    [Federal Register Volume 91, Number 58 (Thursday, March 26, 2026)]
    [Rules and Regulations]
    [Pages 14643-14645]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 2026-05883]

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    DEPARTMENT OF TRANSPORTATION

    Federal Aviation Administration

    14 CFR Part 39

    [Docket No. FAA-2025-5397; Project Identifier MCAI-2025-00972-A;
    Amendment 39-23291; AD 2026-06-03]
    RIN 2120-AA64

    Airworthiness Directives; Diamond Aircraft Industries Inc.
    Airplanes

    AGENCY: Federal Aviation Administration (FAA), DOT.

    ACTION: Final rule.

    -----------------------------------------------------------------------

    SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2020-14-
    06, which applied to all Diamond Aircraft Industries Inc. (DAI) Model
    DA 40, DA 40 F, and DA 40 NG airplanes. AD 2020-14-06 required
    replacing affected parts, inspecting the fuel tank chambers, and
    removing rubber material that has detached from the fuel tank
    connection hoses. AD 2020-14-06 also prohibited installing an affected
    part on any airplane. Since the FAA issued AD 2020-14-06, additional
    affected parts installed during production on Model DA 40 NG airplanes
    have been reported. As a result, the manufacturer has published updated
    service material for the Model DA 40 NG. This AD requires the same
    actions as AD 2020-14-06 and requires updated service material to be
    used for the Model DA 40 NG airplanes. The FAA is issuing this AD to
    address the unsafe condition on these products.

    DATES: This AD is effective April 30, 2026.
        The Director of the Federal Register approved the incorporation by
    reference of a certain publication listed in this AD as of April 30,
    2026.
        The Director of the Federal Register approved the incorporation by
    reference of certain other publications listed in this AD as of August
    4, 2020 (85 FR 42687, July 15, 2020).

    ADDRESSES:
        AD Docket: You may examine the AD docket at regulations.gov under
    Docket No. FAA-2025-5397; 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-30, West Building Ground Floor, Room W12-140, 1200
    New Jersey Avenue SE, Washington, DC 20590.
        Material Incorporated by Reference:
         For Diamond Aircraft Industries material identified in
    this AD, contact DAI, 1560 Crumlin Sideroad, London, Ontario, Canada,
    N5V 1S2; phone: (519) 457-4041, fax: (519) 457-4045; email: support-canada@diamondaircraft.com.
         You may view this material at the FAA, Airworthiness
    Products Section, Operational Safety Branch, 901 Locust, Kansas City,
    MO 64106. 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-2025-5397.

    FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aviation Safety
    Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
    phone: (516) 228-7366; email: joseph.catanzaro@faa.gov.

    SUPPLEMENTARY INFORMATION:

    Background

        The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
    CFR part 39 to supersede AD 2020-14-06, Amendment 39-21160 (85 FR
    42687, July 15, 2020), (AD 2020-14-06). AD 2020-14-06 applied to DAI
    Model DA 40, DA 40 F, and DA 40 NG airplanes (including Model DA 40 NG
    airplanes that have been converted from the Model DA 40 D). AD 2020-14-
    06 required replacing affected parts, inspecting the fuel tank
    chambers, and removing rubber material that has detached from the fuel
    tank connection hoses. AD 2020-14-06 also prohibited installing an
    affected part on any airplane. The FAA issued AD 2020-14-06 to detect
    and prevent fuel starvation and reduced control of the airplane. AD
    2020-14-16 was prompted by Transport Canada CF-2019-39, dated October
    31, 2019 (Transport Canada AD CF-2019-39) issued by Transport Canada,
    which is the aviation authority for Canada.
        The NPRM was published in the Federal Register on December 23, 2025
    (90 FR 60031). The NPRM was prompted by Transport Canada AD CF-2019-
    39R1, dated May 21, 2025 (also referred to as the MCAI), which
    superseded Transport Canada AD CF-2019-39 based on reports of
    additional affected parts installed during production on DAI Model DA
    40 NG airplanes. As a result, the manufacturer published updated
    service material for the Model DA 40 NG. The MCAI also continues to
    require replacing affected fuel tank connection hoses, inspecting the
    fuel tank chambers, and removing rubber material that has detached from
    the fuel tank connection hoses.
        In the NPRM, the FAA proposed to require the same actions as AD
    2020-14-06 and to require updated service material to be used for the
    Model DA 40 NG airplanes.
        You may examine the MCAI in the AD docket at regulations.gov under
    Docket No. FAA-2025-5397.

    Discussion of Final Airworthiness Directive

    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, and any other changes described previously,
    this AD is adopted as proposed in the NPRM. None of the changes will
    increase the economic burden on any operator.

    Material Incorporated by Reference Under 1 CFR Part 51

        The FAA reviewed Diamond Aircraft Industries Mandatory Service
    Bulletin

    [[Page 14644]]

    No. MSB 40NG-064 Rev. 3, dated January 23, 2025, which specifies
    procedures for replacing affected parts, inspecting the fuel tank
    chambers, and removing rubber material that has detached from the
    hoses. This material also specifies the service centers from which the
    affected parts could have been obtained and the serial numbers for
    additional DAI Model DA 40 NG airplanes that are affected by the unsafe
    condition and were not in the previous version of the material.
        This AD also requires the following Diamond Aircraft Industries
    Mandatory Service Bulletins, which the Director of the Federal Register
    approved for incorporation by reference as of August 4, 2020 (85 FR
    42687, July 15, 2020):
         Diamond Aircraft Industries Mandatory Service Bulletin No.
    MSB 40-087, Revision 3, dated November 5, 2019.
         Diamond Aircraft Industries Mandatory Service Bulletin No.
    MSB F4-037, Revision 3, dated November 5, 2019.
         Diamond Aircraft Industries Work Instruction WI-MSB 40-
    087, Revision 0, dated July 1, 2019.
         Diamond Aircraft Industries Work Instruction WI-MSB F4-
    037, Revision 0, dated July 1, 2019.
         Diamond Aircraft Industries Work Instruction WI-MSB 40 NG-
    064, Revision 0, dated July 1, 2019.
        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.

    Costs of Compliance

        The FAA estimates that this AD affects 987 airplanes 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
    ----------------------------------------------------------------------------------------------------------------
    Inspect the fuel tank chambers...........  1 work-hour x $85 per hour            $0          $85         $83,895
                                                = $85.
    Remove detached rubber material..........  5 work hours x $85 per hour            0          425         419,475
                                                = $425.
    Replace fuel tank connection hose........  10 work hours x $85 per              383        1,233       1,216,971
                                                hour = $850.
    ----------------------------------------------------------------------------------------------------------------

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

    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

        The FAA has determined that 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.

    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:
    0
    a. Removing Airworthiness Directive 2020-14-06, Amendment 39-21160 (85
    FR 42687, July 15, 2020); and
    0
    b. Adding the following new airworthiness directive:

    2026-06-03 Diamond Aircraft Industries Inc: Amendment 39-23291;
    Docket No. FAA-2025-5397; Project Identifier MCAI-2025-00972-A.

    (a) Effective Date

        This airworthiness directive (AD) is effective April 30, 2026.

    (b) Affected ADs

        This AD replaces AD 2020-14-06, Amendment 39-21160 (85 FR 42687,
    July 15, 2020); (AD 2020-14-06).

    (c) Applicability

        This AD applies to all Diamond Aircraft Industries Inc. Model DA
    40, DA 40 F, and DA 40 NG airplanes (including Model DA 40 NG
    airplanes that have been converted from the Model DA 40 D),
    certificated in any category.

    (d) Subject

        Joint Aircraft System Component (JASC) Code 1410, Hoses and
    tubes.

    (e) Unsafe Condition

        This AD was prompted by reports of fuel tank connection hose
    deterioration and reports of affected parts that were installed
    during production on Model DA 40 NG airplanes. The FAA is issuing
    this AD to detect and address such deterioration, which, if not
    corrected, could result in contamination of the fuel system and
    restriction of fuel flow and could lead to fuel starvation and
    reduced control of the airplane.

    (f) Compliance

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

    (g) Definitions

        For the purpose of this AD, ``affected part'' means a fuel tank
    connection hose that meets the criteria in paragraph (g)(1), (2), or
    (3) of this AD.
        (1) Part number (P/N) D4D-2817-10-70 installed during production
    on Model DA 40 NG airplanes with a serial number listed in

    [[Page 14645]]

    Section I.2. of Diamond Aircraft Industries Mandatory Service
    Bulletin MSB 40NG-064 Rev. 3, dated January 23, 2025; or
        (2) P/N D4D-2817-10-70 or BENOLPRESS (no part number) purchased
    between July 13, 2017, and February 26, 2019, as listed in Section
    I.11 of Diamond Aircraft Industries Mandatory Service Bulletin No.
    MSB 40-087, Revision 3, dated November 5, 2019; Diamond Aircraft
    Industries Mandatory Service Bulletin No. MSB 40NG-064 Rev. 3, dated
    January 23, 2025; or Diamond Aircraft Industries Mandatory Service
    Bulletin No. MSB F4-037, Revision 3, dated November 5, 2019; or
        (3) P/N D4D-2817-10-70 installed as a replacement part on or
    after July 13, 2017, if it is unknown whether the part meets the
    criteria in paragraph (g)(1) or (2) of this AD.

    (h) Required Actions

        Within 100 hours time-in-service or within 2 months, whichever
    occurs first after the effective date of this AD, replace each
    affected part as defined in paragraph (g) of this AD, inspect the
    main fuel tank chambers, and remove any detached rubber material in
    accordance with Sections III.1 and III.2 of the Instructions in
    Diamond Aircraft Industries Work Instruction WI-MSB 40-087, Revision
    0, dated July 1, 2019; Diamond Aircraft Industries Work Instruction
    WI-MSB F4-037, Revision 0, dated July 1, 2019; or Diamond Aircraft
    Industries Work Instruction WI-MSB 40NG-064, Revision 0, dated July
    1, 2019; as applicable to your model airplane.

    (i) No Reporting Requirement

        Although the service material specifies to submit information to
    the manufacturer, this AD does not require that action.

    (j) Installation Prohibition

        As of the effective date of this AD, do not install an affected
    part, as defined in paragraph (g) of this AD, on any airplane.

    (k) Credit for Previous Actions

        This paragraph provides credit for the actions required by
    paragraph (h) of this AD if those actions were performed before the
    effective date of this AD, and the affected part for the Model DA 40
    NG airplane was identified using Diamond Aircraft Industries
    Mandatory Service Bulletin No. MSB 40NG-064, Revision 2, dated
    August 29, 2019.

    (l) Alternative Methods of Compliance (AMOCs)

        (1) 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 (m)(1) of
    this AD and email it to: AMOC@faa.gov.
        (2) 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.

    (m) Additional Information

        (1) For more information about this AD, contact Joseph
    Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite
    410, Westbury, NY 11590; phone: (516) 228-7366; email:
    joseph.catanzaro@faa.gov.
        (2) Material identified in this AD that is not incorporated by
    reference is available at the address specified in paragraph (n)(5)
    of this AD.

    (n) 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 the AD specifies otherwise.
        (3) The following material was approved for IBR on April 30,
    2026.
        (i) Diamond Aircraft Industries Mandatory Service Bulletin MSB
    40NG-064 Rev. 3, dated January 23, 2025.
        (ii) [Reserved]
        (4) The following material was approved for IBR on August 4,
    2020 (85 FR 42687, July 15, 2020).
        (i) Diamond Aircraft Industries Mandatory Service Bulletin No.
    MSB 40-087, Revision 3, dated November 5, 2019.
        (ii) Diamond Aircraft Industries Mandatory Service Bulletin No.
    MSB F4-037, Revision 3, dated November 5, 2019.
        (iii) Diamond Aircraft Industries Work Instruction WI-MSB 40-
    087, Revision 0, dated July 1, 2019.
        (iv) Diamond Aircraft Industries Work Instruction WI-MSB 40NG-
    064, Revision 0, dated July 1, 2019.
        (v) Diamond Aircraft Industries Work Instruction WI-MSB F4-037,
    Revision 0, dated July 1, 2019.
        (5) For Diamond Aircraft Industries material identified in this
    AD, contact Diamond Aircraft Industries Inc., 1560 Crumlin Sideroad,
    London, Ontario, Canada, N5V 1S2; phone: (519) 457-4041, fax: (519)
    457-4045; email: support-canada@diamondaircraft.com.
        (6) You may view this material at the FAA, Airworthiness
    Products Section, Operational Safety Branch, 901 Locust, Kansas
    City, MO 64106. For information on the availability of this material
    at the FAA, call (817) 222-5110.
        (7) 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 March 18, 2026.
    Steven W. Thompson,
    Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
    Certification Service.
    [FR Doc. 2026-05883 Filed 3-25-26; 8:45 am]
    BILLING CODE 4910-13-P