DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0452; Directorate Identifier 2017-NE-14-AD]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turboshaft
Engines

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
certain General Electric Company (GE) CT7-8A and CT7-9B model
turboshaft engines. This proposed AD was prompted by reports from the
manufacturer that the high-pressure compressor (HPC) impeller installed
on these engines may have suffered from material degradation during the
manufacturing process. This proposed AD would require removal of the
affected HPC impellers. We are proposing this AD to address the unsafe
condition on these products.

DATES: We must receive comments on this proposed AD by July 31, 2017.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

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

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

For service information identified in this NPRM, contact General
Electric Company, GE-Aviation, Room 285, 1 Neumann Way, Cincinnati, OH
45215; phone: 513-552-3272; fax: 513-552-3329; email: geae.aoc@ge.com.
You may view this service information at the FAA, Engine & Propeller
Directorate, 1200 District Avenue, Burlington, MA. For information on
the availability of this material at the FAA, call 781-238-7125.

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-
0452; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this NPRM, the regulatory evaluation, any comments received,
and other information. The street address for the Docket Office (phone:
800-647-5527) is in the ADDRESSES section. Comments will be available
in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Martin Adler, Aerospace Engineer,
Engine Certification Office, FAA, Engine & Propeller Directorate, 1200
District Avenue, Burlington, MA 01803; phone: 781-238-7157; fax: 781-
238-7199; email: martin.adler@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2017-0452;
Directorate Identifier 2017-NE-14-AD" at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. We will
consider all comments received by the closing date and may amend this
NPRM because of those comments.

We will post all comments we receive, without change, to
http://www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this NPRM.

Discussion

We learned from the manufacturer that the affected HPC impellers
installed on CT7-8A and CT7-9B turboshaft engines may have suffered
from material degradation during the manufacturing process. This
condition, if not corrected, could result in failure of the HPC
impeller, uncontained HPC impeller release, damage to the engine, and
damage to the airplane/helicopter.

Related Service Information

We reviewed GE Service Bulletin (SB) CT7-TP S/B 72-0524, dated June
16, 2016. The SB describes procedures for replacing the affected HPC impellers.

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 products of the same type design.

Proposed AD Requirements

This proposed AD would require removal of the affected HPC impellers.

Costs of Compliance

We estimate that this proposed AD affects 1 engine installed on a
helicopter of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

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 above, 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.

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):