Boeing 747-400 Crew Oxygen Bottle Hose Inspection Airworthiness Directive

Rule

Airworthiness Directives; The Boeing Company Airplanes

A Rule by the Federal Aviation Administration on 04/22/2026

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• Public Inspection Published Document: 2026-07808 (91 FR 21373) Document Headings ###### Department of Transportation

Federal Aviation Administration

1. 14 CFR Part 39
2. [Docket No. FAA-2026-3486; Project Identifier MCAI-2026-00002-T; Amendment 39-23314; AD 2026-08-06]
3. RIN 2120-AA64 ( printed page 21373) # AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for The Boeing Company Model 747-400 series airplanes modified by certain supplemental type certificates (STCs). This AD was prompted by a report of a ruptured crew oxygen bottle flexible hose and arcing damage on an adjacent cargo loading system wiring harness. This AD requires a detailed inspection of the crew oxygen bottle flexible hoses and adjacent wire harnesses for chafing and arcing damage and for a minimum clearance between the crew oxygen bottle flexible hoses and adjacent wiring harnesses, and applicable repairs. The FAA is issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective May 7, 2026.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of May 7, 2026.

The FAA must receive comments on this AD by June 8, 2026.

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-2026-3486; 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, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above.

Material Incorporated by Reference:

• For IAI-Aviation Group material identified in this AD, contact Israel Aerospace Industries, Ltd., Ben Gurion International Airport, Israel 7010000; telephone 972-3-9353090; email: AOGBDK@iai.co.il.
• 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-2026-3486.

FOR FURTHER INFORMATION CONTACT:

Narbeh Mardirosian, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 562-627-5354; email: narbeh.mardirosian@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this final rule. Send your comments using a method listed under the ADDRESSES section. Include “Docket No. FAA-2026-3486; Project Identifier MCAI-2026-00002-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 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 Narbeh Mardirosian, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 562-627-5354; email: narbeh.mardirosian@faa.gov. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

Background

The Civil Aviation Authority of Israel (CAAI), which is the aviation authority for Israel, has issued CAAI AD ISR I-35-26-01-01, dated January 1, 2026 (CAAI AD ISR I-35-26-01-01) (also referred to as the MCAI), to correct an unsafe condition on The Boeing Company Model 747-400 series airplanes converted to freighters in accordance with CAAI Supplemental Type Certificate (STC) SA-151 or validated equivalent, including FAA STC ST01676SE; or CAAI STC SA-152 or validated equivalent, including FAA STC ST01706SE. Only FAA STC ST01676SE and FAA STC ST01706SE are approved for U.S. operators.

The MCAI states that, on one converted airplane, the crew oxygen bottle flexible hose, part number (P/N) 96431-2, was found ruptured, and arcing damage was identified on an adjacent cargo loading system (CLS) wire harness, P/N W9914-301-12, near station (STA) 680. CAAI determined ( printed page 21374) that this condition was caused by chafing of the oxygen hose against the CLS wire harness.

The FAA is issuing this AD to address chafing, arcing damage, and insufficient clearance between the crew oxygen bottle flexible hoses and adjacent wire harnesses. The unsafe condition, if not addressed, could result in fire and loss of crew oxygen supply due to insufficient clearance between electrical wiring and the crew oxygen bottle flexible hose. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-3486.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Israel Aerospace Industry Ltd., Service Bulletin 366-35-157, dated January 2026. This material specifies procedures for a detailed inspection of the crew oxygen bottle flexible hoses and adjacent wire harnesses, near STA 680 for signs of chafing and arcing damage, and for a minimum clearance of 2 inches between the crew oxygen bottle flexible hose and the adjacent wire harnesses, and repair, as applicable.

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.

FAA's Determination

These products have been approved by the civil aviation authority of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, that authority has notified the FAA of the unsafe condition described in the MCAI and material referenced above. The FAA is issuing this AD after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.

AD Requirements

This AD requires accomplishing the actions specified in the material already described.

