DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0991; Product Identifier 2017-SW-050-AD]
RIN 2120-AA64

Airworthiness Directives; MD Helicopters Inc. (MDHI) 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
MDHI Model 369A, 369D, 369E, 369FF, 369H, 369HE, 369HM, 369HS, 500N,
and 600N helicopters. This proposed AD would require inspecting each
main rotor blade (MRB) for a crack. This proposed AD is prompted by
reports of cracked MRBs. The actions of this proposed AD are intended
to address an unsafe condition on these helicopters.

DATES: We must receive comments on this proposed AD by January 25, 2019.

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-2018-0991;
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 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 Helicopter Technology Company, LLC service information
identified in this proposed rule, contact Helicopter Technology
Company, LLC, 12902 South Broadway, Los Angeles, CA 90061; telephone
(310) 523-2750; or at www.helicoptertech.com. 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 MD Helicopters service information identified in this proposed
rule, contact MD Helicopters, Inc., Attn: Customer Support Division,
4555 E. McDowell Rd., Mail Stop M615, Mesa, AZ 85215-9734; telephone 1-
800-388-3378; fax 480-346-6813; or at http://www.mdhelicopters.com.

FOR FURTHER INFORMATION CONTACT: Galib Abumeri, Aviation Safety
Engineer, Los Angeles ACO Branch, Compliance and Airworthiness
Division, FAA, 3960 Paramount Blvd., Lakewood, California 90712;
telephone (562) 627-5374; email galib.abumeri@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

We propose to adopt a new AD for MDHI Model 369A, 369D, 369E,
369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters with a
Helicopter Technology Company, LLC (HTC) MRB part number 369A1100,
369D21100, 369D21102, 369D21120, 369D21121, 369D21123, 500P2100, or
500P2300 installed. This proposed AD would require repetitively
inspecting the MRB trim tab for gouges, nicks, scratches, and cracks.

This proposed AD is prompted by reports of two operators finding
cracks on an HTC-manufactured MRB. In both cases, the cracking was
located on the MRB skin adjacent to the trim tab, and they were
discovered following flights in which an increase in vibration levels
was noticed. HTC determined the root cause of the cracking to be
fatigue. HTC also stated that there was evidence of impact damage,
filing, and sanding under the paint of the cracked MRBs. If not
detected and corrected, this condition could result in failure of an
MRB and subsequent loss of control of the helicopter.

FAA's Determination

We are proposing this AD because we evaluated all known relevant
information and determined that an unsafe condition exists and is
likely to exist or develop on other helicopters of these same type
designs.

Related Service Information

We reviewed HTC Mandatory Service Bulletin Notice No. 2100-9, dated
May 25, 2017 (SB 2100-9), which contains procedures for inspecting each
MRB for a crack in an area adjacent to the inboard edge of the MRB trim
tab.

We also reviewed MD Helicopters Service Bulletin No. SB369D-221,
SB369E-119, SB369F-106, SB369H-257, SB500N-057, and SB600N-069, each
dated April 2, 2018. This service information specifies inspecting the
MRBs for cracks near the trim tab by following the instructions in SB
2100-9.

Proposed AD Requirements

This proposed AD would require, within 25 hours time-in-service and
thereafter at each 100-hour or annual inspection, inspecting each MRB
trim tab end at the trailing edge corner where the trim tab and MRB
meet for cracks, and inspecting the top and bottom surface of each MRB
for a crack in the area adjacent to inboard trim tab the trim tab
corner for a crack, from the trailing edge towards the leading edge. If
there is a crack, this proposed AD would require replacing the MRB.

Differences Between This Proposed AD and the Service Information

The service information specifies procedures for inspecting each
MRB for nicks, gouges, and scratches. This proposed AD does not, as the
unsafe condition concerns a crack in the MRB. This proposed AD would
require using a 10X magnifying glass for both inspections, while the
service information only specifies this level of magnification for the
inspection of the top and bottom surfaces of the MRB.

Costs of Compliance

We estimate that this proposed AD would affect 622 helicopters of
U.S. Registry.

At an average labor rate of $85 per work-hour, we estimate that
operators may incur the following costs in order to comply with this
AD. Inspecting one MRB would require about 0.1 work-hour, for a cost
per helicopter of $43 for MDHI Model 369-series and 500N helicopters
and $51 for MDHI Model 600N helicopters, and a total cost of $25,320 to
U.S. operators per inspection cycle.

If required, replacing one MRB would require 3 work-hours, and
required parts would cost $13,000, for a cost per MRB of $13,255.

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):