[Federal Register Volume 88, Number 168 (Thursday, August 31, 2023)]
[Rules and Regulations]
[Pages 60111-60116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-18835]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1814; Project Identifier AD-2023-00773-T; 
Amendment 39-22541; AD 2023-17-14]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2022-18-
11, which applied to all The Boeing Company Model 777 airplanes. AD 
2022-18-11 required repetitive inspections for cracking of the left- 
and right-side ring chords, repair angles, front spar lower chords, and 
front spar webs (depending on configuration) common to a certain 
underwing longeron; modification of the front spar lower chord for some 
airplanes; repetitive post-modification inspections; and applicable on-
condition actions. This AD was prompted by a report of a crack found in 
a front spar lower chord, and the determination that errors in the 
service information mandated by AD 2022-18-11 introduced a new unsafe 
condition related to the application of

[[Page 60112]]

certain fastener cap seals. This AD retains the actions required by AD 
2022-18-11, and requires a maintenance records review of previously 
modified airplanes for the procedures used during that modification, 
and applicable corrective actions. The FAA is issuing this AD to 
address the unsafe condition on these products.

DATES: This AD is effective September 15, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 31, 
2022 (87 FR 58259, September 26, 2022).
    The FAA must receive comments on this AD by October 16, 2023.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    AD Docket: You may examine the AD docket at regulations.gov by 
searching for and locating Docket No. FAA-2023-1814; or in person at 
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The AD docket contains this final rule, any 
comments received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Kevin Nguyen, Aviation Safety 
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3555; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued AD 2022-18-11, Amendment 39-22162 (87 FR 58259, 
September 26, 2022) (AD 2022-18-11), for all The Boeing Company Model 
777 airplanes. AD 2022-18-11 required repetitive inspections for 
cracking of the left- and right-side ring chords, repair angles, front 
spar lower chords, and front spar webs (depending on configuration) 
common to the underwing longeron located at station (STA) 1035; 
modification of the front spar lower chord for some airplanes; 
repetitive post-modification inspections; and applicable on-condition 
actions. AD 2022-18-11 was prompted by a report of a crack found in the 
front spar lower chord of a Model 777-300ER airplane undergoing an 
underwing longeron replacement. The FAA issued AD 2022-18-11 to 
address, detect, and correct such cracking, which in combination with 
cracking in the front spar web, could result in a fuel leak and fire 
hazard, or in the case of more severe cracking, could also affect the 
structural integrity of the airplane.

Actions Since AD 2022-18-11 Was Issued

    Since the FAA issued AD 2022-18-11, the manufacturer has discovered 
that Boeing Alert Requirements Bulletin 777-57A0122 RB, dated October 
8, 2021, which was mandated by AD 2022-18-11, contains errors relating 
to the application of cap seals to fasteners penetrating the center 
wing fuel tank which introduce a second, urgent unsafe condition. These 
errors necessitate superseding AD 2022-18-11 to add additional actions 
to correct this new unsafe condition.
    Fastener cap seals interior to the airplane's fuel tanks are a 
critical lightning protection feature. This is particularly true for 
the center wing fuel tank, which typically contains flammable fuel 
vapors more frequently than the main wing fuel tanks. As part of the 
front spar lower chord and underwing longeron work described in the 
manufacturer's requirements bulletin and mandated by AD 2022-18-11, 
many cap seals are removed to accomplish the various modifications and 
inspections. If these seals are not replaced properly, and the 
associated fastener has poor electrical bonding to the airplane 
structure for any reason, the fastener may spark during a lightning 
strike and cause a fuel tank explosion.
    The lack of fault-tolerance introduced by these cap sealing errors 
in the manufacturer's requirements bulletin places an airplane with 
compromised cap seals that has no flammability reduction or ignition 
mitigation means at a level of risk that requires urgent action to 
address. Airplanes equipped with flammability reduction or ignition 
mitigation means are also affected by this newly created unsafe 
condition, but at a lower level of risk. Paragraph (e) of this AD, 
Unsafe Condition, has been revised to reflect the second unsafe 
condition created by the errors in the manufacturer's requirements 
bulletin as described above. Paragraph (e) of this AD has also been 
revised to reflect the determination that existing structural 
inspections are expected to detect severe front spar lower chord 
cracking before the structural integrity of the airplane is put at 
risk, but are not expected to detect cracking before a possible fuel 
leak. The unsafe condition therefore now consists of two distinct 
aspects: structural cracking of the front spar lower chord leading to a 
fuel leak and possible fire, and failure of fastener cap seals to 
contain a possible spark following a lightning strike leading to a 
possible fuel tank explosion.
    The manufacturer submitted an initial report of errors in the 
requirements bulletin affecting cap sealing instructions in late 2022. 
However, given the length and complexity of the requirements bulletin, 
detailed and complete documentation of these errors was not received 
until late July 2023. The manufacturer has stated its intent to revise 
the requirements bulletin; however, this work will take longer to 
accomplish than the risk to public safety allows. Therefore, the FAA 
has proceeded with this supersedure without additional service 
information as soon as possible following the manufacturer's delivery 
of the necessary information. The three categories of errors affecting 
cap sealing instructions in the manufacturer's requirements bulletin 
are described as follows.
    First, certain groups and configurations of airplanes have no 
requirement to apply cap seals to fasteners associated with the 
underwing longeron. Without this requirement, a cap seal may fail to be 
applied following modification of the underwing longeron, compromising 
the required fault tolerance of the fuel tank lightning protection 
design. For those airplanes, this AD requires application of a cap seal 
of the correct sealant type to the minimum thickness or greater, if not 
already done.
    Second, certain other groups and configurations have no thickness 
requirement for the applied cap seal, and the requirements bulletin 
mistakenly refers to the Boeing Standard Overhaul Practices Manual 
(SOPM) section 20-50-19 for procedures to apply the cap seal. The SOPM 
procedure specifies a thickness that is half the necessary thickness, 
while the Boeing Model 777 aircraft maintenance manual (AMM) procedure, 
which is also referred to in the requirements bulletin, specifies the 
correct thickness for cap seals. It is also possible that operators may 
have used an accepted method other than that specified in the SOPM and 
AMM, as no specific procedure was required by the requirements 
bulletin. A cap seal of insufficient thickness may fail to contain a 
spark resulting from a lightning strike, similarly compromising

[[Page 60113]]

the fault tolerance of the fuel tank lightning protection. This AD 
specifies the minimum thickness and sealant type for an applied cap 
seal, and requires replacement of any seal that was previously applied 
using a procedure that specifies an inadequate thickness.
    Third, some structural inspections described by the requirements 
bulletin may require the removal of certain fastener cap seals; 
however, the requirements bulletin either does not require that the cap 
seal be replaced, or does not provide a thickness requirement for the 
replaced seal. These errors affect the fuel tank lightning protection 
for the same reasons as already described. This AD requires that any 
seal removed for the inspections required by the requirements bulletin 
be replaced with a cap seal of correct sealant type and adequate 
thickness.
    Therefore, for airplanes on which the actions of the requirements 
bulletin have not yet been accomplished, and for airplanes for which 
this AD requires rework of already applied cap seals, those cap sealing 
differences are defined in paragraph (h) of this AD as exceptions to 
the requirements bulletin. For airplanes on which the actions of the 
requirements bulletin have been accomplished but a maintenance records 
check cannot conclusively determine that an appropriate procedure was 
used to apply the cap seals, paragraph (i) of this AD requires rework 
of the applied cap seals.
    This AD also corrects and clarifies other aspects of AD 2022-18-11 
as follows.
    Following the publication of AD 2022-18-11, the FAA and 
manufacturer discovered that Model 777-200 airplanes that do not have a 
fuel tank in the area affected by the unsafe condition were erroneously 
included in the applicability of AD 2022-18-11. As the design of these 
airplanes does not allow fuel to be present in the affected area 
(between the side-of-body ribs), the unsafe condition is not present on 
these airplanes. These airplanes are now identified in this AD by their 
maximum taxi weight of 547,000 pounds or less. Model 777-200 airplanes 
greater than 547,000 pounds maximum taxi weight, commonly referred to 
as ``777-200ERs'' (extended range), remain affected by the unsafe 
condition. Since the issuance of AD 2022-18-11, the manufacturer has 
also implemented a design change in production to address the unsafe 
condition. As a result, the unsafe condition does not exist on Model 
777F airplanes having manufacturer line numbers 1743 and subsequent. 
Paragraph (c) of this AD, Applicability, has been revised accordingly.
    In addition, the effectivity of the manufacturer's requirements 
bulletin also has the potential to cause confusion regarding the 
required actions for certain Model 777F airplanes. These airplanes, 
Model 777Fs having line numbers 1713, 1717, 1720, and 1724 through 1742 
inclusive were not included in the effectivity of the requirements 
bulletin. While these airplanes were included in the applicability of 
AD 2022-18-11 and remain included in the applicability of this AD, the 
specific instructions applicable to them were not clearly identified in 
the requirements bulletin. Paragraph (h)(7) of this AD clarifies that 
Group 6 actions are the applicable actions for these airplanes.

