DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2015-0397; Directorate Identifier 2014-SW-048-AD;
Amendment 39-18107; AD 2015-04-05]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation
(Sikorsky) Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Sikorsky Model S-76A, B, C, and D helicopters. This AD requires
inspecting the tail rotor drive shaft (TDS) flange-to-shaft attachment
hardware for correct assembly and correct torque of the fasteners. If
there is a discrepancy, this AD requires, before further flight,
applying an index mark to the flange and TDS, inspecting the flange and
shaft for a crack, fracture, wear, and certain measurements, and
replacing any part that does not meet the approved criteria before
further flight. This AD is prompted by a partial loss of tail rotor
drive resulting in a forced landing. The actions specified by this AD
are intended to prevent failure at the flange-to-shaft attachment, loss
of a tail rotor drive, and subsequent loss of control of the
helicopter.

DATES: This AD becomes effective March 12, 2015.
The Director of the Federal Register approved the incorporation by
reference of a certain document as of March 12, 2015.
We must receive comments on this AD by April 27, 2015.

ADDRESSES: You may send comments by any of the following methods:
Federal eRulemaking Docket: Go to http://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 http://www.regulations.
gov or in person at the Docket Operations Office
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, any incorporated by reference
service information, the economic evaluation, any comments received,
and other information. The street address for the Docket Operations
Office (telephone 800-647-5527) is in the ADDRESSES section. Comments
will be available in the AD docket shortly after receipt.
For service information identified in this AD, contact Sikorsky
Aircraft Corporation, Customer Service Engineering, 124 Quarry Road,
Trumbull, CT 06611; telephone 1-800-Winged-S or 203-416-4299; email
sikorskywcs@sikorsky.com. You may review the referenced service
information at the FAA, Office of the Regional Counsel, Southwest
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. It is
also available on the Internet at http://www.regulations.gov by
searching for and locating Docket No. FAA-2015-0397.

FOR FURTHER INFORMATION CONTACT: Michael Schwetz, Aviation Safety
Engineer, Boston Aircraft Certification Office, Engine & Propeller
Directorate, FAA, 12 New England Executive Park, Burlington,
Massachusetts 01803; telephone (781) 238-7761; email
michael.schwetz@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

This AD is a final rule that involves requirements affecting flight
safety, and we did not provide you with notice and an opportunity to
provide your comments prior to it becoming effective. However, we
invite you to participate in this rulemaking by submitting written
comments, data, or views. We also invite comments relating to the
economic, environmental, energy, or federalism impacts that resulted
from adopting this AD. The most helpful comments reference a specific
portion of the AD, 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 them only one time. We will file in the docket all comments that
we receive, as well as a report summarizing each substantive public
contact with FAA personnel concerning this rulemaking during the
comment period. We will consider all the comments we receive and may
conduct additional rulemaking based on those comments.

Discussion

We are adopting a new AD for certain Sikorsky Model S-76A, B, C,
and D helicopters. This AD requires inspecting the TDS flange-to-shaft
attachment hardware at four locations for correct installation and
correct torque of the fasteners. If there is movement, misalignment of
the torque stripe, a misassembled part, or torque of less than 105
inch-pounds on any nut, this AD requires applying an index mark to the
flange and shaft to make sure the flange is reinstalled in the same
position to maintain shaft balance, and, before further flight,
inspecting the flange and shaft for a crack, fracture, wear on the
mounting hole, and diameter measurements, and replacing the TDS if the
flange or stub does not meet the inspection criteria. This AD is
prompted by a partial loss of tail rotor drive resulting in a forced
landing, and instances where TDS flange-to-shaft attachment hardware
was found to be loose or fractured. The actions specified by this AD
are intended to detect loose or fractured hardware and prevent failure
of the TDS at the flange-to-shaft attachment, loss of a tail rotor
drive, and subsequent loss of control of the helicopter.

FAA's Determination

We are issuing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of these same type
designs.

Related Service Information Under 1 CFR Part 51

Sikorsky issued Alert Service Bulletin ASB 76-66-52, Basic Issue,
on April 1, 2014, which specifies a one-time inspection of the TDS
flange-to-shaft attachment hardware for proper installation and torque.
If there is movement, torque stripe misalignment, or misassembled
hardware, the ASB specifies removing and returning the hardware to
Sikorsky with certain forms and replacing hardware with airworthy TDS
hardware before returning the helicopter to service. The ASB also
specifies either replacing the TDS or inspecting the flange and shaft
for a crack, fracture, wear of the mounting hole, and diameter and
replacing any part that does not meet the approved criteria. The ASB
states there were instances where the TDS flange-to-shaft attachment
hardware was found loose or fractured. This service information is
reasonably available; see ADDRESSES for ways to access this service
information.

AD Requirements

This AD requires, within 30 days:
Inspecting each TDS flange attachment hardware at all four
locations for looseness and torque stripe misalignment, inspecting each
nut to determine whether it can be rotated by hand, determining whether
the hardware is assembled correctly, and determining the torque of each
nut.
If there is no looseness, torque stripe misalignment,
incorrect hardware assembly, and if no nut can be rotated by hand and
the torque of any nut is not less than 105 inch-pounds, no further
action is required by this AD.
If there is looseness, torque stripe misalignment,
incorrect hardware assembly, a nut rotated by hand, or the torque of
any nut is less than 105 inch-pounds:
- Applying an index mark to the flange and shaft, unbolting and
removing the flange from the shaft, visually inspecting each radius
washer for wear or fretting, and replacing any washer with wear or
fretting.
- Inspecting the flange and shaft for a crack, fracture, wear
on the mounting hole, and diameter, and replacing the TDS with an
airworthy TDS if the flange and shaft fail any of the inspection
criteria.
- Aligning index marks, installing the flange on the shaft, and
coating the grip length of each bolt and the contact surfaces on each
radius washer and washer with epoxy polyamide primer.
- Torquing each nut.

Differences Between This AD and the Service Information

The AD does not require returning the unairworthy parts with
certain forms to the manufacturer as does the service information.

Costs of Compliance

We estimate that this AD affects 260 helicopters of U.S. Registry.
We estimate that operators may incur the following costs in order to
comply with this AD. We estimate $85 per work-hour for labor. We
estimate 2.2 work-hours to inspect the hardware assembly and torque at
a cost of $187 per helicopter and $48,620 for the fleet. We estimate
2.2 work-hours if the hardware is replaced and $1,200 for the required
parts, for a total cost of $1,387 per helicopter.

FAA's Justification and Determination of the Effective Date

Providing an opportunity for public comments before adopting these
AD requirements would delay implementing the safety actions needed to
correct this known unsafe condition. Therefore, we find that the risk
to the flying public justifies waiving notice and comment before
adopting this rule because the required corrective actions must be done
within 30 days, a very short time period based on the average flight-
hour utilization rate of these helicopters used for commuter, air
ambulance, and offshore operations.
Since an unsafe condition exists that requires the immediate
adoption of this AD, we determined that notice and opportunity for
public comment before issuing this AD are impracticable and that good
cause exists for making this amendment effective in less than 30 days.

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.
We are 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

We determined that 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, I certify that this AD:
1. Is not a ``significant regulatory action'' under Executive Order
12866;
2. Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979);
3. Will not affect intrastate aviation in Alaska to the extent that
it justifies making a regulatory distinction; and
4. 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.
We prepared an economic evaluation of the estimated costs to comply
with this AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of 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 (AD):