  LBBL
16.49  7.50  0.00  7.50  16.49
+
+  +
+  +  +  +
FITTING
LOWER  SKIN  FITTING  FITTING  TO EDGE OF  FILLER  RADIUS  FITTING  TO EDGE OF  2.25  2.00  CONSTANT  LOWER  CHORD
1) 2) 3)
(VIEW LOOKING DOWN)
— REAR SPAR
FITTING
FITTING
(VIEW ROTATED 90 DEGREE CLOCKWISE)
_ DETAILED INSPECTION AREA  A-A  2958341
FIGURE 4: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL DETAILED
INSPECTION
(SHEET 2 OF 3)
Original Issue: August 25, 2021
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Copyright © Unpublished
Work - See page 1 for details.  31 of 32

### Page 32

The step numbers shown below agree with the numbers shown in the circle symbols in the figure. The QTY
numbers shown below are the number of parts necessary for this figure.
More DataQtyIdentificationNameTaskStep
(a)--SEALANTRemove1
(b)1-LOWER SKINInspect2
(c)1-LOWER CHORDInspect
(d)-BMS 5-45FUEL TANK SEALANTApply3
(d)-BMS 5-168FAST CURE FUEL
TANK SEALANT
Apply
(a) Remove any sealant from the lower skin or lower chord inspection area. Refer to 757-200 SRM 51-80-
01, 757-200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01 as an accepted
procedure.
(b) Do an internal detailed inspection of lower skin at the rear spar for any crack.
(c) Do an internal detailed inspection of the rear spar lower chord for any crack.
(d) In areas where the sealant was removed, apply sealant in accordance with 757-200 SRM 51-80-01, 757-
200PF SRM 51-80-01, 757-200CB SRM 51-80-01 or 757-300 SRM 51-80-01.
FIGURE 4: CENTER WING BOX - REAR SPAR, LOWER SKIN AND LOWER CHORD - INTERNAL DETAILED
INSPECTION
(SHEET 3 OF 3)
Export Controlled ECCN: 9E991
Copyright © Unpublished
Work - See page 1 for details.
Original Issue: August 25, 2021
757-57A0075 RB
32 of 32
REQUIREMENTS BULLETIN 757-57A0075
ALERTALERT

---
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