DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0507; Project Identifier 2018-SW-117-AD]
RIN 2120-AA64

Airworthiness Directives; Leonardo S.p.a. 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 Leonardo S.p.a. Model AB139 and Model AW139 helicopters.
This proposed AD was prompted by a report that, during a post-flight
inspection of an in-service helicopter, a tail rotor slider assembly
was found fractured, and the bushing and the actuator rod in the tail
rotor servo were partially damaged. This proposed AD would require an
inspection of the tail rotor slider assembly for corrosion and signs of
circumferential refinishing and, depending on the findings, replacement
of the tail rotor slider assembly with a serviceable part or repetitive
inspections of the of the tail rotor slider assembly for corrosion and
signs of circumferential refinishing, as specified in a European
Aviation Safety Agency (now European Union Aviation Safety Agency)
(EASA) AD, which is proposed for incorporation by reference (IBR). 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 August 9,
2021.

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 https://www.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.

For EASA material that is proposed for IBR in this AD, contact
EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221
8999 000; email ADs@easa.europa.eu; internet www.easa.europa.eu. You
may find this IBR material on the EASA website at https://ad.easa.europa.
eu. You may view the EASA 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 the
EASA material at the FAA, call (817) 222-5110. The EASA material is
also available at https://www.regulations.gov by searching for and
locating Docket No. FAA-2021-0507.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0507; 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 EASA AD,
any comments received, and other information. The street address for
Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Andrea Jimenez, Aerospace Engineer,
COS Program Management Section, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY
11590; telephone (516) 228-7330; email andrea.jimenez@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-2021-0507; Project Identifier
2018-SW-117-AD" 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
https://www.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
Andrea Jimenez, Aerospace Engineer, COS Program Management Section,
Operational Safety Branch, Compliance & Airworthiness Division, FAA,
1600 Stewart Ave., Suite 410, Westbury, NY 11590; telephone (516) 228-
7330; email andrea.jimenez@faa.gov. Any commentary that the FAA
receives that 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 2018-0292, dated December 28, 2018
(EASA AD 2018-0292) to correct an unsafe condition for Leonardo S.p.A.
(formerly Finmeccanica S.p.A, AgustaWestland S.p.A., Agusta S.p.A.;
AgustaWestland Philadelphia Corporation, formerly Agusta Aerospace
Corporation) Model AB139 and Model AW139 helicopters, all serial
numbers. Although EASA AD 2018-0292 applies to all Model AB139 and
Model AW139 helicopters, this proposed AD would apply to helicopters
with an affected part installed instead.

This proposed AD was prompted by a report that, during a post-
flight inspection of an in-service helicopter, a tail rotor slider
assembly was found fractured, and the bushing and the actuator rod in
the tail rotor servo were partially damaged. The subsequent
investigation revealed that the failure was due to fatigue, initiated
from corroded areas (corrosion craters) on the surface of the tail
rotor slider assembly characterized by signs of circumferential
refinishing. The corrosion craters originated along finishing signs
consistent with low grit sanding operations, which can remove the
passivation corrosion protection from the tail rotor slider assembly.
Sanding is a maintenance activity that is not included in the
maintenance manual for Leonardo S.p.a. Model AB139 and AW139
helicopters and is not allowed on in-service helicopters. The FAA is
proposing this AD to address corrosion in the tail rotor slider
assembly caused by improper refinishing (characterized by signs of
circumferential refinishing consistent with sanding). The unsafe
condition, if not addressed, could result in fatigue cracks and
fracture of the tail rotor slider assembly, resulting in failure of the
tail rotor controls and consequent loss of yaw control of the
helicopter. See EASA AD 2018-0292 for additional background
information.

FAA's Determination and Requirements of This Proposed AD

These helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to the FAA's bilateral
agreement with the European Union, EASA has notified the FAA about the
unsafe condition described in its AD. The FAA is proposing this AD
after evaluating all known relevant information and determining that
the unsafe condition described previously is likely to exist or develop
on other helicopters of these same type designs.

Related Service Information Under 1 CFR Part 51

EASA AD 2018-0292 requires a detailed inspection of the tail rotor
slide assembly for corrosion and signs of circumferential refinishing
and, depending on the findings, applicable corrective actions. If there
is any evidence of corrosion craters the corrective action is
replacement of the affected part with a serviceable part. If there is
any evidence of surface imperfections caused by circumferential
refinishing but no evidence of corrosion, the corrective action is
repetitive inspections of the tail rotor slide assembly for corrosion
and signs of circumferential refinishing. Replacement of an affected
part with a serviceable part is terminating action for the repetitive
inspections.

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 EASA AD 2018-0292, 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 certain civil aviation
authority (CAA) ADs as the primary source of information for compliance
with requirements for corresponding FAA ADs. The FAA has been
coordinating this process with manufacturers and CAAs. As a result,
EASA AD 2018-0292 will be incorporated by reference in the FAA final
rule. This proposed AD would, therefore, require compliance with EASA
AD 2018-0292 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 2018-0292 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 2018-
0292. Service information specified in EASA AD 2018-0292 that is
required for compliance with it will be available at https://www.
regulations.gov by searching for and locating Docket No. FAA-2021-
0507 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 129 helicopters of U.S. Registry. The FAA estimates the
following costs to comply with this proposed AD.

Estimated Costs

The FAA estimates the following costs to do any necessary
replacement that would be required based on the results of the proposed
inspection. The agency has no way of determining the number of aircraft
that might need this replacement:

On-Condition Costs

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some or all 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

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: