[Federal Register Volume 89, Number 72 (Friday, April 12, 2024)]
[Proposed Rules]
[Pages 25823-25825]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07562]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 89, No. 72 / Friday, April 12, 2024 / 
Proposed Rules  

[[Page 25823]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1000; Project Identifier AD-2023-01051-T]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain The Boeing Company Model 747-400F series airplanes. This 
proposed AD was prompted by a report that cap seals were not applied to 
certain fasteners in the fuel tanks during production. This proposed AD 
would require applying cap seals to certain fastener collars inside the 
fuel tanks. The FAA is proposing this AD to address the unsafe 
condition on these products.

DATES: The FAA must receive comments on this proposed AD by May 28, 
2024.

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 under 
Docket No. FAA-2024-1000; 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 NPRM, any comments received, and other 
information. The street address for Docket Operations is listed above.
    Material Incorporated by Reference:
     For service information identified in this NPRM, 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; website myboeingfleet.com.
     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. It is also available at 
regulations.gov by searching for and locating Docket No. FAA-2024-1000.

FOR FURTHER INFORMATION CONTACT: Samuel Dorsey, Aviation Safety 
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3415; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2024-1000; Project Identifier 
AD-2023-01051-T'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, 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 proposal 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 NPRM.

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 NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, 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 NPRM. Submissions containing CBI should be sent to 
Samuel Dorsey, Aviation Safety Engineer, FAA, 2200 South 216th St., Des 
Moines, WA 98198; phone: 206-231-3415; 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.

Background

    The FAA has examined the underlying safety issues involved in fuel 
tank explosions on several large transport airplanes, including the 
adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, the FAA issued a 
final rule titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction, and Maintenance and Inspection Requirements'' 
(66 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, that rule 
included Amendment 21-78, which established Special Federal Aviation 
Regulation No. 88 (``SFAR 88'') at 14 CFR part 21. Subsequently, SFAR 
88 was amended by Amendment 21-82 (67 FR 57490, September 10, 2002; 
corrected at 67 FR 70809, November 26, 2002) and Amendment 21-83 (67 FR 
72830, December 9, 2002; corrected at 68 FR 37735, June 25, 2003, to 
change ``21-82'' to ``21-83'').

[[Page 25824]]

    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the final rule published on 
May 7, 2001, the FAA intended to adopt airworthiness directives to 
mandate any changes found necessary to address unsafe conditions 
identified as a result of these reviews.
    In evaluating these design reviews, the FAA has established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: Single failures, combination of 
failures, and unacceptable (failure) experience. For all three failure 
criteria, the evaluations included consideration of previous actions 
taken that may mitigate the need for further action.
    The FAA has determined that the actions identified in this proposed 
AD are necessary to reduce the potential of ignition sources inside 
fuel tanks, which, in combination with flammable fuel vapors, could 
result in fuel tank explosion or fire.
    The FAA has received a report indicating that cap seals were not 
applied to certain fasteners in the fuel tank during production. The 
FAA issued AD 2022-10-11, Amendment 39-22049 (87 FR 34120, June 6, 
2022) to require, among other actions, application of cap seals to 
certain fasteners in the fuel tank on airplanes having line numbers 645 
through 1363 inclusive. Cap seals were determined to be a necessary 
feature by SFAR 88 reviews and were required to be retrofitted onto 
existing airplanes by AD 2022-10-11 and earlier ADs. Boeing intended to 
incorporate similar changes on future airplanes, ultimately those 
having line numbers 1364 through 1419 inclusive, via a production 
design change. However, Boeing discovered that the design change 
omitted application of the cap seals on eight fasteners (four each on 
the left and right wings in the inboard main fuel tanks). Without these 
cap seals, the ends of the fasteners do not have sufficient electrical 
insulation to prevent arcing in the event of a lightning strike or 
high-powered short circuit, possibly creating an ignition source in the 
inboard main fuel tanks. A failure to prevent possible ignition sources 
in the fuel tank, in combination with flammable fuel vapors, could 
result in an explosion or fire and consequent loss of the airplane.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 747-57A2371 RB, 
dated September 29, 2023. This service information specifies procedures 
for applying cap seals to four fastener collars inside the fuel tank 
common to the stiffeners located at the front spar on the left and 
right wings. 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 ADDRESSES.

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the service information already described, except for any 
differences identified as exceptions in the regulatory text of this 
proposed AD. For information on the procedures and compliance times, 
see this service information at regulations.gov under Docket No. FAA-
2024-1000.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 15 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Apply cap seals.......................  37 work-hours x $85 per           $1,000          $4,145         $62,175
                                         hour = $3,145.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this proposed 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

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and

[[Page 25825]]

    (3) Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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 adding the following new airworthiness 
directive:

The Boeing Company: Docket No. FAA-2024-1000; Project Identifier AD-
2023-01051-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by May 28, 2024.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 747-400F series 
airplanes, certificated in any category, as identified in Boeing 
Alert Requirements Bulletin 747-57A2371 RB, dated September 29, 
2023.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report that cap seals were not applied 
to certain fasteners in the fuel tanks during production. The FAA is 
issuing this AD to address missing cap seals in the fuel tanks. The 
unsafe condition, if not addressed, could result in a failure to 
prevent possible ignition sources in the fuel tanks, which in 
combination with flammable fuel vapors, could result in an explosion 
or fire and consequent loss of the airplane.

(f) Compliance

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

(g) Required Actions

    Except as specified by paragraph (h) of this AD: At the 
applicable times specified in the ``Compliance'' paragraph of Boeing 
Alert Requirements Bulletin 747-57A2371 RB, dated September 29, 
2023, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Alert Requirements 
Bulletin 747-57A2371 RB, dated September 29, 2023.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
747-57A2371, dated September 29, 2023, which is referred to in 
Boeing Alert Requirements Bulletin 747-57A2371 RB, dated September 
29, 2023.

(h) Exceptions to Service Information Specifications

    (1) Where Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 747-
57A2371 RB, dated September 29, 2023, use the phrase ``the original 
issue date of Requirements Bulletin 747-57A2371 RB,'' this AD 
requires using the effective date of this AD.

(i) 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 
(j)(1) 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.

(j) Related Information

    (1) For more information about this AD, contact Samuel Dorsey, 
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 
98198; phone: 206-231-3415; email: [email protected].
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the address specified in 
paragraphs (k)(3) of this AD.

(k) 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 the AD specifies otherwise.
    (i) Boeing Alert Requirements Bulletin 747-57A2371 RB, dated 
September 29, 2023.
    (ii) [Reserved]
    (3) 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; website myboeingfleet.com.
    (4) 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.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on April 4, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-07562 Filed 4-11-24; 8:45 am]
BILLING CODE 4910-13-P