DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0438; Product Identifier 2017-SW-062-AD]
RIN 2120-AA64

Airworthiness Directives; Airbus 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 Model AS355E, AS355F, AS355F1, AS355F2, and AS355N
helicopters. This proposed AD would require measuring a vibration level
in the tail rotor (T/R) drive. This proposed AD is prompted by reports
of bearing degradation. The actions of this proposed AD are intended to
prevent an unsafe condition on these helicopters.

DATES: We must receive comments on this proposed AD by July 16, 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-2018-0438;
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: Rao Edupuganti, Aviation Safety
Engineer, Regulations and Policy Section, Rotorcraft Standards Branch,
FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-
5110; email rao.edupuganti@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. 2017-0159, dated August 25,
2017, to correct an unsafe condition for Airbus Helicopters Model
AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. EASA advises
of two occurrences on AS355 military helicopters in which the main
gearbox (MGB) oil cooler fan bearing (bearing) installed on the TR
drive shaft experienced significant degradation. EASA states that while
investigation has not determined the cause of the failures, this
condition may also occur on other AS355 helicopters due to design
commonality. According to EASA, this condition, if not detected and
corrected, could result in loss of MGB and engine oil cooling function,
loss of the rear transmission, and subsequent loss of control of the
helicopter. To address this unsafe condition and as an interim measure,
the EASA AD requires two vibration level measurements of the forward
portion of the tail rotor drive line, one before and one after cleaning
the MGB oil cooler fan, and replacing the bearings if excessive level
or level trends are detected. The EASA AD also specifies that after the
effective date of the AD, only those MGB oil cooler fan assembly
bearings that are new or that have passed the vibration level
measurements may be installed.

FAA's Determination

These helicopters have been approved by the aviation authority of
France and are approved for operation in the United States. Pursuant to
our bilateral agreement with France, 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

We reviewed Airbus Helicopters Alert Service Bulletin No. AS355-
05.00.77, Revision 0, dated July 3, 2017, which contains procedures for
checking the condition of the fan assembly bearings by measuring the
vibration levels of the first section of the T/R drive.

Proposed AD Requirements

This proposed AD would require, within 165 hours time-in-service,
measuring the T/R drive vibration level without balancing, cleaning the
fan, and repeating the vibration level measurement. If the difference
between the two amplitude values is greater than 0.75 inch per second
(ips), the proposed AD would require, before further flight, replacing
each T/R fan bearing.

Interim Action

We consider this proposed AD to be an interim action. The
manufacturer is currently developing a terminating action for the
unsafe condition described in this proposed AD. If a terminating action
is identified, we may consider further rulemaking then.

Costs of Compliance

We estimate that this proposed AD would affect 104 helicopters of
U.S. Registry.

We estimate that operators may incur the following costs in order
to comply with this AD. At an average labor rate of $85 per work-hour,
measuring the vibration levels would require about 5 work-hours, for a
cost of $425 per helicopter and $44,200 for the U.S. operator fleet. If
required, replacing both fan assembly bearings would require about 8
work-hours, and required parts would cost $1,064, for a cost per
helicopter of $1,744.

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):