Justification for Immediate Adoption and Determination of the Effective Date

Section 553(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 chafing, arcing damage, and insufficient clearance between the crew oxygen bottle flexible hoses and adjacent wire harnesses could result in fire, or loss of crew oxygen supply. Additionally, the compliance time in this AD is before further flight, which is shorter than the time necessary for the public to comment and for publication of the final rule. Accordingly, notice and opportunity for prior public comment are impracticable and contrary to the public interest pursuant to 5 U.S.C. 553(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.

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 prior notice and comment, RFA analysis is not required.

Costs of Compliance

The FAA estimates that this AD affects 5 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

| Labor cost | Parts cost | Cost per
product | Cost on U.S.
operators |
| --- | --- | --- | --- |
| 1 work-hour × $85 per hour = $85 | $0 | $85 | $425 |
The FAA has received no definitive data on which to base the cost estimates for the repairs specified in this AD.

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:

( printed page 21375)

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 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive:

2026-08-06 The Boeing Company: Amendment 39-23314; Docket No. FAA-2026-3486; Project Identifier MCAI-2026-00002-T.

(a) Effective Date

This airworthiness directive (AD) is effective May 7, 2026.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company Model 747-400 series airplanes, certificated in any category, that have been converted to a freighter configuration in accordance with Supplemental Type Certificate (STC) ST01676SE or converted to special freighter configuration in accordance with STC ST01706SE.

(d) Subject

Air Transport Association (ATA) of America Code 35, Oxygen.

(e) Unsafe Condition

This AD was prompted by a report of a ruptured crew oxygen bottle flexible hose and arcing damage on an adjacent cargo loading system (CLS) wiring harness near station (STA) 680. The FAA is issuing this AD to address chafing, arcing damage, and insufficient clearance between the crew oxygen bottle flexible hoses and adjacent wire harnesses. The unsafe condition, if not addressed, could result in fire and loss of crew oxygen supply.

(f) Compliance

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

(g) Required Actions

(1) Before further flight after the effective date of this AD, do a detailed inspection for chafing and arcing damage of the crew oxygen bottle flexible hoses and the adjacent wire harnesses, and for minimum clearance between the crew oxygen bottle flexible hose and the adjacent wire harnesses, in accordance with the Accomplishment Instructions of Israel Aerospace Industries Ltd. Service Bulletin 366-35-157, dated January 2026.

(2) If, during any inspection required by paragraph (g)(1) of this AD, any chafing or arcing damage is found, or the clearance is less than 2 inches, before further flight, repair using a method approved by the Manager, International Validation Branch, FAA; or the Civil Aviation Authority of Israel (CAAI); or the CAAI's authorized Designee. If approved by the CAAI Designee, the approval must include the Designee's authorized signature.

(h) No Reporting Requirement

Although Israel Aerospace Industries Ltd., Service Bulletin 366-35-157, dated January 2026, specifies to submit certain information to the manufacturer, this AD does not include that requirement.

(i) Special Flight Permits

A special flight permit may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the airplane to a location where the corrective actions for insufficient clearance required by this AD can be performed, provided that there are no signs of wear or chafing on either the oxygen tubes or electrical wires or harnesses.

(j) Additional AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, International Validation 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 International Validation Branch, Continued Operational Safety Branch, send it to the attention of the person identified in paragraph (k) of this AD and email to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office.

(2) Contacting the Manufacturer: For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, International Validation Branch, FAA; or the Civil Aviation Authority of Israel (CAAI); or the CAAI's authorized Designee. If approved by the CAAI Designee, the approval must include the Designee's authorized signature.

(k) Additional Information

For more information about this AD, contact Narbeh Mardirosian, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 562-627-5354; email: narbeh.mardirosian@faa.gov.

(l) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) 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 this AD specifies otherwise.

(i) Israel Aerospace Industries Ltd., Service Bulletin 366-35-157, dated January 2026.

(ii) [Reserved]

(3) For IAI-Aviation Group material identified in this AD, contact Israel Aerospace Industries, Ltd., Ben Gurion International Airport, Israel 7010000; telephone 972-3-9353090; email: AOGBDK@iai.co.il.

(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 April 13, 2026.

Steven W. Thompson,

Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.

[FR Doc. 2026-07808 Filed 4-20-26; 4:15 pm]

BILLING CODE 4910-13-P

Published Document: 2026-07808 (91 FR 21373)