[Federal Register Volume 89, Number 58 (Monday, March 25, 2024)]
[Proposed Rules]
[Pages 20553-20555]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-05995]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0755; Project Identifier AD-2023-00521-E]
RIN 2120-AA64


Airworthiness Directives; General Electric Company 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) Model GEnx-1B64/P1, GEnx-
1B64/P2, GEnx-1B67, GEnx-1B67/P1, GEnx-1B67/P2, GEnx-1B70, GEnx-1B70/
75/P1, GEnx-1B70/75/P2, GEnx-1B70/P1, GEnx-1B70/P2, GEnx-1B70C/P1, 
GEnx-1B70C/P2, GEnx-1B74/75/P1, GEnx-1B74/75/P2, GEnx-1B76/P2, GEnx-
1B76A/P2, GEnx-2B67, GEnx-2B67B, and GEnx-2B67/P engines. This proposed 
AD was prompted by a manufacturer evaluation that determined a lower 
life limit is necessary for certain stages 6-10 compressor rotor spools 
(stages 6-10 spools) than allowed by the engine shop manual (ESM). This 
proposed AD would require a one-time inspection of the stages 6-10 
spools for previously accomplished blend repairs, a one-time inspection 
of the blend repairs on the stages 6-10 spools for compliance with the 
updated allowable limits, and replacement if necessary. 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 May 9, 
2024.

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-2024-0755; 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.
    Material Incorporated by Reference:
     For service information identified in this NPRM, contact 
GE, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: 
ge.com">aviation.fleetsupport@ge.com; website: 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 (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: [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-2024-0755; Project Identifier 
AD-2023-00521-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 
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 
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 was notified of a manufacturer evaluation, which consisted 
of a heat transfer analysis, that revealed significant changes in 
thermal gradients in certain areas of the high-pressure compressor 
rotor (HPCR) assembly on GE Model GEnx-1B64/P1, GEnx-1B64/P2, GEnx-
1B67, GEnx-1B67/P1, GEnx-1B67/P2, GEnx-1B70, GEnx-1B70/75/P1, GEnx-
1B70/75/P2, GEnx-1B70/P1, GEnx-1B70/P2, GEnx-1B70C/P1, GEnx-1B70C/P2, 
GEnx-1B74/75/P1, GEnx-1B74/75/P2, GEnx-1B76/P2, GEnx-1B76A/P2, GEnx-
2B67, GEnx-2B67B, and GEnx-2B67/P engines. The results of the heat 
transfer analysis were used to determine that a lower life limit is 
required for certain areas of the HPCR. Consequently, the manufacturer 
re-checked the serviceable and repairable limits of the stages 6-10 
spools to determine if they still maintained the threshold limit for 
serviceability, where it was discovered that two repair procedures 
listed in the ESM exceeded the updated repair limits at certain 
locations of the HPCR assembly.
    Due to the findings of the previous evaluations, the manufacturer 
performed an updated analysis and determined that a new threshold for 
the repairable limits for blend-repaired stages 6-10 spools is 
necessary. The manufacturer also determined that certain areas of 
previous blend-repaired stages 6-10 spools may have a lower life limit 
than the ultimate life limit of the HPCR disks.
    This condition, if not addressed, could result in fracture and 
potential uncontained failure of the stages 6-10 spools, with 
consequent uncontained

[[Page 20554]]

debris release, damage to the engine, and damage to the aircraft.

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 Under 1 CFR Part 51

    The FAA reviewed GE GEnx-1B Service Bulletin 72-0525, R00, dated 
October 4, 2023 (GEnx-1B SB 72-0525, R00), and GEnx-2B Service Bulletin 
72-0460, R00, dated October 4, 2023 (GEnx-2B SB 72-0460, R00). This 
service information identifies the part numbers and serial numbers of 
affected stages 6-10 spools; and specifies instructions for a one-time 
inspection of the stages 6-10 spools for previously accomplished blend 
repairs, a one-time inspection of the blend repairs on the stages 6-10 
spools for compliance with the updated allowable limits, and 
replacement if necessary. These documents are distinct since they apply 
to different engine models.
    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 ADDRESSES section.

Proposed AD Requirements in This NPRM

    This NPRM would require accomplishing a one-time inspection of the 
stages 6-10 spools for previously accomplished blend repairs, a one-
time inspection of the blend repairs on the stages 6-10 spools for 
compliance with the updated allowable limits, and replacement, if 
necessary, within compliance times specified in GE GEnx-1B SB 72-0525, 
R00 or GEnx-2B SB 72-0460, R00. Depending on the part numbers and 
serial numbers of the affected stages 6-10 spools, this NPRM proposes 
to require these actions to be accomplished at the next piece-part 
exposure after the effective date of this proposed AD, or before the 
affected stages 6-10 spool reaches the cyclic removal threshold of up 
to 11,894 cycles since new.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 6 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
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Inspect stages 6-10 spools............  8 work-hours x $85 per                $0            $680          $4,080
                                         hour = $680.
Inspect previous blend repairs........  1 work-hours x $85 per                 0              85             510
                                         hour = $85.
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    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
proposed inspections. The agency has no way of determining the number 
of engines that might need this replacement:

                                               On-Condition Costs
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                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace stages 6-10 spool.....................  8 work-hours x $85 per hour =         $1,307,600      $1,308,280
                                                 $680.
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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
    (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-2024-0755; Project 
Identifier AD-2023-00521-E.

[[Page 20555]]

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by May 9, 2024.

 (b) Affected ADs

    None.

 (c) Applicability

    This AD applies to General Electric Company (GE) Model GEnx-
1B64/P1, GEnx-1B64/P2, GEnx-1B67, GEnx-1B67/P1, GEnx-1B67/P2, GEnx-
1B70, GEnx-1B70/75/P1, GEnx-1B70/75/P2, GEnx-1B70/P1, GEnx-1B70/P2, 
GEnx-1B70C/P1, GEnx-1B70C/P2, GEnx-1B74/75/P1, GEnx-1B74/75/P2, 
GEnx-1B76/P2, GEnx-1B76A/P2, GEnx-2B67, GEnx-2B67B, and GEnx-2B67/P 
engines with an installed:
    (1) Stages 6-10 compressor rotor spool (stages 6-10 spool) 
having a part number (P/N) and serial number (S/N) listed in 
paragraph 4, Appendix--A, Table 1 of GE GEnx-1B Service Bulletin 72-
0525, R00, dated October 4, 2023 (GEnx-1B SB 72-0525, R00); or
    (2) Stages 6-10 spool having a P/N and S/N listed in paragraph 
4, Appendix--A, Table 1 of GE GEnx-2B Service Bulletin 72-0460, R00, 
dated October 4, 2023 (GEnx-2B SB 72-0460, R00).

 (d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section.

 (e) Unsafe Condition

    This AD was prompted by a manufacturer evaluation which 
determined that a lower life limit is necessary for certain stages 
6-10 spools than that allowed in the engine shop manual. The FAA is 
issuing this AD to prevent fracture and potential uncontained 
failure of the stages 6-10 spools. The unsafe condition, if not 
addressed, could result in uncontained debris release, damage to the 
engine, and damage to the aircraft.

 (f) Compliance

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

 (g) Required Actions

    At the next piece-part exposure after the effective date of this 
AD or before the affected stages 6-10 spool reaches the cyclic 
removal threshold specified in paragraph 4., Appendix--A, Table 1 of 
GEnx-1B 72-0525, R00 or GEnx-2B SB 72-0460, R00, as applicable, do 
the following actions:
    (1) Inspect the stages 6-10 spool for previously accomplished 
blend repairs in accordance with the Accomplishment Instructions, 
paragraph 3.B.(1) of GEnx-1B SB 72-0525, R00 or GEnx-2B SB 72-0460, 
R00, as applicable.
    (2) If during any inspection required by paragraph (g)(1) of 
this AD, any stages 6-10 spool is found to have a previously 
accomplished blend repair, before further flight, inspect the blend 
repair for compliance with the allowable limits in accordance with 
the Accomplishment Instructions, paragraph 3.B.(2) of GEnx-1B SB 72-
0525, R00 or GEnx-2B SB 72-0460, R00, as applicable.
    (3) If during any inspection required by paragraph (g)(2) of 
this AD, any stages 6-10 spool is found to have a previously 
accomplished blend repair that is not within the allowable limits, 
before further flight, remove the stages 6-10 spool from service and 
replace with a part eligible for installation in accordance with the 
Accomplishment Instructions, paragraph 3.B.(2)(a)1 or 3.B.(2)(b)1 of 
GEnx-1B SB 72-0525, R00 or GEnx-2B SB 72-0460, R00, as applicable.

 (h) Definition

    (1) For the purpose of this AD, a ``piece-part exposure'' is 
when the stages 6-10 spool is disassembled from the high-pressure 
compressor rotor assembly.
    (2) For the purpose of this AD, a ``part eligible for 
installation'' is a stages 6-10 spool that does not have a P/N and 
S/N identified in paragraph 4, Appendix--A, Table 1 of GEnx-1B 72-
0525, R00 or GEnx-2B 72-0460, R00.

 (i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520 Continued Operational Safety 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 AIR-520 Continued 
Operational Safety Branch, send it to the attention of the person 
identified in paragraph (j) 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.

 (j) Related Information

    For more information about this AD, contact Alexei Marqueen, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: (781) 238-7178; email: [email protected].

 (l) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) General Electric Company (GE) GEnx-1B Service Bulletin 72-
0525, R00, dated October 4, 2023.
    (ii) GE GEnx-2B Service Bulletin 72-0460, R00, dated October 4, 
2023.
    (4) You may view this service information at 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.
    (5) You may view this material at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].

    Issued on March 15, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-05995 Filed 3-22-24; 8:45 am]
BILLING CODE 4910-13-P