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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
 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 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: 
                        *james.laubaugh@faa.gov*.


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: 
                    *james.laubaugh@faa.gov*. 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 
                    ( print 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
Action
Labor cost
Parts cost
Cost per product
Cost on 
                             U.S.  
                             operatorsGVI
31 work-hours × $85 per hour = $2,635
$0
$2,635
$1,035,555
 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
Action
Labor cost
Parts cost
Cost per productReplace clip-on nuts
42 work-hours × $85 per hour = $3,570
$692
$4,262
 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
 1.The authority citation for part 39 continues to read as follows: Authority:
                    49 U.S.C. 106(g), 40113, 44701. § 39.13
 2.The FAA amends § 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 
                        ( print 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: 
                        *AMOC@faa.gov.* (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: 
                        *james.laubaugh@faa.gov.* (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 
                        *fr.inspection@nara.gov.* 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