DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2011; Project Identifier AD-2023-01121-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 adopt a new airworthiness directive (AD)
for certain MD Helicopters, LLC (MDHI), Model 369, 369A, 369D, 369E,
369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters.
This proposed AD was prompted by a report of a seized and damaged
roller bearing in the pilot interconnecting cyclic torque tube (torque
tube) assembly. This proposed AD would require repetitively inspecting
the torque tube assembly for corrosion and cracks and the roller
bearings for corrosion and degradation. This proposed AD would also
require repetitively inspecting the torque tube assembly for freedom-
of-movement. Depending on the results, this proposed AD would require
replacing parts or accomplishing additional inspections. 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 September
23, 2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to regulations.gov. Follow
the instructions for submitting comments.
Fax: (202) 493-2251.
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.
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 regulations.gov under
Docket No. FAA-2024-2011; 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: eduardo.orozco-duran@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2024-2011; Project Identifier
AD-2023-01121-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 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
regulations.gov, 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, CA 90712; phone: (562) 627-5264; email:
eduardo.orozco-duran@faa.gov. 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 received 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, causing a
crack to initiate and eventually propagate until the part failed and
longitudinal control was lost. Since 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.
Accordingly, this proposed AD would require repetitively visually
inspecting the torque tube for corrosion and cracks, repetitively
visually inspecting the roller bearings for corrosion and degradation,
performing a repetitive freedom-of-movement inspection of the torque
tube assembly for binding or ratcheting, and corrective or additional
action as necessary. This condition, if not addressed, could result in
reduced controllability and subsequent loss of control of the
helicopter.

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 require repetitive visual inspections of the
torque tube assembly for cracks and corrosion and the roller bearings
for corrosion and degradation. This proposed AD would also require
repetitively inspecting the freedom of movement of the torque tube
assembly for binding and ratcheting. Depending on the results, this
proposed AD would require replacing parts or accomplishing additional
inspections.

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. Labor costs are
estimated at $85 per work-hour.
Visually inspecting the torque tube and roller bearings would take
approximately 1 work-hour for an estimated cost of $85 per helicopter
and $30,005 for the U.S. fleet, per inspection cycle. Inspecting the
torque tube assembly for freedom of movement would take approximately
0.75 work-hour for an estimated cost of $64 per helicopter and $22,595
for U.S fleet cost, per inspection cycle. If required, a more in-depth
inspection of the roller bearings would take approximately 0.25 work-
hour for an estimated cost of $21 per helicopter, per instance.
If required, replacing a torque tube would take approximately 6
work-hours and parts would cost approximately $4,773 for an estimated
cost of $5,283 per torque tube replacement. Replacing a roller bearing
would take approximately 6 work-hours and parts would cost
approximately $210 for an estimated cost of $720 per roller bearing
replacement.

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

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]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: