[Federal Register Volume 90, Number 143 (Tuesday, July 29, 2025)]
[Proposed Rules]
[Pages 35642-35645]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-14287]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-1364; Project Identifier AD-2024-00613-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 GE90-90B, GE90-94B,
GE90-110B1, and GE90-115B engines. This proposed AD was prompted by a
manufacturer investigation that revealed certain high-pressure turbine
(HPT) stage 1 and HPT stage 2 disks were manufactured from powder metal
material suspected to contain iron inclusion. This proposed AD would
require replacement of affected HPT stage 1 and HPT stage 2 disks with
parts 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
12, 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-2025-1364; 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 GE material identified in this proposed AD, 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 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: [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 using a method listed
under the ADDRESSES section. Include ``Docket No. FAA-2025-1364;
Project Identifier AD-2024-00613-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 revise 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
[[Page 35643]]
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 by the manufacturer of the detection of iron
inclusion in a turbine disk manufactured from the same powder metal
material used to manufacture certain HPT stage 1 and HPT stage 2 disks
for GE Model GE90-90B, GE90-94B, GE90-110B1, and GE90-115B engines.
Further investigation by the manufacturer determined that the iron
inclusion is attributed to deficiencies in the manufacturing process
and may cause reduced material properties and a lower fatigue life
capability, which may result in premature fracture and uncontained
failure. The manufacturer also informed the FAA that additional risk
assessments determined that there were no incidents of premature
fracture and uncontained failure associated with the discovery of this
iron inclusion material on these engines but concluded that replacement
of the affected HPT stage 1 and HPT stage 2 disks is necessary to
prevent any future failure events. The exposure of HPT stage 1 and HPT
stage 2 disks to iron inclusion, if not addressed, could result in
uncontained debris 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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed GE GE90-100 Service Bulletin (SB) 72-0926,
Revision 01, dated December 22, 2023 (GE GE90-100 SB 72-0926, Revision
01). This material specifies the affected part numbers, serial numbers,
and cyclic removal thresholds for the HPT stage 1 and HPT stage 2
disks. This material 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 NPRM
This proposed AD would require replacement of certain HPT stage 1
disks and HPT stage 2 disks with parts eligible for installation. Table
1 to paragraph (c) of this AD includes all part numbers and serial
numbers for affected HPT stage 1 disks that have been scrapped or that
have already been removed from GE Model GE90-90B and GE90-94B engines,
and certain part numbers and serial numbers for affected HPT stage 1
disks and HPT stage 2 disks that have been scrapped or that have
already been removed from GE Model GE90-110B1 and GE90-115B engines. GE
GE90 SB 72-1229, dated October 11, 2023, includes these part numbers
and serial numbers. Therefore, the part numbers and serial numbers for
affected HPT stage 1 disks listed in table 1 to paragraph (c) of this
AD take precedence over those listed in GE GE90 SB 72-1229, dated
October 11, 2023.
Differences Between This Proposed AD and the Referenced Material
GE GE90-100 SB 72-0926, Revision 01 includes cyclic removal
thresholds for certain parts that have already been removed or scrapped
while this proposed AD requires those parts to be removed from service
and replaced before further flight.
GE GE90-100 SB 72-0926, Revision 01 uses the term ``high pressure
turbine rotor (HPTR),'' while this proposed AD uses the term ``high
pressure turbine (HPT).''
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect two engines installed on airplanes of U.S. registry. The FAA
estimates that one engine installed on an airplane of U.S. registry
would require replacement of the HPT stage 1 disk, and one engine
installed on an airplane of U.S. registry would require replacement of
the HPT stage 2 disk. 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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Replace HPT stage 1 disk............. 8 work-hours x $85 per $932,136 (prorated).... $932,816 $932,816
hour = $680.
Replace HPT stage 2 disk............. 8 work-hours x $85 per $186,406 (prorated).... 187,086 187,086
hour = $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
[[Page 35644]]
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-2025-1364; Project
Identifier AD-2024-00613-E.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive
(AD) by September 12, 2025.
(b) Affected ADs
None.
(c) Applicability
This AD applies to the following General Electric Company (GE)
Model engines:
(1) GE90-90B and GE90-94B engines with a high pressure turbine
(HPT) stage 1 disk having a part number and serial number identified
in table 1 to paragraph (c) of this AD installed; and
(2) GE90-110B1 and GE90-115B engines with an HPT stage 1 disk or
HPT stage 2 disk having a part number and serial number identified
in table 1 to paragraph (c) of this AD or Table 1 or Table 2 of GE
GE90-100 Service Bulletin 72-0926, Revision 01, dated December 22,
2023 (GE GE90-100 SB 72-0926, Revision 01) installed.
Table 1 to Paragraph (c)--Affected HPT Stage 1 and 2 Disks
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Part name Part No. Serial No.
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HPT Stage 1 Disk............ 1847M95G01.......... GWN05K5J
HPT Stage 1 Disk............ 1847M95G01.......... GWN05K5M
HPT Stage 1 Disk............ 1847M95G01.......... GWN05NP6
HPT Stage 1 Disk............ 1865M13G08.......... GWN10N9A
HPT Stage 1 Disk............ 1865M13G08.......... GWN0NJ92
HPT Stage 1 Disk............ 1865M13G08.......... GWN0NJ94
HPT Stage 1 Disk............ 1865M13G08.......... GWN0NK87
HPT Stage 1 Disk............ 1865M13G08.......... GWN0RJ4G
HPT Stage 1 Disk............ 1865M13G08.......... GWN0WPEC
HPT Stage 2 Disk............ 1865M14P04.......... TMT4RK67
HPT Stage 2 Disk............ 1865M14P04.......... TMT4RG10
HPT Stage 2 Disk............ 1865M14P04.......... TMT4RG11
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(d) Subject
Joint Aircraft System Component (JASC) Code 7250, Turbine
Section.
(e) Unsafe Condition
This AD was prompted by a manufacturer investigation that
revealed certain HPT stage 1 disks and HPT stage 2 disks were
manufactured from powder metal material suspected to contain iron
inclusion. The FAA is issuing this AD to prevent premature fracture
and uncontained failure of the HPT stage 1 disks and HPT stage 2
disks. The unsafe condition, if not addressed, could result in
uncontained debris 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
At the applicable times specified in paragraphs (g)(1) through
(3) of this AD, remove each affected HPT stage 1 disk and HPT stage
2 disk from service and replace with a part eligible for
installation.
(1) For HPT stage 1 disks and HPT stage 2 disks with a part
number and serial number identified in table 1 to paragraph (c) of
this AD, before further flight.
(2) For HPT stage 1 disks with a part number and serial number
identified in Table 1 of GE GE90-100 SB 72-0926, Revision 01, that
are not identified in table 1 to paragraph (c) of this AD, at the
next piece-part exposure or before exceeding 4,650 cycles since new
(CSN), whichever occurs first.
(3) For HPT stage 2 disks with a part number and serial number
identified in Table 2 of GE GE90-100 SB 72-0926, Revision 01, that
are not identified in table 1 to paragraph (c) of this AD, at the
next piece-part exposure or before exceeding 11,300 CSN, whichever
occurs first.
(h) Grace Period for HPT Stage 1 Disk Replacement
For affected HPT stage 1 disks having greater than 4,650 CSN on
the effective date of this AD, the replacement required by paragraph
(g)(2) of this AD may be deferred up to 50 flight cycles after the
effective date of this AD.
(i) Definitions
(1) For the purpose of this AD, a ``part eligible for
installation'' is any HPT stage 1 disk or HPT stage 2 disk having a
part number and serial number that is not identified in table 1 to
paragraph (c) of this AD or Table 1 or Table 2 of GE GE90-100 SB 72-
0926, Revision 01.
(2) For the purpose of this AD, a ``piece-part exposure'' is
when the affected HPT stage 1 disk or HPT stage 2 disk is removed
from the engine and completely disassembled.
(j) 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 AIR-520 Continued Operational
Safety Branch, send it to the attention of the person identified in
paragraph (k) of this AD and email to: [email protected]. 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) Additional 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 material listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions
required by this AD, unless the AD specifies otherwise.
[[Page 35645]]
(i) GE GE90-100 Service Bulletin 72-0926, Revision 01, dated
December 22, 2023.
(ii) [Reserved]
(3) For GE material identified in this AD, contact General
Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513)
552-3272; email: ge.com">aviation.fleetsupport@ge.com; website: ge.com.
(4) 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.
(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 July 25, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2025-14287 Filed 7-28-25; 8:45 am]
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