[Federal Register Volume 90, Number 225 (Tuesday, November 25, 2025)]
[Rules and Regulations]
[Pages 53210-53215]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-20946]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-0922; Project Identifier MCAI-2024-00650-R;
Amendment 39-23163; AD 2025-20-10]
RIN 2120-AA64
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2021-26-
07, which applies to all Airbus Helicopters Model EC120B helicopters.
AD 2021-26-07 requires performing repetitive inspections of the tail
rotor (TR) hub body and, depending on the inspection results, replacing
certain parts, and accomplishing further inspections. AD 2021-26-07
also requires for certain helicopters removing from service any bolt,
washer, and nut installed on the TR hub body at certain life limits and
replacing them with airworthy parts and accomplishing further
inspections. Additionally, AD 2021-26-07 prohibits the installation of
a certain part-numbered TR hub body unless certain requirements are
met. Since the FAA issued AD 2021-26-07, it was determined that
modifying the link of the TR hub body and splined flange by adding red
paint marks is necessary to enable the detection of any loss of
tightening torque. This AD retains the same repetitive inspections and
corrective actions as AD 2021-26-07 and requires modification of the
link of the TR hub body, which is a terminating action for the
repetitive inspections. This AD also requires repetitive inspections of
the red paint line added during the modification of the link of the TR
hub body for alignment. The FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective December 30, 2025.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of December 30,
2025.
[[Page 53211]]
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2025-0922; 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, the mandatory continuing airworthiness
information (MCAI), 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:
For Airbus Helicopters material identified in this AD,
contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie, TX
75052; phone: (972) 641-0000 or: (800) 232-0323; fax: (972) 641-3775;
website: airbus.com/en/products-services/helicopters/hcare-services/airbusworld.
You may view this material at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N-
321, Fort Worth, TX 76177. For information on the availability of this
material at the FAA, call (817) 222-5110. It is also available at
regulations.gov under Docket No. FAA-2025-0922.
FOR FURTHER INFORMATION CONTACT: Camille Seay, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (817) 222-5149; email: [email protected].
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2021-26-07, Amendment 39-21866 (86 FR
72829, December 23, 2021) (AD 2021-26-07), which applied to all Airbus
Helicopters Model EC120B helicopters.
The NPRM published in the Federal Register on June 25, 2025 (90 FR
26951). The NPRM was prompted by European Union Aviation Safety Agency
(EASA) AD 2024-0209, dated October 28, 2024 (EASA AD 2024-0209) (also
referred to as the MCAI). EASA, the Technical Agent for the Member
States of the European Union, issued EASA AD 2024-0209 to address loss
of tightening torque in the interface between the TR hub body and
splined flange, which creates the risk of crack initiation from a
fretting area located on the TR hub body and splined flange or on the
TR hub body and flange bolts. The MCAI states that Airbus Helicopters
developed a modification, which consists of adding a line of red paint
on each bolt and each nut of the link between the TR hub and the
splined flange. The MCAI further states that an Airworthiness
Limitations Section task was published for checking alignment of the
marks.
The FAA is issuing this AD to detect cracking and fretting of the
TR hub body, which, if not addressed, could lead to loss of the TR
drive, and consequent loss of yaw control of the helicopter.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-0922.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of
the costs.
Conclusion
These products have been approved by the civil aviation authority
of another country and are approved for operation in the United States.
Pursuant to the FAA's bilateral agreement with this State of Design
Authority, that authority has notified the FAA of the unsafe condition
described in the MCAI referenced above. The FAA reviewed the relevant
data and determined that air safety requires adopting this 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 Airbus Helicopters Emergency Alert Service
Bulletin 05A020, Revision 3, dated September 19, 2024 (EASB 05A0020 Rev
3), which specifies procedures for repetitive inspections of the TR hub
body for cracks and the TR spline flange for cracks and fretting and
the appropriate corrective actions to include replacing the hub body
and the splined flange. EASB 05A0020 Rev. 3 also excludes helicopters
that have complied with Airbus Helicopters Alert Service Bulletin
EC120-64-21-0001, Issue 001, dated September 19, 2024 (ASB EC120-64-21-
0001) from its effectivity and limits the effectivity for ``non
installed equipment or parts''.
The FAA also reviewed ASB EC120-64-21-0001, which specifies
procedures for inspecting the torque applied on the nut of the link
between the TR hub and the splined flange, and depending on the
inspection results, applying torque and replacing parts. ASB EC120-64-
21-0001 also specifies procedures for applying a red paint line on the
screw, nut, washer, TR hub, and splined flange.
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.
Differences Between This AD and the MCAI
EASA AD 2024-0209 allows a non-cumulative tolerance of 100 FH
[flight hours] to be applied to the compliance times to allow for
synchronization of the required inspections with other maintenance
tasks, whereas this AD does not allow a non-cumulative tolerance to be
applied to the compliance times.
Costs of Compliance
The FAA estimates that this AD affects 70 helicopters of U.S.
registry. Labor rates are estimated at $85 per hour. Based on these
numbers, the FAA estimates the following costs to comply with this AD.
Visually inspecting a TR hub body for a crack takes 0.25 work-hour
for an estimated cost of $22 per helicopter and $1,540 for the U.S.
fleet.
Visually inspecting a TR spline flange for corrosion, impacts,
fretting, wear, and a crack takes 0.25 work-hour for an estimated cost
of $22 per helicopter and $1,540 for the U.S. fleet.
Replacing a T/R hub body bolt, washer, and nut takes 0.5 work-hour
and parts cost $25 (per hardware set) for an estimated cost of $68 per
helicopter.
Inspecting torque and adding a red paint line on each bolt and each
nut takes 4 work-hours for an estimated cost of $340 per helicopter and
$23,800 for the U.S. fleet.
If required, replacing a TR hub body takes 2 work-hours, and parts
cost $16,485 for an estimated cost of $16,655 per helicopter.
If required, replacing a TR spline flange takes 0.5 work-hour, and
parts cost $2,950 for an estimated cost of $2,993 per helicopter.
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
[[Page 53212]]
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
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 2021-26-07, Amendment 39-21866 (86
FR 72829, December 23, 2021); and
0
b. Adding the following new airworthiness directive:
2025-20-10 Airbus Helicopters: Amendment 39-23163; Docket No. FAA-
2025-0922; Project Identifier MCAI-2024-00650-R.
(a) Effective Date
This airworthiness directive (AD) is effective December 30,
2025.
(b) Affected ADs
This AD replaces AD 2021-26-07, Amendment 39-21866 (86 FR 72829,
December 23, 2021).
(c) Applicability
This AD applies to Airbus Helicopters Model EC120B helicopters,
certificated in any category.
(d) Subject
Joint Aircraft System Component (JASC) Code 6422, Tail Rotor
System.
(e) Unsafe Condition
This AD was prompted by analysis of recurrent loss of tightening
torque on several attachment bolts on the tail rotor (TR) hub body.
The FAA is issuing this AD to detect cracking and fretting of the TR
hub body. The unsafe condition, if not addressed, could lead to loss
of the TR drive, and consequent loss of yaw control of the
helicopter.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Required Actions
(1) Within 15 hours time-in-service (TIS) or 7 days, whichever
occurs first after the effective date of this AD, and thereafter at
intervals not to exceed 15 hours TIS, using a light source and
mirror, visually inspect TR hub body part number (P/N) C642A0100103
for a crack in the entire inspection area depicted in Figure 1 of
Airbus Helicopters Emergency Alert Service Bulletin 05A020 Revision
3, dated September 19, 2024. If any crack is found, before further
flight, perform the actions in paragraphs (g)(1)(i) and (ii) of this
AD.
(i) Remove the TR hub body and each bolt, washer, and nut
installed on the TR hub body from service and replace with airworthy
parts.
(ii) Inspect the TR splined flange for corrosion, impacts,
fretting, wear, and a crack in the areas identified in Figure 2 to
paragraph (g)(1)(ii) of this AD. If the condition of the part
(including corrosion, impacts, fretting, wear, or cracks) exceeds
the criteria as specified in Figure 1 to paragraph (g)(1)(ii) of
this AD, before further flight, remove the splined flange from
service and replace with an airworthy part.
Note 1 to paragraph (g)(1)(ii): You may refer to ``Detailed
Check-Splined Flange,'' Task 64-21-00, 6-5, Airbus Aircraft
Maintenance Manual (AMM), dated October 15, 2020, which pertains to
the TR splined flange inspection.
Figure 1 to paragraph (g)(1)(ii)--Inspection Criteria for TR Splined
Flange
[[Page 53213]]
[GRAPHIC] [TIFF OMITTED] TR25NO25.300
Figure 2 to paragraph (g)(1)(ii)--Inpsection Area of Tail Rotor Splined
Flange
[[Page 53214]]
[GRAPHIC] [TIFF OMITTED] TR25NO25.301
(2) For helicopters with 9,000 or more total hours TIS or with
unknown total hours TIS, within 15 hours TIS or 7 days, whichever
occurs first after the effective date of this AD, and thereafter at
intervals not to exceed 1,000 hours TIS, remove each bolt washer,
and nut installed on the TR hub body from service and replace with
airworthy parts and perform the actions in paragraph (g)(1)(ii) of
this AD.
(3) For helicopters with less than 9,000 total hours TIS, within
1,000 hours TIS or before accumulating 9,000 total hours TIS,
whichever occurs first after the effective date of this AD, and
thereafter at intervals not to exceed 1,000 hours TIS, remove each
bolt, washer, and nut installed on the TR hub body from service and
replace with airworthy parts and perform the actions in paragraph
(g)(1)(ii) of this AD.
(4) Within 24 months after the effective date of this AD,
inspect the torque on the nut of the TR hub body in accordance with
paragraph 4.1.2 of Airbus Helicopters Alert Service Bulletin ASB
EC120-64-21-0001, Issue 001, dated September 19, 2024.
(i) If the torque is not within allowable limits, before further
flight, remove the nut on the TR hub body from service and replace
it with an airworthy nut; and accomplish the actions in paragraph
(g)(4)(ii) of this AD.
(ii) If the torque is within allowable limits, before further
flight, using polyurethane paint, apply a red paint line to the bolt
and washer on the TR hub body; and apply a red paint line to the nut
and washer on the splined flange. These actions terminate the
repetitive inspections and replacements required by paragraphs
(g)(1) through (3) of this AD.
(5) Within 100 hours TIS or 12 months, whichever occurs first
after the action required in paragraph (g)(4)(ii) of this AD, and
thereafter at intervals not to exceed 100 hours TIS or 12 months,
whichever occurs first, inspect the red paint line for alignment. If
the red paint line is misaligned, before further flight, perform the
actions as specified in paragraphs (g)(4)(i) of this AD.
(h) Parts Installation Limitations
As of the effective date of this AD, do not install on any
helicopter a TR hub body P/N C642A0100103 or a splined flange unless
[[Page 53215]]
the part is new (zero hours TIS) or has passed the inspection
requirements required by paragraph (g)(1) of this AD.
(i) Credit for Previous Actions
This paragraph provides credit for the initial instance of the
actions required by paragraphs (g)(1) through (3) of this AD, if
those actions were performed before the effective date of this AD in
accordance with Airbus Helicopters Emergency Alert Service Bulletin
05A020 Revision 0, dated October 29, 2019; Revision 1, dated
November 8, 2019; or Revision 2, dated February 8, 2021.
(j) Alternative Methods of Compliance (AMOCs)
(1) The Manager, International Validation 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 responsible Flight
Standards Office, as appropriate. If sending information directly to
the manager of the International Validation Branch, send it to the
attention of the person identified in paragraph (k)(1) of this AD
and email to: [email protected].
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the responsible Flight Standards Office. The following provisions
also apply to this AD.
(k) Additional Information
(1) For more information about this AD, contact Camille Seay,
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410,
Westbury, NY 11590; phone: (817) 222-5149; email:
[email protected].
(2) For Airbus Helicopters material identified in this AD that
is not incorporated by reference, can be found at the contact
information identified 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) Airbus Helicopters Emergency Alert Service Bulletin 05A020,
Revision 3, dated September 19, 2024.
(ii) Airbus Helicopters Alert Service Bulletin EC120-64-21-0001,
Issue 001, dated September 19, 2024.
(3) For Airbus Helicopters material identified in this AD,
contact Airbus Helicopters, 2701 North Forum Drive, Grand Prairie,
TX 75052; phone: (972) 641-0000 or: (800) 232-0323; fax: (972) 641-
3775; website: airbus.com/en/products-services/helicopters/hcare-services/airbusworld.
(4) You may view this material at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N-
321, 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 www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
Issued on November 20, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2025-20946 Filed 11-24-25; 8:45 am]
BILLING CODE 4910-13-P