AD 2026-15-04

[Federal Register Volume 91, Number 141 (Friday, July 24, 2026)]
[Rules and Regulations]
[Pages 46709-46712]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-15004]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2026-7222; Project Identifier MCAI-2026-00565-G; 
Amendment 39-23416; AD 2026-15-04]
RIN 2120-AA64


Airworthiness Directives; Stemme GmbH Gliders

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Stemme GmbH (Stemme) TSA-M Model S6-RT and Stemme S 12 gliders. This AD 
was prompted by a report of a leaking electrical fuel transfer pump. 
This AD requires inspecting affected electrical fuel transfer pumps for 
certain non-conforming parts, and if found, replacing them with 
approved parts. This AD also prohibits installation of certain non-
conforming parts on affected gliders. The FAA is issuing this AD to 
address the unsafe condition on these products.

DATES: This AD is effective July 24, 2026.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of July 24, 
2026.
    The FAA must receive comments on this AD by September 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-2026-7222; 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 Stemme material identified in this AD, contact Stemme,

[[Page 46710]]

Flugplatzstrasse F2 Nr. 6-7, Strausberg, Germany 15344; phone: +49 (0) 
3341 3612; email: stemme.com">airworthiness@stemme.com; website: stemme.com.
     You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 1100 Main, Kansas City, MO 
64105. For information on the availability of this material at the FAA, 
call (817) 222-5110. It is also available at regulations.gov under 
Docket No. FAA-2026-7222.

FOR FURTHER INFORMATION CONTACT: George Weir, Aviation Safety Engineer, 
FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 
222-4045; email: [email protected].

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 
the ADDRESSES section. Include ``Docket No. FAA-2026-7222; Project 
Identifier MCAI-2026-00565-G'' 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 George 
Weir, 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 Emergency AD 2026-0108-E, dated June 5, 2026 (referred to as the 
MCAI), to correct an unsafe condition on all Stemme TSA-M Model S6-RT 
and Stemme S 12 gliders. The MCAI states that a leaking electrical fuel 
transfer pump installed on a Model Stemme S 12 glider was found. The 
two glider models share the same electrical fuel transfer pump design. 
Each of these glider models have two electrical fuel transfer pumps. An 
investigation revealed that leakage resulted from the installation of 
non-conforming parts that occurred during manufacturing and that also 
have been delivered as spare parts. Non-conforming parts are electrical 
fuel transfer pumps identified with ``HEP-02A'' (unknown manufacturer) 
instead of ``HEP-02'' under part number 830521. To address the unsafe 
condition, Stemme published service material to provide inspection 
instructions to identify affected electrical fuel transfer pumps. This 
condition, if not addressed, could result in an in-flight fire and a 
potential explosion in the wing or center fuselage.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2026-7222.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed Stemme Service Bulletin P062-980092, Revision 00, 
dated May 29, 2026. This material specifies procedures for a one-time 
inspection of the two electrical fuel pumps to verify if non-conforming 
parts, as defined in this AD, are installed. 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 visual inspection of both electrical fuel transfer 
pumps for non-conforming parts, and replacement of any electrical fuel 
transfer pumps if non-conforming parts are identified. This AD also 
prohibits the installation of certain non-conforming parts.

Interim Action

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

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 EASA issued an emergency AD indicating that fuel leakage from 
an electrical fuel transfer pump on TSA-M Model S6-RT and Stemme S 12 
gliders could result in an in-flight fire and a possible explosion in 
the wing or center fuselage, which could injure occupants and persons 
on the ground. Thus, an inspection of these gliders is necessary before 
further flight. 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.

[[Page 46711]]

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

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                       Cost per    Cost on U.S.
                  Action                            Labor cost           Parts cost    product       operators
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Inspect both electrical fuel transfer      3 work-hours x $85 per hour          $0         $255          $8,415
 pumps.                                     = $255.
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    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
inspection. The agency has no way of determining the number of gliders 
that might need these replacements.

                                               On-Condition Costs
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                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace both electrical fuel transfer pumps...  3 work-hours x $85 per hour =       $48 (up to)    $303 (up to)
                                                 $255 (up to).
----------------------------------------------------------------------------------------------------------------

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:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13   [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2026-15-04 Stemme GmbH: Amendment 39-23416; Docket No. FAA-2026-
7222; Project Identifier MCAI-2026-00565-G.

(a) Effective Date

    This airworthiness directive (AD) is effective July 24, 2026.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Stemme GmbH TSA-M Model S6-RT and Stemme 
S 12 gliders, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) Code 2800, Aircraft Fuel 
System.

(e) Unsafe Condition

    This AD was prompted by a report of a leaking electrical fuel 
transfer pump. The FAA is issuing this AD to detect and replace 
certain non-conforming parts. The unsafe condition, if not 
addressed, could result in an in-flight fire and possible explosion 
in the wing or center fuselage.

(f) Compliance

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

(g) Definitions

    For the purpose of this AD the definitions in paragraphs (g)(1) 
through (4) of this AD apply.
    (1) Non-conforming part: Any electrical fuel pump defined as 
``non-conforming'' as described in Stemme Service Bulletin (SB) 
P062-980092, Revision 00, dated May 29, 2026 (Stemme SB P062-
980092).
    (2) Conforming part: Any electrical fuel pump defined as 
``conforming'' as described in Stemme SB P062-980092.
    (3) Group 1 gliders: Model Stemme S 12 gliders, serial numbers 
(S/Ns) 12-057 through 12-062 and TSA-M Model S6-RT gliders, S/Ns 
019, 029, and 030.
    (4) Group 2 gliders: Gliders that are not Group 1.

(h) Required Actions

    (1) For Group 1 gliders: Before further flight after the 
effective date of this AD, accomplish a one-time inspection of the 
two electrical fuel pumps to verify if non-conforming parts are 
installed, in accordance with Stemme SB P062-980092.
    (2) For Group 2 gliders: The inspection required by paragraph 
(h)(1) of this AD is not

[[Page 46712]]

required for a Group 2 glider, provided that no electrical fuel pump 
has been replaced on that glider after January 1, 2023.
    (3) If, during the inspection required by paragraph (h)(1) of 
this AD, any non-conforming part as defined in paragraph (g)(1) of 
this AD, is found, before further flight, replace any non-conforming 
electrical fuel pump with a conforming electrical fuel pump by 
contacting either the Manager, International Validation Branch, FAA; 
European Union Aviation Safety Agency (EASA); or Stemme's EASA 
Design Organization Approval (DOA); for approved replacement 
instructions and, within the compliance time specified therein, 
accomplish those instructions accordingly, including any follow-on 
action(s), as applicable. If approved by the DOA, the approval must 
include the DOA-authorized signature.

(i) Parts Installation Prohibition

    As of the effective date of this AD, do not install a non-
conforming part, as defined paragraph (g)(1) of this AD, on any 
glider.

(j) 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 local Flight 
Standards District Office, as appropriate. If sending information 
directly to the manager of the International Validation Branch, send 
it to the attention of the person identified in paragraph (k) of 
this AD and email to [email protected]. Before using any approved AMOC, 
notify your appropriate principal inspector, or lacking a principal 
inspector, the manager of the local flight standards district 
office/certificate holding district office.

(k) Additional Information

    George Weir, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, 
Suite 410, Westbury, NY 11590; phone: (817) 222-4045; email: 
[email protected].

(l) 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) Stemme Service Bulletin P062-980092, Revision 00, dated May 
29, 2026.
    (ii) [Reserved]
    (3) For Stemme material identified in this AD, contact Stemme 
GmbH, Flugplatzstrasse F2 Nr. 6-7, Strausberg, Germany 15344; phone: 
+49 (0) 3341 3612; email: stemme.com">airworthiness@stemme.com; website: 
stemme.com.
    (4) You may view this material at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 1100 Main, Kansas City, 
MO 64105. For information on the availability of this material at 
the FAA, call (817) 222-5110.
    (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 [email protected].

    Issued on July 16, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2026-15004 Filed 7-23-26; 8:45 am]
BILLING CODE 4910-13-P