SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under ADDRESSES . Include “Docket No. FAA-2026-13798; Project Identifier MCAI-2026-00797-A” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, 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 the proposal 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 NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to Doug Rudolph, 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 FAA issued AD 2025-20-02, Amendment 39-23155 (90 FR 53208, November 25, 2025) (AD 2025-20-02), for all Pilatus Model PC-24 airplanes. AD 2025-20-02 was prompted by EASA AD 2024-0240, dated December 10, 2024 (EASA AD 2024-0240), issued by EASA, which is the Technical Agent for the Member States of the European Union. EASA issued EASA AD 2024-0240, dated December 10, 2024 (EASA AD 2024-0240), to address an unsafe condition identified as an occurrence of an inaccurate flight director calculation on approach. The MCAI stated that heading splits can cause errors in the flight director calculations, which results in lateral offsets to the desired approach course. The FAA issued AD 2025-20-02 as an interim action to address the unsafe condition described above.

AD 2025-20-02 requires incorporating a temporary revision into the existing AFM for the affected ( printed page 69507) airplanes, which revises the Abnormal Procedures Section.

Actions Since AD 2025-20-02 Was Issued

Since the FAA issued AD 2025-20-02, EASA superseded EASA AD 2024-0240 and issued EASA AD 2026-0149, dated July 28, 2026 (EASA AD 2026-0149) (also referred to as the MCAI). The MCAI states that, since EASA AD 2024-0240 was issued, Pilatus developed Primus APEX DFZ Build 6.0 software and issued service information providing instructions for installing the software. Pilatus also issued AFM-TR 02371-081, which provides operational instructions applicable after installation of Primus APEX DFZ Build 6.0 software.

The MCAI retains the requirement to incorporate the existing AFM instructions and adds requirements to install the updated software and, after installation of the updated software, incorporate the revised operational instructions into the AFM. The FAA is issuing this AD to prevent heading splits that can cause errors in flight director calculations, resulting in lateral offsets to the desired approach course. The unsafe condition, if not addressed, could result in an increased pilot workload and a reduction of the safety margins.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-13798.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed EASA AD 2026-0149, which specifies procedures for installing Primus APEX DFZ Build 6.0 software and, after installation of the software, incorporating Pilatus PC-24 AFM-TR 02371-081 into the AFM. AFM-TR 02371-081 provides operational instructions applicable after installation of Primus APEX DFZ Build 6.0 software. EASA AD 2026-0149 also allows incorporation of a later AFM revision that includes the applicable AFM instructions.

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 (CAA) 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 NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified in the MCAI, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this proposed AD.

The owner or operator (pilot) holding at least a private pilot certificate may revise the existing AFM for the airplane as specified in paragraphs (h)(3) and (4) of this proposed AD and must enter compliance with the applicable paragraph of this proposed AD into the airplane maintenance records in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The pilot may perform these actions because they only involve revising the AFM. These actions could be performed equally well by a pilot or a mechanic. This is an exception to the FAA's standard maintenance regulations.

Explanation of Required Compliance Information

In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some CAA ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to incorporate EASA AD 2026-0149 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2026-0149 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Using common terms that are the same as the heading of a particular section in EASA AD 2026-0149 does not mean that operators need comply only with that section. For example, where the AD requirement refers to “all required actions and compliance times,” compliance with this AD requirement is not limited to the section titled “Required Action(s) and Compliance Time(s)” in EASA AD 2026-0149. Material required by EASA AD 2026-0149 for compliance will be available at regulations.gov under Docket No FAA-2026-13798 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 150 airplanes of U.S. registry.

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

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some of the costs of this proposed 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. ( printed page 69508) 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 determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 the proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

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

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

The Proposed Amendment

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

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

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

2. The FAA amends § 39.13 by:

a. Removing Airworthiness Directive 2025-20-02, Amendment 39-23155 ( 90 FR 53208, November 25, 2025); and

b. Adding the following new airworthiness directive:

Pilatus Aircraft Ltd: Docket No. FAA-2026-13798; Project Identifier MCAI-2026-00797-A.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by December 21, 2026.

(b) Affected ADs

This AD replaces AD 2025-20-02, Amendment 39-23155 (90 FR 53208, November 25, 2025).

(c) Applicability

This AD applies to Pilatus Aircraft Ltd. Model PC-24 airplanes, certificated in any category, as identified in European Union Aviation Safety Agency AD 2026-0149, dated July 28, 2026 (EASA AD 2026-0149).

(d) Subject

Joint Aircraft System Component (JASC) Code 3400, Navigation System.

(e) Unsafe Condition

This AD was prompted by an occurrence of an inaccurate flight director calculation on approach. The FAA is issuing this AD to prevent heading splits that can cause errors in flight director calculations, resulting in lateral offsets to the desired approach course. The unsafe condition, if not addressed, could result in an increased pilot workload and a reduction of the safety margins.

(f) Compliance

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

(g) Required Actions

(1) Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, EASA AD 2026-0149.

(2) The AFM revisions required by this AD may be performed by the owner or operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD 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.

(h) Exceptions to EASA AD 2026-0149

(1) Where EASA AD 2026-0149 refers to its effective date, this AD requires using the effective date of this AD.

(2) Where EASA AD 2026-0149 refers to December 24, 2024 (the effective date of EASA AD 2024-0240), this AD requires using December 30, 2025 (the effective date of AD 2025-20-02).

(3) Where paragraph (1) of EASA AD 2026-0149 specifies to “implement the instructions of AFM-TR 02371-075”, this AD requires replacing that text with “revise the Abnormal Procedures Section of the existing AFM for your airplane by inserting a copy of AFM-TR 02371-075”.

(4) Where paragraph (5) of EASA AD 2026-0149 specifies to “implement the instructions of AFM-TR 02371-081”, this AD requires replacing that text with “revise the Normal Procedures Section of the existing AFM for your airplane by inserting a copy of AFM-TR 02371-081”.

(5) This AD does not adopt the “Remarks” section of EASA AD 2026-0149.

(i) No Reporting Requirement

Although the material referenced in EASA AD 2026-0149 specifies to submit certain information to the manufacturer, this AD does not include that requirement.

(j) 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 (k) of this AD and email 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.

(k) Additional Information

For more information about this AD, contact Doug Rudolph, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (816) 329-4059; email: doug.rudolph@faa.gov.

(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) European Union Aviation Safety Agency (EASA) AD 2026-0149, dated July 28, 2026.

(ii) [Reserved]

(3) For EASA material identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999 000; email: ADs@easa.europa.eu; website: easa.europa.eu. You may find this EASA AD on the EASA website at ad.easa.europa.eu.

(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 fr.inspection@nara.gov.

91 FR 69506