DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1085; Product Identifier 2016-SW-094-AD]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters Deutschland GmbH
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt 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 proposed AD would
require repetitive inspections of the tail rotor (T/R) gearbox housing.
This proposed AD is prompted by a report that a crack was found in a T/
R gearbox housing. The actions of this proposed AD are intended to
address an unsafe condition on these products.

DATES: We must receive comments on this proposed AD by November 9, 2018.

ADDRESSES: You may send comments by any of the following methods:

Federal eRulemaking Docket: Go to http://www.regulations.gov. Follow the
online instructions for sending your comments electronically.

Fax: 202-493-2251.

Mail: Send comments to the U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590-0001.

Hand Delivery: Deliver to the "Mail" address between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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 proposed AD, the European Aviation Safety Agency (EASA) AD, the
economic evaluation, any comments received, and other information. The
street address for Docket Operations (telephone 800-647-5527) is in the
ADDRESSES section. Comments will be available in the AD docket shortly
after receipt.

For service information identified in this proposed 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.

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:

Comments Invited

We invite you to participate in this rulemaking by submitting
written comments, data, or views. We also invite comments relating to
the economic, environmental, energy, or federalism impacts that might
result from adopting the proposals in this document. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. To
ensure the docket does not contain duplicate comments, commenters
should send only one copy of written comments, or if comments are filed
electronically, commenters should submit only one time.

We will file in the docket all comments that we receive, as well as
a report summarizing each substantive public contact with FAA personnel
concerning this proposed rulemaking. Before acting on this proposal, we
will consider all comments we receive on or before the closing date for
comments. We will consider comments filed after the comment period has
closed if it is possible to do so without incurring expense or delay.
We may change this proposal in light of the comments we receive.

Discussion

EASA, which is the Technical Agent for the Member States of the
European Union, has issued EASA AD No. 2016-0134, dated July 8, 2016,
to correct an unsafe condition on 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.

FAA's Determination

These helicopters have been approved by the aviation authority of
Germany and are approved for operation in the United States. Pursuant
to our bilateral agreement with Germany, EASA, its technical
representative, has notified us of the unsafe condition described in
its AD. We are proposing this AD because we evaluated all known
relevant information and determined that an unsafe condition is likely
to exist or develop on other products of the same type design.

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.

Proposed AD Requirements

This proposed AD would require within 100 hours time-in-service
(TIS) and thereafter at intervals not to exceed 100 hours TIS, cleaning
and visually inspecting the T/R gearbox housing for a crack. If there
is a crack, this proposed AD would require replacing the T/R gearbox
before further flight.

Differences Between This Proposed AD and the EASA AD

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

Costs of Compliance

We estimate that this proposed AD would affect 176 helicopters of
U.S. Registry and that labor costs average $85 a work-hour. Based on
these estimates, we expect that inspecting the T/R gearbox would
require 1 work-hour and no parts would be required for a cost of $85
per helicopter and $14,960 for the U.S. fleet per inspection cycle.
Replacing the T/R gearbox would require 4.5 work-hours and parts would
cost $69,219 for a 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 products identified in this
rulemaking action.

Regulatory Findings

We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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, I certify this proposed regulation:

1. Is not a "significant regulatory action" under Executive Order
12866;

2. Is not a "significant rule" under the 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 proposed 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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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):