DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2019-0663; Product Identifier 2018-SW-057-AD; Amendment
39-21025; AD 2020-02-17]
RIN 2120-AA64
Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
for
certain Sikorsky Aircraft Corporation (Sikorsky) Model S-70, S-70A, S-
70C, S-70C(M), and S-70C(M1) helicopters. This AD was prompted by four
incidents of disbonding between the tail rotor (T/R) blade pitch horn
and the torque tube. This AD requires recurring visual and tap
inspections of the T/R blade, and depending on the outcome, replacing
the T/R blade. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective March 13, 2020.
ADDRESSES: For service information related to this final 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 or 203-416-4299; 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
related service information at the FAA, Office of the Regional Counsel,
Southwest Region, 10101 Hillwood Pkwy, Room 6N-321, Fort Worth, TX
76177.
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-2019-
0663; 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 AD, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations is Docket
Operations, 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: Kristopher Greer, Aviation Safety
Engineer, Boston ACO Branch, Compliance & Airworthiness Division, FAA,
1200 District Avenue, Burlington, MA 01803; telephone 781-238-7799;
email kristopher.greer@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Sikorsky Model S-70, S-
70A, S-70C, S-70C(M), and S-70C(M1) helicopters with T/R blade part
number 70101-31000 (all dash numbers) and with a serial number up to
and including A009-08915. The NPRM published in the Federal Register on
September 6, 2019 (84 FR 46903). The NPRM was prompted by four
incidents of disbonding between the T/R blade pitch horn and the torque
tube on military-operated Model UH-60L and SH-60F helicopters. The
disbonding produced minor to severe vibrations due to the mass
imbalance. This condition may also occur on Sikorsky Model S-70, S-70A,
S-70C, S-70C(M), and S-70C(M1) helicopters due to design similarity.
Disbonding between the T/R blade pitch horn and the torque tube, if
not addressed, could result in the T/R blade pitch horn rocking in the
torque tube, leading to increased T/R vibrations. These vibrations
could lead to crushing of the torque tube and subsequent loss of
control of the helicopter. While Sikorsky continues to test T/R blades
returned from the field, investigation has revealed blades produced
prior to manufacturing improvements implemented between 2006 and 2007
are prone to this disbonding. To address this condition, Sikorsky is
assessing design change options to retrofit the affected T/R blades.
The NPRM proposed to require, before the first flight of each day,
visually inspecting each T/R blade for any crack, leading edge erosion,
and trailing edge skin disbonding and separation, paying particular
attention to the area from the midspan to the pitch control horn; and
tap inspecting for disbonding in the pitch horn to torque tube bond
area. Depending on the outcome of these inspections, the NPRM proposed
to require replacing the T/R blade. The FAA is issuing this AD to
address the unsafe condition on these products.
Comments
The FAA gave the public the opportunity to participate in
developing this AD. The FAA received no comments on the NPRM or on the
determination of the cost to the public.
FAA's Determination
The FAA reviewed the relevant data and determined that air safety
and the public interest require adopting this AD as proposed.
Related Service Information
The FAA reviewed Sikorsky Aircraft Model S-70 Blackhawk Derivatives
Maintenance Manual Temporary Revision No. 72, dated October 12, 2017.
This service information specifies replacing a 10-hour/14-day T/R
inspection with a before first flight of the day T/R inspection.
The FAA also reviewed section 5-3-13.2 Coin-Tapping Inspection
Method of Sikorsky Technical Manual TM 1-70-23-3, Change 12, dated July
1, 2018. This service information specifies procedures for coin-tap
inspecting T/R blades. This service information also specifies general
repair limits and includes figures illustrating the different types of
materials of the T/R blade skin and core regions.
Interim Action
The FAA considers this AD an interim action. The design approval
holder is currently developing a modification that will address the
unsafe condition identified in this AD. Once this modification is
developed, approved, and available, we might consider additional
rulemaking.
Costs of Compliance
The FAA estimates that this AD affects 13 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 T/R blades takes about 1 work-hour for an estimated
cost of $85 per helicopter and $1,105 for the U.S. fleet, per
inspection cycle.
Replacing a set of two T/R blades takes about 6 work-hours and
parts cost about $192,304 for an estimated replacement cost of $192,814
per helicopter.
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 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.
The FAA 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):
|