Proposed Rule2026-09576
Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes
Primary source
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Published
May 13, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) for certain Pilatus Aircraft Ltd. (Pilatus) Model PC-24 airplanes. This proposed 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 proposed AD would require modification of the airplane and replacement of the affected SSR with a serviceable part. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 92 (Wednesday, May 13, 2026)</title>
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[Federal Register Volume 91, Number 92 (Wednesday, May 13, 2026)]
[Proposed Rules]
[Pages 26949-26952]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-09576]
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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]
RIN 2120-AA64
Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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[[Page 26950]]
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Pilatus Aircraft Ltd. (Pilatus) Model PC-24 airplanes. This
proposed 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 proposed AD would require
modification of the airplane and replacement of the affected SSR with a
serviceable part. The FAA is proposing this AD to address the unsafe
condition on these products.
DATES: The FAA must receive comments on this NPRM by June 29, 2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> 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 <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 NPRM, 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:
<bullet> For European Union Aviation Safety Agency (EASA) material
identified in this NPRM, contact EASA, Konrad-Adenauer-Ufer 3, 50668
Cologne, Germany; phone: +49 221 8999 000; email: <a href="/cdn-cgi/l/email-protection#96d7d2e5d6f3f7e5f7b8f3e3e4f9e6f7b8f3e3"><span class="__cf_email__" data-cfemail="febfba8dbe9b9f8d9fd09b8b8c918e9fd09b8b">[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.
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#ed8982988ac39f988982819d85ad8b8c8cc38a829b"><span class="__cf_email__" data-cfemail="fc9893899bd28e899893908c94bc9a9d9dd29b938a">[email protected]</span></a>.
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-2026-4632; Project Identifier
MCAI-2026-00036-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
this 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
<a href="http://regulations.gov">regulations.gov</a>, 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
EASA, which is the Technical Agent for the Member States of the
European Union, has issued EASA AD 2026-0008, dated January 15, 2026
(EASA AD 2026-0008) (also referred to as the MCAI), to correct an
unsafe condition on certain Pilatus Model PC-24 airplanes. 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. To address this unsafe
condition, Pilatus issued service material to provide replacement
instructions for the affected SSR. This condition, if not addressed,
could lead to a failure of the emergency windshield heat function,
which could result in the loss of outside visibility.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-4632.
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.
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.
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
[[Page 26951]]
source of information for compliance with requirements for
corresponding FAA ADs. The FAA has been coordinating with manufacturers
and CAAs. As a result, the FAA proposes to incorporate EASA AD 2026-
0008 by reference in the FAA final rule. This proposed AD would,
therefore, require compliance with EASA AD 2026-0008 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 2026-0008 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 2026-0008. Material required by EASA AD 2026-0008
for compliance will be available at <a href="http://regulations.gov">regulations.gov</a> under Docket No.
FAA-2026-4632 after the FAA final rule is published.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 168 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost per Cost on U.S.
Action Labor cost Parts cost product operators
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Replace SSR and cables (125 airplanes) 5 work-hours x $85 per $1,032 $1,457 $182,125
hour = $425.
Replace SSR (43 airplanes)............ 2.5 work-hours x $85 per 32 244.50 10,513.50
hour = $212.50.
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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. 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 this 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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:
Pilatus Aircraft Ltd.: Docket No. FAA-2026-4632; Project Identifier
MCAI-2026-00036-A.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by June 29, 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
[[Page 26952]]
identified in paragraph (k) of this AD and email to: <a href="/cdn-cgi/l/email-protection#b5f4f8faf6f5d3d4d49bd2dac3"><span class="__cf_email__" data-cfemail="23626e6c60634542420d444c55">[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#90f4ffe5f7bee2e5f4fffce0f8d0f6f1f1bef7ffe6"><span class="__cf_email__" data-cfemail="91f5fee4f6bfe3e4f5fefde1f9d1f7f0f0bff6fee7">[email protected]</span></a>.
(l) 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.
(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#6021241320050113014e0515120f10014e0515"><span class="__cf_email__" data-cfemail="2160655261444052400f4454534e51400f4454">[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#aec8dc80c7c0dddecbcddac7c1c0eec0cfdccf80c9c1d8"><span class="__cf_email__" data-cfemail="1e786c3077706d6e7b7d6a7771705e707f6c7f30797168">[email protected]</span></a>.
Issued on May 6, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-09576 Filed 5-12-26; 8:45 am]
BILLING CODE 4910-13-P
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