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[Federal Register Volume 89, Number 250 (Tuesday, December 31, 2024)]
[Proposed Rules]
[Pages 107067-107069]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-31348]

[[Page 107067]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2716; Project Identifier AD-2024-00262-T]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain The Boeing Company Model 737-8, 737-9, and 737-8200 
airplanes. This proposed AD was prompted by a report indicating that 
certain clip-on nuts with primer, in lieu of clip-on nuts with cadmium 
surface finish only (without primer), were inadvertently used to 
install the self-bonded saddle clamps, which support the fuel tank 
system tubing inside the left main, center, and right main fuel tanks. 
This proposed AD would require a general visual inspection (GVI) to 
identify affected parts, and applicable on-condition actions. 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 February 
14, 2025.

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-2024-2716; 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 the Boeing material identified in this proposed 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.
     You may view this material 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 under 
Docket No. FAA-2024-2716.

FOR FURTHER INFORMATION CONTACT: James Laubaugh, Aviation Safety 
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3622; 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 the ADDRESSES section. Include ``Docket No. FAA-2024-2716; 
Project Identifier AD-2024-00262-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 James 
Laubaugh, Aviation Safety Engineer, FAA, 2200 South 216th St., Des 
Moines, WA 98198; phone: 206-231-3622; 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 received a report indicating that certain clip-on nuts 
with primer, in lieu of clip-on nuts with cadmium surface finish only 
(without primer), were inadvertently used to install the self-bonded 
saddle clamps, which support the fuel tank system tubing inside the 
left main, center, and right main fuel tanks. The self-bonded saddle 
clamps are designed to be attached to the structure with clip-on nuts 
with cadmium surface finish only (without primer). The cadmium plating 
is an electrically conductive finish and bonds the fuel tank system 
tubing to the structure. Each self-bonded saddle clamp has two 
independent and redundant bond paths from the fuel system tubing to the 
structure. These bond paths are necessary for the dissipation of 
conducted lightning current, induced lightning current, and 
electrostatic energy. The clip-on nuts with non-conductive primer can 
interrupt or reduce the capability of the electrical bond. This 
condition, if not addressed, could disperse lightning and electrostatic 
energy to the structure, creating a possible ignition source inside a 
fuel tank and subsequent fuel tank explosion.

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.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Boeing Special Attention Requirements Bulletin 
737-28-1376 RB, dated May 3, 2024. This material specifies procedures 
for a general visual inspection (GVI) of the self-bonded saddle clamps 
installed with clip-on nuts to determine whether the surface finish is 
primer or cadmium surface finish only (no primer) in the left main, 
center, and right main fuel tanks, and applicable on-condition actions. 
The on-condition actions include replacing any clip-on nut with primer 
with a clip-on nut that has

[[Page 107068]]

cadmium surface finish only (no primer). This material 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the material already described, except for any differences 
identified as exceptions in the regulatory text of this proposed AD. 
This proposed AD would also prohibit the installation of affected 
parts. For information on the procedures and compliance times, see this 
material at regulations.gov under Docket No. FAA-2024-2716.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 393 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                             Estimated Costs
------------------------------------------------------------------------
                                                               Cost on
   Action        Labor cost      Parts cost     Cost per        U.S.
                                                 product      operators
------------------------------------------------------------------------
GVI.........  31 work-hours x            $0        $2,635    $1,035,555
               $85 per hour =
               $2,635.
------------------------------------------------------------------------

    The FAA estimates the following costs to do any replacements that 
would be required based on the results of the proposed inspection. The 
agency has no way of determining the number of aircraft that might need 
this replacement:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                      Cost per
                     Action                                   Labor cost               Parts cost      product
----------------------------------------------------------------------------------------------------------------
Replace clip-on nuts............................  42 work-hours x $85 per hour =             $692        $4,262
                                                   $3,570.
----------------------------------------------------------------------------------------------------------------

    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
    (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-2024-2716; Project Identifier 
AD-2024-00262-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by February 14, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-8, 737-9, and 
737-8200 airplanes, certificated in any category, as identified in 
Boeing Special Attention Requirements Bulletin 737-28-1376 RB, dated 
May 3, 2024.

(d) Subject

    Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

    This AD was prompted by a report indicating that certain clip-on 
nuts with primer, in lieu of the clip-on nuts with cadmium surface 
finish only (without primer), were inadvertently used to install the 
self-bonded saddle clamps, which support the fuel tank system tubing 
inside the left main, center, and right main fuel tanks. The FAA is 
issuing this AD to address clip-on nuts with the non-conductive 
primer that can interrupt or reduce the capability of the electrical 
bond. The unsafe condition, if

[[Page 107069]]

not addressed, could disperse lightning and electrostatic energy to 
the structure, creating a possible ignition source inside a fuel 
tank and subsequent fuel tank explosion.

(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 
Special Attention Requirements Bulletin 737-28-1376 RB, dated May 3, 
2024, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Special Attention 
Requirements Bulletin 737-28-1376 RB, dated May 3, 2024.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Special Attention Service 
Bulletin 737-28-1376, dated May 3, 2024, which is referred to in 
Boeing Special Attention Requirements Bulletin 737-28-1376 RB, dated 
May 3, 2024.

(h) Exceptions to Requirements Bulletin Specifications

    Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Special Attention Requirements 
Bulletin 737-28-1376 RB, dated May 3, 2024, refer to the original 
issue date of Requirements Bulletin 737-28-1376 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 James Laubaugh, 
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 
98198; phone: 206-231-3622; email: [email protected].
    (2) Material identified in this AD that is not incorporated by 
reference is available at the address specified in paragraph (k)(3) 
of this AD.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference of the material listed in this paragraph 
under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this material as applicable to do the actions 
required by this AD, unless the AD specifies otherwise.
    (i) Boeing Special Attention Requirements Bulletin 737-28-1376 
RB, dated May 3, 2024.
    (ii) [Reserved]
    (3) For the material 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 material 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 December 20, 2024.
Suzanne Masterson,
Deputy Director, Integrated Certificate Management Division, Aircraft 
Certification Service.
[FR Doc. 2024-31348 Filed 12-30-24; 8:45 am]
BILLING CODE 4910-13-P
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