# Boeing Alert Requirements Bulletin 747-57A2371 RB: No revision named

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2024-1000; AD 2024-16-03 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Requirements Bulletin 747-57A2371 RB](https://openairdocs.org/service-documents/boeing/747-57a2371-rb.md)
- Title as filed: SB-747-57A2371-RB-00
- Pages: 18
- PDF: https://openairdocs.org/files/sha256/dc/11/dc11665404caa3188312a483544dd41de1947dccb873b900ce6f7e0add5cf183
- Page: https://openairdocs.org/service-documents/boeing/747-57a2371-rb/file/dc11665404ca

## Text

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### Page 1

Commercial 
Airplanes
747
Requirements Bulletin
ALERT
Number: 747-57A2371 RB
Original Issue: September 29, 2023
ATA System: 5720 2811
SUBJECT: WINGS - Fuel Tanks and Auxiliary Structure - Fuel Tank Fasteners Change
EXPORT CONTROLLED - This technology or software is subject to the U.S. Export Administration Regulations
(EAR), (15 C.F.R. Parts 730-774). No authorization from the U.S. Department of Commerce is required for
export, re-export, in-country transfer, or access EXCEPT to country group E:1 or E:2 countries/persons per
Supp.1 to Part 740 of the EAR.
9E991ECCN:
Copyright © 2023 The Boeing Company
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.
Original Issue: September 29, 2023
747-57A2371 RB
1 of 18
6.0

### Page 2

Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
2 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT
BLANK PAGE

### Page 3

Table of Contents
1. EFFECTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
A. Airplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
B. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. CONCURRENT REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. APPROVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
A. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
B. Work Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION . 9
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION. 14
Export Controlled ECCN: 9E991
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Original Issue: September 29, 2023
747-57A2371 RB
3 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

### Page 4

Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
4 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT
BLANK PAGE

### Page 5

Commercial 
Airplanes
747
Requirements Bulletin
ALERT
Number: 747-57A2371 RB
Original Issue: September 29, 2023
ATA System: 5720 2811
SUBJECT: WINGS - Fuel Tanks and Auxiliary Structure - Fuel Tank Fasteners Change
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 747-400F Airplane(s), line number(s) 1364-1419 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
747-400F Airplanes with missing fuel tank fastener cap seals.-1
Airplane Models:
747-400F
GroupVariable Number
1RL429 - RL430
1RL435 - RL436
1RL454 - RL456
1RL473 - RL481
1RL491 - RL492
1RL501 - RL502
GroupVariable Number
1RL511 - RL516
1RL521 - RL522
1RL531 - RL534
1RL551
1RL561 - RL568
1RL571 - RL572
GroupVariable Number
1RL576 - RL577
1RL579
1RL581 - RL586
1RL684
1RM863
1RM889 - RM890
B. Spares Affected
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
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### Page 6

None.
2. CONCURRENT REQUIREMENTS
None.
3. COMPLIANCE
The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to
Requirements Bulletin 747-57A2371 RB. The Airworthiness Directive will make the compliance tasks and
times given in Requirements Bulletin 747-57A2371 RB mandatory.
Accomplish the required action(s), based on the applicable condition(s) in Table(s) 1 and 2, in accordance
with Accomplishment Instructions.
Table 1: Cap Seal Application for Fasteners at Front Spar Station 600, Left Wing
Repeat Interval
(Not to Exceed)
Boeing Recommended
Compliance Time
ActionCondition
-Within 60 months after
the original issue date of
Requirements Bulletin
747-57A2371 RB.
Apply cap seal to four
fastener collars with
missing cap seal inside
the fuel tank common to
the stiffeners located at
the left wing front spar.
All airplanes.
Table 2: Cap Seal Application for Fasteners at Front Spar Station 600, Right Wing
Repeat Interval
(Not to Exceed)
Boeing Recommended
Compliance Time
ActionCondition
-Within 60 months after
the original issue date of
Requirements Bulletin
747-57A2371 RB.
Apply cap seal to four
fastener collars with
missing cap seal inside
the fuel tank common to
the stiffeners located at
the right wing front spar.
All airplanes.
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.
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
6 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

### Page 7

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. Some Work Instructions task(s) can be related to Critical Design Configuration Control
Limitation (CDCCL) required by Airworthiness Limitations (AWLs) and Certification
Maintenance Requirements (CMRs) 747-400 MPD Section 9. Strict adherence to
Airworthiness Limitations are required.
5. 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.
6. 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.
7. Cap sealing for this bulletin is applying fillet seal to the fastener ensuring the fastener
is fully encapsulated.
B. WORK INSTRUCTIONS
Actions Required For Compliance
1. Requirements
a. WORK PACKAGE 1: Cap Seal Application for Fasteners, Left Wing
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
7 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

### Page 8

Table 1: Cap Seal Application for Fasteners at Front Spar Station 600, Left Wing
Refer to the listed pro-
cedures in SB 747-
57A2371 Original Issue
or later approved revi-
sions as an accepted
procedure.
Method of Com-
pliance
ActionCondition
PART 1: OPEN AC-
CESS, LEFT WING
-Apply cap seal to four fastener collars
with missing cap seal inside the fuel
tanks common to the stiffeners locat-
ed at the left wing front spar.
All airplanes.
-FIGURE 1
PART 2: CLOSE AC-
CESS, LEFT WING
-
b. WORK PACKAGE 2: Cap Seal Application for Fasteners, Right Wing
Table 2: Cap Seal Application for Fasteners at Front Spar Station 600, Right Wing
Refer to the listed pro-
cedures in SB 747-
57A2371 Original Issue
or later approved revi-
sions as an accepted
procedure.
Method of Com-
pliance
ActionCondition
PART 3: OPEN AC-
CESS, RIGHT WING
-Apply cap seal to four fastener collars
with missing cap seal inside the fuel
tanks common to the stiffeners locat-
ed at the right wing front spar.
All airplanes.
-FIGURE 2
PART 4: CLOSE AC-
CESS, RIGHT WING
-
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
8 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

