
[Federal Register Volume 88, Number 170 (Tuesday, September 5, 2023)]
[Proposed Rules]
[Pages 60603-60605]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-18858]


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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]
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 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 proposed AD would require 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 proposing 
this AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by October 20, 
2023.

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 by 
searching for and locating 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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.
    Material Incorporated by Reference:
     For service information incorporated by reference in this 
NPRM, 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.

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-2023-1647; Project Identifier 
AD-2023-00487-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 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 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 has been informed that GE has communicated 
with affected operators with affected HPT stage 1 and stage 2 disks 
regarding the proposed corrective action for this unsafe condition. As 
a result, affected operators are already aware of the proposed 
corrective action and have already performed the actions proposed in 
this AD. Therefore, the FAA has determined that the compliance time to 
replace the affected HPT stage 1 and stage 2 disks before further 
flight is

[[Page 60604]]

appropriate. This condition, if not addressed, could result in 
uncontained debris release, damage to the engine, and damage to the 
airplane. The FAA is proposing this AD to address the unsafe condition 
on these products.

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 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 ADDRESSES.

Proposed AD Requirements in This NPRM

    This proposed AD would 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.

Differences Between This Proposed AD and the Service Information

    GE GE90-100 SB 72-0914, uses the term ``HPT rotor stage 2 disk,'' 
while this proposed AD uses the term ``HPT stage 2 disk.''
    GE GE90-100 SB 72-0914, Effectivity, identifies GE Model GE-90-
110B1 and GE-90-115B engines. The GE Model GE90-90B and GE90-94B 
engines are also affected by the unsafe condition, however, the FAA is 
not incorporating service information that is specific to GE Model 
GE90-90B and GE90-94B engines.

Interim Action

    The FAA considers that this proposed AD would 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, if adopted as proposed, would 
affect 9 engines installed on airplanes of U.S. registry. The FAA 
estimates that 0 engines installed on airplanes of U.S. registry would 
require replacement of the interstage HPT seal. 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
----------------------------------------------------------------------------------------------------------------
Replace HPT stage 1 disk..............  8 work-hours x $85 per        $1,116,300      $1,116,980      $2,233,960
                                         hour = $680.
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.
----------------------------------------------------------------------------------------------------------------

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-2023-1647; Project 
Identifier AD-2023-00487-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by October 20, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) Model GE90-90B 
and GE90-94B with interstage HPT seals listed in Table 1 to 
Paragraph (c) 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

[[Page 60605]]

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
----------------------------------------------------------------------------------------------------------------
                Part name                                P/N                                 S/N
----------------------------------------------------------------------------------------------------------------
HPT stage 1 disk........................  1865M13G08......................  GWN11657
                                                                            GWN117GN
                                                                            GWN10NNW
                                                                            GWN10PGW
                                                                            GWN10T0A
                                                                            GWN10T0C
                                                                            GWN10THW
                                                                            GWN10TJ0
----------------------------------------------------------------------------------------------------------------
HPT stage 2 disk........................  1865M14P04......................  TMT4RN06
                                                                            TMT4RN26
----------------------------------------------------------------------------------------------------------------
Interstage HPT seal.....................  2453M60P01......................  NCU61528
                                                                            NCU61686
                                                                            NCU56200
                                                                            NCU61527
                                                                            NCU61687
----------------------------------------------------------------------------------------------------------------

(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 P/N and S/N 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 P/N and S/N identified in Table 
1 to paragraph (c) of this AD, before further flight.
    (4) For forward HPT rotor seals with a P/N and S/N 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.
    (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 
P/N and S/N 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) 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].

(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 incorporated by reference 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, email: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on August 11, 2023.
Ross Landes,
Deputy Director for Regulatory Operations, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2023-18858 Filed 9-1-23; 8:45 am]
BILLING CODE 4910-13-P


