DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1883; Project Identifier AD-2023-01120-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM).

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SUMMARY: The FAA is revising a notice of proposed rulemaking (NPRM)
that applied to all General Electric Company (GE) Model CF34-10E2A1,
CF34-10E6, CF34-10E6A1, CF34-10E7, and CF34-10E7-B engines with certain
part-numbered high-pressure turbine (HPT) shroud/low pressure turbine
(LPT) nozzle assemblies installed. This action revises the NPRM by
adding Model CF34-10E5 and CF34-10E5A1 engines to the applicability.
The FAA is proposing this airworthiness directive (AD) to address the
unsafe condition on these products. Since these actions would impose an
additional burden over those in the NPRM the agency is requesting
comments on this SNPRM.

DATES: The FAA must receive comments on this SNPRM by March 10, 2025.

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 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.

AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-1883; 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 SNPRM, any comments received, and other
information. The street address for Docket Operations is listed above.

Material Incorporated by Reference:

For GE material identified in this proposed AD, contact
GE, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email:
aviation.fleetsupport@ge.com; website: ge.com.

You may view this material at the FAA, Airworthiness
Products Section, Operational Safety Branch, 1200 District Avenue,
Burlington, MA 01803. For information on the availability of this
material at the FAA, call (817) 222-5110.

FOR FURTHER INFORMATION CONTACT: Alexei Marqueen, Aviation Safety
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone:
(781) 238-7178; email: alexei.t.marqueen@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-2024-1883;
Project Identifier AD-2023-01120-E" at the beginning of your comments.
The most helpful comments reference a specific portion of the proposal,
explain the reason for any recommended change, and include supporting
data. The FAA will consider all comments received by the closing date
and may again revise the proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this SNPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this SNPRM contain
commercial or financial information that is customarily treated as
private, that you actually treat as private, and that is relevant or
responsive to this SNPRM, it is important that you clearly designate
the submitted comments as CBI. Please mark each page of your submission
containing CBI as "PROPIN." The FAA will treat such marked
submissions as confidential under the FOIA, and they will not be placed
in the public docket of this SNPRM. Submissions containing CBI should
be sent to Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South
216th Street, Des Moines, WA 98198. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

Background

The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that
would apply to GE Model CF34-10E2A1, CF34-10E6, CF34-10E6A1, CF34-10E7,
and CF34-10E7-B engines with an installed HPT shroud/LPT nozzle
assembly having part number (P/N) 2205M38G01, 2205M38G02, 2205M38G03,
2205M38G04, or 2205M38G05. The NPRM published in the Federal Register
on July 10, 2024 (89 FR 56674). The NPRM was prompted by a report from
the manufacturer that during disassembly, the retention features of the
inner and outer support air ducts on GE Model CF34-10E series engines
were found to have failed. This condition, if not addressed, could
result in the inner surface of the combustion case having reduced load
carrying capability for fan blade out or other extreme event with
possible engine separation and loss of the airplane. In the NPRM, the
FAA proposed to require a visual inspection of the combustion case for
wear and gouges, repair if necessary, and rework of the affected HPT
shroud/LPT nozzle assemblies.

Actions Since the NPRM Was Issued

Since the FAA issued the NPRM, the FAA received comments and
determined that Model CF34-10E5 and CF34-10E5A1 engines were
inadvertently omitted from the applicability of the NPRM. In addition,
the Cost of Compliance section was modified to reflect a more accurate
estimate of the number of affected engines. While the number of
affected models increased, the number of affected engines is lower than
previously estimated.

Comments

The FAA received comments from three commenters. The commenters
were the Air Line Pilots Association, International (ALPA), Japan
Airlines, and GE. ALPA supported the NPRM without change. The following
presents the comments received from Japan Airlines and GE and the FAA's
response.

Request To Update the Applicability

Japan Airlines and GE suggested that engine Model CF34-10E5 and
CF34-10E5A1 be included in the applicability of the NPRM because the
effectivity of GE CF34-10E Service Bulletin (SB) 72-0351 R01, dated
July 17, 2019 (GE CF34-10E SB 72-0351 R01) applies to all CF34-10E
engines with an installed HPT shroud/LPT nozzle assembly having part
number (P/N) 2205M38G01, 2205M38G02, 2205M38G03, 2205M38G04, or
2205M38G05.

The FAA agrees and has revised paragraph (c) of this proposed AD to
add engine Model CF34-10E5 and CF34-10E5A1.

FAA's Determination

The FAA is proposing this AD after determining the unsafe condition
described previously is likely to exist or develop in other products of
the same type design. Certain changes described above expand the scope
of the NPRM. As a result, it is necessary to reopen the comment period
to provide additional opportunity for the public to comment on this SNPRM.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed GE CF34-10E SB 72-0351 R01, which provides
instructions for a visual inspection of the combustion case for wear
and gouges, repair if necessary, and rework of the affected HPT shroud/
LPT nozzle assemblies. This material also introduces a new HPT shroud/
LPT nozzle assembly P/N 2205M38G07 with welded retaining rings. 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 in This SNPRM

This proposed AD would require a visual inspection of the
combustion case for wear and gouges, repair if necessary, and rework of
the affected HPT shroud/LPT nozzle assemblies to add a positive retention of
the support air duct.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, affects 221
engines installed on airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

Estimated Costs

The FAA estimates the following costs to do any necessary repairs
that would be required based on the results of the proposed inspection.
The agency has no way of determining the number of engines that might
need these repairs.

On-Condition 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.

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) Would not affect intrastate aviation in Alaska, and

(3) Would 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: