DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-1123; Project Identifier MCAI-2020-01294-R;
Amendment 39-21448; AD 2021-05-05]
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2016-23-
05, which applied to certain Airbus Helicopters Model SA-365N1, AS-
365N2, AS 365 N3, SA-366G1, EC 155B, and EC155B1 helicopters. AD 2016-
23-05 required repetitive checks of the oil level of the tail rotor
gearbox and, if necessary, filling the oil to the maximum level; and
replacement of a certain control rod double bearing (bearing) with a
new bearing. This AD retains the requirements of AD 2016-23-05 and also
requires modifying the helicopter by replacing the tail gearbox (TGB)
control shaft guide bushes; repetitive inspections of the TGB magnetic
plug and corrective actions if necessary; repetitive replacements of
the bearing; and modifying the helicopter by replacing the TGB; as
specified in a European Aviation Safety Agency (now European Union
Aviation Safety Agency) (EASA) AD, which is incorporated by reference.
This AD also adds helicopters to the applicability. This AD was
prompted by reports of occurrences of loss of yaw control due to
failure of the TGB bearing. The FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective April 16, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of April 16,
ADDRESSES: For material incorporated by reference (IBR) in this
contact the EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany;
telephone +49 221 8999 000; email ADs@easa.europa.eu; internet
www.easa.europa.eu. You may find this material on the EASA website at
https://ad.easa.europa.eu. You may view this material 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. It is also available in
the AD docket on the internet at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-1123.
Examining the AD Docket
You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2020-
1123; 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: Kathleen Arrigotti, Aviation Safety
Engineer, Large Aircraft Section, International Validation Branch, FAA,
2200 South 216th St., Des Moines, WA 98198; telephone and fax 206-231-
3218; email firstname.lastname@example.org.
The EASA, which is the Technical Agent for the Member States of the
European Union, has issued EASA AD 2017-0125, dated July 21, 2017 (EASA
AD 2017-0125) (also referred to as the Mandatory Continuing
Airworthiness Information, or the MCAI), to correct an unsafe condition
for all Airbus Helicopters Model SA 365 N1, AS 365 N2, AS 365 N3, SA
366 G1, EC 155 B, and EC 155 B1 helicopters. EASA AD 2017-0125
supersedes EASA AD 2017-0007, dated January 13, 2017, which superseded
EASA AD 2016-0097R1, dated May 25, 2016 (which corresponds to FAA AD
2016-23-05). EASA AD 2017-0125 adds helicopters to the applicability,
adds repetitive inspections of the magnetic plug after bearing
replacement, requires the use of the revised Airbus Helicopters Alert
Service Bulletin (ASB) instructions, and requires replacement of the
TGB with a modified unit, which terminates the repetitive inspections.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2016-23-05, Amendment 39-18712 (81 FR
85126, November 25, 2016) (AD 2016-23-05). AD 2016-23-05 applied to
certain Airbus Helicopters Model SA-365N1, AS-365N2, AS 365 N3, SA-
366G1, EC 155B, and EC155B1 helicopters. The NPRM published in the
Federal Register on December 14, 2020 (85 FR 80689). The NPRM was
prompted by a determination that additional inspections, replacements,
and modifications are necessary to address the unsafe condition. The
NPRM proposed to retain the requirements of AD 2016-23-05 and also
require modifying the helicopter by replacing the TGB control shaft
guide bushes; repetitive inspections of the TGB magnetic plug and
corrective actions if necessary; repetitive replacements of the
bearing; and modifying the helicopter by replacing the TGB; as
specified in an EASA AD. The NPRM also proposed to add helicopters to
The FAA is issuing this AD to address damage to the bearing, which
could result in end play, loss of tail rotor pitch control, and
subsequent loss of control of the helicopter. See the MCAI for
additional background information.
The FAA gave the public the opportunity to participate in
developing this final rule. The FAA received no comments on the NPRM or
on the determination of the cost to the public.
Update to the Costs of Compliance
The FAA has updated the costs for the new required actions and on-
condition actions based on data received since the NPRM was issued.
The FAA reviewed the relevant data and determined that air safety
and the public interest require adopting this final rule as proposed,
except for minor editorial changes. The FAA has determined that these
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
EASA AD 2017-0125 describes procedures for modifying the helicopter
by replacing TGB control shaft guide bushes, repetitive inspections
(checks) of the oil level of the tail rotor gearbox and, if necessary,
filling the oil to the maximum level, repetitive inspections of the TGB
magnetic plug for the presence of particles and corrective actions if
necessary (corrective actions include removing the TGB, complying with
certain work cards to address particles and other conditions such as
abrasions, scales, flakes, and splinters, and replacing the bearing),
repetitive replacements of the bearing; and modifying the helicopter by
replacing the TGB.
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.
Explanation of Retained Requirements
Although this AD does not explicitly restate the requirements of AD
2016-23-05, this AD retains certain requirements of AD 2016-23-05.
Those requirements are referenced in paragraphs (2) and (5) of EASA AD
2017-0125, which, in turn, is referenced in paragraph (g) of this AD.
Costs of Compliance
The FAA estimates that this AD affects 52 helicopters of U.S.
registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs for Required Actions
||Cost per product
||Cost on U.S. operators
|Retained actions from AD 2016-23-05
||17 work-hours x $85 per hour
||71 work-hours x $85 per hour
||Up to $155,300
||Up to $161,335
||Up to $8,389,420
Estimated Costs for Optional Actions
||Cost per product
|Up to 8 work-hours x $85 per
hour = $680
Estimated Costs of On-Condition
||Cost per product
|Up to 4 work-hours x $85 per
hour = $340
||Up to $1,395
||Up to $1,735
According to the manufacturer, some
or all of the costs of this AD
may be covered under warranty, thereby reducing the cost impact on
affected operators. The FAA does not control warranty coverage for
affected operators. As a result, the FAA has included all known costs
in this cost estimate.
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.
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
(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
Adoption of 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 removing Airworthiness Directive (AD)
2016-23-05, Amendment 39-18712 (81 FR 85126, November 25, 2016), and
adding the following new AD: