DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-1002; Project Identifier AD-2021-00332-R]
Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for certain Sikorsky Aircraft Corporation Model S-76D helicopters. This
proposed AD was prompted by reports that certain Thales global
positioning system (GPS) satellite based augmentation system (SBAS)
receivers provided, under certain conditions, erroneous outputs on
aircraft positions. This proposed AD would require replacing affected
GPS receivers and prohibit installing those GPS receivers. 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 [January
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
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, Mailstop K100, 124 Quarry Road,
Trumbull, CT 06611; telephone 1-800-946-4337 (1-800-Winged-S); email
email@example.com. Operators may also log on to the
Sikorsky 360 website at https://www.sikorsky360.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 at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-1002; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.
FOR FURTHER INFORMATION CONTACT: Nicholas Rediess, Aviation Safety
Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA
01803; phone: (781) 238-7159; fax: (781) 238-7199; email:
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2021-1002; Project Identifier
AD-2021-00332-R'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.
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 post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.
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
Nicholas Rediess, Aviation Safety Engineer, Boston ACO Branch, FAA,
1200 District Avenue, Burlington, MA 01803; phone: (781) 238-7159; fax:
(781) 238-7199; email: firstname.lastname@example.org. Any commentary that
the FAA receives which is not specifically designated as CBI will be
placed in the public docket for this rulemaking.
The European Aviation Safety Agency (now European Union Aviation
Safety Agency) (EASA), which is the Technical Agent for the Member
States of the European Union, has issued EASA AD 2019-0004, dated
January 11, 2019, and corrected on January 17, 2019 (EASA AD 2019-
0004), to correct an unsafe condition for Thales AVS France SAS
(Thales), formerly Thales Avionics SAS, GPS/SBAS receivers, Topstar 200
LPV, part number (P/N) C17149HA01 and C17149JA02, using SBAS, which are
known to be installed on, but not limited to, certain Model ATR 42-500
and ATR 72-212A aeroplanes and Sikorsky Model S-76D helicopters. EASA
advises of reports indicating that Thales GPS SBAS receivers provided,
under certain conditions, erroneous outputs on aircraft positions. EASA
AD 2019-0004 requires actions to prevent compromise of the safety
margins when the receiver is used for Localizer Performance with
Vertical guidance (LPV) and/or RNP-AR (Required Navigation
Performance--Authorization Required) operations. Following the issuance
of EASA AD 2019-0004, the FAA issued AD 2020-08-02, Amendment 39-21108
(85 FR 20586, April 14, 2020), to address the unsafe condition on these
After the issuance of EASA AD 2019-0004, EASA issued related EASA
AD 2021-0013, dated January 13, 2021 (EASA AD 2021-0013), in response
to a software update that was developed to ensure correct navigational
performance of certain Thales GPS SBAS receivers installed on ATR-GIE
Avions de Transport R[eacute]gional, formerly EADS ATR--Alenia,
Aerospatiale Matra ATR--ALENIA, Aerospatiale--Alenia, Aerospatiale--
Aeritalia, Model ATR 42-500 and ATR 72-212A aeroplanes.
This proposed AD would require replacing affected GPS TopStar 200
LPV receivers installed on Sikorsky Aircraft Corporation Model S-76D
helicopters. The FAA is proposing this AD to address erroneous aircraft
position outputs from the GPS SBAS receivers, which could result in
controlled flight into terrain, and subsequent loss of control of the
The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Sikorsky S-76D Helicopter Service Bulletin SB 76-
017, Basic Issue, dated May 11, 2021 (SB 76-017). SB 76-017 specifies
procedures for removing, updating, and installing GPS TopStar 200 LPV
receivers. SB 76-017 also provides instructions for sending the GPS
receiver(s) to Thales Authorized Repair Stations for the software
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.
Proposed AD Requirements in This NPRM
This proposed AD would require replacing each affected GPS receiver
and prohibit installing an affected GPS receiver on any helicopter.
Differences Between This Proposed AD and the Service Information
SB 76-017 requires returning the GPS receiver(s) to Thales
Authorized Repair Stations for the software update, while this proposed
AD would require replacing the GPS receiver(s) instead.
Costs of Compliance
The FAA estimates that this proposed AD would affect 22 helicopters
of U.S. Registry and that operators may incur the following costs in
order to comply with this proposed AD. Labor costs are estimated at $85
Replacing a GPS receiver would take about 3 work-hours and parts
would cost about $7,400, for an estimated cost of $7,655 per GPS
receiver and $336,820 for the U.S. fleet.
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.
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
(1) Is not a ``significant regulatory action'' under Executive
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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
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