AD 2026-13-51

This AD is effective July 17, 2026. Emergency AD 2026-13-51, issued on June 18, 2026, which contains the requirements of this amendment, was effective with actual notice.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of July 17, 2026.

The FAA must receive comments on this AD by August 17, 2026.

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-2026-4667; 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, any comments received, and other information. The street address for Docket Operations is listed above.

Material Incorporated by Reference:

• For Gulfstream Aerospace Corporation material identified in this AD, contact Gulfstream Aerospace Corporation, Technical Publications Dept., P.O. Box 2206, Savannah, GA 31402-2206; telephone 800-810-4853; email pubs@gulfstream.com; website gulfstream.com/en/customer-support.

• 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-2026-4667.

Jeff Johnson, Senior Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: 404-474-5554; email: ecb-cos@faa.gov.

The FAA invites you to send any written relevant data, views, or arguments about this AD. Send your comments using a method listed under the ADDRESSES section. Include “Docket No. FAA-2026-4667; Project Identifier AD-2026-00584-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.

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 Jeff Johnson, Senior Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: 404-474-5554; email: ecb-cos@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.

The FAA issued Emergency AD 2026-13-51, dated June 18, 2026 (the emergency AD), to address an unsafe condition on certain Gulfstream Aerospace Corporation Model GVIII-G700 and GVIII-G800 airplanes. The FAA sent the emergency AD to all known U.S. owners and operators of these airplanes. The emergency AD requires a visual inspection of the upper surface of the engine mount to the forward and aft thrust strut mount at the hollow pin head interface, of the left and right engines, for evidence of movement or distress; an inspection of the forward and aft thrust strut mount hardware to ensure the sleeve bushing, nut, washers, and cotter pins are properly installed; and applicable corrective actions.

The emergency AD was prompted by a report indicating that a hollow pin cap on the right-side engine aft thrust strut mount interface was found broken due to a missing sleeve bushing. Further investigation found the sleeve bushing was loose (displaced) within the engine pylon. The airplane had accumulated 1,056 total flight hours and 324 total flight cycles. During a subsequent audit, an additional airplane failed a gap check at the right-side engine forward thrust strut mount interface. The additional airplane had accumulated 551 total flight hours and 182 total flight cycles. The engine thrust struts on both airplanes were previously disconnected to perform production retrofit activities prior to entry into service. An improperly installed engine thrust strut could compromise the structural integrity of the engine mount system and lead to failure of the engine mount system. This condition, if not addressed, could result in an in-flight separation of the engine from the airplane, leading to loss of control of the airplane.

The FAA reviewed Gulfstream GVIII-G700 Alert Customer Bulletin No. 001, dated June 16, 2026; and Gulfstream GVIII-G800 Alert Customer Bulletin No. 001, dated June 16, 2026. This material specifies procedures for visually inspecting the upper surface of the engine mount to the forward and aft thrust strut mount at the hollow pin head interface, of the left and right engines, for evidence of movement or distress ( i.e., paint abrasion or witness marks, gouging or surface damage, a broken or compromised hollow pin); inspecting the forward and aft thrust strut mount hardware to ensure the sleeve bushing, nut, washers, and cotter pins are properly installed; and depending on findings, submitting certain information to the manufacturer for further evaluation and engineering disposition ( i.e., corrective action).

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.

The FAA is issuing this AD because the agency has determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

This AD requires accomplishing the actions specified in the material already described, except for any differences identified as exceptions in the regulatory text of this AD.

The FAA considers this AD to be an interim action. If a final action is later identified, the FAA might consider further rulemaking then.

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 required the immediate adoption of Emergency AD 2026-13-51 issued on June 18, 2026, to all known U.S. owners and operators of these airplanes. The FAA found that the risk to the flying public justified forgoing notice and comment prior to adoption of this rule because the urgency of the unsafe condition necessitates prohibiting further flight until the airplane is inspected and the applicable corrective actions are performed. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to 14 CFR 39.13 to make it effective to all persons. Given the significance of the risk presented by this unsafe condition, it must be immediately addressed. 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.

The requirements of the 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 notice and comment, RFA analysis is not required.

The FAA estimates that this AD affects 37 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA has received no definitive data on which to base the cost estimates for the on-condition actions specified in this AD.

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a currently valid OMB Control Number. The OMB Control Number for the collection of information required by this AD is 2120-0056. The paperwork cost associated with this AD has been detailed in the Costs of Compliance section of this document and includes time for reviewing instructions, as well as completing and reviewing the collection of information. Therefore, all reporting associated with this AD is mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to: Information Collection Clearance Officer, Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX 76177-1524.

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.

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.

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

1. The authority citation for part 39 continues to read as follows:

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