Document ID: FAA-2022-0977-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2022-08-01T04:00Z

[Federal Register Volume 87, Number 146 (Monday, August 1, 2022)]
[Proposed Rules]
[Pages 46906-46908]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-16011]

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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: [email protected]; 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

[[Page 46907]]

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: [email protected].

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

[[Page 46908]]

    (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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

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 removed 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: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, 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: 
[email protected].

    Issued on July 21, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-16011 Filed 7-29-22; 8:45 am]
BILLING CODE 4910-13-P