DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0943; Product Identifier 2017-NE-34-AD; Amendment
39-19186; AD 2018-03-13]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turboprop
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
General Electric Company (GE) CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-
9B, CT7-9B1, CT7-9B2, CT7-9C and CT7-9C3 model turboprop engines. This
AD requires initial and repetitive visual inspection and fluorescent-
penetrant inspection (FPI) of the main propeller shaft. This AD was
prompted by the failure of a main propeller shaft. We are issuing this
AD to address the unsafe condition on these products.

DATES: This AD is effective February 28, 2018.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of February 28,
2018.
We must receive comments on this AD by March 30, 2018.

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: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
For service information identified in this final rule, 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 and Propeller Standards Branch, 1200 District Avenue,
Burlington, MA 01803. For information on the availability of this
material at the FAA, call 781-238-7759. It is also available on the
internet at http://www.regulations.gov by searching for and locating
Docket No. FAA-2017-0943.

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-
0943; 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 final rule, 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: Michael Richardson-Bach, Aerospace
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: 781-238-7747; fax: 781-238-7199; email: michael.richardson-bach@
faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We received a report that a condition was found after an incident
where the main propeller shaft on a GE CT7-9B failed in flight,
resulting in the loss of the propeller. The condition is cracking
initiating from undiscovered corrosion in the dowel pin hole on the
flange of the main propeller shaft. This proposed AD would require
visually inspecting the main propeller shaft for wear and corrosion and
FPI for cracks. This condition, if not addressed, could result in
failure of the main propeller shaft, resulting in in-flight loss of the
propeller, loss of engine thrust control, and damage to the airplane.
We are issuing this AD to address the unsafe condition on these
products.
A similar propeller separation incident occurred in 1992 because of
a material defect. The affected parts were purged from the field at
that time.

Related Service Information Under 1 CFR Part 51

We reviewed SPM 70-32-03, SPOT-FLUORESCENT PENETRANT INSPECTION,
TASK 70-32-03-230-002, from the GE Commercial Engine Standard Practices
Manual GEK 9250, Rev. 106, dated April 01, 2007. This procedure
provides instruction for spot FPI.
We also reviewed MM 72-10-00, PROPELLER GEARBOX INSPECTION and MM
72-10-00, PROPELLER GEARBOX--CLEANING, from the GE CT7B Maintenance
Manual SEI-576, Rev. 60, dated October 1, 2017. These procedures
provides instructions for inspection and cleaning, respectively, of the
main propeller shaft.
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.

Other Related Service Information

We reviewed GE Service Bulletin (SB) CT7-TP S/B 72-0531, dated June
22, 2017. The SB references standard procedures for initial and
repetitive visual and FPI of the main propeller shaft for SF340
aircraft.
We also reviewed GE SB CT7-TP S/B 72-0533, dated October 3, 2017.
The SB references standard procedures for initial and repetitive visual
and FPI of the main propeller shaft for CN235 aircraft.

FAA's Determination

We are issuing 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.

AD Requirements

This AD requires visually inspecting the main propeller shaft for
wear and corrosion and FPI for cracks.

Differences Between This AD and the Service Information

The inspection plan in this AD adds visual inspection and FPI to
the repetitive inspections. This AD adds upper limits to the ``inspect
within'' times to avoid conflicting times to inspect.

FAA's Justification and Determination of the Effective Date

An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies waiving notice and comment prior to adoption of this rule
because the compliance time for the action is less than the time
required for public comment. Therefore, we find that notice and
opportunity for prior public comment are impracticable. In addition,
for the reason stated above, we find that good cause exists for making
this amendment effective in less than 30 days.

Comments Invited

This AD is a final rule that involves requirements affecting flight
safety and was not preceded by notice and an opportunity for public
comment. However, we invite you to send any written data, views, or
arguments about this final rule. Send your comments to an address
listed under the ADDRESSES section. Include the docket number Docket
No. FAA-2017-0943 and Product Identifier 2017-NE-34-AD at the beginning
of your comments. We specifically invite comments on the overall
regulatory, economic, environmental, and energy aspects of this final
rule. We will consider all comments received by the closing date and
may amend this final rule 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 final rule.

Costs of Compliance

We estimate that this AD affects 176 engines installed on airplanes
of U.S. registry. We estimate the following costs to comply with this
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.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to engines, propellers, and
associated appliances to the Manager, Engine and Propeller Standards
Branch, Policy and Innovation Division.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will 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 that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, 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.

Adoption of the Amendment

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