Proposed Rule2026-07937
Airworthiness Directives; Various Helicopters
Primary source
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Published
April 23, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2020-02-17, which applies to certain Sikorsky Aircraft Corporation (Sikorsky) Model S-70, S-70A, S-70C, S-70C(M), and S-70C(M1) helicopters. AD 2020-02-17 requires recurring visual and tap inspections of the tail rotor blade (TRB) and, depending on the results, replacing the TRB. Since the FAA issued AD 2020-02-17, it was determined additional helicopter models are affected by the unsafe condition. The manufacturer has developed a split pitch horn modification and a safety enhancement modification kit for the TRB. This proposed AD would continue to require the actions of AD 2020-02- 17, would expand the applicability, and would require modifying and re- identifying the TRB. This proposed AD would also require revising the airworthiness limitations section (ALS) of the existing helicopter maintenance manual or instructions for continued airworthiness and the existing approved maintenance or inspection program, as applicable, to incorporate recurring inspections of the TRB disbond indicator. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 78 (Thursday, April 23, 2026)</title>
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[Federal Register Volume 91, Number 78 (Thursday, April 23, 2026)]
[Proposed Rules]
[Pages 21738-21741]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-07937]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-3863; Project Identifier AD-2024-00567-R]
RIN 2120-AA64
Airworthiness Directives; Various Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2020-02-17, which applies to certain Sikorsky Aircraft Corporation
(Sikorsky) Model S-70, S-70A, S-70C, S-70C(M), and S-70C(M1)
helicopters. AD 2020-02-17 requires recurring visual and tap
inspections of the tail rotor blade (TRB) and, depending on the
results, replacing the TRB. Since the FAA issued AD 2020-02-17, it was
determined additional helicopter models are affected by the unsafe
condition. The manufacturer has developed a split pitch horn
modification and a safety enhancement modification kit for the TRB.
This proposed AD would continue to require the actions of AD 2020-02-
17, would expand the applicability, and would require modifying and re-
identifying the TRB. This proposed AD would also require revising the
airworthiness limitations section (ALS) of the existing helicopter
maintenance manual or instructions for continued airworthiness and the
existing approved maintenance or inspection program, as applicable, to
incorporate recurring inspections of the TRB disbond indicator. 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 June 8,
2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: (202) 493-2251.
<bullet> 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.
<bullet> Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-3863; 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.
Material Incorporated by Reference:
<bullet> For Sikorsky material identified in this proposed AD,
contact your local Sikorsky Field Representative or Sikorsky's Service
Engineering Group at Sikorsky Aircraft Corporation, 124
[[Page 21739]]
Quarry Road, Trumbull, CT 06611; phone: (800) Winged-S or (203) 416-
4299; email: <a href="/cdn-cgi/l/email-protection#0b7c687854687e787f54786e797d62686e546e656c256c79267862604b6766686425686466"><span class="__cf_email__" data-cfemail="037460705c607670775c706671756a60665c666d642d64712e706a68436f6e606c2d606c6e">[email protected]</span></a>. Operators may also
log on to the Sikorsky 360 website at <a href="http://sikorsky360.com">sikorsky360.com</a>.
<bullet> You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 10101 Hillwood Parkway,
Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110. It is also available at
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2026-3863.
FOR FURTHER INFORMATION CONTACT: Isabel Saltzman, Aviation Safety
Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone:
(781) 238-7649; email: <a href="/cdn-cgi/l/email-protection#5411171679171b07143235357a333b22"><span class="__cf_email__" data-cfemail="165355543b5559455670777738717960">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments using a method listed
under ADDRESSES. Include ``Docket No. FAA-2026-3863; Project Identifier
AD-2024-00567-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 revise
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
<a href="http://regulations.gov">regulations.gov</a>, 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
Isabel Saltzman, Aviation Safety Engineer, FAA, 1701 Columbia Avenue,
College Park, GA 30337. Any commentary that the FAA receives which is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.