### Page 9 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
FSS
AN  628.06
FSS
335.46
3014105
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 1 OF 5)
Original Issue: September 29, 2023
Export Controlled ECCN: 9E991  747-57A2371 RB
See page 1 for details  9 of 18

### Page 10 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
FSS  FSS  FSS  UPPER SKIN
610.00  600.00  590.00
+  +
+ +
L++.  → B  +  - +  - FRONT SPAR
LOWER SKIN
VIEW LOOKING FORWARD
A-A
3014109
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 2 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  10 of 18

### Page 11 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
FASTENER
TANK SIDE
DRY SIDE
B-B
WEB.
FASTENER
3)4
TANK SIDE
DRY SIDE
FWD
C-C  3014115
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 3 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  11 of 18

### Page 12 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
0.10
0.10  MINIMUM
MINIMUM  0.10
MINIMUM
TANK SIDE
TANK SIDE
• 0.12
MINIMUM  0.12
MINIMUM
0.10
0.10  MINIMUM
MINIMUM
MAKE THIS AREA
TANK SIDE  SMOOTH (EXAMPLE)  TANK SIDE
0.12
0.12  MINIMUM
MINIMUM
NOTE: ALL DIMENSIONS ARE IN INCHES.
TYPICAL FASTENER INSTALLATIONS
3038616
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 4 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  12 of 18

### Page 13

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)(b)--FRONT SPARClean1
(c)(d)4-FASTENERSClean2
(e)-BMS 5-45, CLASS A-2,
GRADE 1
SEALANTApply3
(f)-BMS 5-45, CLASS B-2,
GRADE 1
SEALANTApply4
(a) Remove any dirt or debris from the area to be sealed on the front spar.
(b) Make sure that an area of 0.5 inch or greater from the base of the fastener is clean. The cleaned area
must be larger than the area that must have sealant.
(c) Solvent clean the fasteners using a non-metallic bristle brush and wiper wet with solvent. Refer to SOPM
20-30-93 as an accepted procedure for selection of solvent.
(d) Removal of any remaining solvent must be done while wet with a clean, dry wiper.
(e) Precoat seal the fastener. Refer to 747-400 AMM 28-11-00 as an accepted procedure.
(f) Fillet seal the fastener. Ensure the minimum thickness, per view B, is met. Refer to 747-400 AMM 28-11-
00 as an accepted procedure.
FIGURE 1: FRONT SPAR - STATION 600 LEFT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 5 OF 5)
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
13 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

### Page 14 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
FSS
628.06
FSS
335.46
3014156
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 1 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  14 of 18

### Page 15 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
UPPER SKIN  FSS  FSS  FSS
590.00  600.00  610.00
+  +
— FRONT SPAR
LOWER SKIN
VIEW LOOKING FORWARD
A-A
3014159
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 2 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  15 of 18

### Page 16 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
FASTENER
TANK SIDE
DRY SIDE
B-B
_ WEB
→ FASTENER
TANK SIDE
• DRY SIDE
FWD
C-C  3014160
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 3 OF 5)
Original Issue: September 29, 2023
Export Controlled ECCN: 9E991  747-57A2371 RB
See page 1 for details  16 of 18

### Page 17 (OCR)

REQUIREMENTS BULLETIN 747-57A2371
ALERT  ALERT
0.10
0.10  MINIMUM
MINIMUM  0.10  0.10
MINIMUM
TANK SIDE
TANK SIDE
0.12
MINIMUM  0.12
MINIMUM
0.10
0.10  MINIMUM
MINIMUM
MAKE THIS AREA
TANK SIDE  SMOOTH (EXAMPLE)  TANK SIDE
0.12
0.12  MINIMUM
MINIMUM
NOTE: ALL DIMENSIONS ARE IN INCHES.
TYPICAL FASTENER INSTALLATIONS
3038617
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 4 OF 5)
Original Issue: September 29, 2023
747-57A2371 RB
Export Controlled ECCN: 9E991
See page 1 for details  17 of 18

### Page 18

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)(b)--FRONT SPARClean1
(c)(d)4-FASTENERSClean2
(e)-BMS 5-45, CLASS A-2,
GRADE 1
SEALANTApply3
(f)-BMS 5-45, CLASS B-2,
GRADE 1
SEALANTApply4
(a) Remove any dirt or debris from the area to be sealed on the front spar.
(b) Make sure that an area of 0.5 inch or greater from the base of the fastener is clean. The cleaned area
must be larger than the area that must have sealant.
(c) Solvent clean the fasteners using a non-metallic bristle brush and wiper wet with solvent. Refer to SOPM
20-30-93 as an accepted procedure for selection of solvent.
(d) Removal of any remaining solvent must be done while wet with a clean, dry wiper.
(e) Precoat seal the fastener. Refer to 747-400 AMM 28-11-00 as an accepted procedure.
(f) Fillet seal the fastener. Ensure the minimum thickness, per view B, is met. Refer to 747-400 AMM 28-11-
00 as an accepted procedure.
FIGURE 2: FRONT SPAR - STATION 600 RIGHT WING - FASTENERS FILLET SEAL APPLICATION
(SHEET 5 OF 5)
Export Controlled ECCN: 9E991
See page 1 for details
Original Issue: September 29, 2023
747-57A2371 RB
18 of 18
REQUIREMENTS BULLETIN 747-57A2371
ALERTALERT

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