SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written data, views, or arguments about this final rule. Send your comments using a method listed under ADDRESSES . Include “Docket No. FAA-2026-11805; Project Identifier MCAI-2026-00811-R” 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 ( printed page 64607) of this AD. Submissions containing CBI should be sent to Aryanna Sanchez, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590. 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 European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2026-0152, dated July 30, 2026 (EASA AD 2026-0152) (also referred to as “the MCAI”), to correct an unsafe condition on all AHD Model MBB-BK 117 C-1 helicopters. The MCAI states an occurrence was reported of an affected louver box assembly of the vapor cycle air cooling system part number (P/N) 117-820014 detaching in-flight due to incorrect installation. This condition, if not addressed, could lead to in-flight loss of parts, which could impact the main or tail rotor, lead to reduced control of the helicopter, necessitate an emergency landing, or cause injury to persons on the ground.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-11805.

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 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 repetitively accomplishing a play check of the louver box assembly of vapor cycle air cooling system part number (P/N) 117-820014, and if there is any play accomplishing corrective actions in accordance with a method approved by the Manager, International Validation Branch, FAA; or EASA; or AHD's EASA Design Organization Approval (DOA).

The owner/operator (pilot) holding at least a private pilot certificate may accomplish a play check of the louver box assembly of vapor cycle air cooling system installed on the helicopter, by pulling it upward by hand on all four corners, and must enter compliance into the helicopter maintenance records in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417, 121.380, or 135.439. The pilot may perform this action because it only involves checking to see if the louver box assembly is installed firmly, which could be performed equally well by a pilot or mechanic. This is an exception to the FAA's standard maintenance regulations.

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 if a louver box assembly is incorrectly installed, it could lead to parts separating from the helicopter in flight and impacting the main rotor blade or the tail rotor blade. This condition could also lead to an emergency landing, or impact of parts to persons on ground. The root cause of this separation has been identified as incorrect installation; however, the specific installation deficiency has not yet been fully determined. To ensure this unsafe condition is immediately detected and does not reoccur, a play check for looseness must be done before the first flight of each day. This compliance time 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.

Interim Action

The FAA considers that this AD is an interim action. If final actions are later identified, the FAA might consider further rulemaking.

Costs of Compliance

The FAA estimates that this AD affects 9 helicopters of U.S. registry.

The FAA estimates the following costs to comply with this AD:

The actions needed as a result of any play in the assembly could vary significantly from helicopter to helicopter. The FAA was unable to obtain costs of any corrective actions from the design approval holders within the time necessary to address the unsafe condition.

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 ( printed page 64608) 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.

The Amendment

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