DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1085; Product Identifier 2016-SW-094-AD; Amendment
39-19603; AD 2019-06-05]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters Deutschland GmbH Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: We are adopting a new airworthiness directive (AD) for Airbus
Helicopters Deutschland GmbH (Airbus Helicopters) Model MBB-BK 117 A-1,
MBB-BK 117A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, MBB-BK
117 C-1, and MBB-BK 117 C-2 helicopters. This AD requires repetitive
inspections of the tail rotor (T/R) gearbox housing. This AD was
prompted by a report that a crack was found in a T/R gearbox housing.
The actions of this AD are intended to correct an unsafe condition on
these products.

DATES: This AD is effective May 7, 2019.
The Director of the Federal Register approved the incorporation by
reference of certain documents listed in this AD as of May 7, 2019.

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 http://www.helicopters.airbus.com/website/en/ref/Technical-Support_
73.html. You may review 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
on the internet at http://www.regulations.gov by searching for and
locating Docket No. FAA-2017-1085.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2017-
1085; 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 AD, the European Aviation Safety Agency (EASA) AD, any
incorporated-by-reference service information, the economic evaluation,
any comments received, and other information. The street address for
Docket Operations (phone: 800-647-5527) 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: David Hatfield, Aviation Safety
Engineer, Safety Management Section, Rotorcraft Standards Branch, FAA,
10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-5110;
email david.hatfield@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

On September 10, 2018, at 83 FR 45578, the Federal Register
published our notice of proposed rulemaking (NPRM), which proposed to
amend 14 CFR part 39 by adding an AD that would apply to Airbus
Helicopters Model MBB-BK 117 A-1, MBB-BK 117A-3, MBB-BK 117 A-4, MBB-BK
117 B-1, MBB-BK 117 B-2, MBB-BK 117 C-1, and MBB-BK 117 C-2
helicopters. The NPRM proposed to require a repetitive cleaning and
visual inspection of the T/R gearbox housing for a crack, and replacing
the T/R gearbox if there is a crack. The proposed requirements were
intended to detect a crack in a T/R gearbox housing, which could result
in the loss of the T/R gearbox and subsequent loss of helicopter
control.
The NPRM was prompted by EASA AD No. 2016-0134, dated July 8, 2016,
issued by EASA, which is the Technical Agent for the Member States of
the European Union, to correct an unsafe condition for Airbus
Helicopters Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-
BK 117 B-1, MBB-BK 117 B-2, MBB-BK 117 C-1, MBB BK 117 C-2, and MBB-BK
117 C-2e helicopters. EASA advises that a crack was found in the T/R
gearbox housing of a Model MBB-BK117 C-2 helicopter. According to EASA,
investigations determined high vibrations caused by T/R imbalance were
a contributing factor to the crack. EASA states that this condition, if
not detected and corrected, could lead to the loss of the T/R gearbox
and subsequent loss of control of the helicopter. As a result, the EASA
AD requires repetitive inspections of the T/R gearbox housing and
replacing the housing if a crack is found.

Comments

We gave the public the opportunity to participate in developing
this AD, but we did not receive any comments on the NPRM.

FAA's Determination

These helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to our bilateral agreement
with the European Union, EASA has notified us of the unsafe condition
described in the EASA AD. We are issuing this AD because we evaluated
all information provided by EASA and determined the unsafe condition
exists and is likely to exist or develop on other helicopters of these
same type designs and that air safety and the public interest require
adopting the AD requirements as proposed.

Differences Between This AD and the EASA AD

The EASA AD applies to Model MBB-BK117 C-2e helicopters, and this
AD does not because it is not an FAA type-certificated model. The EASA
AD allows a non-cumulative tolerance of 10 hours time-in-service for
the inspections, and this AD does not. The EASA AD requires performing
the inspection after a certain maintenance action and before a T/R
gearbox housing is installed, and this AD does not.

Related Service Information Under 1 CFR Part 51

We reviewed Airbus Helicopters Alert Service Bulletin (ASB) MBB-
BK117-30A-119, Revision 0, dated May 24, 2016, for Model MBB-BK 117 A-
1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and
MBB-BK 117 C-1 helicopters and ASB MBB-BK117 C-2-65A-007, Revision 0,
dated May 24, 2016, for MBB-BK 117 C-2 helicopters. This service
information specifies an initial and repetitive inspections of the T/R
gearbox housing for cracks.
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.

Costs of Compliance

We estimate that this AD affects 176 helicopters of U.S. Registry.
We estimate that operators may incur the following costs in order to
comply with this AD. Labor costs are estimated at $85 per work-hour.
Inspecting the T/R gearbox requires 1 work-hour for an estimated
cost of $85 per helicopter and $14,960 for the U.S. fleet per
inspection cycle. Replacing the T/R gearbox requires 4.5 work-hours and
parts cost $69,219 for an estimated cost of $69,602 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.
We are 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.

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) Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979);
(3) Will not affect intrastate aviation in Alaska to the extent
that it justifies making a regulatory distinction; and
(4) 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.
We prepared an economic evaluation of the estimated costs to comply
with this AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

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 adding the following new airworthiness
directive (AD):