Rule2026-18848
Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
September 15, 2026
Effective
October 20, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
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.
Full Text
<html>
<head>
<title>Federal Register, Volume 91 Issue 177 (Tuesday, September 15, 2026)</title>
</head>
<body><pre>
[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 [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-18848]
=======================================================================
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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 <a href="http://regulations.gov">regulations.gov</a> 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: <a href="/cdn-cgi/l/email-protection#ce8f8abd8eabafbdafe0abbbbca1beafe0abbb"><span class="__cf_email__" data-cfemail="4d0c093e0d282c3e2c6328383f223d2c632838">[email protected]</span></a>;
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 <a href="http://regulations.gov">regulations.gov</a> 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: <a href="/cdn-cgi/l/email-protection#85e1eaf0e2abf7f0e1eae9f5edc5e3e4e4abe2eaf3"><span class="__cf_email__" data-cfemail="60040f15074e1215040f0c1008200601014e070f16">[email protected]</span></a>.
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 <a href="http://regulations.gov">regulations.gov</a> 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: <a href="/cdn-cgi/l/email-protection#3574787a76755354541b525a43"><span class="__cf_email__" data-cfemail="4c0d01030f0c2a2d2d622b233a">[email protected]</span></a>. 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:
<a href="/cdn-cgi/l/email-protection#670308120049151203080b170f2701060649000811"><span class="__cf_email__" data-cfemail="1a7e756f7d34686f7e75766a725a7c7b7b347d756c">[email protected]</span></a>.
(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: <a href="/cdn-cgi/l/email-protection#c58481b685a0a4b6a4eba0b0b7aab5a4eba0b0"><span class="__cf_email__" data-cfemail="4504013605202436246b2030372a35246b2030">[email protected]</span></a>; 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 <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#a7c1d589cec9d4d7c2c4d3cec8c9e7c9c6d5c689c0c8d1"><span class="__cf_email__" data-cfemail="4422366a2d2a37342127302d2b2a042a2536256a232b32">[email protected]</span></a>.
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
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on September 15, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.