DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0665; Product Identifier 2019-NE-25-AD]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain General Electric Company (GE) CF34-1A, CF34-3A, CF34-3A1,
CF34-3A2, CF34-3B, and CF34-3B1 model turbofan engines. This proposed
AD was prompted by an in-flight failure of a fan blade that led to an
in-flight shutdown. This proposed AD would require removal and
replacement of the affected fan blades. The FAA is proposing this AD to
address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by November 29,
2019.

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; email: aviation.fleetsupport@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.

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-2019-0665;
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 NPRM, the regulatory evaluation, any comments received, and other
information. The street address for Docket Operations is listed above.
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Christopher McGuire, Aerospace
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: 781-238-7120; fax: 781-238-7199; email: chris.mcguire@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites 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-2019-0665;
Product Identifier 2019-NE-25-AD" at the beginning of your comments.
The FAA specifically invites comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. The FAA will
consider all comments received by the closing date and may amend this
NPRM because of those comments.

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

Discussion

The FAA was notified of an in-flight failure of a fan blade
installed on a GE CF34-3B1 engine. As a result of this failure, the
crew shut down the engine and performed an air turnback and a safe
landing. A review by GE determined that a lance peen was not performed
on certain fan blades after a repair done at a repair station between
2007 and 2009. Fan blades can lose their compressive residual stress
during certain electron beam weld repairs and hot form repairs. The
loss of mechanical properties is restored with the lance peening
process called out in these repairs. During an audit, GE identified the
fan blades referenced in paragraph (c) of this AD as suspected of
missing lance peening. This condition, if not addressed, could result
in failure of one or more engines, loss of thrust control, and loss of
the airplane.

Related Service Information Under 1 CFR Part 51

The FAA reviewed GE Service Bulletin (SB) CF34-BJ S/B 72-0306,
dated September 27, 2017, and GE SB CF34-AL S/B 72-0314, dated
September 27, 2017. GE SB CF34-BJ S/B 72-0306 describes procedures for
removal and replacement of affected fan blades installed on CF34-1A, -
3A, -3A1, -3A2, and -3B model turbofan engines. GE SB CF34-AL S/B 72-
0314 describes procedures for removal and replacement of affected fan
blades installed on CF34-3A1 and -3B1 model turbofan engines.

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

The FAA also reviewed GE SB CF34-AL S/B 72-0148, Revision 05, dated
July 23, 2015; and GE SB CF34-BJ S/B 72-0123, Revision 04, dated
October 21, 2015. GE SB CF34-AL S/B 72-0148 describes procedures for
repair of fan blades installed on GE CF34-3A1 and -3B1 model turbofan
engines. GE SB CF34-BJ S/B 72-0123 describes procedures for repair of
fan blades installed on GE CF34-1A, -3A, -3A1, -3A2, and -3B model
turbofan engines.

FAA's Determination

The FAA is 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 and replacement of the
affected fan blades.

Costs of Compliance

The FAA estimates that this proposed AD affects 121 engines
installed on airplanes of U.S. registry.

The FAA estimates 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.

The FAA is 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

The FAA 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) Will not affect intrastate aviation in Alaska, and

(3) 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):