DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6968; Directorate Identifier 2015-SW-020-AD;
Amendment 39-18950; AD 2017-14-06]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation
Helicopters (Type Certificate Previously Held by Schweizer Aircraft
Corporation)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding airworthiness directive (AD) 93-17-13 for
Schweizer Aircraft Corporation and Hughes Helicopters, Inc. (now
Sikorsky Aircraft Corporation) (Sikorsky) Model TH55A, 269A, 269A-1,
269B, and 269C helicopters. AD 93-17-13 required installing tachometer
markings and inspecting the lower coupling driveshaft (driveshaft).
This new AD requires repetitive inspections of the driveshaft and
expands the applicability to include Model 269C-1 helicopters. This AD
is prompted by reports of accidents because of driveshaft failures. The
actions of this AD are intended to prevent the unsafe condition on
these products.

DATES: This AD is effective August 25, 2017.
The Director of the Federal Register approved the incorporation by
reference of certain documents listed in this AD as of August 25, 2017.
The Director of the Federal Register approved the incorporation by
reference of a certain other publication listed in this AD as of
October 20, 1993 (58 FR 51770, October 5, 1993).

ADDRESSES: For Schweizer or Sikorsky service information identified in
this final rule, contact Sikorsky Aircraft Corporation, Customer
Service Engineering, 124 Quarry Road, Trumbull, CT 06611; telephone 1-
800-Winged-S or 203-416-4299; email wcs_cust_service_eng.gr-sik@lmco.com.
You may review a copy of the referenced service
information at the FAA, Office of the Regional Counsel, Southwest
Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX 76177. It is
also available on the Internet at http://www.regulations.gov by
searching for and locating Docket No. FAA-2016-6968.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2016-
6968; 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 (phone: 800-647-
5527) is U.S. Department of Transportation, Docket Operations Office,
M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue
SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Blaine Williams, Aerospace Engineer,
Boston Aircraft Certification Office, Engine & Propeller Directorate,
1200 District Avenue, Burlington, Massachusetts 01803; telephone (781)
238-7161; email blaine.williams@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 to remove AD 93-17-13, Amendment 39-8684 (58 FR 51770, October
5, 1993) and add a new AD. AD 93-17-13 applied to Schweizer Aircraft
Corporation and Hughes Helicopters, Inc. (now Sikorsky) Model TH55A,
269A, 269A-1, 269B, and 269C helicopters. AD 93-17-13 required within
30 days or 100 hours time-in-service (TIS), whichever occurs first and
thereafter every 300 hours TIS, visually inspecting for cracks,
machining steps, manufacturing tool marks, surface defects, and lack of
cleanup during the production grinding operation. AD 93-17-13 also
required installing engine and rotor tachometer markings and replacing
any unairworthy driveshaft before further flight.
The NPRM published in the Federal Register on January 5, 2017 (82
FR 1267) and was prompted by a safety analysis by Sikorsky that
determined the initial and recurrent inspection intervals and
inspection method required by AD 93-17-13 were not adequate to detect
all corrosion, pits, nicks, scratches, dents, and cracks. Accidents due
to driveshaft failures continued to occur after AD 93-17-13 was issued.
Therefore, the NPRM proposed to require, within 25 hours TIS and
thereafter at intervals not to exceed 150 hours TIS, visually
inspecting the driveshaft. If there are no cracks, corrosion, or other
damage, the NPRM proposed performing a magnetic particle inspection. If
there is a crack or other damage, the NPRM proposed to require replacing the
driveshaft before further flight. The NPRM also proposed adding tachometer
markings if not previously performed. Expanding the applicability to
include Model 269C-1 helicopters was also proposed because these
helicopters were not manufactured when AD 93-17-13 was issued but have
the applicable driveshafts installed. Finally, the NPRM proposed to
include specific part-numbered driveshafts to the applicability because
Sikorsky is developing a new driveshaft that we do not expect to be
subject to this AD.

Comments

We gave the public the opportunity to participate in developing
this AD, but we received no comments on the NPRM.

FAA's Determination

We have reviewed the relevant information and determined that an
unsafe condition exists and is likely to exist or develop on other
products of these same type designs and that air safety and the public
interest require adopting the AD requirements as proposed.

Interim Action

We consider this AD to be an interim action. The design approval
holder is developing a replacement driveshaft that will address the
unsafe condition identified in this AD. Once the replacement driveshaft
is developed, approved, and available, we might consider additional
rulemaking.

Related Service Information Under 1 CFR Part 51

We reviewed Sikorsky 269C Helicopter Alert Service Bulletin B-307,
Basic Issue, dated December 18, 2014, and Sikorsky 269C-1 Helicopter
Alert Service Bulletin C1B-043, Basic Issue, dated December 18, 2014
(ASBs). The ASBs call for a one-time visual and magnetic particle
inspection of the driveshaft and driveshaft assembly for damage. The
ASBs advise that the driveshaft be sent to Sikorsky and replaced if
damaged. The inspection is to be accomplished within 25 hours TIS or
within 180 days from the ASBs' issue date, whichever comes first.
Sikorsky has since revised its maintenance manual to incorporate these
inspections every 150 hours TIS.
We also reviewed Schweizer Aircraft Service Bulletin B-257.1, dated
May 21, 1993 (ASB B-257.1). ASB B-257.1 calls for a one-time inspection
to look for drive-shaft defects; installing declutched limit markings
on the engine/rotor tachometer to reinforce operating limits; and
prohibiting engine declutched operations above 1600 RPM.
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 the ADDRESSES section.

Differences Between This AD and the Service Information

The Sikorsky service information calls for the initial inspection
to be completed within 180 days or 25 hours TIS. This AD requires that
the initial inspection to be completed within 25 hours TIS only. The
service information requires contacting Sikorsky if a certain part-
numbered driveshaft is installed, emailing information to Sikorsky, and
returning damaged parts to Sikorsky; this AD does not.

Costs of Compliance

We estimate that this AD affects 619 helicopters of U.S. Registry
and that labor costs average $85 per work hour. Based on these
estimates, we expect the following costs:
We estimate that the visual and magnetic particle
inspections of the driveshaft requires 11 work hours for a cost of $935
per helicopter and $578,765 for the U.S. fleet per inspection cycle.
Replacing the driveshaft, if needed, costs about $4,574
for parts. No additional labor costs are necessary.
Installing engine and rotor tachometer markings requires
0.5 work-hour for a labor cost of about $43. The cost of parts is
minimal.

Interim Action

We consider this AD to be an interim action. The design approval
holder is developing a replacement driveshaft that will address the
unsafe condition identified in this AD. Once the replacement driveshaft
is developed, approved and available, we might consider additional
rulemaking.

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

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) 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 removing Airworthiness Directive (AD)
93-17-13, Amendment 39-8684 (58 FR 51770, October 5, 1993) and adding
the following new AD: