Airworthiness Directives; Pilatus Aircraft Ltd. Airplanes

[Federal Register Volume 90, Number 104 (Monday, June 2, 2025)]
[Rules and Regulations]
[Pages 23271-23273]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-09885]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-0208; Project Identifier MCAI-2024-00555-A; 
Amendment 39-23044; AD 2025-10-10]
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 superseding Airworthiness Directive (AD) 2023-26-
05, which applied to certain Pilatus Aircraft Ltd. (Pilatus) Model PC-
24 airplanes. AD 2023-26-05 required periodic replacement of affected 
titanium threaded bolts, a one-time inspection of the rudder mass 
balance arm and other elements of the rudder trim tab installation for 
correct attachment, damage (gouges), cracks, deformation, surface 
finish, and corrosion on any surrounding parts and, depending on 
findings, the accomplishment of applicable corrective actions. Since 
the FAA issued AD 2023-26-05, it was determined that some batches of 
titanium bolts had variations in the microstructure that could affect 
the fatigue characteristics. This AD requires replacing affected short 
rudder-trim control rod assemblies with serviceable rudder-trim control 
rod assemblies having threaded steel bolts and prohibits the 
installation of affected parts. The FAA is issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective July 7, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of July 7, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2025-0208; 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

[[Page 23272]]

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, 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-2025-0208.

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 to supersede AD 2023-26-05, Amendment 39-22648 (88 FR 
90091, December 29, 2023), (AD 2023-26-05). AD 2023-26-05 applied to 
certain Pilatus Model PC-24 airplanes. AD 2023-26-05 required periodic 
replacement of affected titanium threaded bolts, a one-time inspection 
of the rudder mass balance arm and other elements of the rudder trim 
tab installation for correct attachment, damage (gouges), cracks, 
deformation, surface finish, and corrosion on any surrounding parts 
and, depending on findings, accomplishment of applicable corrective 
actions. The FAA issued AD 2023-26-05 to address certain batches of 
titanium bolts having variations in the microstructure that could 
affect the fatigue characteristics.
    If not corrected, the unsafe condition could lead to failure of the 
titanium threaded bolts with consequent damage to the rudder and rudder 
trim tab, which could result in loss of rudder control and reduced or 
loss of control of the airplane. EASA Emergency AD 2023-0219-E 
identified the affected parts as titanium threaded bolts, part number 
(P/N) 527.20.24.489, installed on the rudder trim tab short control 
rods.
    The NPRM was published in the Federal Register on February 24, 2025 
(90 FR 10467). The NPRM was prompted by AD 2024-0181R1, dated September 
24, 2024 (EASA AD 2024-0181R1) (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 titanium threaded bolts at the 
forward end of the short rudder trim tab actuating rods may be subject 
to unexpectedly high oscillating loads due to aerodynamic forces acting 
on the rudder trim tab. This condition could lead to failure of the 
bolt and consequent damage to the rudder and rudder trim tab, possibly 
resulting in loss of rudder control and reduced or loss of control of 
the airplane. The MCAI also states that variations in the structures of 
the replacement titanium bolt batches could affect their fatigue 
characteristics.
    EASA AD 2024-0181R1 retains the actions of EASA Emergency AD 2023-
0219-E. EASA AD 2024-0181R1 amends paragraph (1) of EASA Emergency AD 
2023-0219-E to clarify the required action and to modify its compliance 
time.
    In the NPRM, the FAA proposed to require replacing affected short 
rudder-trim control rod assemblies with serviceable rudder-trim control 
rod assemblies having threaded steel bolts and would prohibit the 
installation of affected parts, as specified in EASA AD 2024-0181R1. 
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-2025-0208.

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. This AD is 
adopted as proposed in the NPRM.

Material Incorporated by Reference Under 1 CFR Part 51

    The FAA reviewed EASA AD 2024-0181R1, which specifies replacing an 
affected part, short rudder-trim control rod assembly P/N 
527.20.24.464, which has threaded titanium bolts, with a serviceable 
part, short rudder-trim control rod assembly P/N 527.20.24.069, which 
has threaded steel bolts. EASA AD 2024-0181R1 prohibits the 
installation of an affected part on any airplane.
    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 120 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
----------------------------------------------------------------------------------------------------------------
Replacement of affected rudder-trim control  8 work-hours x $85 per hour =        $288        $968      $116,160
 rod assemblies.                              $680.
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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 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

[[Page 23273]]

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 2023-26-05, Amendment 39-22648 (88 
FR 90091, December 29, 2023); and
0
b. Adding the following new airworthiness directive:

2025-10-10 Pilatus Aircraft Ltd.: Amendment 39-23044; Docket No. 
FAA-2025-0208; Project Identifier MCAI-2024-00555-A.

(a) Effective Date

    This airworthiness directive (AD) is effective July 7, 2025.

(b) Affected ADs

    This AD replaces AD 2023-26-05, Amendment 39-22648 (88 FR 90091, 
December 29, 2023) (AD 2023-26-05).

(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 (EASA) AD 2024-0181R1, dated September 24, 
2024 (EASA AD 2024-0181R1).

(d) Subject

    Joint Aircraft System Component (JASC) Code 2721, Rudder Tab 
Control System.

(e) Unsafe Condition

    This AD was prompted by a determination that the titanium 
threaded bolts installed at the forward end of the short rudder trim 
tab actuating rods could be subject to unexpectedly high oscillating 
loads due to aerodynamic forces acting on the rudder trim tab. The 
FAA is issuing this AD to address the unsafe condition. The unsafe 
condition, if not addressed, could result in failure of the titanium 
threaded bolts with consequent damage to the rudder and rudder trim 
tab, which could result in loss of rudder control and reduced or 
loss of control of the airplane.

(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 2024-0181R1.

(h) Exceptions to EASA AD 2024-0181R1

    (1) Where EASA AD 2024-0181R1 refers to its effective date, this 
AD requires using the effective date of this AD.
    (2) Where EASA AD 2024-0181R1 requires compliance in terms of 
flight hours, this AD requires using hours time-in-service.
    (3) Where paragraph (1) of EASA AD 2024-0181R1 specifies ``as 
required by EASA AD 2023-0219-E'', this AD requires replacing that 
text with ``as required by AD 2023-26-05.''
    (4) Where the material identified in EASA AD 2024-0181R1 
specifies to ``discard'' certain parts, this AD requires replacing 
that text with ``remove from service.''
    (5) This AD does not adopt the Remarks section of EASA AD 2024-
0181R1.

(i) 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, mail 
it to the address identified in paragraph (j) of this AD and email 
to: [email protected]. If mailing information, also submit information by 
email. 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. Only Global AMOC letter 731-24-00656, dated July 
24, 2024, approved for AD 2023-26-05, is approved as an AMOC for the 
corresponding provisions of this AD.

(j) 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].

(k) 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 2024-0181R1, 
dated September 24, 2024.
    (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 Emergency 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, 901 Locust, Kansas 
City, MO 64106. 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 May 22, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2025-09885 Filed 5-30-25; 8:45 am]
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