Background
The FAA issued AD 2020-02-17, Amendment 39-21025 (85 FR 7191,
February 7, 2020) (AD 2020-02-17), for Sikorsky Model S-70, S-70A, S-
70C, S-70C(M), and S-70C(M1) helicopters with a TRB part number 70101-
31000 (all dash numbers) with a serial number up to and including A009-
08915. AD 2020-02-17 was prompted by four incidents of disbonding
between the TRB pitch horn and the torque tube. AD 2020-02-17 requires
recurring visual and tap inspections of the TRB and, depending on the
results, replacing the TRB. The agency issued AD 2020-02-17 to detect
disbonding. The unsafe condition, if not addressed, could result in
increased tail rotor vibrations, physical failure of the torque tube,
and consequent loss of control of the helicopter.
Actions Since AD 2020-02-17 Was Issued
Since the FAA issued AD 2020-02-17, a determination was made that
Sikorsky Model S-70M helicopters and restricted category military
surplus Models EH-60A, HH-60L, UH-60A, and UH-60L helicopters are also
affected by the unsafe condition defined in AD 2020-02-17. Sikorsky has
developed a split pitch horn modification for certain TRBs and a safety
enhancement modification kit for certain TRBs, which consists of a
disbond indicator (three white stripes applied to both upper and lower
airfoil blade surfaces). Sikorsky has also issued a temporary revision
to the maintenance manual to specify procedures for recurring
inspections of the disbond indicator for TRBs modified with the safety
enhancement modification kit. In addition, Sikorsky updated the service
information into two separate bulletins based on the TRB manufactured
date. A manufacturing improvement was implemented between 2006 and
2007, and the service bulletin reflects this difference.
FAA's Determination
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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Sikorsky Aircraft Model S-70A Blackhawk
Derivatives Maintenance Manual Temporary Revision No. 82, dated June
27, 2023. This material specifies procedures for the visual, tap test,
and borescope inspections of the modified TRBs with the disbond
indicator. This material also provides instructions for maintaining the
disbond indicator.
This material 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 continue to require the actions of AD 2020-
02-17. This proposed AD would require modifying and re-identifying the
TRB. This proposed AD would also require revising the ALS of the
existing helicopter maintenance manual or instructions for continued
airworthiness and the existing approved maintenance or inspection
program, as applicable, to incorporate recurring inspections of the TRB
disbond indicator. This proposed AD would also expand the applicability
by adding helicopter models.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 96 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated Costs
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Cost on U.S.
Action Labor cost Parts cost Cost per product operators
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Inspect and tap test TRBs 1 work-hour x $85 $0 $85 per inspection $8,160 per
(retained from AD 2020-02-17). per hour = $85. cycle. inspection cycle.
[[Page 21740]]
Install split pitch horn 6 work-hours x $85 50,000 50,510............. Up to $4,848,960.
modification (for certain TRBs). per hour = $510.
Install safety enhancement 6 work-hours x $85 300,000 300,510............ Up to $28,848,960.
modification kit (for certain per hour = $510.
TRBs).
Revise ALS....................... 1 work-hour x $85 0 85................. $8,160.
per hour = $85.
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The FAA estimates the following costs to do any on-condition
actions that would be required based on the results of the proposed
inspection. The agency has no way of determining the number of
helicopters that might need these on-condition actions:
On-Condition Costs
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Cost per
Action Labor cost Parts cost product
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Perform tap test or borescope inspection...... 1 work-hour x $85 per hour = $85 $0 $85
Replace TRBs.................................. 6 work-hours x $85 per hour = 192,304 192,814
(set of two--unmodified)...................... $510.
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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 that the proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(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
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:
0
a. Removing Airworthiness Directive 2020-02-17, Amendment 39-21025 (85
FR 7191, February 7, 2020); and
0
b. Adding the following new airworthiness directive:
Various Helicopters: Docket No. FAA-2026-3863; Project Identifier
AD-2024-00567-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by June 8, 2026.
(b) Affected ADs
This AD replaces AD 2020-02-17, Amendment 39-21025 (85 FR 7191,
February 7, 2020) (AD 2020-02-17).