FAA's Determination

    The FAA is issuing this AD because the agency has determined the 
unsafe condition described previously is likely to exist or develop in 
other products of the same type design.

Related Service Information Under 1 CFR Part 51

    This AD requires Boeing Alert Requirements Bulletin 777-57A0122 RB, 
dated October 8, 2021, which the Director of the Federal Register 
approved for incorporation by reference as of October 31, 2022 (87 FR 
58259, dated September 26, 2022). This service information is 
reasonably available because the interested parties have access to it 
through their normal course of business or by the means identified in 
the ADDRESSES section.

AD Requirements

    This AD requires accomplishing the actions specified in the service 
information already described, except for any differences identified as 
exceptions in the regulatory text of this AD. This AD also requires 
reviewing the maintenance records of previously modified airplanes to 
determine the procedure used to apply cap seals, and applying and 
replacing certain cap seals using new specified thickness dimensions.

Justification for Immediate Adoption and Determination of the Effective 
Date

    Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5 
U.S.C. 551 et seq.) authorizes agencies to dispense with notice and 
comment procedures for rules when the agency, for ``good cause,'' finds 
that those procedures are ``impracticable, unnecessary, or contrary to 
the public interest.'' Under this section, an agency, upon finding good 
cause, may issue a final rule without providing notice and seeking 
comment prior to issuance. Further, section 553(d) of the APA 
authorizes agencies to make rules effective in less than thirty days, 
upon a finding of good cause.
    An unsafe condition exists that requires the immediate adoption of 
this AD without providing an opportunity for public comments prior to 
adoption. The FAA has found that the risk to the flying public 
justifies forgoing notice and comment prior to adoption of this rule 
because a cap seal below the minimum thickness may fail to contain 
arcing at a fastener penetrating the center wing fuel tank during a 
lightning strike, potentially creating an ignition source within the 
fuel tank and leading to a fuel tank explosion. Accordingly, notice and 
opportunity for prior public comment are impracticable and contrary to 
the public interest pursuant to 5 U.S.C. 553(b)(3)(B).
    In addition, the FAA finds that good cause exists pursuant to 5 
U.S.C. 553(d) for making this amendment effective in less than 30 days, 
for the same reasons the FAA found good cause to forgo notice and 
comment.

Comments Invited

    The FAA invites you to send any written data, views, or arguments 
about this final rule. Send your comments to an address listed under 
ADDRESSES. Include ``Docket No. FAA-2023-1814 and Project Identifier 
AD-2023-00773-T'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the final rule, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
this final rule because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this final rule.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this AD contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and

[[Page 60114]]

that is relevant or responsive to this AD, it is important that you 
clearly designate the submitted comments as CBI. Please mark each page 
of your submission containing CBI as ``PROPIN.'' The FAA will treat 
such marked submissions as confidential under the FOIA, and they will 
not be placed in the public docket of this AD. Submissions containing 
CBI should be sent to Kevin Nguyen, Aviation Safety Engineer, FAA, 2200 
South 216th St., Des Moines, WA 98198; phone: 206-231-3555; email: 
[email protected]. Any commentary that the FAA receives that is not 
specifically designated as CBI will be placed in the public docket for 
this rulemaking.

Regulatory Flexibility Act

    The requirements of the Regulatory Flexibility Act (RFA) do not 
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt 
a rule without prior notice and comment. Because the FAA has determined 
that it has good cause to adopt this rule without notice and comment, 
RFA analysis is not required.

Costs of Compliance

    The FAA estimates that this AD affects 291 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspection(s) (retained actions    44 work-hours x $85              $0  $3,740 per           $1,088,340 per
 from AD 2022-18-11).               per hour = $3,740                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
Modification* (retained actions    137 work-hours x             47,964  $59,609............  $17,346,219.
 from AD 2022-18-11).               $85 per hour =
                                    $11,645.
Post-modification inspection(s)*   46 work-hours x $85               0  $3,910 per           $1,137,810 per
 (retained actions from AD 2022-    per hour = $3,910                    inspection cycle.    inspection cycle.
 18-11).                            per inspection
                                    cycle.
Maintenance records review* (new   1 work-hour x $85                85  $85................  Up to $24,735.
 action).                           per hour = $85.
----------------------------------------------------------------------------------------------------------------
*Number of affected airplanes that will be required to do this action is unknown.

    The FAA estimates the following costs to do any necessary cap 
sealing that would be required based on the results of the maintenance 
records review. The FAA has no way of determining the number of 
aircraft that might need the cap sealing:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                 Action                          Labor cost             Parts cost         Cost per product
----------------------------------------------------------------------------------------------------------------
Cap sealing............................  Up to 109 work-hours x $85             $90   Up to $9,355.
                                          per hour = Up to $9,265.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this AD may be covered under warranty, thereby reducing the cost impact 
on affected operators.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866, and
    (2) Will not affect intrastate aviation in Alaska.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by:
0
a. Removing Airworthiness Directive (AD) 2022-18-11, Amendment 39-22162 
(87 FR 58259, September 26, 2022); and
0
b. Adding the following new AD:

2023-17-14 The Boeing Company: Amendment 39-22541; Docket No. FAA-
2023-1814; Project Identifier AD-2023-00773-T.

(a) Effective Date

    This airworthiness directive (AD) is effective September 15, 
2023.

[[Page 60115]]

(b) Affected ADs

    This AD replaces AD 2022-18-11, Amendment 39-22162 (87 FR 58259, 
September 26, 2022) (AD 2022-18-11).

(c) Applicability

    This AD applies to all The Boeing Company Model 777-200, -200LR, 
-300, -300ER, and 777F series airplanes, certificated in any 
category, excluding the airplanes identified in paragraphs (c)(1) 
and (2) of this AD.
    (1) Boeing Model 777-200 series airplanes having a maximum taxi 
weight equal to or less than 547,000 pounds.
    (2) Boeing Model 777F series airplanes with manufacturer line 
numbers of 1743 and subsequent.

(d) Subject

    Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report of a crack found in a front 
spar lower chord undergoing an underwing longeron replacement, and 
the determination that AD 2022-18-11 did not specify the appropriate 
thickness for the application of cap seals to fasteners penetrating 
the center wing fuel tank. The FAA is issuing this AD to detect and 
correct such cracking, which in combination with cracking in the 
front spar web, could result in a fuel leak and fire hazard. In 
addition, cap seals applied below the necessary thickness may fail 
to contain a spark resulting from a lightning strike, possibly 
resulting in a fuel tank explosion.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Retained Required Actions, With No Changes

    This paragraph restates the requirements of paragraph (g) of AD 
2022-18-11, with no changes. Except as specified by paragraph (h) of 
this AD: At the applicable times specified in the ``Compliance'' 
paragraph of Boeing Alert Requirements Bulletin 777-57A0122 RB, 
dated October 8, 2021, do all applicable actions identified in, and 
in accordance with, the Accomplishment Instructions of Boeing Alert 
Requirements Bulletin 777-57A0122 RB, dated October 8, 2021. Actions 
identified as terminating action in Boeing Alert Requirements 
Bulletin 777-57A0122 RB, dated October 8, 2021, terminate the 
applicable required actions of this AD, provided the terminating 
action is done in accordance with the Accomplishment Instructions of 
Boeing Alert Requirements Bulletin 777-57A0122 RB, dated October 8, 
2021.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
777-57A0122, dated October 8, 2021, which is referred to in Boeing 
Alert Requirements Bulletin 777-57A0122 RB, dated October 8, 2021.

(h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 777-
57A0122 RB, dated October 8, 2021, use the phrase ``the original 
issue date of Requirements Bulletin 777-57A0122 RB,'' this AD 
requires replacing those words with ``October 31, 2022, the 
effective date of AD 2022-18-11.''
    (2) Where Boeing Alert Requirements Bulletin 777-57A0122 RB, 
dated October 8, 2021, specifies contacting Boeing for repair 
instructions: This AD requires repair using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD.
    (3) Where the ``Compliance'' paragraph of Boeing Alert 
Requirements Bulletin 777-57A0122 RB, dated October 8, 2021, uses 
the phrase ``Tables 1 through 50,'' this AD requires replacing those 
words with ``Tables 1 through 54.''
    (4) During application of any cap seal to a fastener, fastener 
head, and fastener threads and collars, as required by this AD, the 
cap seal must be applied with a thickness equal to or greater than 
the dimensions specified in figure 1 to paragraph (h)(4) of this AD.

Figure 1 to paragraph (h)(4)--Cap seal minimum thickness (all 
dimensions in inches)
[GRAPHIC] [TIFF OMITTED] TR31AU23.000

    (5) Boeing Alert Requirements Bulletin 777-57A0122 RB, dated 
October 8, 2021, does not require the application of cap seals to 
underwing longeron fasteners, fastener heads, and fastener threads 
and collars for the airplane groups and configurations

[[Page 60116]]

identified in paragraphs (h)(5)(i) through (iv) of this AD. For 
those airplane groups and configurations, however, this AD requires 
application of a cap seal to the underwing longeron fasteners at the 
locations identified in Figures 81 and 144 of Boeing Alert 
Requirements Bulletin 777-57A0122 RB, dated October 8, 2021, during 
installation of the underwing longeron.
    (i) Groups 7 and 8, Configurations 5 through 8, on the left 
side.
    (ii) Group 9, Configurations 1 and 2, on the left side.
    (iii) Groups 7 and 8, Configurations 2, 6, 10, and 14, on the 
right side.
    (iv) Group 9, Configurations 1 and 3, on the right side.
    (6) Where Boeing Alert Requirements Bulletin 777-57A0122 RB, 
dated October 8, 2021, requires inspections that may require the 
removal of fastener cap seals, this AD requires that if the cap seal 
is removed, a cap seal of BMS 5-45 sealant be reapplied with a 
thickness equal to or greater than the dimensions specified in 
figure 1 to paragraph (h)(4) of this AD before further flight after 
completion of the inspection.
    (7) The Effectivity of Boeing Alert Requirements Bulletin 777-
57A0122 RB, dated October 8, 2021, does not include Boeing Model 
777F series airplanes having line numbers 1713, 1717, 1720, and 1724 
through 1742 inclusive. However, for those airplanes, this AD 
requires accomplishment of the applicable actions specified in the 
Boeing Alert Requirements Bulletin for Group 6.

(i) Actions for Previously Modified Airplanes

    For airplanes on which the applicable actions of Boeing Alert 
Requirements Bulletin 777-57A0122 RB, dated October 8, 2021, have 
been accomplished before the effective date of this AD: Within 30 
days after the effective date of this AD, review the maintenance 
records to determine the procedures used to apply cap seals during 
accomplishment of the actions in Boeing Alert Requirements Bulletin 
777-57A0122 RB, dated October 8, 2021.
    (1) If all of the conditions specified in paragraphs (i)(1)(i) 
through (iii) of this AD are met, no further work is required by 
paragraph (i) of this AD.
    (i) If the underwing longeron was removed for any reason during 
accomplishment of the actions in Boeing Alert Requirements Bulletin 
777-57A0122 RB, dated October 8, 2021, a cap seal was applied to the 
underwing longeron fasteners, fastener threads, and fastener collars 
at the locations identified in Figures 81 and 144 of Boeing Alert 
Requirements Bulletin 777-57A0122 RB, dated October 8, 2021, during 
installation.
    (ii) All cap seals were applied using procedures with thickness 
dimensions greater than or equal to those given in figure 1 to 
paragraph (h)(4) of this AD.
    (iii) All cap seals that were removed to accomplish any 
inspection in accordance with Boeing Alert Requirements Bulletin 
777-57A0122 RB, dated October 8, 2021, were replaced with cap seals 
of BMS 5-45 sealant of thickness dimensions greater than or equal to 
those given in figure 1 to paragraph (h)(4) of this AD.
    (2) If any cap seal was applied using procedures with thickness 
dimensions less than those given in figure 1 to paragraph (h)(4) of 
this AD, or if the maintenance records do not definitively specify 
the procedures used: At the applicable time specified in paragraph 
(i)(2)(i) or (ii) of this AD, replace the cap seal in accordance 
with the Accomplishment Instructions of Boeing Alert Requirements 
Bulletin 777-57A0122 RB, dated October 8, 2021, using a cap sealing 
procedure with thickness greater than or equal to the dimensions 
given in figure 1 to paragraph (h)(4) of this AD.
    (i) For airplanes equipped with a flammability reduction means 
approved by the FAA as compliant with the fuel tank flammability 
reduction (FTFR) requirements of 14 CFR 25.981(b) or 26.33(c)(1), or 
an ignition mitigation means approved by the FAA as compliant with 
the FTFR requirements of 14 CFR 25.981(c) or 26.33(c)(2): Within 180 
days after the effective date of this AD,
    (ii) For airplanes not described in paragraph (i)(2)(i) of this 
AD: Within 90 days after the effective date of this AD.
    (3) For any cap seal that was not applied, or for any cap seal 
that was removed for inspections and not replaced, or if the 
maintenance records do not definitively specify the procedures used: 
At the applicable time specified in paragraph (i)(3)(i) or (ii) of 
this AD, apply a cap seal of BMS 5-45 sealant using an accepted 
method with thickness greater than or equal to the dimensions given 
in figure 1 to paragraph (h)(4) of this AD.

    Note 2 to paragraph (i)(3):  Guidance for applying a cap seal 
can be found in the Boeing Model 777 Aircraft Maintenance Manual 
section 28-11-00.

    (i) For airplanes equipped with a flammability reduction means 
approved by the FAA as compliant with the fuel tank flammability 
reduction (FTFR) requirements of 14 CFR 25.981(b) or 26.33(c)(1), or 
an ignition mitigation means approved by the FAA as compliant with 
the FTFR requirements of 14 CFR 25.981(c) or 26.33(c)(2): Within 180 
days after the effective date of this AD.
    (ii) For airplanes not described in paragraph (i)(3)(i) of this 
AD: Within 90 days after the effective date of this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520, Continued Operational Safety Branch, 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or 
responsible Flight Standards Office, as appropriate. If sending 
information directly to the manager of the certification office, 
send it to the attention of the person identified in paragraph (k) 
of this AD. Information may be emailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the responsible Flight Standards Office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by The Boeing Company Organization Designation 
Authorization (ODA) that has been authorized by the Manager, AIR-
520, Continued Operational Safety Branch, FAA, to make those 
findings. To be approved, the repair method, modification deviation, 
or alteration deviation must meet the certification basis of the 
airplane, and the approval must specifically refer to this AD.
    (4) AMOCs approved for AD 2022-18-11 are approved as AMOCs for 
the corresponding provisions of Boeing Alert Requirements Bulletin 
777-57A0122 RB, dated October 8, 2021, that are required by 
paragraph (g) of this AD.

(k) Related Information

    For more information about this AD, contact Kevin Nguyen, 
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 
98198; phone: 206-231-3555; email: [email protected].

(l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless this AD specifies otherwise.
    (3) The following service information was approved for IBR on 
October 31, 2022 (87 FR 58259, dated September 26, 2022).
    (i) Boeing Alert Requirements Bulletin 777-57A0122 RB, dated 
October 8, 2021.
    (ii) [Reserved]
    (4) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-
5600; telephone 562-797-1717; internet myboeingfleet.com.
    (5) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability 
of this material at the FAA, call 206-231-3195.
    (6) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on August 28, 2023.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.


[FR Doc. 2023-18835 Filed 8-28-23; 4:15 pm]
BILLING CODE 4910-13-P