[Federal Register Volume 84, Number 173 (Friday, September 6, 2019)]
[Proposed Rules]
[Pages 46903-46904]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-19104]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0663; Product Identifier 2018-SW-057-AD]
RIN 2120-AA64


Airworthiness Directives; Sikorsky Aircraft Corporation 
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 certain Sikorsky Aircraft Corporation (Sikorsky) Model S-70, S-70A, 
S-70C, S-70C(M), and S-70C(M1) helicopters. This proposed AD was 
prompted by four incidents of disbonding between the tail rotor (T/R) 
blade pitch horn and the torque tube. This proposed AD would require 
recurring visual and tap inspections of the T/R blade, and depending on 
the outcome, replacing the T/R blade. The FAA is proposing this AD to 
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by October 21, 
2019.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this NPRM, 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. 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.

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-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 NPRM, the regulatory evaluation, 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 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: 

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2019-0663; 
Product Identifier 2018-SW-057-AD'' at the beginning of your comments. 
The FAA specifically invites comments on the overall regulatory, 
economic, environmental, and energy aspects of this NPRM. The FAA will 
consider all comments received by the closing date and may amend this 
NPRM because of those comments.
    The FAA will post all comments the FAA receives, without change, to 
http://www.regulations.gov, including any personal information you 
provide. The FAA will also post a report summarizing each substantive 
verbal contact the FAA receives about this NPRM.

Discussion

    The FAA proposes to adopt a new AD for 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.
    This proposed AD is prompted by four incidents of disbonding 
between the T/R blade pitch horn and the torque tube on 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.

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.

FAA's Determination

    The FAA is proposing this AD because the FAA 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.

Proposed AD Requirements

    This proposed AD would require, before the first flight of each 
day,

[[Page 46904]]

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, this proposed AD 
would require replacing the T/R blade.

Interim Action

    The FAA considers this proposed AD 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 proposed AD affects 13 helicopters of 
U.S. registry. The FAA estimates the following costs to comply with 
this proposed AD. Labor costs are estimated at $85 per work-hour.
    Inspecting the T/R blades would take 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 would take about 6 
work-hours and parts would cost about $192,304 for an estimated 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 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 above, 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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

Sikorsky Aircraft Corporation: Docket No. FAA-2019-0663; Product 
Identifier 2018-SW-057-AD.

(a) Comments Due Date

    The FAA must receive comments by October 21, 2019.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Model S-70, S-70A, S-70C, S-70C(M), and S-
70C(M1) helicopters, certificated in any category, with a tail rotor 
(T/R) blade part number 70101-31000 (all dash numbers) with a serial 
number (S/N) up to and including A009-08915.

    Note 1 to paragraph (c) of this AD:  Each T/R blade is marked 
with the S/N.

(d) Subject

    Joint Aircraft System Component (JASC): 6410, Tail Rotor Blades.

(e) Unsafe Condition

    This AD was prompted by four incidents of disbonding between the 
T/R blade pitch horn and the torque tube. The FAA is issuing this AD 
to detect disbonding. The unsafe condition, if not addressed, could 
result in increased T/R vibrations, physical failure of the torque 
tube, and subsequent loss of control of the helicopter.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) T/R Blade Inspection

    Before the first flight of each day:
    (1) Visually inspect each T/R blade for a 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. If there is a crack, any leading edge erosion, 
trailing edge disbonding, or trailing edge separation, before 
further flight, replace the T/R blade with an airworthy part.
    (2) Tap test inspect each T/R blade for disbonding in the pitch 
horn to torque tube bond area. If there is any disbonding, before 
further flight, replace the T/R blade with an airworthy part.

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Boston ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (i)(1) of this AD.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(i) Related Information

    (1) For more information about this AD, 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.
    (2) For service information identified in this AD, 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_govt_field_serv_eng.gr-sik@lmco.com. You may view this 
referenced 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.

    Issued in Fort Worth, Texas, on August 23, 2019.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2019-19104 Filed 9-5-19; 8:45 am]
 BILLING CODE 4910-13-P


