Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes

[Federal Register Volume 91, Number 177 (Tuesday, September 15, 2026)]
[Rules and Regulations]
[Pages 58364-58365]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-18848]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2026-4632; Project Identifier MCAI-2026-00036-A; 
Amendment 39-23455; AD 2026-17-11]
RIN 2120-AA64


Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Pilatus Aircraft Ltd. (Pilatus) Model PC-24 airplanes. This AD 
was prompted by a report that a solid-state relay (SSR) used in the 
left-hand (LH) windshield heating system may allow reverse current flow 
when in the OFF position. This AD requires modification of the airplane 
and replacement of the affected SSR with a serviceable part. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective October 20, 2026.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 20, 
2026.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2026-4632; 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:
    <bullet> For European Union Aviation Safety Agency (EASA) material 
identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 
Cologne, Germany; phone: +49 221 8999 000; email: [email protected]; 
website: easa.europa.eu. You may find this material on the EASA website 
at ad.easa.europa.eu.
    <bullet> 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-2026-4632.

FOR FURTHER INFORMATION CONTACT: Doug Rudolph, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
phone: (816) 329-4059; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain Pilatus Model 
PC-24 airplanes. The NPRM was published in the Federal Register on May 
13, 2026 (91 FR 26949). The NPRM was prompted by EASA AD 2026-0008, 
dated January 15, 2026 (EASA AD 2026-0008) (also referred to as the 
MCAI), issued by EASA, which is the Technical Agent for the Member 
States of the European Union. The MCAI states that the PC-24 windshield 
de-fog (low power windshield heating) is switched ON and OFF by an SSR. 
The affected part allows current to flow in reverse direction when it 
is in the OFF position. If, during a dual generator failure, the 
emergency windshield heat button is pushed, the batteries power the 
windshield heating. The batteries also power the electrical power 
distribution units (EPDU) 1 and 3 via the affected part. A reversal of 
current flow could cause the function of the emergency windshield heat 
to fail when required. As a result, the LH side window may not be fully 
de-fogged, and ice may not be cleared from either the LH or the right-
hand windshield.
    In the NPRM, the FAA proposed to require modification of the 
airplane and replacement of the affected SSR with a serviceable part. 
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-2026-4632.

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, 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 EASA AD 2026-0008, which specifies procedures for 
replacement of the LH windshield heating SSR with a serviceable part. 
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 168 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
----------------------------------------------------------------------------------------------------------------
Replace SSR and cables (125 airplanes)...  5 work-hours x $85 per hour       $1,032       $1,457        $182,125
                                            = $425.
Replace SSR (43 airplanes)...............  2.5 work-hours x $85 per              32       244.50       10,513.50
                                            hour = $212.50.
----------------------------------------------------------------------------------------------------------------


[[Page 58365]]

    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

    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 adding the following new airworthiness 
directive:

2026-17-11 Pilatus Aircraft Ltd.: Amendment 39-23455; Docket No. 
FAA-2026-4632; Project Identifier MCAI-2026-00036-A.

(a) Effective Date

    This airworthiness directive (AD) is effective October 20, 2026.

(b) Affected ADs

    None.

(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 2026-0008, dated January 15, 2026 (EASA AD 
2026-0008).

(d) Subject

    Joint Aircraft System Component (JASC) Code 3040, Windshield/
Door Rain/Ice Removal.

(e) Unsafe Condition

    This AD was prompted by a report that a solid-state relay used 
in the left-hand windshield heating system may allow reverse current 
flow when in the OFF position. The FAA is issuing this AD to prevent 
failure of the emergency windshield heat function. The unsafe 
condition, if not addressed, could result in a failure of the 
emergency windshield heat function, which could result in the loss 
of outside visibility.

(f) Compliance

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

(g) Required Actions

    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 2026-0008.

(h) Exceptions to EASA AD 2026-0008

    (1) Where EASA AD 2026-0008 refers to its effective date, this 
AD requires using the effective date of this AD.
    (2) This AD does not adopt the ``Remarks'' section of EASA AD 
2026-0008.

(i) No Reporting Requirement

    Although the material referenced in EASA AD 2026-0008 specifies 
to submit certain information, this AD does not include that 
requirement.

(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 responsible Flight Standards 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: 
[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) European Union Aviation Safety Agency (EASA) AD 2026-0008, 
dated January 15, 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: [email protected]; 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 [email protected].

    Issued on August 21, 2026.
Paul R. Bernado,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2026-18848 Filed 9-14-26; 8:45 am]
BILLING CODE 4910-13-P

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