Rule2026-15978
Airworthiness Directives; Various Helicopters
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 6, 2026
Effective
September 10, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is superseding Airworthiness Directive (AD) 2015-20-12 for certain Sikorsky Aircraft Corporation Model S-61A, D, E, L, N, NM, 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 required performing calculations to determine whether the main rotor shaft (MRS) was used in repetitive external lift (REL) operations or non-REL operations, performing a nondestructive inspection (NDI) of the REL MRS for cracks and, depending on the results of the NDI, replacing the MRS, marking any REL MRS at the time of the NDI, establishing retirement lives for each REL MRS, and removing from service 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 AD retains some of the requirements of AD 2015-20-12, and also reduces the retirement life for a certain MRS installed on certain helicopters and updates the type certificate holder name for some of the affected helicopter models. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 150 (Thursday, August 6, 2026)</title>
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[Federal Register Volume 91, Number 150 (Thursday, August 6, 2026)]
[Rules and Regulations]
[Pages 50696-50698]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-15978]
[[Page 50696]]
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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;
Amendment 39-23429; AD 2026-15-17]
RIN 2120-AA64
Airworthiness Directives; Various Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2015-20-12
for certain Sikorsky Aircraft Corporation Model S-61A, D, E, L, N, NM,
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 required
performing calculations to determine whether the main rotor shaft (MRS)
was used in repetitive external lift (REL) operations or non-REL
operations, performing a nondestructive inspection (NDI) of the REL MRS
for cracks and, depending on the results of the NDI, replacing the MRS,
marking any REL MRS at the time of the NDI, establishing retirement
lives for each REL MRS, and removing from service 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 AD retains some of the requirements of AD
2015-20-12, and also reduces the retirement life for a certain MRS
installed on certain helicopters and updates the type certificate
holder name for some of the affected helicopter models. The FAA is
issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective September 10, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of September
10, 2026.
ADDRESSES:
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 final rule, any comments received, and other
information. The address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
<bullet> For Sikorsky material identified in this AD, contact a
Sikorsky Field Representative or Sikorsky's Service Engineering Group
at Sikorsky Aircraft Corporation, Mailstop K100, 124 Quarry Road,
Trumbull, CT 06611; phone: (800) 946-4337 (1-800-Winged-S); email:
<a href="/cdn-cgi/l/email-protection#106773634f736563644f637562667973754f757e773e77623d63797b507c7d737f3e737f7d"><span class="__cf_email__" data-cfemail="443327371b273137301b372136322d27211b212a236a233669372d2f042829272b6a272b29">[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#365355541b5559457650575718515940"><span class="__cf_email__" data-cfemail="b4d1d7d699d7dbc7f4d2d5d59ad3dbc2">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2015-20-12, Amendment 39-18291 (80 FR
63422, October 20, 2015) (AD 2015-20-12). AD 2015-20-12 applied to
certain 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. The NPRM was published in the Federal
Register on April 21, 2026 (91 FR 21269). The NPRM was prompted by the
manufacturer's 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. In the NPRM, the FAA
proposed to retain the requirements of AD 2015-20-12, except the
retirement life of a Non-REL MRS. The FAA also proposed to require
reducing the retirement life of a Non-REL MRS currently assigned a
13,000-hour time-in-service (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, the FAA proposed to 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, the FAA proposed to require removing it from service. If
the hours TIS on a Non-REL MRS are less than 7,300 hours TIS, the FAA
proposed to require removing the MRS from service before exceeding
7,300 hours TIS.
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.
The FAA is issuing this AD to address the unsafe condition on these
products.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of
the costs.
Conclusion
The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting the AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, this
AD is adopted as proposed in the NPRM. None of the changes will
increase the economic burden on any operator.
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.
Costs of Compliance
The FAA estimates that this AD affects 76 helicopters of U.S.
registry.
The FAA estimates the following costs to comply with this AD:
[[Page 50697]]
Estimated Costs
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Cost per Cost on U.S.
Action Labor rate Parts cost product operators
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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 hour 81,471 81,471 6,191,796
= 255.
Revise the log card.................... 1 work-hour x 85 per hour 0 85 6,460
= 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
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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
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
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:
2026-15-17 Various Helicopters: Amendment 39-23429; Docket No. FAA-
2026-3488; Project Identifier AD-2024-00583-R.
(a) Effective Date
This airworthiness directive (AD) is effective September 10,
2026.
(b) Affected ADs
This AD replaces AD 2015-20-12, Amendment 39-18291 (80 FR 63422,
October 20, 2015) (AD 2015-20-12).
(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.
(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
[[Page 50698]]
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): 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.
61B35-69, 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#fabbb7b5b9ba9c9b9bd49d958c"><span class="__cf_email__" data-cfemail="30717d7f73705651511e575f46">[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#b9dcdadb94dad6caf9dfd8d897ded6cf"><span class="__cf_email__" data-cfemail="ee8b8d8cc38d819dae888f8fc0898198">[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 K100, 124 Quarry
Road, Trumbull, CT 06611; phone: (800) 946-4337 (1-800-Winged-S);
email: <a href="/cdn-cgi/l/email-protection#e7908494b884929493b8948295918e8482b8828980c98095ca948e8ca78b8a8488c984888a"><span class="__cf_email__" data-cfemail="83f4e0f0dce0f6f0f7dcf0e6f1f5eae0e6dce6ede4ade4f1aef0eae8c3efeee0ecade0ecee">[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/">www.archives.gov/federal-register/cfr/</a>ibr-locations or email <a href="/cdn-cgi/l/email-protection#4325316d2a2d30332620372a2c2d032d2231226d242c35"><span class="__cf_email__" data-cfemail="81e7f3afe8eff2f1e4e2f5e8eeefc1efe0f3e0afe6eef7">[email protected]</span></a>.
Issued on July 28, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-15978 Filed 8-5-26; 8:45 am]
BILLING CODE 4910-13-P
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