DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0625; Product Identifier 2016-SW-007-AD]
RIN 2120-AA64

Airworthiness Directives; Various Restricted Category 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 various restricted category helicopters, originally manufactured by
Sikorsky Aircraft Corporation (Sikorsky), Model EH-60A, HH-60L, S-70,
S-70A, S-70C, S-70C(M), S-70C(M1), and UH-60A. This proposed AD would
require initial and recurring inspections of the main rotor (M/R) blade
spindle cuff for a crack. This proposed AD is prompted by multiple
reports of a cracked M/R blade spindle cuff. The proposed actions are
intended to prevent an unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by August 24,
2020.

ADDRESSES: You may send comments by any of the following methods:

Federal eRulemaking Docket: Go to https://www.regulations.gov. Follow the
online instructions for sending your comments electronically.

Fax: 202-493-2251.

Mail: Send comments to the U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590-0001.

Hand Delivery: Deliver to the "Mail" address between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2020-
0625; 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 proposed AD, any comments
received, and other information. The street address for Docket
Operations is listed above. Comments will be available in the AD docket
shortly after receipt.

For service information identified in this proposed rule, contact
your local Sikorsky Field Representative or Sikorsky's Service
Engineering Group at Sikorsky Aircraft Corporation, 124 Quarry Road,
Trumbull, CT 06611; telephone 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 the
referenced service information at the FAA, Office of the Regional
Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort
Worth, TX 76177.

FOR FURTHER INFORMATION CONTACT: Kristopher Greer, Aerospace Engineer,
Boston ACO Branch, Compliance and Airworthiness Division, FAA, 1200
District Avenue, Burlington, Massachusetts 01803; telephone 781-238-
7799; email kristopher.greer@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to participate in this rulemaking by submitting
written comments, data, or views. The most helpful comments reference a
specific portion of the proposal, explain the reason for any
recommended change, and include supporting data. To ensure the docket
does not contain duplicate comments, commenters should send only one
copy of written comments, or if comments are filed electronically,
commenters should submit only one time.

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 file in the docket all comments received, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this proposed rulemaking. Before acting on this
proposal, the FAA will consider all comments received on or before the
closing date for comments. The FAA will consider comments filed after
the comment period has closed if it is possible to do so without
incurring expense or delay. The FAA may change this proposal in light
of the comments received.

Confidential Business Information

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 Kristopher Greer, Aerospace Engineer, Boston ACO
Branch, Compliance and Airworthiness Division, FAA, 1200 District
Avenue, Burlington, Massachusetts 01803; telephone 781-238-7799; email
kristopher.greer@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.

Discussion

The FAA proposes to adopt a new AD for various restricted category
helicopters, originally manufactured by Sikorsky, Model EH-60A, HH-60L,
S-70, S-70A, S-70C, S-70C(M), S-70C(M1), and UH-60A, with an M/R blade
spindle cuff part number 70150-09109-041 installed. This proposed AD
would require initial and recurring inspections of the M/R blade
spindle cuff for a crack.

This proposed AD is prompted by multiple reports of a cracked M/R
blade spindle cuff. In 2008, Sikorsky reported an M/R blade spindle
cuff on a Model UH-60A helicopter that cracked across the lower inboard
bolt holes. Investigation determined the crack was caused by a non-
conforming hole edge break, specifically a burr, introduced during an
overhaul at a non-Sikorsky overhaul facility. Sikorsky issued Sikorsky
Safety Advisory No. SSA-S70-08-002, dated December 11, 2008 (SSA-S70-
08-002), for Black Hawk Model H-60- and S-70-series helicopters to
inform operators of the incident and recommend compliance with
Sikorsky's preventative maintenance inspections. The safety advisory
also recommended that operators with M/R blades overhauled by a non-
Sikorsky repair facility contact that facility to verify whether the
hole edge radius requirement was met during the overhaul.

In 2015, the FAA received an additional report of an M/R blade
spindle cuff on a military model helicopter that cracked. Investigation
from this reporting has revealed no anomalies at the crack initiation
site. In each instance, a crack initiated at a bolt hole and spread to
either an adjacent bolt hole or to the free edge. Due to design
similarity, Model EH-60A, HH-60L, S-70, S-70A, S-70C, S-70C(M), S-
70C(M1), and UH-60A helicopters are all affected by this unsafe
condition. The proposed actions are intended to detect a crack, prevent
failure of an M/R blade spindle cuff, loss of an M/R blade, and loss of
control of the helicopter.

FAA's Determination

The FAA is proposing this AD after evaluating all known relevant
information and determining that an unsafe condition exists and is
likely to exist or develop on other helicopters of these same type
designs.

Related Service Information

The FAA reviewed SSA-S70-08-002. This service information
recommends, for helicopters with M/R blades overhauled by non-Sikorsky
M/R blade repair facilities, contacting the facilities to verify
whether the hole edge radius requirement was met during cuff
replacement. The safety advisory also recommends operators conduct 10
hour/14 day visual inspections and follow the inspection procedures
regarding sudden onset of low frequency vibration or an out of track
condition.

The FAA also reviewed Sikorsky Technical Manual Preventative
Maintenance Services 10 Hour/14 Day (30 Hour/42 Day) Inspection
Checklist TM 1-70-PMS-1, dated December 1, 2014, for Sikorsky Model S-
70 helicopters. This service information contains procedures for the 10
hour/14 day and 30 hour/42 day inspections.

Proposed AD Requirements

This proposed AD would require, using 10X or higher power
magnification, visually inspecting each M/R blade spindle cuff for a
crack, and replacing the M/R blade spindle cuff if there is a crack.

Costs of Compliance

The FAA estimates that this proposed AD affects 204 helicopters of
U.S. Registry. The FAA estimates that operators may incur the following
costs in order to comply with this AD. Labor
costs are estimated at $85 per work-hour.

Inspecting the M/R blade spindle cuffs would take about 1 work-hour
for an estimated cost of $85 per helicopter and $17,340 for the U.S.
fleet. Replacing an M/R blade spindle cuff would take about 175 work-
hours and required parts would cost about $10,000 for a total estimated
replacement cost of $24,875 per M/R blade spindle cuff.

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, I certify this proposed regulation:

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 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 (AD):