Proposed Rule2026-07720
Airworthiness Directives; Various Helicopters
Primary source
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Published
April 21, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to supersede Airworthiness Directive (AD) 2015-20-12, which applies to certain Sikorsky Aircraft Corporation Model S-61A, D, E, L, N, NM serial number (S/N) 61454, R, and V; Croman Corporation Model SH-3H; Carson Helicopters, Inc., Model S-61L and SH- 3H; Glacier Helicopter, Inc., Model CH-3E; Robinson Air Crane, Inc., Model CH-3E, CH-3C, HH-3C and HH-3E; and Siller Helicopters Model CH-3E and SH-3A helicopters. AD 2015-20-12 requires calculating or recalculating the hours time-in-service (TIS) of the main rotor shaft (MRS), determining whether the MRS is repetitive external lift (REL) or non-REL, performing a nondestructive inspection (NDI) for cracks, replacing any MRS that has cracks, replacing parts before their life limits and removing from service any parts that have exceeded their life limits. This proposed AD would also require establishing retirement lives for each REL MRS, including reducing life limits and allowing for modification of life limits based on service information, and removing any MRS with oversized dowel pin bores. Since the FAA issued AD 2015-20-12, a design re-evaluation shows that the MRS on certain helicopter models requires a lower life limit. This proposed AD would retain some of the requirements of AD 2015-20-12, and would also lower the retirement life for a certain MRS installed on certain helicopters and would update the type certificate holder name for some of the affected helicopter models. 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 76 (Tuesday, April 21, 2026)</title>
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[Federal Register Volume 91, Number 76 (Tuesday, April 21, 2026)]
[Proposed Rules]
[Pages 21269-21273]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-07720]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-3488; Project Identifier AD-2024-00583-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)
2015-20-12, which applies to certain Sikorsky Aircraft Corporation
Model S-61A, D, E, L, N, NM serial number (S/N) 61454, R, and V; Croman
Corporation Model SH-3H; Carson Helicopters, Inc., Model S-61L and SH-
3H; Glacier Helicopter, Inc., Model CH-3E; Robinson Air Crane, Inc.,
Model CH-3E, CH-3C, HH-3C and HH-3E; and Siller Helicopters Model CH-3E
and SH-3A helicopters. AD 2015-20-12 requires calculating or
recalculating the hours time-in-service (TIS) of the main rotor shaft
(MRS), determining whether the MRS is repetitive external lift (REL) or
non-REL, performing a nondestructive inspection (NDI) for cracks,
replacing any MRS that has cracks, replacing parts before their life
limits and removing from service any parts that have exceeded their
life limits. This proposed AD would also require establishing
retirement lives for each REL MRS, including reducing life limits and
allowing for modification of life limits based on service information,
and removing any MRS with oversized dowel pin bores. Since the FAA
issued AD 2015-20-12, a design re-evaluation shows that the MRS on
certain helicopter models requires a lower life limit. This proposed AD
would retain some of the requirements of AD 2015-20-12, and would also
lower the retirement life for a certain MRS installed on certain
helicopters and would update the type certificate holder name for some
of the affected helicopter models. The FAA is proposing this AD
[[Page 21270]]
to address the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by June 5,
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-2026-3488; 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 a 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: <a href="/cdn-cgi/l/email-protection#186f7b6b477b6d6b6c476b7d6a6e717b7d477d767f367f6a356b71735874757b77367b7775"><span class="__cf_email__" data-cfemail="76011505291503050229051304001f1513291318115811045b051f1d361a1b15195815191b">[email protected]</span></a>; website:
<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-2026-3488.
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#3471777619777b67745255551a535b42"><span class="__cf_email__" data-cfemail="f7b2b4b5dab4b8a4b7919696d9909881">[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-2026-3488; Project Identifier
AD-2024-00583-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 2015-20-12, Amendment 39-18291 (80 FR 63422,
October 20, 2015) (AD 2015-20-12), for Sikorsky Aircraft Corporation;
Sikorsky Aircraft; Croman Corporation; Carson Helicopters, Inc.;
Glacier Helicopter, Inc.; Robinson Air Crane, Inc.; and Siller
Helicopters Model S-61A, D, E, L, N, NM (S/N 61454), R, V, CH-3C, CH-
3E, HH-3C, HH-3E, SH-3A, and SH-3H helicopters with a MRS, part number
S6135-20640-001, S6135-20640-002, or S6137-23040-001, installed. AD
2015-20-12 was prompted by the manufacturer's re-evaluation of the
retirement life for the MRS based on torque, ground-air-ground (GAG)
cycle, and fatigue testing. AD 2015-20-12 requires recording the number
of external lift cycles (lift cycles) performed and the hours TIS,
determining whether the MRS is REL or Non-REL (see paragraph (h) of
this AD for calculation), performing an NDI for any MRS used in REL
operations and replacing a cracked MRS, and marking any REL MRS at the
time of the NDI. AD 2015-20-12 also requires, when recording the number
of hours TIS, using either the helicopter's hours TIS or the
helicopter's transmission hours TIS if both the shaft and transmission
were installed new at the same time where there is no record of the
hours TIS on an individual MRS. AD 2015-20-12 also requires calculating
a 250-hour TIS moving average of lift cycles to determine whether the
MRS is an REL MRS (see paragraph (h) of this AD for calculation);
determining a new retirement life for each MRS based on hours TIS and
lift cycles; removing from service any MRS with oversized dowel pin
bores; extending the hours TIS required for identifying the MRS as an
REL MRS to coincide with the NDI to prevent repeated disassembly of the
shaft; and extending the time required to replace the MRS and revising
calculations for establishing the retirement life. The FAA issued AD
2015-20-12 to prevent MRS structural failure, loss of power to the main
rotor, and subsequent loss of control of the helicopter.
Actions Since AD 2015-20-12 Was Issued
Since the FAA issued AD 2015-20-12, another design re-evaluation of
the MRS was performed and the re-evaluation showed that further
reducing the retirement life for Non-REL MRS is required to address the
unsafe condition.
Additionally, this proposed AD would update the current type
certificate holder information for Model USAF CH-3C, HH-3C, CH-3E, and
HH-3E helicopters from Robinson Air Crane, Inc. to Reynolds Aviation,
as reflected in Type Certificate Data Sheet R00007AT Revision 1, dated
August 25, 2015.
AD 2015-20-12 describes life limits as retirement lives. Retirement
lives and life limits are used interchangeably throughout this AD.
While life limit is the 14 CFR part 43 terminology, the FAA uses
retirement life and life limit in this AD because some of the initial
requirements of this AD have been in place for over a decade.
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.
[[Page 21271]]
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Sikorsky Alert Service Bulletin (ASB) No. 61B-35-
69 Revision A, dated October 10, 2023, which specifies procedures for
determining the total number of accumulated cycles since new for the
MRS, determining REL and Non-REL status, assigning new REL and Non-REL
MRS retirement lives, marking the REL MRS, and annotating the
retirement life of the MRS in the existing helicopter logbook.
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 retain the requirements of AD 2015-20-12,
except the retirement life of a Non-REL MRS. This proposed AD would
require reducing the retirement life of a Non-REL MRS currently
assigned a 13,000-hour TIS retirement life to 7,300 hours TIS. If the
hours TIS on a Non-REL MRS are greater than 7,300 hours TIS and the MRS
is installed, this proposed AD would require removing it from service
at the next main gearbox overhaul. If the hours TIS on a Non-REL MRS
are greater than 7,300 hours TIS, and the MRS is uninstalled or in
overhaul, this proposed AD would require removing it from service. If
the hours TIS on a Non-REL MRS are less than 7,300 hours TIS, this
proposed AD would require removing the MRS from service before
exceeding 7,300 hours TIS.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 76 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:
Estimated costs
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
NDI of an REL MRS..................... 3 work-hours x $85 per $50 $305 $23,180
hour = $255.
Replace/remove an MRS................. 3 work-hours x 85 per 81,216 81,471 6,191,796
hour = 255.
Revise the log card................... 1 work-hour x 85 per 0 85 6,460
hour = 85.
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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 2015-20-12, Amendment 39-18291 (80
FR 63422, October 20, 2015); and
0
b. Adding the following new airworthiness directive:
Various Helicopters: Docket No. FAA-2026-3488; Project Identifier
AD-2024-00583-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by June 5, 2026.
(b) Affected ADs
This AD replaces AD 2015-20-12, Amendment 39-18291 (80 FR 63422,
October 20, 2015).
(c) Applicability
This AD applies to various helicopters, certificated in any
category, identified in paragraphs (c)(1) through (7) of this AD,
with a main rotor shaft (MRS) part number S6135-20640-001, S6135-
20640-002, or S6137-23040-001, installed.
(1) Model CH-3E helicopters; current type certificate holders
include but are not limited to, Glacier Helicopter, Inc. and Siller
Helicopters.
(2) Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and
S-61V helicopters.
(3) Sikorsky Aircraft Model S-61L, S-61N, S-61NM (serial number
(S/N) 61454), and S-61R helicopters.
(4) Model S-61L helicopters; current type certificate holders
include but are not limited to, Carson Helicopters.
(5) Model SH-3A helicopters; current type certificate holders
include but are not limited to, Siller Helicopters.
(6) Model SH-3H helicopters; current type certificate holders
include but are not limited to, Carson Helicopters and Croman
Corporation.
(7) Model USAF CH-3C, CH-3E, HH-3C, and HH-3E helicopters;
current type certificate holders include but are not limited to,
Reynolds Aviation.
(d) Subject
Joint Aircraft System Component (JASC) Code/Air Transport
Association (ATA) of America Code 6320, Main Rotor Gearbox.
(e) Unsafe Condition
This AD was prompted by a design re-evaluation that shows that
the MRS on certain helicopter models requires a lower life limit
based on torque, ground-air-ground (GAG) cycle, and fatigue testing.
The FAA is issuing this AD to detect and correct a fatigue crack in
the MRS. The unsafe condition, if not addressed, could result in a
MRS structural failure, loss of power to the main rotor, and
subsequent loss of control of the helicopter.
[[Page 21272]]
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within 10 hours time-in-service (TIS) after November 24,
2015 (the effective date of AD 2015-20-12):
(i) Create a component history card or equivalent record for
each MRS.
(ii) If there is no record of the hours TIS on an individual
MRS, substitute the helicopter's hours TIS or the helicopter's
transmission hours TIS if both the shaft and transmission were
installed new at the same time.
(iii) If the record of external lift cycles (lift cycles) on an
individual MRS is incomplete, add the known number of lift cycles to
a number calculated by multiplying the number of hours TIS of the
individual MRS by the average lift cycles calculated according to
the instructions in paragraph (h)(1) of this AD or by a factor of
13.6, whichever is higher. An external lift cycle is defined as a
flight cycle in which an external load is picked up, the helicopter
is repositioned (through flight or hover), and the helicopter hovers
and releases the load and departs or lands and departs.
(iv) At the end of each day's operations, record the number of
lift cycles performed and the hours TIS.
(2) Within 250 hours TIS after November 24, 2015 (the effective
date of AD 2015-20-12), determine whether the MRS is a repetitive
external lift (REL) or Non-REL MRS.
(i) Calculate the first moving average of lift cycles by
following the instructions in paragraph (h)(1) of this AD.
(A) If the calculation results in 6 or more lift cycles per hour
TIS, the MRS is an REL MRS.
(B) If the calculation results in less than 6 lift cycles per
hour TIS, the MRS is a Non-REL MRS.
(ii) If the MRS is a Non-REL MRS based on the calculation
performed in accordance with paragraph (g)(2)(i) of this AD,
thereafter at intervals of 50 hours TIS, recalculate the average
lift cycles per hour TIS by following the instructions in paragraph
(h)(2) of this AD.
(iii) Once an MRS is determined to be an REL MRS, you no longer
need to perform the 250-hour TIS moving average calculation, but you
must continue to count and record the lift cycles and number of
hours TIS.
(iv) If an MRS is determined to be an REL MRS, it remains an REL
MRS for the rest of its service life and is subject to the
retirement times for an REL MRS.
(3) Within 1,100 hours TIS after November 24, 2015 (the
effective date of AD 2015-20-12):
(i) Conduct a Non-Destructive Inspection for a crack on each
MRS. If there is a crack in an MRS, before further flight, replace
it with an airworthy MRS.
(ii) If an MRS is determined to be an REL MRS, identify it as an
REL MRS by etching ``REL'' on the outside diameter of the MRS near
the part S/N by following the Accomplishment Instructions, paragraph
3.C., of Sikorsky Alert Service Bulletin No. 61B-35-69 Revision A,
dated October 10, 2023.
(4) Replace each MRS with an airworthy MRS on or before reaching
the revised retirement life as follows:
(i) For an REL MRS that is not modified by following Sikorsky
Customer Service Notice (CSN) No. 6135-10, dated March 18, 1987, and
Sikorsky Service Bulletin (SB) No. 61B35-53, dated December 2, 1981
(unmodified REL MRS), the retirement life is 30,000 lift cycles or
1,500 hours TIS, whichever occurs first.
(ii) For an REL MRS that is modified by following Sikorsky CSN
No. 6135-10, dated March 18, 1987, and Sikorsky SB No. 61B35-53
dated December 2, 1981; or Sikorsky CSN No. 6135-10A and Sikorsky SB
No. 61B35-53A, both Revision A, and both dated April 19, 2004
(modified REL MRS), the retirement life is 30,000 lift cycles or
5,000 hours TIS, whichever occurs first.
(iii) For a Non-REL MRS, within 5 days after the effective date
of this AD, revise the 13,000-hour TIS retirement life to 7,300
hours TIS by recording the new or revised retirement life on the MRS
component history card or equivalent record.
(A) If the hours TIS on the MRS are 7,300 hours TIS or greater
as of the effective date of this AD, and the MRS is installed, at
the next main gearbox overhaul, remove it from service.
(B) If the hours TIS on the MRS are 7,300 hours TIS or greater
as of the effective date of this AD, and the MRS is uninstalled or
in overhaul, before further flight, remove it from service.
(C) If the hours TIS on the MRS are less than 7,300 hours TIS as
of the effective date of the AD, remove the MRS from service before
exceeding 7,300 hours TIS.
(5) Within 5 days after the effective date of this AD, establish
or revise the retirement lives of the MRS as indicated in paragraphs
(g)(4)(i) through (g)(4)(ii) of this AD by recording the new or
revised retirement life on the MRS component history card or
equivalent record.
(6) Within 50 hours TIS after November 24, 2015 (the effective
date of AD 2015-20-12), remove from service any MRS with oversized
(0.8860'' or greater diameter) dowel pin bores.
(h) Calculating Average Lift Cycles per Hour TIS
(1) Calculating the first moving average of lift cycles per hour
TIS. The first moving average calculation is performed on the MRS
assembly when the external lift component history card record
reflects that the MRS assembly has reached its first 250 hours TIS.
To perform the calculation, divide the total number of lift cycles
performed during the first 250 hours TIS by 250. The result will be
the first moving average calculation of lift cycles per hour TIS.
(2) Calculating subsequent moving average of lift cycles per
hour TIS. Subsequent moving average calculations are performed on
the MRS assembly at intervals of 50 hours TIS after the first moving
average calculation. Subtract the total number of lift cycles
performed during the first 50-hour TIS interval used in the previous
moving average calculation from the total number of lift cycles
performed on the MRS assembly during the previous 300 hours TIS.
Divide this result by 250. The result will be the next or subsequent
moving average calculation of lift cycles per hour TIS. (See Note 1
to paragraph (h)(2) of this AD for a sample calculation of
subsequent 50-hour TIS intervals).
Note 1 to paragraph (h)(2) of this AD: Sample calculation for
subsequent 50-hour TIS intervals. Assume the total number of lift
cycles for the first 50-hour TIS interval used in the previous
moving average calculation = 450 lift cycles and the total number of
lift cycles for the previous 300 hours TIS = 2,700 lift cycles. The
subsequent moving average of lift cycles per hour TIS = (2,700--450)
divided by 250 = 9 lift cycles per hour TIS.
(i) Credit for Previous Actions
This paragraph provides credit for the actions identified in
paragraph (g)(3)(ii) of this AD if they were completed before the
effective date of this AD using Sikorsky Alert Service Bulletin No.
61B-35-69, dated April 19, 2004.
(j) 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 (k)(1) of this
AD and email to: <a href="/cdn-cgi/l/email-protection#2465696b67644245450a434b52"><span class="__cf_email__" data-cfemail="cf8e82808c8fa9aeaee1a8a0b9">[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.
(k) 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#dc999f9ef19f938f9cbabdbdf2bbb3aa"><span class="__cf_email__" data-cfemail="d99c9a9bf49a968a99bfb8b8f7beb6af">[email protected]</span></a>.
(2) Material identified in this AD that is not incorporated by
reference contains additional information about the subject of this
AD and is available at the address specified in paragraph (l)(3) of
this AD.
(l) 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 Alert Service Bulletin No. 61B-35-69 Revision A,
dated October 10, 2023.
(ii) [Reserved]
(3) For Sikorsky material identified in this AD, contact a
Sikorsky Field Representative or Sikorsky's Service Engineering
Group at Sikorsky Aircraft Corporation, Mailstop
[[Page 21273]]
K100, 124 Quarry Road, Trumbull, CT 06611; telephone 1-800-946-4337
(1-800-Winged-S); email: <a href="/cdn-cgi/l/email-protection#8bfce8f8d4e8fef8ffd4f8eef9fde2e8eed4eee5eca5ecf9a6f8e2e0cbe7e6e8e4a5e8e4e6"><span class="__cf_email__" data-cfemail="4e392d3d112d3b3d3a113d2b3c38272d2b112b202960293c633d27250e22232d21602d2123">[email protected]</span></a>;
website: <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#93f5e1bdfafde0e3f6f0e7fafcfdd3fdf2e1f2bdf4fce5"><span class="__cf_email__" data-cfemail="e98f9bc780879a998c8a9d808687a987889b88c78e869f">[email protected]</span></a>.
Issued on April 16, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-07720 Filed 4-20-26; 8:45 am]
BILLING CODE 4910-13-P
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</html>Indexed from Federal Register on April 21, 2026.
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