Document ID: FAA-2021-0869-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2021-10-08T04:00Z

[Federal Register Volume 86, Number 193 (Friday, October 8, 2021)]
[Proposed Rules]
[Pages 56217-56220]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-21905]

 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 86, No. 193 / Friday, October 8, 2021 / 
Proposed Rules  

[[Page 56217]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0869; Project Identifier AD-2021-00176-E]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

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 
quality escape during the manufacturing of a high-pressure turbine 
(HPT) rotor stage 1 disk. This proposed AD would require removing the 
HPT rotor stage 1 disk from service and replacing the HPT rotor stage 1 
disk with a part eligible for installation. The FAA is proposing this 
AD to the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by November 
22, 2021.

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 https://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@ae.ge.com; website: https://www.ge.com. You may view this service information 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 (781) 238-7759.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0869; 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; fax: (781) 238-7199; 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-2021-0869; Project Identifier 
AD-2021-00176-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 
https://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 was notified by GE of a quality escape that occurred during 
the manufacturing of an HPT rotor stage 1 disk. The quality escape 
occurred at a supplier that began production in August 2019. On 
November 25, 2019, the supplier discovered tool gouges at the forward 
chamfer of the air holes in an HPT rotor stage 1 disk. These gouges can 
reduce the life of the HPT rotor stage 1 disk. This condition, if not 
addressed, could result in uncontained disk release, damage to the 
engine, and damage to 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 Alert Service Bulletin (ASB) 72-A0344 
R01 and GE CF34-8E ASB 72-A0228 R01, both dated December 19, 2019. The 
ASBs describe procedures for removing the HPT rotor stage 1 disk. The 
FAA also reviewed GE Repair Document RD #150-1811-P1, dated March 17, 
2020. This document describes procedures for repairing the HPT rotor 
stage 1 disk.

[[Page 56218]]

Proposed AD Requirements in This NPRM

    This proposed AD would require removing a certain HPT rotor stage 1 
disk from service and replacing the HPT rotor stage 1 disk with a part 
eligible for installation.

Differences Between This Proposed AD and the Service Information

    The ASBs instruct operators to perform a visual inspection of the 
HPT rotor stage 1 disk and re-mark the HPT rotor stage 1 disk, while 
this proposed AD would not mandate visual inspection or re-marking. The 
ASBs also instruct operators to perform an inspection of the removed 
HPT rotor stage 1 disk and send it to an authorized service center for 
repair, while this proposed AD would require removal of the HPT rotor 
stage 1 disk from service and replacement with a part eligible for 
installation.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 23 engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Remove and replace HPT rotor stage 1    812 work-hours x $85 per        $258,100        $327,120      $7,523,760
 disk.                                   hour = $69,020.
----------------------------------------------------------------------------------------------------------------

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

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-2021-0869; Project 
Identifier AD-2021-00176-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by November 22, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) CF34-8C5, CF34-
8C5B1, CF34-8E2, CF34-8E2A1, CF34-8E5, CF34-8E5A1, CF34-8E5A2, CF34-
8E6, and CF34-8E6A1 model turbofan engines with an installed high-
pressure turbine (HPT) rotor stage 1 disk, part number (P/N) 
4125T22P04, and a serial number (S/N) listed in Figure 1 or Figure 2 
to paragraph (c) of this AD.
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[[Page 56219]]

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(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report of a quality escape during the 
manufacturing of an HPT rotor stage 1 disk. The FAA is issuing this 
AD to prevent failure of the HPT rotor stage 1 disk. The unsafe 
condition, if not addressed, could result in uncontained disk 
release, damage to the engine, and damage to the airplane.

(f) Compliance

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

(g) Required Actions

    For all affected engines, at the next engine shop visit or 
before the HPT rotor stage 1 disk accumulates 7,600 cycles since 
new, whichever occurs first after the effective date of this AD, 
remove the HPT rotor stage 1 disk from service and replace with a 
part eligible for installation.

[[Page 56220]]

(h) Definitions

    For the purpose of this AD:
    (1) An ``engine shop visit'' is the induction of an engine into 
the shop for maintenance involving the separation of pairs of major 
mating engine flanges, except that the separation of engine flanges 
solely for the purposes of transportation without subsequent engine 
maintenance does not constitute an engine shop visit.
    (2) A ``part eligible for installation'' is an HPT rotor stage 1 
disk that is not listed in Figure 1 or Figure 2 to paragraph (c) of 
this AD or an HPT rotor stage 1 disk that has been repaired using an 
FAA-approved repair.

    Note 1 to paragraph (h)(2):  Guidance for repairing the HPT 
rotor stage 1 disk can be found in GE Repair Document RD # 150-1811-
P1, dated March 17, 2020.

(i) 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 (j)(1) of this AD. Information may be 
emailed to: ANE-AD-AMOC@faa.gov.
    (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.

(j) Related Information

    (1) 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; fax: (781) 238-7759; 
email: Scott.M.Stevenson@faa.gov.
    (2) For service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: aviation.fleetsupport@ae.ge.com; 
website: https://www.ge.com. You may view this referenced service 
information at the FAA, Airworthiness Products Section, 1200 
District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call (781) 238-7759.

    Issued on September 30, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-21905 Filed 10-7-21; 8:45 am]
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