DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0126; Project Identifier MCAI-2020-00266-R;
Amendment 39-21556; AD 2021-10-23]
Airworthiness Directives; Airbus Helicopters Deutschland GmbH
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 D-2
helicopters. This AD was prompted by a report of a broken Titanium (Ti)
bolt. This AD requires removing certain Ti-bolts from service and
prohibits installing these Ti-bolts in a critical area. The FAA is
issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective July 6, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain document listed in this AD as of July 6, 2021.
ADDRESSES: For service information identified in this final rule,
contact Airbus Helicopters, 2701 N Forum Drive, Grand Prairie, TX
75052; telephone (972) 641-0000 or (800) 232-0323; fax (972) 641-3775;
or at https://www.airbus.com/helicopters/services/technical-support.html.
You may view the referenced service information at the
FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood
Pkwy., Room 6N-321, Fort Worth, TX 76177. It is also available at
https://www.regulations.gov by searching for and locating Docket No.
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0126; 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
European Union Aviation Safety Agency (EASA) AD, any service
information that is incorporated by reference, any comments received,
and other information. The street 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
FOR FURTHER INFORMATION CONTACT: Matt Fuller, AD Program Manager,
General Aviation & Rotorcraft Unit, Airworthiness Products Section,
Operational Safety Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX
76177; telephone (817) 222-5110; email email@example.com.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Airbus Helicopters
Deutschland GmbH (AHD) Model MBB-BK 117 D-2 helicopters with a Ti-bolt
part number (P/N) EN3740-060022F marked with manufacturer monogram
``D'' or with an illegible manufacturer monogram, installed on the aft
connection of the tail rotor ball bearing control. The NPRM published
in the Federal Register on March 3, 2021 (86 FR 12294). In the NPRM,
the FAA proposed to require removing any affected Ti-bolt P/N EN3740-
060022F from service. The NPRM also to prohibit installing an affected
Ti-bolt on the aft connection of the ball bearing control of any
helicopter. The NPRM was prompted by EASA AD 2019-0258, dated October
18, 2019 (EASA AD 2019-0258), issued by EASA, which is the Technical
Agent for the Member States of the European Union, to correct an unsafe
condition for Airbus Helicopters Deutschland GmbH (AHD), formerly
Eurocopter Deutschland GmbH, Model MBB-BK117 D-2 helicopters. EASA
advises of a report of a broken Ti-bolt. Subsequent investigation
revealed that an improper heat treatment process was accomplished on a
batch of Ti-bolts, which can lead to hydrogen embrittlement. Hydrogen
embrittlement can make high-strength bolts susceptible to stress
corrosion, pitting, and failure. EASA states that this condition, if
not detected and corrected, could lead to failure of an affected Ti-
bolt installed in a critical location, possibly resulting in reduced
control of the helicopter.
Accordingly, EASA AD 2019-0258 requires a one-time inspection for
Ti-bolt P/N EN3740-060022F marked with manufacturer monogram ``D'' or
with an illegible manufacturer monogram installed on the aft connection
of the tail rotor ball bearing control (ball bearing control) and,
depending on findings, contacting AHD for corrective action. EASA AD
2019-0258 also prohibits the (re)installation of these Ti-bolts.
Discussion of Final Airworthiness Directive
The FAA received no comments on the NPRM or on the determination of
These helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to the FAA's bilateral
agreement with the European Union, EASA has notified the FAA about the
unsafe condition described in its AD. 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 helicopters.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Airbus Helicopters Alert Service Bulletin No. ASB
MBB-BK117 D-2-00A-001, Revision 1, dated October 16, 2019, which
specifies replacing each Ti-bolt P/N EN3740-060022F that is marked with
manufacturer monogram ``D'' or if the manufacturer monogram cannot be
identified with an airworthy Ti-bolt in both locations of the aft
connection of ball bearing control and both high frequency (HF) antenna
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.
Differences Between This AD and the EASA AD
EASA AD 2019-0258 applies to Model MBB-BK117 D-2 helicopters and
requires inspecting for Ti-bolt P/N EN3740-060022F marked with
manufacturer monogram ``D'' or with an illegible manufacturer monogram
installed on the aft connection of the ball bearing control. This AD
applies to Model MBB-BK 117 D-2 helicopters with a Ti-bolt P/N EN3740-
060022F marked with manufacturer monogram ``D'' or with an illegible
manufacturer monogram installed on the aft connection of the ball
bearing control instead. EASA AD 2019-0258 requires contacting AHD for
approved instructions if an affected Ti-bolt is found, whereas this AD
requires removing an affected Ti-bolt from service instead.
Costs of Compliance
The FAA estimates that this AD affects 29 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
Replacing a Ti-bolt takes about 2 work-hours and parts cost about
$100 for an estimated cost of $270 per Ti-bolt.
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 helicopters 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
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 adding the following new airworthiness