DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2009; Project Identifier AD-2023-01286-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, Model 369 (Army YOH-6A), 369A (Army
OH-6A), 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and
600N helicopters. This proposed AD was prompted by multiple reports of
cracked tail rotor (T/R) pedal support brackets. This proposed AD would
require repetitively inspecting certain part-numbered T/R pedal support
brackets and depending on the results, replacing the T/R pedal support
bracket or refinishing any exposed areas. This proposed AD would also
prohibit installing certain part-numbered T/R pedal support brackets.
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 October 15,
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-2024-2009; 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.
Material Incorporated by Reference:
For MD Helicopters material identified in this AD, contact
MD Helicopters, LLC, 4555 East McDowell Road, Mesa, AZ 85215-9734;
phone: (480) 346-6300; email: info@mdhelicopters.com; website:
mdhelicopters.com/contact/.
You may view this material at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321,
Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110.

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 the ADDRESSES section. Include ``Docket No. FAA-2024-2009;
Project Identifier AD-2023-01286-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 forced emergency landing involving
an MD Helicopters, LLC, Model 369D helicopter in Canada in 2022 that
was caused by a cracked magnesium cast T/R pedal support bracket having
part number (P/N) 369A7505-8. There have been 16 other reports of
cracked magnesium cast T/R pedal support brackets having P/Ns 369A7505-
7, 369A7505-8, 369A7505-14, or 369A7505-15 discovered during
maintenance in the last 30 years. Material deficiencies associated with
magnesium cast parts, as well as fatigue damage and successive in-
flight loading have been determined to cause the parts to fail.
Additionally, magnesium cast parts are susceptible to corrosion where
insufficient protective coatings have shown to wear and deteriorate.
All reported failures of this part have been the magnesium cast
369A7505 configuration. The aluminum cast T/R pedal support bracket P/N
369N2640 have no reported failures but are still subject to the
inspection requirements of this AD. The natural corrosion advantages of
aluminum, as well as the coating requirements of its anodization offer
greater mitigation of the risks of corrosion in comparison to the
magnesium cast part. Although superior to the magnesium cast part, the
alternate aluminum cast part could still be prone to these material
deficiencies of cast parts.
This proposed AD would require repetitively inspecting magnesium
cast T/R pedal support brackets having P/N 369A7505-7, 369A7505-8,
369A7505-14, or 369A7505-15, and aluminum cast T/R pedal support
brackets having P/N 369N2640-1 or 369N2640-2. These T/R pedal support
brackets may be installed on MD Helicopters, LLC, Model 369 (Army YOH-
6A), 369A (Army OH-6A), 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM,
369HS, 500N, and 600N helicopters. This proposed AD would also prohibit
installing magnesium cast T/R pedal support bracket P/N 369A7505-7,
369A7505-8, 369A7505-14, or 369A7505-15 on any helicopter. This
condition, if not addressed, could result in failure of the T/R pedal
support bracket, reduced controllability of the helicopter, 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 these same type designs.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed MD Helicopters Service Bulletin SB369D-231R2 for
Model 369D helicopters, SB369E-131R2 for Model 369E helicopters,
SB369F-122R2 for Model 369F and 369FF helicopters, SB369H-265R2 for
Model 369H, 369HE, 369HM, and 369HS helicopters, SB500N-068R2 for Model
500N helicopters, and SB600N-082R2 for Model 600N helicopters, each
dated November 1, 2023 (co-published as one document). For magnesium
cast T/R pedal support brackets P/N 369A7505-7, 369A7505-8, 369A7505-
14, and 369A7505-15, this material specifies procedures for visually
inspecting each T/R pedal support bracket for a crack and corrosion and
depending on the results, replacing the bracket with an aluminum cast
T/R pedal support bracket having P/N 369N2640-1 or 369N2640-2, or
refinishing any exposed areas. For magnesium cast T/R pedal support
brackets P/N 369A7505-7, 369A7505-8, 369A7505-14, and 369A7505-15, this
material also specifies procedures for fluorescent penetrant
inspecting, eddy current inspecting, or dye penetrant inspecting each
T/R pedal support bracket for a crack and depending on the results,
replacing the bracket with an aluminum cast T/R pedal support bracket
having P/N 369N2640-1 or 369N2640-2, or refinishing any exposed areas.
For the purposes of this proposed AD, MD Helicopters, LLC, Model 369
(Army YOH-6A) and 369A (Army OH-6A) helicopters would use MD
Helicopters Service Bulletin SB369D-231R2, dated November 1, 2023, to
accomplish certain actions required by this proposed AD.
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.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in the material already described except as discussed under
"Differences Between this Proposed AD and the Referenced Material."

Differences Between This Proposed AD and the Referenced Material

The related material applies to magnesium cast T/R pedal support
brackets having P/N 369A7505-7, 369A7505-8, 369A7505-14, or 369A7505-
15, whereas this proposed AD would apply to those part-numbered
magnesium cast T/R pedal support brackets and aluminum cast T/R pedal
support brackets having P/N 369N2640-1 or 369N2640-2. This proposed AD
would prohibit installing magnesium cast T/R pedal support brackets
having P/N 369A7505-7, 369A7505-8, 369A7505-14, or 369A7505-15, whereas
the related material does not.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 353 helicopters of U.S. registry. Labor rates are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates the
following costs to comply with this proposed AD.
Visually inspecting the T/R pedal support brackets (up to two T/R
pedal support brackets per helicopter) would take approximately 0.5
work-hour for an estimated cost of up to $43 per helicopter and $15,179
for the U.S. fleet per inspection cycle. Non-destructive inspection of
the T/R pedal support brackets would take approximately 2 work-hours
for an estimated cost of up to $170 per helicopter and $60,010 for the
U.S. fleet per inspection cycle.
If required, replacing a T/R pedal support bracket would take
approximately 8 work-hours and parts would cost approximately $2,075
for an estimated cost of $2,755 per T/R pedal support bracket.
Refinishing any exposed areas could vary significantly from helicopter
to helicopter. The FAA has no data to determine the costs to accomplish
this action or the number of helicopters that may require this action.

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: