AD 2026-15-08

This AD is effective September 3, 2026.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of September 3, 2026.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2026-4637; 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 address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-91, West Building Fifth Floor, Room W58-213, 1200 New Jersey Avenue SE, Washington, DC 20590.

George Weir, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 222-4045; email: george.a.weir@faa.gov.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Stemme Model Stemme S 12 gliders. The NPRM was published in the Federal Register on May 15, 2026 (91 FR 27876). The NPRM was prompted by European Union Aviation Safety Agency (EASA) AD 2025-0155, dated July 21, 2025, issued by EASA, which is the Technical Agent for the Member States of the European Union (EASA AD 2025-0155) (referred to as the MCAI). The MCAI states that occurrences of fuel leaks at multiple locations within the fuel system have been reported. To address the unsafe condition, Stemme published service material to provide replacement instructions for affected copper sealing rings, and a parts installation restriction. This condition, if not addressed, could result in an in-flight fire.

In the NPRM, the FAA proposed to require repetitive visual checks of the fuel system for fuel leakage (staining, wetness, dripping, etc.), and replacement of the affected copper sealing rings if leakage is detected. In addition, the FAA proposed to prohibit the installation of affected parts. The owner/operator (pilot) holding at least a private pilot certificate may perform the visual check and must enter compliance with the applicable paragraph of this AD into the glider maintenance records in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The pilot may perform this action because it only involves visually checking affected locations for fuel leakage. This action could be performed equally well by a pilot or a mechanic. This is an exception to the FAA's standard maintenance regulations. The FAA is issuing this AD to address the unsafe condition on these products.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-4637.

Comments

The FAA received no comments on the NPRM or on the determination of the costs.

Conclusion

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 reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

The FAA reviewed Stemme Service Bulletin (SB) P062-980082, Revision 01, dated July 15, 2025. This material specifies procedures for replacement of affected copper sealing rings within the fuel pump set assembly and drainer complete assembly.

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 estimates that this AD affects 31 gliders of U.S. registry. The FAA estimates the following costs to comply with this AD:

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,

(2) Will not affect intrastate aviation in Alaska, and

(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

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: