Airworthiness Directives; General Electric Company Turbofan Engines

[Federal Register Volume 87, Number 182 (Wednesday, September 21, 2022)]
[Rules and Regulations]
[Pages 57575-57578]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-19853]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0516; Project Identifier AD-2022-00262-E; 
Amendment 39-22157; AD 2022-18-06]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
General Electric Company (GE) GE90-110B1 and GE90-115B model turbofan 
engines and certain GE90-76B, GE90-85B, GE90-90B, and GE90-94B model 
turbofan engines. This AD was prompted by the detection of melt-related 
freckles in the forgings and billets, which may reduce the life of 
certain rotating compressor discharge pressure (CDP) high-pressure 
turbine (HPT) seals (rotating CDP seals), interstage HPT rotor seals, 
and HPT rotor stage 2 disks. This AD requires revising the 
airworthiness limitations section (ALS) of the applicable GE90-100 
Engine Manual (EM) and the operator's existing approved maintenance 
program or inspection program, as applicable, to incorporate reduced 
life limits for these parts. This AD also requires the removal and 
replacement of certain interstage HPT rotor seals, identified by serial 
number (S/N), installed on GE90-76B, GE90-85B, GE90-90B, and GE90-94B 
model turbofan engines. The FAA is issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective October 26, 2022.

ADDRESSES: For 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: 
www.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.

Examining the AD Docket

    You may examine the AD docket at www.regulations.gov by searching 
for and locating Docket No. FAA-2022-0516; 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.

FOR FURTHER INFORMATION CONTACT: Alexei Marqueen, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7178; email: [email protected].

SUPPLEMENTARY INFORMATION:

[[Page 57576]]

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all GE GE90-110B1 and 
GE90-115B model turbofan engines and certain GE90-76B, GE90-85B, GE90-
90B, and GE90-94B model turbofan engines. The NPRM published in the 
Federal Register on May 27, 2022 (87 FR 32098). The NPRM was prompted 
by notification by the engine manufacturer of the detection of melt-
related freckles in the forgings and billets, which may reduce the life 
of certain rotating CDP seals, interstage HPT rotor seals, and HPT 
rotor stage 2 disks on GE90-110B1 and GE90-115B model turbofan engines 
and may reduce the life of certain interstage HPT rotor seals on GE90-
76B, GE90-85B, GE90-90B, and GE90-94B model turbofan engines. The 
manufacturer's investigation determined that, as a result of such 
freckles forming in the forgings and billets, certain rotating CDP 
seals, interstage HPT rotor seals, and HPT rotor stage 2 disks (life-
limited parts (LLPs)) may have undetected subsurface anomalies that 
developed during the manufacturing process, resulting in reduced 
material properties and a lower fatigue life capability. Reduced 
material properties may cause premature LLP fracture, which could 
result in uncontained debris release. As a result of its investigation, 
the manufacturer determined the need to reduce the life limits of 
certain LLPs. To reflect these reduced life limits, the manufacturer 
revised the ALS of the affected GE90-100 EMs. Additionally, the 
manufacturer published service information that specifies procedures 
for the removal and replacement of certain interstage HPT rotor seals 
installed on GE90-76B, GE90-85B, GE90-90B, and GE90-94B model turbofan 
engines. In the NPRM, the FAA proposed to require revising the ALS of 
the applicable GE90-100 EM and the operator's existing approved 
maintenance program or inspection program, as applicable, to 
incorporate reduced life limits for certain LLPs. The NPRM also 
proposed to require the removal and replacement of certain interstage 
HPT rotor seals. 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 six commenters. The commenters were 
Air Line Pilots Association, International (ALPA), American Airlines, 
The Boeing Company (Boeing), FedEx Express, Japan Airlines, and United 
Airlines. Five of the commenters, ALPA, American Airlines, Boeing, 
FedEx Express, and United Airlines, supported the proposal without 
change. The following presents the comment received on the NPRM and the 
FAA's response.

Request To Refer to Service Information

    Japan Airlines requested that the FAA refer to GE90 SB 72-1211, 
latest revision, in the AD as the appropriate source of service 
information for the required actions. Japan Airlines noted that this 
would confirm the source of the affected interstage HPT rotor seal for 
the GE90-76B, GE90-85B, GE90-90B, and GE90-94B model engines. The FAA 
infers that Japan Airlines is requesting for GE90 SB 72-1211 to be 
incorporated by reference. The FAA disagrees with the request to 
incorporate GE90 SB 72-1211 by reference. Paragraph (c)(2) of this AD 
identifies the affected interstage HPT rotor seal installed on the 
GE90-76B, GE90-85B, and GE90-94B model turbofan engines by part number 
and serial number. The FAA did not change this AD as a result of this 
comment.

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, this 
AD is adopted as proposed in the NPRM. None of the changes will 
increase the economic burden on any operator.

Related Service Information

    The FAA reviewed GE GE90-100 SB 72-0851 R00, dated August 17, 2021. 
This service information provides reduced life limits for certain LLPs. 
The FAA also reviewed GE GE90 SB 72-1211 R00, dated March 9, 2022. This 
service information describes procedures for removing and replacing 
certain interstage HPT rotor seals.

Costs of Compliance

    The FAA estimates that this AD affects 248 engines installed on 
airplanes of U.S. registry. The FAA estimates that zero engines 
installed on airplanes of U.S. registry will require replacement of the 
interstage HPT rotor 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
----------------------------------------------------------------------------------------------------------------
Revise ALS of EM and the operator's     1 work-hour x $85 per                 $0             $85         $21,080
 existing approved maintenance program   hour = $85.
 or inspection program.
Replace interstage HPT rotor seal.....  1,500 work-hours x $85           286,331         413,831               0
                                         per hour = $127,500.
----------------------------------------------------------------------------------------------------------------

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

[[Page 57577]]

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:

2022-18-06 General Electric Company: Amendment 39-22157; Docket No. 
FAA-2022-0516; Project Identifier AD-2022-00262-E.

(a) Effective Date

    This airworthiness directive (AD) is effective October 26, 2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to:
    (1) General Electric Company (GE) GE90-110B1 and GE90-115B model 
turbofan engines; and
    (2) GE GE90-76B, GE90-85B, GE90-90B, and GE90-94B model turbofan 
engines with an installed interstage high-pressure turbine (HPT) 
rotor seal with part number (P/N) 2629M47P01 and serial number (S/N) 
NCU5430D.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by the detection of melt-related freckles 
in the forgings and billets, which may reduce the life of certain 
rotating compressor discharge pressure (CDP) HPT seals (rotating CDP 
seals), interstage HPT rotor seals, and HPT rotor stage 2 disks. The 
FAA is issuing this AD to prevent failure of the rotating CDP seal, 
interstage HPT rotor seal, and HPT rotor stage 2 disk. 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

    (1) For affected GE90-110B1 and GE90-115B model turbofan 
engines, within 90 days after the effective date of this AD, revise 
the airworthiness limitations section (ALS) of the existing GE90-100 
Engine Manual (EM) and the operator's existing approved maintenance 
program or inspection program, as applicable, by inserting the 
following information:
    (i) For rotating CDP seal P/N 2479M03P01, insert the information 
in Table 1 to paragraph (g)(1)(i) of this AD.

    Table 1 to Paragraph (g)(1)(i)--Rotating CDP Seal P/N 2479M03P01
------------------------------------------------------------------------
           Part name                     Part No.           Life cycles
------------------------------------------------------------------------
Seal, CDP......................  2479M03P01, For part             15,000
                                  serial numbers NOT
                                  listed in SB 72-0851,
                                  latest revision.
Seal, CDP......................  2479M03P01, For part              5,300
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 11.
Seal, CDP......................  2479M03P01, For part             10,400
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 12.
Seal, CDP......................  2479M03P01, For part             13,900
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A,
                                  Table 13.
------------------------------------------------------------------------

    (ii) For interstage HPT rotor seal P/N 2505M72P01, insert the 
information in Table 2 to paragraph (g)(1)(ii) of this AD.

     Table 2 to Paragraph (g)(1)(ii)--Interstage HPT Rotor Seal P/N
                               2505M72P01
------------------------------------------------------------------------
           Part name                     Part No.           Life cycles
------------------------------------------------------------------------
Seal, Interstage...............  2505M72P01, For part             15,000
                                  serial numbers NOT
                                  listed in SB 72-0851,
                                  latest revision.
Seal, Interstage...............  2505M72P01, For part              5,500
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 8.
Seal, Interstage...............  2505M72P01, For part             10,900
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 9.
Seal, Interstage...............  2505M72P01, For part             14,300
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 10.
------------------------------------------------------------------------

    (iii) For HPT rotor stage 2 disk P/N 2505M73P03, insert the 
information in Table 3 to paragraph (g)(1)(iii) of this AD.

 Table 3 to Paragraph (g)(1)(iii)--HPT Rotor Stage 2 Disk P/N 2505M73P03
------------------------------------------------------------------------
           Part name                     Part No.           Life cycles
------------------------------------------------------------------------
Disk, Stage 2..................  2505M73P03, For part             15,000
                                  serial numbers NOT
                                  listed in SB 72-0851,
                                  latest revision.

[[Page 57578]]

 
Disk, Stage 2..................  2505M73P03, For part              3,500
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 1.
Disk, Stage 2..................  2505M73P03, For part              5,100
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 2.
Disk, Stage 2..................  2505M73P03, For part              5,800
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 3.
Disk, Stage 2..................  2505M73P03, For part              7,200
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 4.
Disk, Stage 2..................  2505M73P03, For part              8,000
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 5.
Disk, Stage 2..................  2505M73P03, For part              8,300
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 6.
Disk, Stage 2..................  2505M73P03, For part              8,800
                                  serial numbers listed
                                  in SB 72-0851, latest
                                  revision APPENDIX A
                                  Table 7.
------------------------------------------------------------------------

    (2) For affected GE90-76B, GE90-85B, GE90-90B, and GE90-94B 
model turbofan engines, before the interstage HPT rotor seal, P/N 
2629M47P01 and S/N NCU5430D, accumulates 7,400 cycles since new, 
remove the affected interstage HPT rotor seal from service and 
replace with a part eligible for installation.

(h) Definitions

    For the purpose of this AD, a ``part eligible for installation'' 
is any interstage HPT rotor seal that does not have P/N 2629M47P01 
and S/N NCU5430D.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO 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)(1) 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

    (1) For more information about this AD, contact Alexei Marqueen, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7178; email: 
[email protected].
    (2) For service information identified (but not incorporated by 
reference) in this AD, contact General Electric Company, 1 Neumann 
Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: 
[email protected]; website: www.ge.com. You may view this 
referenced 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.

(k) Material Incorporated by Reference

    None.

    Issued on August 18, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-19853 Filed 9-20-22; 8:45 am]
BILLING CODE 4910-13-P

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