(c) Applicability
This AD applies to the helicopters listed in paragraphs (c)(1)
through (5) of this AD, certificated in any category, with a tail
rotor blade (TRB) part number (P/N) 70101-31000 (all dash numbers)
installed.
(1) Model EH-60A helicopters; type certificate holders include,
but are not limited to, Delta Enterprise, LLC; Heliqwest
International Inc.; Pickering Aviation, Inc.; and Sixtyhawk TC, LLC.
(2) Model HH-60L helicopters; type certificate holders include,
but are not limited to, Capitol Helicopters Inc.; Central Copters
Inc.; and Sixtyhawk TC, LLC.
(3) Sikorsky Aircraft Corporation Model S-70, S-70A, S-70C, S-
70C(M), S-70C(M1), and S-70M helicopters.
(4) Model UH-60A helicopters; type certificate holders include,
but are not limited to, ACE Aeronautics, LLC.; Air Resources
Helicopters Inc.; Billings Flying Service Inc.; Blackhawk Mission
Equipment; Capitol Helicopters Inc.; Carson Helicopters, Inc.; Delta
Enterprise, LLC; H-60, LLC; Hallux Aerospace, LLC.; Heliqwest
International Inc.; High Performance Helicopters Corp.; Northwest
Rotorcraft LLC; Pickering Aviation, Inc.; PJ Helicopters Inc.;
Reeder Flying Service Inc.; Sixtyhawk TC, LLC; Skydance Blackhawk
Operations, LLC; Timberline Helicopters, Inc.; and Unical Air Inc.
(5) Model UH-60L helicopters; type certificate holders include,
but are not limited to, ACE Aeronautics, LLC.; Air Resources
Helicopters Inc.; Delta Enterprise, LLC; H-60, LLC.; Hallux
Aerospace, LLC.; Pickering Aviation, Inc.; and Timberline
Helicopters, Inc.
(d) Subject
Joint Aircraft System Component (JASC) Code 6400, Tail Rotor
System.
(e) Unsafe Condition
This AD was prompted by four incidents of disbonding between the
TRB pitch horn
[[Page 21741]]
and the torque tube. The FAA is issuing this AD to detect and
address disbonding. The unsafe condition, if not addressed, could
result in increased tail rotor vibrations, physical failure of the
torque tube, and consequent loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) TRB Inspection With Applicable Corrective Actions
For helicopters with TRB P/N 70101-31000 (all dash numbers),
before the first flight of each day:
(1) Visually inspect each TRB 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,
remove the TRB from service and replace with a serviceable part.
(2) Tap test inspect each TRB for disbonding in the pitch horn
to torque tube bond area. If there is any disbonding, before further
flight remove the TRB from service and replace with a serviceable
part.
(h) TRB Modification and Applicable Re-Identification
(1) For helicopters with TRB P/N 70101-31000-043, P/N 70101-
31000-048, P/N 70101-31000-050, P/N 70101-31000-051, or P/N 70101-
31000-052 without a split pitch horn installed, accomplish the
safety enhancement modification kit. This action must be
accomplished by an authorized Sikorsky Aircraft overhaul facility,
or by a method approved by the Manager, East Certification Branch,
FAA, within the compliance time specified in paragraph (h)(1)(i) or
(ii) of this AD.
Note 1 to the introductory text of paragraph (h)(1): Upon
completion of the safety enhancement modification kit, the TRB is
marked with P/N 70070-10052-041.
Note 2 to the introductory text of paragraph (h)(1): Information
on the safety enhancement modification kit is in Sikorsky Aircraft
Corporation (Sikorsky) Alert Service Bulletin 70-05-52, Revision B,
dated March 27, 2025, and Sikorsky Alert Service Bulletin 70-05-58,
Revision A, dated July 10, 2025.
(i) TRBs manufactured on or before December 31, 2007: within 12
months after the effective date of this AD.
(ii) TRBs manufactured on or after January 1, 2008: within 48
months after the effective date of this AD.
(2) For helicopters with TRB P/N 70101-31000-046 without a split
pitch horn installed, accomplish the split pitch horn modification.
This action must be accomplished by an authorized Sikorsky Aircraft
overhaul facility or by a method approved by the Manager, East
Certification Branch, FAA, within the compliance time specified in
paragraph (h)(2)(i) or (ii) of this AD.
Note 3 to the introductory text of paragraph (h)(2): Upon
completion of the split pitch horn modification, the TRB is marked
with P/N 70070-15005-042.
Note 4 to the introductory text of paragraph (h)(2): Information
on the split pitch horn modification is in Sikorsky Alert Service
Bulletin 70-05-52, Revision B, dated March 27, 2025, and Sikorsky
Alert Service Bulletin 70-05-58, Revision A, dated July 10, 2025.
(i) TRBs manufactured on or before December 31, 2007: within 12
months after the effective date of this AD.
(ii) TRBs manufactured on or after January 1, 2008: within 48
months after the effective date of this AD.
(i) Revise Maintenance Procedures Manual
Upon completion of the modification required by paragraph (h)(1)
of this AD (when the TRB P/N is changed to P/N 70070-10052-041),
revise the airworthiness limitation section of the existing
helicopter maintenance manual or instructions for continued
airworthiness and the existing approved maintenance or inspection
program, as applicable, by incorporating Sikorsky Aircraft Model S-
70A Blackhawk Derivatives Maintenance Manual Temporary Revision No.
82, dated June 27, 2023.
(j) Provisions for Alternative Actions and Intervals
After the action required by paragraph (i) of this AD has been
done, no alternative actions and associated intervals are allowed
unless they are approved as specified in the provisions of the
alternative methods of compliance (AMOC) paragraph.
(k) Alternative Methods of Compliance (AMOCs)
(1) The Manager, East Certification 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 East Certification Branch, send it to
the attention of the person identified in paragraph (l)(1) of this
AD and email to: <a href="/cdn-cgi/l/email-protection#c2838f8d8182a4a3a3eca5adb4"><span class="__cf_email__" data-cfemail="195854565a597f7878377e766f">[email protected]</span></a>.
(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.
(l) Additional Information
(1) For more information about this AD, contact Isabel Saltzman,
Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park,
GA 30337; phone: (781) 238-7649; email: <a href="/cdn-cgi/l/email-protection#8acfc9c8a7c9c5d9caecebeba4ede5fc"><span class="__cf_email__" data-cfemail="672224254a2428342701060649000811">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference is available at the address specified in paragraph (m)(3)
of this AD.
(m) Material Incorporated by Reference
(1) The Director of the Federal Register approved the
incorporation by reference of the material listed in this paragraph
under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions
required by this AD, unless the AD specifies otherwise.
(i) Sikorsky Aircraft Corporation Model S-70A Blackhawk
Derivatives Maintenance Manual Temporary Revision No. 82, dated June
27, 2023.
(ii) [Reserved]
(3) For Sikorsky Aircraft Corporation material 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; phone 1-800-
Winged-S or 203-416-4299; email <a href="/cdn-cgi/l/email-protection#027561715d617771765d716770746b61675d676c652c65702f716b69426e6f616d2c616d6f"><span class="__cf_email__" data-cfemail="8bfce8f8d4e8fef8ffd4f8eef9fde2e8eed4eee5eca5ecf9a6f8e2e0cbe7e6e8e4a5e8e4e6">[email protected]</span></a>. Operators may also log on to the Sikorsky 360 website
at <a href="http://sikorsky360.com">sikorsky360.com</a>.
(4) You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 10101 Hillwood Parkway,
Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110.
(5) You may view this material at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA, visit <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#7c1a0e5215120f0c191f081513123c121d0e1d521b130a"><span class="__cf_email__" data-cfemail="2543570b4c4b56554046514c4a4b654b4457440b424a53">[email protected]</span></a>.
Issued on April 20, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-07937 Filed 4-22-26; 8:45 am]
BILLING CODE 4910-13-P
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