
[Federal Register Volume 88, Number 179 (Monday, September 18, 2023)]
[Rules and Regulations]
[Pages 63834-63836]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-20063]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0663; Project Identifier AD-2023-00020-E; 
Amendment 39-22534; AD 2023-17-08]
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 GEnx-1B and GEnx-2B 
engines. This AD was prompted by a manufacturer investigation that 
revealed that certain stages 6-10 compressor rotor spools and forward 
seals were manufactured from powder metal material suspected to contain 
iron inclusion. This AD requires the replacement of the affected stages 
6-10 compressor rotor spools and forward seals. The FAA is issuing this 
AD to address the unsafe condition on these products.

DATES: This AD is effective October 23, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of October 23, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov by 
searching for and locating Docket No. FAA-2023-0663; 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 GE service information identified in this final rule, 
contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: [email protected]; website: 
geaviation.com/support.
     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 by searching for and locating Docket 
No. FAA-2023-0663.

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 GEnx-
1B64/P2, GEnx-1B67/P2, GEnx-1B70/75/P2, GEnx-1B70/P2, GEnx-1B70C/P2, 
GEnx-1B74/75/P2, GEnx-1B76/P2, GEnx-1B76A/P2, and GEnx-2B67/P engines. 
The NPRM published in the Federal Register on April 13, 2023 (88 FR 
22383). The NPRM was prompted by a report from the manufacturer of the 
detection of iron inclusion in a high-pressure turbine stage 2 disk 
manufactured from the same powder metal material used to manufacture 
certain stages 6-10 compressor rotor spools and forward seals. A 
manufacturer investigation determined that the iron inclusion was 
introduced during the manufacturing process from raw material filtering 
screens that had degraded, and certain stages 6-10 compressor rotor 
spools and forward seals manufactured using the same process may have 
reduced material properties and a lower fatigue life capability due to 
the iron inclusion. Further investigation by the manufacturer 
identified additional degraded filtering screens which had the 
potential to increase the population of parts that were subjected to 
iron inclusion during manufacturing. As a result of its investigation, 
GE published service information that specifies procedures for the 
removal and replacement of certain stages 6-10 compressor rotor spools 
and forward seals. In the NPRM, the FAA proposed to require removal of 
the affected stages 6-10 compressor rotor spools and forward seals and 
replacement with a part 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 three commenters. The commenters 
were the Airline Pilots Association, International (ALPA), American 
Airlines (AA), and United Airlines. AA requested changes to the NPRM. 
ALPA supported the NPRM without change. United Airlines reviewed the 
NPRM but did not include any additional comments. The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Request for Guidance on Thrust Limit

    AA requested that the FAA provide guidance on which thrust limit to 
apply for engines with multiple thrust ratings. AA also asked if the 
FAA's intention is to set the thrust limit based on the thrust rating 
at removal, or if the expectation is to apply the lowest limit that the 
engine operated under. AA noted that it has a spool operating where the 
proposed AD limit would be 6,200 cycles, but it previously operated at 
a higher thrust rating such that the limit was 1,000 cycles less.
    The FAA agrees to clarify. The intention of the thrust limit is for 
operators to remove the affected stages 6-10 compressor rotor spool or 
affected forward seal from service at the next piece-part exposure, or 
no later than the cyclic thresholds listed in the applicable service 
bulletins that are incorporated by reference. The FAA notes that since 
multiple thrust ratings are listed in the service bulletins, the intent 
is to set the cyclic removal threshold based on the thrust rating that 
is applicable at the time the AD is issued, not at the lowest thrust 
rating that a part has ever operated under. The FAA did not change this 
AD as a result of this comment.

Request To Update Service Bulletin Shorthand

    AA requested that the FAA add the revision levels to the shorthand 
reference of each service bulletin in paragraph (g) and (h) of this AD. 
AA noted that -1B operators do not have access to -2B bulletins, and 
vice versa, so -1B operators will not be notified if the -2B service 
bulletin is revised, and

[[Page 63835]]

will not be able to confirm that the information between the two 
service bulletins continues to match.
    The FAA agrees and has revised the shorthand reference for each 
applicable service bulletin to include the revision level in paragraphs 
(c), (g) and (h) of this AD.

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 GEnx-1B Service Bulletin 72-0515, R00, dated 
January 31, 2023. The FAA also reviewed GE GEnx-2B Service Bulletin 72-
0452, R00, dated January 31, 2023. This service information specifies 
procedures for removal and replacement of the stages 6-10 compressor 
rotor spool and forward seal. 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 
the ADDRESSES section.

Interim Action

    The FAA considers this AD to be an interim action. If final action 
is later identified, the FAA might consider additional rulemaking.

Costs of Compliance

    The FAA estimates that this AD affects 13 engines installed on 
airplanes of U.S. registry. The FAA estimates that 9 of the 13 engines 
will require replacing the stages 6-10 compressor rotor spool and 4 of 
the 13 engines will require replacing the forward 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 stages 6-10 compressor       8 work-hours x $85 per hour        $841,088        $841,768      $7,575,912
 rotor spool.                         = $680.
Replace forward seal...............  8 work-hours x $85 per hour         389,976         390,656       1,562,624
                                      = $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:
    (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:

2023-17-08 General Electric Company: Amendment 39-22534; Docket No. 
FAA-2023-0663; Project Identifier AD-2023-00020-E.

(a) Effective Date

    This airworthiness directive (AD) is effective October 23, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) Model GEnx-
1B64/P2, GEnx-1B67/P2, GEnx-1B70/75/P2, GEnx-1B70/P2, GEnx-1B70C/P2, 
GEnx-1B74/75/P2, GEnx-1B76/P2, GEnx-1B76A/P2, and GEnx-2B67/P 
engines with an installed:
    (1) Stages 6-10 compressor rotor 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 72-0515, R00, dated January 31, 
2023 (GEnx-1B 72-0515 R00); or
    (2) Forward seal having a P/N and S/N listed in paragraph 4, 
Appendix--A, Table 2 of GEnx-1B 72-0515 R00; or
    (3) Stages 6-10 compressor rotor spool having a P/N and S/N 
listed in paragraph 4, Appendix--A, Table 1 of GE GEnx-2B Service 
Bulletin 72-0452, R00, dated January 31, 2023. (GEnx-2B 72-0452 
R00); or
    (4) Forward seal having a P/N and S/N listed in paragraph 4, 
Appendix--A, Table 2 of GEnx-2B 72-0452 R00.

(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 stages 6-10 compressor rotor spools and forward 
seals were subject to iron inclusion introduced during the 
manufacturing process. The FAA is issuing this AD to prevent 
fracture and potential uncontained failure of certain stages 6-10 
compressor rotor spools and forward seals. The unsafe condition, if 
not addressed, could result in uncontained debris release, damage to 
the engine, and damage to the aircraft.

[[Page 63836]]

(f) Compliance

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

(g) Required Actions

    (1) For affected Model GEnx-1B engines, at the next piece-part 
exposure after the effective date of this AD, or before the affected 
stages 6-10 compressor rotor spool reaches the cyclic removal 
threshold listed in paragraph 4., Appendix--A, Table 1 of GEnx-1B 
72-0515 R00, whichever occurs first, remove the affected stages 6-10 
compressor rotor spool from service and replace with a part eligible 
for installation.
    (2) For affected Model GEnx-1B engines, at the next piece-part 
exposure after the effective date of this AD, or before the affected 
forward seal exceeds the cyclic removal threshold listed in 
paragraph 4., Appendix--A, Table 2 of GEnx-1B 72-0515 R00, whichever 
occurs first, remove the affected forward seal from service and 
replace with a part eligible for installation.
    (3) For affected Model GEnx-2B engines, at the next piece-part 
exposure after the effective date of this AD, or before the affected 
stages 6-10 compressor rotor spool exceeds the cyclic removal 
threshold listed in paragraph 4., Appendix--A, Table 1 of GEnx-2B 
72-0452 R00, whichever occurs first, remove the affected stages 6-10 
compressor rotor spool from service and replace with a part eligible 
for installation.
    (4) For affected Model GEnx-2B engines, at the next piece-part 
exposure after the effective date of this AD, or before the affected 
forward seal exceeds the cyclic removal threshold listed in 
paragraph 4., Appendix--A, Table 2 of GEnx-2B 72-0452 R00, whichever 
occurs first, remove the affected forward seal from service and 
replace with a part eligible for installation.

(h) Definitions

    (1) For the purpose of this AD, a ``part eligible for 
installation'' is any stages 6-10 compressor rotor spool or forward 
seal with a P/N and S/N not listed in paragraph 4, Appendix--A, 
Table 1 or paragraph 4, Appendix--A, Table 2 of GEnx-1B 72-0515 R00 
or GEnx-2B 72-0452 R00.
    (2) For the purpose of this AD, ``piece-part exposure'' is when 
the affected part is removed from the engine.

(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 certification office, 
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 Company (GE) GEnx-1B Service Bulletin 72-
0515, R00, dated January 31, 2023.
    (ii) GE GEnx-2B Service Bulletin 72-0452, R00, dated January 31, 
2023.
    (3) For GE service information identified in this AD, contact 
General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; 
phone: (513) 552-3272; email: [email protected]; website: 
geaviation.com/support.
    (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 24, 2023.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-20063 Filed 9-15-23; 8:45 am]
BILLING CODE 4910-13-P


