DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0465; Project Identifier AD-2022-00330-R;
Amendment 39-22288; AD 2022-27-03]
RIN 2120-AA64

Airworthiness Directives; Leonardo S.p.a. Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2021-20-10
for certain Leonardo S.p.a. Model AB139 and AW139 helicopters. AD 2021-
20-10 required removing from service a certain part-numbered main
gearbox (MGB) spherical bearing lock nut (lock nut) that is installed
on certain part-numbered MGBs and replacing it with a newly designed
MGB lock nut. AD 2021-20-10 also prohibited installing any MGB with the
affected MGB lock nut and prohibited installing any affected MGB lock
nut on any helicopter. Since the FAA issued AD 2021-20-10, it was
discovered that a part number (P/N) was incorrectly listed and that the
applicability needed to be clarified. This AD retains the requirements
of AD 2021-20-10 and clarifies the applicability. The FAA is issuing
this AD to address the unsafe condition on these products.

DATES: This AD is effective January 31, 2023.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of November 22,
2021 (86 FR 57574, October 18, 2021).

ADDRESSES: For service information identified in this final rule,
contact Leonardo S.p.a. Helicopters, Emanuele Bufano, Head of
Airworthiness, Viale G. Agusta 520, 21017 C. Costa di Samarate (Va)
Italy; telephone +39-0331-225074; fax +39-0331-229046; or at
customerportal.leonardocompany.com/en-US/. 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. Service information that is incorporated by reference is also
available at regulations.gov by searching for and locating Docket No.
FAA-2022-0465.

Examining the AD Docket

You may examine the AD docket at regulations.govby searching for
and locating Docket No. FAA-2022-0465; 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.

FOR FURTHER INFORMATION CONTACT: Kristi Bradley, Program Manager, COS
Program Management Section, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 10101 Hillwood Pkwy., Fort Worth, TX
76177; telephone (817) 222-5110; email kristin.bradley@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2021-20-10, Amendment 39-21748 (86 FR
57574, October 18, 2021) (AD 2021-20-10). AD 2021-20-10 applied to
Leonardo S.p.a. Model AB139 and AW139 helicopters, without MGB lock nut
P/N 3G6320A09152 installed and with MGB P/N 3G6320A00131, 3G6320A00132,
3G6320A00133, 3G6320A00134, 3G6320A00135, 3G6320A00136, 3G6320A22031,
4G6320A00132, or 4G6320A00133 installed; or MGB P/N 3G320A00133 with
serial number (S/N) M23 installed, or MGB P/N 3G6320A00134, with S/N
M6, N76, N92, P124, P129, P131, P162, P184, Q230, Q243, Q249, R272,
V21, V39, V96, V163, V211, V241, V272, V281, V384, V386, or V622
installed; or MGB P/N 3G6320A00136 with S/N AW1, AW2, AW3, AW5, or AW10
installed.
AD 2021-20-10 required, within 100 hours time-in-service (TIS), or
during the next scheduled MGB overhaul, whichever occurs first after
the effective date of the AD, removing a certain part-numbered MGB lock nut from
service and replacing it with a different part-numbered MGB lock nut.
AD 2021-20-10 also prohibited installing an MGB having an affected MGB
lock nut on any helicopter and also prohibited installing an affected
MGB lock nut on any helicopter as of the effective date of the AD.
AD 2021-20-10 was prompted by a series of EASA ADs beginning with
EASA AD 2019-0036, dated February 15, 2019 (EASA AD 2019-0036), issued
by EASA, which is the Technical Agent for the Member States of the
European Union, to correct an unsafe condition for all serial-numbered
Leonardo S.p.a. Helicopters (formerly Finmeccanica S.p.A,
AgustaWestland S.p.A., Agusta S.p.A.; and AgustaWestland Philadelphia
Corporation, formerly Agusta Aerospace Corporation) Model AB139 and
AW139 helicopters. EASA advised that an occurrence was reported of a
cracked MGB lock nut P/N 3G6310A09151, which is used to keep the
planetary gears in position. EASA AD 2019-0036 required replacing each
MGB lock nut with an airworthy MGB lock nut. EASA advised this
condition, if not detected and corrected, could lead to failure of the
MGB planetary gears, resulting in loss of control of the helicopter.
After EASA issued EASA AD 2019-0036, an additional occurrence was
reported of a cracked MGB lock nut P/N 3G6320A09151. Accordingly, EASA
superseded EASA AD 2019-0036 with EASA AD 2019-0174, dated July 18,
2019 (EASA AD 2019-0174), which retained the requirements of EASA AD
2019-0036 but reduced the compliance times. After EASA issued EASA AD
2019-0174, Leonardo Helicopters issued Alert Service Bulletin No. 139-
609, dated December 18, 2019, to provide instructions for replacing the
affected MGB lock nut with MGB lock nut P/N 3G6320A09152, which has a
redesigned flange reducing the stress at the bearing nut locations
where cracks were detected.
Accordingly, EASA then issued EASA AD 2020-0011, dated January 29,
2020, and corrected January 30, 2020 (EASA AD 2020-0011), which
superseded EASA AD 2019-0174, and partially retained the requirements
of EASA AD 2019-0174. EASA AD 2020-0011 revised the compliance times in
EASA AD 2019-0174, required replacing each affected MGB lock nut with a
newly designed MGB lock nut, and prohibited installing an affected MGB
on any helicopter. After EASA issued EASA AD 2020-0011, EASA identified
certain MGB part numbers that were inadvertently categorized
incorrectly and therefore listed in the wrong group of helicopters.
Accordingly, EASA issued EASA AD 2020-0011R1, dated November 20, 2020
(EASA AD 2020-011R1), thereby revising EASA AD 2020-0011. EASA AD 2020-
0011R1 retained the requirements of EASA AD 2020-0011 and corrected
Appendix 1 of EASA AD 2020-0011.
After EASA issued EASA AD 2020-0011R1, Leonardo Helicopters issued
Alert Service Bulletin No. 139-609, Revision A, dated April 13, 2021,
which identifies an additional part-numbered MGB, which is also
affected by the unsafe condition. Accordingly, EASA superseded EASA AD
2020-0011R1 with EASA AD 2021-0121, dated May 4, 2021 (EASA AD 2021-
0121). EASA AD 2021-0121 adds an additional part-numbered MGB with a
certain S/N to the list of affected parts. EASA AD 2021-0121 retains
the requirements of EASA AD 2020-0011R1, and corrects Table 1 and
Appendix 1 of EASA AD 2020-0011R1.
Accordingly, EASA AD 2021-0121 requires replacing each affected MGB
lock nut with a newly designed MGB lock nut, and prohibits installing
an affected MGB on any helicopter.
The NPRM published in the Federal Register on April 20, 2022 (87 FR
23477). The NPRM was prompted by the discovery that MGB P/N
3G6320A00133 was incorrectly listed as MGB P/N 3G320A00133 in both the
preamble and applicability paragraph of AD 2021-20-10. Also, the FAA
determined that all MGBs, regardless of S/N, are affected by the unsafe
condition. Therefore, the NPRM proposed to remove any reference to S/Ns
in the applicability. In addition, the NPRM included the total U.S.
fleet costs, which were inadvertently excluded in AD 2021-20-10. In the
NPRM, the FAA also proposed to retain all of the requirements of AD
2021-20-10.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from three commenters. The commenters
were Leonardo Helicopters, Bristow Group, and Chevron Aviation. All
commenters requested a change to the compliance time and two made a
statement concerning who can perform the service task. The following
presents the comments received on the NPRM and the FAA's response to
each comment.

Requests To Change the Compliance Time To Upgrade the MGB Lock Nuts

All commenters referred to an FAA-approved global Alternative
Method of Compliance (AMOC) to AD 2021-20-10 and two commenters
requested that the FAA change the proposed AD's compliance time to
align with the global AMOC. The other commenter specifically requested
that the compliance time approved in the global AMOC of 28,000 landings
or during the next scheduled MGB overhaul be incorporated into the
compliance time of the proposed AD.
The FAA agrees; however, instead of revising the Required Actions
paragraph, the FAA has revised the AMOC paragraph by allowing the AMOC
previously approved for AD 2021-20-10 as an approved AMOC for the
corresponding requirements in paragraph (g) of this AD.

Required Actions

Two commenters noted that replacing the lock nut can only be
performed by Leonardo at the overhaul level, but requested no change to
the required actions of the proposed AD; the FAA, therefore, made no
changes in this regard.

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,
including correcting a part number in paragraph (g)(2) of the required
actions, and any other changes described previously, this AD is adopted
as proposed in the NPRM. None of the changes will increase the economic
burden on any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Leonardo Helicopters Alert Service Bulletin No.
139-609, Revision A, dated April 13, 2021, which the Director of the
Federal Register approved for incorporation by reference as of November
22, 2021 (86 FR 57574, October 18, 2021).
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.

Other Related Service Information

The FAA also reviewed Leonardo Helicopters Alert Service Bulletin
No. 139-567, Revision B, dated October 18, 2019, which provides
additional information for replacing the MGB lock nut.

Differences Between This AD and EASA AD 2021-0121

EASA AD 2021-0121 requires a compliance time based on number of
landings, whereas this AD requires a compliance time based on hours
TIS. The service information referenced in EASA AD 2021-0121 requires
submitting certain information and parts to Leonardo, whereas this AD
does not. EASA AD 2021-0121 applies to all serial-numbered Model AB139
and AW139 helicopters, whereas this AD applies to all Model AB139 and
AW139 helicopters, regardless of S/N, with a certain part-numbered MGB
lock nut and MGB installed.

Costs of Compliance

The FAA estimates that this AD affects 130 helicopters of U.S.
Registry. Labor rates are estimated at $85 per work-hour. Based on
these numbers, the FAA estimates the following costs to comply with
this AD.
Replacing each affected MGB lock nut with a newly designed MGB lock
nut takes about 190 work-hours (during next MGB overhaul) and parts
cost about $7,600 for an estimated cost of $23,750 per helicopter and
$3,087,500 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.

Regulatory Findings

The FAA has determined that 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

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:

a. Removing Airworthiness Directive 2021-20-10, Amendment 39-21748 (86
FR 57574, October 18, 2021); and

b. Adding the following new airworthiness directive: