DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0920; Project Identifier AD-2020-00662-R;
Amendment 39-21462; AD 2021-05-19]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft and Sikorsky Aircraft
Corporation Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
Sikorsky Aircraft Model S-61L, S-61N, S-61NM, and S-61R helicopters and
Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V
restricted category helicopters. This AD was prompted by the
manufacturer determining that there may be arm assemblies in service
that have accumulated 15,000 or more hours time-in-service (TIS), which
exceeds the service life limit for this component. This AD requires
reviewing the mixer unit component log card or equivalent record and,
depending on the number of hours TIS, calculating the remaining life of
the arm assembly or removing the arm assembly from service. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective May 7, 2021.

The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 7, 2021.

ADDRESSES: For service information identified in this final rule,
contact your local Sikorsky Field Representative or Sikorsky's Service
Engineering Group at Sikorsky Aircraft Corporation, Mailstop K100, 124
Quarry Road, Trumbull, CT 06611; telephone 1-800-946-4337 (1-800-
Winged-S); email wcs_cust_service_eng.gr-sik@lmco.com. Operators may
also log on to the Sikorsky 360 website at https://www.sikorsky360.com.
You may view this service information 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. It is also available at
https://www.regulations.gov by searching for and locating Docket No.
FAA-2020-0920.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0920; 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, 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.

FOR FURTHER INFORMATION CONTACT: Isabel L. Saltzman, Aerospace
Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA
01803; phone: (781) 238-7649; email: Isabel.l.saltzman@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Sikorsky Aircraft Model
S-61L, S-61N, S-61NM, and S-61R helicopters and Sikorsky Aircraft
Corporation Model S-61A, S-61D, S-61E, and S-61V restricted category
helicopters, with an arm assembly part number S6140-62614-009,
installed. The NPRM published in the Federal Register on October 26,
2020 (85 FR 67692). The FAA learned from Sikorsky Aircraft Corporation
that Sikorsky S-61 Helicopter Alert Service Bulletin (ASB) 61B General-
1, Revision No. Z, dated November 13, 2018, which is applicable to
Sikorsky Model S-61L, S-61N, S-61NM, and S-61R helicopters, failed to
include the life limit of the redesigned arm assembly. As a result,
Sikorsky Aircraft Corporation determined that there may be arm
assemblies in service with 15,000 or more hours TIS, which exceeds the
service life limit for this component. In the NPRM, the FAA proposed to
require reviewing the mixer unit component log card or equivalent
record and, depending on the hours TIS of the arm assembly, calculating
the remaining life of the arm assembly or removing the arm assembly
from service. The proposed actions are intended to prevent an arm
assembly from remaining in service beyond its life limit. This
condition, if not addressed, could result in reduced or loss of tail
rotor control and reduced control of the helicopter.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the NPRM or on the determination of
the costs.

Conclusion

The FAA reviewed the relevant data 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. Except for
the minor editorial changes of updating the contact information to
obtain service information identified in this final rule and updating
the contact information for the FAA, this AD is adopted as proposed in
the NPRM.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Sikorsky S-61 Helicopter ASB 61B40-11, Basic
Issue, dated March 2, 2020. This service information describes
procedures for a one-time inspection of the mixer unit component log
card to verify the arm assembly life limit and, if the life limit has
been exceeded, to replace the arm assembly for Sikorsky Model S-61L, S-
61N, and S-61NM helicopters.

This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in ADDRESSES.

Other Related Service Information

The FAA also reviewed Sikorsky S-61 Helicopter ASB 61B General-1,
Revision AA, dated February 24, 2020. This service information
summarizes and lists parts with mandatory retirement times and
inspections for Sikorsky Model S-61L, S-61N, and S-61NM helicopters.

Differences Between This AD and the Service Information

The ASB is effective only for Sikorsky Aircraft Model S-61L, S-61N,
and S-61NM helicopters. In addition to these helicopters, the
applicability of this AD also includes Sikorsky Aircraft Model S-61R
helicopters and Sikorsky Aircraft Corporation Model S-61A, S-61D, S-
61E, and S-61V restricted category helicopters. The FAA is expanding
the applicability to prevent the installation of arm assemblies that
have exceeded their life limits on helicopters with a similar type
design as those helicopters affected by the ASB.

Costs of Compliance

The FAA estimates that this AD affects 13 helicopters of U.S.
Registry. Labor rates are estimated at $85 per work-hour. Based on
these numbers, the FAA estimates that operators may incur the following
costs in order to comply with this AD.

Reviewing the mixer unit component log or equivalent record takes
about 1 work-hour for an estimated cost of $85 per helicopter and
$1,105 for the U.S. fleet. Adding the arm assembly entry and determine
the remaining life takes about 1 work-hour for an estimated cost of $85
per helicopter and $1,105 for the U.S. fleet. Replacing the arm
assembly takes about 9 work-hours and parts cost about $5,035, for an
estimated cost of $5,800 per arm assembly.

According to the manufacturer, some of the costs of this AD may be
covered under warranty, thereby reducing the cost impact on affected
individuals. The FAA does not control warranty coverage by the
manufacturer; accordingly, the FAA has included all costs in this cost
estimate.

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

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

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: