Proposed Rule2025-20093
Airworthiness Directives; MD Helicopters, LLC Helicopters
Primary source
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Published
November 18, 2025
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2024-23-06, which applies to certain MD Helicopters, LLC (MDHI) Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. AD 2024-23-06 requires repetitively inspecting the torque tube assembly and roller bearings, and depending on the results, replacing parts or accomplishing additional inspections. Since the FAA issued AD 2024-23-06, it has been determined that additional torque tube assemblies are affected by this unsafe condition. This proposed AD would continue to require the actions of AD 2024-23-06 and would expand the applicability. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 90 Issue 220 (Tuesday, November 18, 2025)</title>
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[Federal Register Volume 90, Number 220 (Tuesday, November 18, 2025)]
[Proposed Rules]
[Pages 51596-51600]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-20093]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-3987; Project Identifier AD-2025-00017-R]
RIN 2120-AA64
Airworthiness Directives; MD Helicopters, LLC Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2024-23-06, which applies to certain MD Helicopters, LLC (MDHI) Model
369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N,
and 600N helicopters. AD 2024-23-06 requires repetitively inspecting
the torque tube assembly and roller bearings, and depending on the
results, replacing parts or accomplishing additional inspections. Since
the FAA issued AD 2024-23-06, it has been determined that additional
torque tube assemblies are affected by this unsafe condition. This
proposed AD would continue to require the actions of AD 2024-23-06 and
would expand the applicability. The FAA is proposing this AD to address
the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by January 2,
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-2025-3987; 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, any comments received, and other
information. The street address for Docket Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Eduardo Orozco-Duran, Aviation Safety
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone:
(562) 627-5264; email: <a href="/cdn-cgi/l/email-protection#751011001407111a5b1a071a0f161a58110007141b351314145b121a03"><span class="__cf_email__" data-cfemail="305554455142545f1e5f425f4a535f1d544542515e705651511e575f46">[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 the ADDRESSES section. Include ``Docket No. FAA-2025-3987;
Project Identifier AD-2025-00017-R'' 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 revise 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
Eduardo Orozco-Duran, Aviation Safety Engineer, FAA, 3960 Paramount
Boulevard, Lakewood,
[[Page 51597]]
CA 90712. 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 2024-23-06, Amendment 39-22885 (89 FR 91248,
November 19, 2024) (AD 2024-23-06), for MDHI Model 369, 369A, 369D,
369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N
helicopters with a pilot interconnecting cyclic torque tube (torque
tube) part number 369H7133-7 installed. AD 2024-23-06 was prompted by a
report of a seized and damaged roller bearing assembly in the torque
tube assembly of an MDHI Model MD369E helicopter. This damage did not
allow the torque tube to rotate as designed, which initiated a crack
and resulted in an emergency landing. The seized roller bearings were
due to rust compounded with dried grease residue and an aggressive
chemical environment. Because the seized roller bearings did not allow
the torque tube to rotate freely, additional torsional stresses
occurred on the torque tube, which caused a crack to initiate and
eventually propagate until the part failed and longitudinal control was
lost. Since certain MDHI Model 369, 369A, 369D, 369F, 369FF, 369H,
369HE, 369HM, 369HS, 500N, and 600N helicopters have the same torque
tube assembly installed, they are also affected by this unsafe
condition. AD 2024-23-06 requires repetitive visual inspections of the
torque tube for corrosion and cracks, repetitive visual inspections of
the roller bearings for corrosion and degradation, a repetitive
freedom-of-movement inspection of the torque tube assembly for binding
or ratcheting, and corrective or additional action as necessary. The
FAA issued AD 2024-23-06 to prevent failure of the torque tube assembly
which, if not addressed, could result in reduced controllability and
subsequent loss of control of the helicopter.
Actions Since AD 2024-23-06 Was Issued
Since AD 2024-23-06 was issued, the FAA received a report that
additional torque tube assemblies are affected by this unsafe condition
and should be included in the AD action. Due to this determination,
this proposed AD would expand the applicability to include all MD
Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE,
369HM, 369HS, 500N, and 600N helicopters regardless of the torque tube
part number.
FAA's Determination
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 retain all requirements of AD 2024-23-06 and
expand the applicability by removing the specific part number
requirement.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 353 helicopters 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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Visual inspection of torque tube and 1 work-hour x $85 per hour $0 $85 $30,005
roller bearings. = $85.
Inspection of torque tube for freedom-of- 0.75 work-hours x $85 per 0 64 22,592
movement. hour = $64.
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The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
proposed inspection. The agency has no way of determining the number of
helicopters that might need these replacements:
On-Condition Costs
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Cost per
Action Labor cost Parts cost product
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Replacement of torque tube.................... 6 work-hours x 85 per hour = $4,773 $5,283
$510.
Visual inspection of roller bearings.......... 0.25 work-hour x $85 per hour = 0 21
$21.
Replacement of roller bearing................. 6 work-hours x 85 per hour = 210 720
$510.
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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 that the proposed
regulation:
[[Page 51598]]
(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:
0
a. Removing Airworthiness Directive AD 2024-23-06, Amendment 39-22885
(89 FR 91248, November 19, 2024); and
0
b. Adding the following new airworthiness directive:
MD Helicopters, LLC: Docket No. FAA-2025-3987; Project Identifier
AD-2025-00017-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by January 2, 2026.
(b) Affected ADs
This AD replaces AD 2024-23-06, Amendment 39-22885 (89 FR 91248,
November 19, 2024) (AD 2024-23-06).
(c) Applicability
This AD applies to MD Helicopters, LLC Model 369, 369A, 369D,
369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N
helicopters, certificated in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 6700, Rotorcraft
Flight Control.
(e) Unsafe Condition
This AD was prompted by a report of a seized and damaged roller
bearing in the torque tube assembly. The FAA is issuing this AD to
prevent failure of the torque tube assembly. The unsafe condition,
if not addressed, could result in reduced controllability and
subsequent loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within 100 hours time-in-service (TIS) or within 12 months
after the effective date of this AD, whichever occurs first, and
thereafter at intervals not to exceed 100 hours TIS, accomplish the
actions required by paragraphs (g)(1)(i) and (ii) of this AD.
(i) Using a flashlight and mirror, visually inspect the torque
tube for corrosion and cracks. If there is any corrosion or a crack,
before further flight, remove the torque tube from service and
install an airworthy torque tube.
(ii) Visually inspect each roller bearing (number 5) as depicted
in Figure 1 to paragraph (g)(1) of this AD for corrosion and
degradation. If a roller bearing has any corrosion or degradation,
before further flight, remove the roller bearing from service and
install an airworthy roller bearing.
BILLING CODE 4910-13-P
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[GRAPHIC] [TIFF OMITTED] TP18NO25.034
BILLING CODE 4910-13-C
(2) Before the helicopter accumulates 3,000 total hours TIS or
within 100 hours TIS after the effective date of this AD, whichever
occurs later, and thereafter at intervals not to exceed 100 hours
TIS, perform a freedom-of-movement inspection on the torque tube
assembly by accomplishing the actions required by paragraphs
(g)(2)(i) through (v) of this AD.
(i) Disconnect the one-way lock (number 6) of the torque tube by
removing the cotter pin (number 7), nut (number 8), bolt (number 9),
washers (number 10), and slotted bushing (number 11) from the torque
tube assembly as depicted in Figure 1 to paragraph (g)(1) of this
AD.
(ii) Loosen the longitudinal cyclic friction knob (number 12 or
13) of the torque tube assembly as depicted in Figure 1 to paragraph
(g)(1) of this AD.
(iii) While moving the cyclic control forward and aft to allow
the torque tube assembly to rotate through its full range of motion,
inspect the torque tube assembly for binding and ratcheting.
(A) If there is any binding or ratcheting as a result of the
action required by paragraph (g)(2)(iii) of this AD, before further
flight,
[[Page 51600]]
inspect each roller bearing (number 5) as depicted in Figure 1 to
paragraph (g)(1) of this AD for damage. For the purposes of this
inspection, damage may be indicated by corrosion, lack of
lubrication (dry exterior surface), or material degradation.
(B) If any roller bearing (number 5) as depicted in Figure 1 to
paragraph (g)(1) of this AD has any damage, before further flight,
remove the roller bearing from service and install an airworthy
roller bearing.
(iv) If there is not any binding or ratcheting as a result of
the action required by paragraph (g)(2)(iii) of this AD or after
accomplishing the action required by paragraph (g)(2)(iii)(B) of
this AD, as applicable, tighten the cyclic friction knob (number 12
or 13) as depicted in Figure 1 to paragraph (g)(1) of this AD.
(v) Connect the one-way lock (number 6) as depicted in Figure 1
to paragraph (g)(1) of this AD by accomplishing the actions required
by paragraphs (g)(2)(v)(A) and (B).
(A) Install the slotted bushing (number 11), washers (number
10), bolt (number 9), nut (number 8), and new (zero total hours TIS)
cotter pin (number 7) as depicted in Figure 1 to paragraph (g)(1) of
this AD.
(B) Ensure the edge of the slotted bushing (number 11) protrudes
0.010 to 0.080 inch (0.25 to 2.03 mm) above the surface of the
cyclic torque tube after the nut is tightened.
(h) Alternative Methods of Compliance (AMOCs)
(1) The Manager, West Certification 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 responsible Flight
Standards Office, as appropriate. If sending information directly to
the manager of the West Certification Branch, send it to the
attention of the person identified in paragraph (i) of this AD and
email to: <a href="/cdn-cgi/l/email-protection#1455595b57547275753a737b62"><span class="__cf_email__" data-cfemail="82c3cfcdc1c2e4e3e3ace5edf4">[email protected]</span></a>.
(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.
(i) Additional Information
For more information about this AD, contact Eduardo Orozco-
Duran, Aviation Safety Engineer, FAA, 3960 Paramount Boulevard,
Lakewood, CA 90712; phone: (562) 627-5264; email: <a href="/cdn-cgi/l/email-protection#593c3d2c382b3d3677362b36233a36743d2c2b3837193f3838773e362f"><span class="__cf_email__" data-cfemail="f49190819586909bda9b869b8e979bd9908186959ab4929595da939b82">[email protected]</span></a>.
(j) Material Incorporated by Reference
None.
Issued on October 22, 2025.
Christopher R. Parker,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-20093 Filed 11-17-25; 8:45 am]
BILLING CODE 4910-13-P
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