[Federal Register Volume 89, Number 15 (Tuesday, January 23, 2024)]
[Rules and Regulations]
[Pages 4184-4187]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-01166]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1647; Project Identifier AD-2023-00487-E; 
Amendment 39-22650; AD 2023-26-07]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain General Electric Company (GE) Model GE90-90B, GE90-94B, GE90-
110B1, and GE90-115B engines. This AD was prompted by a manufacturer 
investigation that revealed certain high-pressure turbine (HPT) stage 1 
disks, HPT stage 2 disks, forward HPT rotor seals, interstage HPT 
seals, and stages 7-9 compressor rotor spools were manufactured from 
powder metal material suspected to contain iron inclusion. This AD 
requires replacement of affected HPT stage 1 disks, HPT stage 2 disks, 
forward HPT rotor seals, interstage HPT seals, and stages 7-9 
compressor rotor spools. The FAA is issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective February 27, 2024.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of February 27, 
2024.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2023-1647; 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 final rule, any comments received, and other 
information. The address for Docket Operations is U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
    Material Incorporated by Reference:
     For service information identified in this final rule, 
contact General Electric Company, 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. It is 
also available at regulations.gov under Docket No. FAA-2023-1647.

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:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain GE Model GE90-
90B, GE90-94B, GE90-110B1, and GE90-115B engines. The NPRM published in 
the Federal Register on September 5, 2023 (88 FR 60603). The NPRM was 
prompted by the manufacturer's detection of iron inclusion in a turbine 
disk manufactured from the same powder metal material used to 
manufacture certain HPT stage 1 disks, HPT stage 2 disks, forward HPT 
rotor seals, interstage HPT seals, and stages 7-9 compressor rotor 
spools for 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 subsequent 
uncontained failure. The FAA was also informed that GE communicated 
with affected operators having affected HPT stage 1 and stage 2 disks 
identified in Table 1 to Paragraph (c) of this AD regarding the 
corrective action for this unsafe condition. As a result, affected 
operators are already aware of the corrective action and have already 
performed the actions required by this AD. Therefore, the FAA has 
determined that the compliance time to replace these affected HPT stage 
1 and stage 2 disks before further flight is appropriate. In the NPRM, 
the FAA proposed to require replacement of certain HPT stage 1 disks, 
HPT stage 2 disks, forward HPT rotor seals, interstage HPT seals, and 
stages 7-9 compressor rotor spools with parts eligible for 
installation. The FAA is issuing this AD to address the unsafe 
condition on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from five commenters. Commenters included

[[Page 4185]]

The Boeing Company (Boeing), Federal Express (FedEx), GE, United 
Airlines, and an individual commenter. Boeing, United Airlines, and the 
individual commenter supported the NPRM without change. FedEx and GE 
requested changes to the proposed AD. The following presents the 
comments received on the NPRM and the FAA's response to each comment.

Request To Reference Additional Service Information

    FedEx and GE requested that the FAA add the following service 
information to the NPRM in a section designated as Other Related 
Service Information: GE GE90-100 Service Bulletin (SB) 72-0904 R00, 
dated May 25, 2022; GE GE90-100 SB 72-0911 R01, dated September 21, 
2022; and GE GE90 SB 72-1223, dated January 25, 2023. FedEx and GE both 
noted that Table 1 to Paragraph (c) of the proposed AD listed affected 
components that were partially copied from those GE SBs, and not 
including mention of those GE SBs could cause confusion for operators, 
even though additional GE SBs would not be incorporated by reference.
    The FAA agrees and for the ease of the reader, instead of including 
these additional GE SBs in a section identified as Other Related 
Service Information in the preamble, has added Note 1 to paragraph (c) 
of this AD to include the three additional GE SBs identified by the 
commenters and to clarify that the affected parts can also be found in 
these additional GE SBs. These additional GE SBs will not be 
incorporated by reference in this AD.

Request To Update Affected Part Number

    GE requested that the FAA update Table 1 to Paragraph (c) of the 
proposed AD by changing the part number (P/N) for an affected HPT stage 
1 disk having serial number (S/N) GWN10NNW from ``1865M13G08'' to 
``2445M04G11.'' GE noted that the HPT stage 1 disk with S/N GWN10NNW 
was repaired and re-marked to P/N 2445M04G11.
    The FAA agrees and has updated Table 1 to Paragraph (c) of this AD 
as requested by GE.

Request To Clarify Language in Background Section

    GE requested that the FAA add language to the Background section of 
the NPRM to clarify that GE communicated with affected operators having 
affected HPT stage 1 and stage 2 disks identified in Table 1 to 
Paragraph (c) of the proposed AD regarding the proposed corrective 
action for the identified unsafe condition. GE noted that the current 
language in the NPRM does not specify that the affected disks are 
identified in Table 1 to Paragraph (c) of the proposed AD, and 
additional HPT stage 2 disks are identified in General Electric GE90-
100 Service Bulletin 72-0914, dated January 25, 2023, which could cause 
a misinterpretation of the required actions on HPT stage 2 disks.
    The FAA agrees and has revised the language in the Background 
section of this final rule accordingly.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, and 
any other changes described previously, this AD is adopted as proposed 
in the NPRM. None of the changes will increase the economic burden on 
any operator.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed GE GE90-100 Service Bulletin (SB) 72-0914, dated 
January 25, 2023 (GE GE90-100 SB 72-0914); which provides the affected 
part and serial numbers of the HPT stage 2 disks, forward HPT rotor 
seals, and stages 7-9 compressor rotor spools; and specifies 
replacement instructions for the HPT stage 2 disks, forward HPT rotor 
seals, and stages 7-9 compressor rotor spools. 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 the ADDRESSES section.

Interim Action

    The FAA considers this AD to be an interim action. This unsafe 
condition is still under investigation by the manufacturer and, 
depending on the results of that investigation, the FAA may consider 
further rulemaking action.

Costs of Compliance

    The FAA estimates that this AD affects 9 engines installed on 
airplanes of U.S. registry. The FAA estimates that 0 engines installed 
on airplanes of U.S. registry require replacement of the interstage HPT 
seal.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Replace HPT stage 2 disk..............  8 work-hours x $85 per          $531,578        $532,258        $532,258
                                         hour = $680.
Replace stages 7-9 compressor rotor     8 work-hours x $85.per           493,588         494,268       1,977,072
 spool.                                  hour = $680.
Replace forward HPT rotor seal........  8 work-hours x $85 per            25,093          25,773          51,546
                                         hour = $680.
Replace interstage HPT seal...........  8 work-hours x $85 per           108,256         108,936               0
                                         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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 that this AD:

[[Page 4186]]

    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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:

2023-26-07 General Electric Company: Amendment 39-22650; Docket No. 
FAA-2023-1647; Project Identifier AD-2023-00487-E.

(a) Effective Date

    This airworthiness directive (AD) is effective February 27, 
2024.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) Model GE90-90B 
and GE90-94B engines with interstage HPT seals listed in Table 1 to 
Paragraph (c) of this AD and GE90-110B1 and GE90-115B engines with 
an installed high-pressure turbine (HPT) stage 1 disk, HPT stage 2 
disk, forward HPT rotor seal, or stages 7-9 compressor rotor spool 
part number (P/N) and serial number (S/N) identified in Table 1 to 
Paragraph (c) of this AD, or identified in Paragraph 4. APPENDIX--A, 
Tables 1, 2, or 3, of GE GE90-100 Service Bulletin (SB) 72-0914, 
dated January 25, 2023 (GE90-100 SB 72-0914).

Table 1 to Paragraph (c)--Affected HPT Stage 1 and Stage 2 Disks, and 
Interstage HPT Seals
[GRAPHIC] [TIFF OMITTED] TR23JA24.021

    Note 1 to paragraph (c): Part numbers and serial numbers for 
affected HPT stage 1 disks, HPT stage 2 disks, and interstage HPT 
seals are also listed in GE GE90-100 Service Bulletin (SB) 72-0904 
R00, dated May 25, 2022; GE GE90-100 SB 72-0911 R01, dated September 
21, 2022; and GE GE90 SB 72-1223, dated January 25, 2023.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section; 7250, Turbine Section.

(e) Unsafe Condition

    This AD was prompted by a manufacturer investigation that 
revealed certain HPT stage 1 disks, HPT stage 2 disks, forward HPT 
rotor seals, interstage HPT seals, and stages 7-9 compressor rotor 
spools were manufactured from powder metal material suspected to 
contain iron inclusion. The FAA is issuing this AD to prevent 
premature fracture and subsequent uncontained failure. 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 
(6) of this AD, remove each affected HPT stage 1 disk, HPT stage 2 
disk, forward HPT rotor seal, interstage HPT seal, and stages 7-9 
compressor rotor spool from service and replace with a part eligible 
for installation.
    (1) For HPT stage 1 disks, before further flight.
    (2) For HPT stage 2 disks with a part number and serial number 
identified in Paragraph 4. APPENDIX--A, Table 1 of GE90-100 SB 72-
0914, at the next piece part exposure or before exceeding 3,500 
cycles since new (CSN), whichever occurs first.
    (3) For HPT stage 2 disks with a part number and serial number 
identified in Table 1 to paragraph (c) of this AD, before further 
flight.
    (4) For forward HPT rotor seals with a part number and serial 
number identified in Paragraph 4. APPENDIX--A, Table 3 of GE90-100 
SB 72-0914, at the next piece part exposure or before exceeding 
14,200 CSN, whichever occurs first.
    (5) For interstage HPT seals, at the next piece part exposure or 
before exceeding 12,600 CSN, whichever occurs first.

[[Page 4187]]

    (6) For stages 7-9 compressor rotor spools, at the next piece 
part exposure or before exceeding the cyclic removal thresholds 
identified in Paragraph 4. APPENDIX--A, Table 2 of GE90-100 SB 72-
0914, whichever occurs first.

(h) Definition

    For the purpose of this AD, a ``part eligible for installation'' 
is any HPT stage 1 disk, HPT stage 2 disk, stages 7-9 compressor 
rotor spool, forward HPT rotor seal, or interstage HPT seal with a 
part number and serial number that is not identified in paragraph 
(c) of this AD.

(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 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) 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].

(k) 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 GE90-100 Service Bulletin 72-0914, dated 
January 25, 2023.
    (ii) [Reserved]
    (3) For service information 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 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 service information that is incorporated 
by reference 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 January 2, 2024.
Caitlin Locke,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2024-01166 Filed 1-22-24; 8:45 am]
BILLING CODE 4910-13-P