DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0270; Directorate Identifier 2016-SW-032-AD]
RIN 2120-AA64

Airworthiness Directives; MD Helicopters, Inc. Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to supersede airworthiness directive (AD) 2014-16-
01 for MD Helicopters, Inc. (MDHI) Model MD900 helicopters. AD 2014-16-
01 requires an eddy current inspection of the main rotor upper hub
assembly (upper hub) for a crack. Since we issued AD 2014-16-01, three
additional upper hub cracks were reported. This proposed AD would
require additional inspections and replacing the fillet seal. These
proposed actions are intended to prevent an unsafe condition on these
products.

DATES: We must receive comments on this proposed AD by June 2, 2017.

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-2017-0270;
or in person at the Docket Operations Office 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 the Docket
Operations Office (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
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. You may review
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: Eric Schrieber, Aviation Safety
Engineer, Los Angeles Aircraft Certification Office, Transport Airplane
Directorate, FAA, 3960 Paramount Blvd., Lakewood, California 90712;
telephone (562) 627-5348; email eric.schrieber@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

On July 24, 2014, we issued AD 2014-16-01, Amendment 39-17925 (79
FR 45322, August 5, 2014), for MDHI Model MD900 helicopters, serial
numbers 900-00008 through 900-00140, with an upper hub part number
(P/N) 900R2101006-105, -107, -109, or -111 installed. AD 2014-16-01
requires, within 25 hours time-in-service (TIS), eddy current
inspecting the upper hub for a crack and replacing the upper hub before
further flight if there is a crack. AD 2014-16-01 was prompted by a
report that four cracks were found at the blade attach holes on a high-
time upper hub. The actions in AD 2014-16-01 were intended to detect a
crack on the upper hub, which if not corrected could result in failure
of the upper hub and subsequent loss of control of the helicopter.

Actions Since AD 2014-16-01 Was Issued

Since we issued AD 2014-16-01, we received reports of three
additional cracks found in the MD900 fleet. These cracks were not
discovered by the one-time eddy current inspection required by AD 2014-
16-01, but were found during regular maintenance of the upper hub. MDHI
determined that in addition to the repetitive inspections of the upper
hub annually and at 100 and 1,000 hours TIS in its maintenance manual,
inspections should be accomplished and a fillet seal should be
installed to prevent moisture in the interface of the bushing and the
flex beam retention bolt hole. MDHI also determined that these
inspections should be accomplished on all P/N 900R2101006-105, -107,
-109, and -111 upper hubs with 1,000 or more hours TIS, regardless of
helicopter serial number.

These proposed actions are intended to detect a crack on the upper
hub, which if not corrected could result in failure of the upper hub
and subsequent loss of control of the helicopter.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously
is likely to exist or develop in other helicopters of the same type
design.

Related Service Information Under 1 CFR Part 51

MDHI has issued Service Bulletin SB900-125, dated February 19,
2016, which describes procedures for repetitive visual and eddy current
inspections of the upper hub upper and lower flexbeam bolthole areas
and for applying a fillet seal on the interface of the bushing and the
flex beam retention bolt hole.

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 for MDHI MD900 helicopters with an
upper hub P/N 900R2101006-105, -107, -109, and -111:

Within 100 hours TIS and thereafter at intervals not exceeding 100
hours TIS, using a 10X or higher magnifying glass, inspecting the
fillet seal and the areas around the flexbeam boltholes for a crack;

Within 12 months and thereafter at intervals not exceeding 12
months, removing the paint, primer, and fillet seal around the flexbeam
boltholes and, using a 10X or higher magnifying glass, inspecting the
area for a crack;

Within 12 months and thereafter at intervals not exceeding 12
months, inspecting the lead leg shims and bushings for corrosion around
the flexbeam boltholes, and if there is corrosion, removing the lead
leg shim and inspecting for a crack;

Within 1,000 hours TIS and thereafter at intervals not exceeding
1,000 hours TIS, eddy-current inspecting the areas adjacent to the
flexbeam boltholes for a crack;

If during any inspection required by the proposed AD there is a
crack, replacing the upper hub before further flight; and

Finally, after each inspection required by the proposed AD,
installing a fillet seal to the bushing and upper hub interface.

Differences Between This Proposed AD and the Service Information

The service information applies to upper hubs with 1,000 or more
hours TIS. This proposed AD would apply to all upper hubs regardless of
hours TIS. The service information applies to upper hub P/N
900R2101006-107 and -109; the proposed AD would also apply to upper hub
P/N 900R2101006-105 and -111.

Costs of Compliance

We estimate that this proposed AD would affect 23 helicopters of
U.S. Registry.

At an average labor rate of $85 per hour, we estimate that
operators may incur the following costs in order to comply with this
AD. Inspecting the fillet seal around the flexbeam boltholes (100 hour
TIS inspection) would require about 1 work-hour, for a cost per
helicopter of $85 and a cost of $1,955 for the fleet, per inspection
cycle. Inspecting the flexbeam area and lead leg shims and bushings
(annual inspection) would require about 2 work-hours, for a cost per
helicopter of $170 and a cost of $3,910 for the fleet, per inspection
cycle. Eddy current inspecting (1,000 hour TIS inspection) the upper
hub would require about 2 work-hours, for a cost per helicopter of $170
and a cost of $3,910 for the fleet.

If required, replacing the upper hub would require about 11 work-
hours, and required parts would cost about $15,998, for a cost per
helicopter of $16,933.

If required, replacing a missing or damaged fillet seal would
require about .5 work-hour, and required parts cost would be minimal,
for a cost per helicopter of $43.

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 removing Airworthiness Directive (AD)
2014-16-01, Amendment 39-17925(79 FR 45322, August 5, 2014), and adding
the following new AD: