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PROPOSED AD GENERAL ELECTRIC COMPANY: Docket No. FAA-2022-0977; Project Identifier AD-2022-00419-E.
(a) COMMENTS DUE DATE

    The FAA must receive comments on this airworthiness directive (AD)  by
    September 15, 2022.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This AD applies to General Electric Company  CF34-8C1, CF34-8C5, CF34-
    8C5A1, CF34-8C5A2, CF34-8C5A3, CF34-8C5B1, CF34-8E2, CF34-8E2A1, CF34-
    8E5, CF34-8E5A1, CF34-8E5A2, CF34-8E6, and CF34-8E6A1  model  turbofan
    engines  with  an  installed  low-pressure turbine (LPT) stage 5 disk,
    part number (P/N) 4117T14P02.

(d) SUBJECT

    Joint Aircraft System Component (JASC) Code 7250, Turbine Section.

(e) UNSAFE CONDITION

    This AD was prompted by a report  of a crack found on the LPT  stage 5
    disk at the forward  arm area. The FAA  is issuing this AD  to prevent
    failure  of  the  LPT  stage 5  disk.  The  unsafe  condition, if  not
    addressed, could result in loss  of engine thrust control and  reduced
    control of the airplane.

(f) COMPLIANCE

    Comply  with this  AD within  the compliance  times specified,  unless
    already done.

(g) REQUIRED ACTIONS

    During the  next piece-part  exposure after  the affected  LPT stage 5
    disk accumulates 8,000 cycles since new (CSN), remove the affected LPT
    stage 5 disk and replace with a part eligible for installation.

(h) INSTALLATION PROHIBITION

    Do not install  an affected LPT  stage 5 disk  with 8,000 CSN  or more
    into the LPT module of the engine.

(i) DEFINITIONS

(1) For the purpose of this AD,  a "part eligible for installation"  is an
    LPT stage 5 disk, P/N 4117T14P03, or later approved P/N.

(2) For the purpose of this AD,  "piece-part exposure"  is  when  the  LPT
    module is separated from the engine and the LPT stage 5 blades are re-
    moved from the LPT stage 5 disk.

(j) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The Manager, ECO Branch,  FAA,  has the authority to approve AMOCs for
    this AD, if requested using the  procedures found in 14 CFR 39.19.  In
    accordance with  14 CFR  39.19, send  your request  to your  principal
    inspector or local Flight  Standards District Office, as  appropriate.
    If sending information  directly to the  manager of the  certification
    office, send it to the attention of the person identified in paragraph
    (k) of this AD and email to: ANE-AD-AMOC@faa.gov.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking  a principal inspector,  the manager of  the local
    flight standards district office/certificate holding district office.

(k) RELATED INFORMATION

    For more information about this AD,  contact Scott Stevenson, Aviation
    Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA
    01803; phone: (781) 238-7132; email: Scott.M.Stevenson@faa.gov.

Issued on July 21, 2022.  Christina Underwood, Acting Director, Compliance
& Airworthiness Division, Aircraft Certification Service.

DATES: The FAA must receive comments on this proposed AD  by September 15,
2022.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0977; Project Identifier AD-2022-00419-E]
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) CF34-8C and CF34-8E model
turbofan engines. This proposed AD was prompted by a report of a crack
found on the low-pressure turbine (LPT) stage 5 disk at the forward arm
area. This proposed AD would require the removal of the affected LPT
stage 5 disk and replacement with a part eligible for installation. 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 September
15, 2022.

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 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, 1 Neumann Way, Cincinnati, OH 45215; phone: (513)
552-3272; email: aviation.fleetsupport@ge.com; website: www.ge.com. You
may view this service information at the Airworthiness Products
Section, Operational Safety Branch, FAA, 1200 District Avenue,
Burlington, MA 01803. For information on the availability of this
material at the FAA, call (817) 222-5110.

Examining the AD Docket

You may examine the AD docket at www.regulations.gov by searching
for and locating Docket No. FAA-2022-0977; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Scott Stevenson, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7132; email: Scott.M.Stevenson@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 ADDRESSES. Include ``Docket No. FAA-2022-0977; Project Identifier
AD-2022-00419-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 amend
this 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
www.regulations.gov, including any personal information you provide.
The agency will also post a report summarizing each substantive verbal
contact received about this NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to Scott
Stevenson, Aviation Safety Engineer, ECO Branch, FAA, 1200 District
Avenue, Burlington, MA 01803. 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 received a report of a crack found on an LPT stage 5 disk
at the forward arm area. The manufacturer's analysis revealed that the
crack was due to high-vibratory stress caused by a bladed disk mode
that resulted in the initiation of multiple high cycle fatigue (HCF)
cracks that connected, resulting in a long circumferential crack. As a
result of its analysis, the manufacturer published service information
that specifies procedures for the removal of the affected LPT stage 5
disk, part number (P/N) 4117T14P02, and replacement with an LPT stage 5
disk, P/N 4117T14P03. The replacement LPT stage 5 disk, P/N 4117T14P03,
has a modified geometry (thicker forward arm) that will improve the HCF
capability and reduce the likelihood of a crack. This condition, if not
addressed, could result in failure of the LPT stage 5 disk, loss of
engine thrust control, and reduced control of the airplane.

FAA's Determination

The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

Related Service Information

The FAA reviewed GE CF34-8C Service Bulletin (SB) 72-0352 R00,
dated September 20, 2021, and GE CF34-8E SB 72-0240 R00, dated
September 20, 2021. These SBs, differentiated by engine model, describe
procedures for removing and replacing the affected LPT stage 5 disk, P/
N 4117T14P02, with a new LPT stage 5 disk, P/N 4117T14P03.

Proposed AD Requirements in This NPRM

This proposed AD would require the removal of the affected LPT
stage 5 disk and replacement with a part eligible for installation.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 112 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs

Action Labor cost Parts cost Cost per product Cost on U.S. operators
Remove and replace the LPT stage 5 disk 2 work-hours x $85 per hour = $170 $30,500 (pro-rated) $30,670 $3,435,040

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: