Airworthiness Directives; General Electric Company Turbofan Engines

[Federal Register Volume 85, Number 189 (Tuesday, September 29, 2020)]
[Rules and Regulations]
[Pages 60898-60900]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-21450]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0555; Project Identifier AD-2020-00615-E; 
Amendment 39-21267; AD 2020-20-11]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Turbofan 
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) GEnx-1B64/P2, -1B67/P2, -1B70/P2, 
-1B70C/P2, -1B70/75/P2, -1B74/75/P2, -1B76/P2, -1B76A/P2, and GEnx-
2B67/P model turbofan engines. This AD was prompted by the detection of 
melt-related freckles in the billet, which may reduce the life limits 
of certain high-pressure turbine (HPT) rotor stage 2 disks and a 
certain stages 6-10 compressor rotor spool. This AD requires the 
removal of certain HPT rotor stage 2 disk and the removal of a certain 
stages 6-10 compressor rotor spool before reaching their new life 
limits. The FAA is issuing this AD to address the unsafe condition on 
these products.

DATES: This AD is effective November 3, 2020.

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 781-238-7759. It is also 
available on the internet at https://www.regulations.gov by searching 
for and locating Docket No. FAA-2020-0555.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0555; 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: Mehdi Lamnyi, Aerospace Engineer, ECO 
Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 781-
238-7743; fax: 781-238-7199; email: [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    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 GEnx-1B64/
P2, -1B67/P2, -1B70/P2, -1B70C/P2, -1B70/75/P2, -1B74/75/P2, -1B76/P2, 
-1B76A/P2, and GEnx-2B67/P model turbofan engines. The NPRM published 
in the Federal Register on June 8, 2020 (85 FR 35021). The NPRM was 
prompted by the detection of melt-related freckles in the billet, which 
may reduce the life limits of certain HPT rotor stage 2 disks and a 
certain stages 6-10 compressor rotor spool. The NPRM proposed to 
require the removal of certain HPT rotor stage 2 disk and the removal 
of a certain stages 6-10 compressor rotor spool before reaching their 
new life limits. The FAA is issuing this AD to address the unsafe 
condition on these products.

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Request to List Part and Serial Numbers

    GE requested that both the affected part and serial numbers be 
listed in the Applicability section of this AD instead of the affected 
engine serial numbers.
    The FAA agrees. The FAA recognizes that affected HPT rotor stage 2 
disks could be moved from one engine to another engine. The intent of 
this AD is to mandate the removal of the affected parts from service, 
regardless of the engine on which they are installed. The FAA is 
revising the Applicability section of this AD as suggested by the 
commenter. This change does not expand the scope of this AD because the 
number of affected engines installed on airplanes of U.S. registry 
remains the same in this final rule compared to what was published in 
the NPRM.

Support for the AD

    The Air Line Pilots Association, International; the Boeing Company; 
and United Airlines Engineering expressed support for the AD as 
written.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule with the changes described previously 
and minor editorial changes. The FAA has determined that these minor 
changes:
    <bullet> Are consistent with the intent that was proposed in the 
NPRM for addressing the unsafe condition; and
    <bullet> Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    The FAA also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Related Service Information

    The FAA reviewed GE GEnx-1B Service Bulletin (SB) 72-0473 R00, 
dated April 14, 2020; GE GEnx-1B SB 72-0474 R00, dated April 14, 2020; 
and GE GEnx-2B SB 72-0416 R00, dated April 14, 2020. GE GEnx-1B SB 72-
0473 R00 describes procedures for removing and replacing the HPT rotor 
stage 2 disks on GE GEnx-1B model engines. GE GEnx-1B SB 72-0474 R00 
describes procedures for removing and replacing the stages 6-10 
compressor rotor spool on GE GEnx-1B model engines. GE GEnx-2B SB 72-
0416 R00 describes procedures for removing and replacing the HPT rotor 
stage 2 disks on GE GEnx-2B model engines.

Costs of Compliance

    The FAA estimates that this AD affects two engines installed on 
airplanes of U.S. registry; one engine requires the HPT rotor stage 2 
disk replacement and one engine requires the stages 6-10 compressor 
rotor spool replacement.
    The FAA estimates the following costs to comply with this AD:

[[Page 60899]]



                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Removal and replacement of the HPT      1,500 work-hours x $85          $458,900        $586,400        $586,400
 rotor stage 2 disk.                     per hour = $127,500.
Removal and replacement of the stages   600 work-hours x $85 per       1,018,600       1,069,600       1,069,600
 6-10 compressor rotor spool.            hour = $51,000.
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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 (AD):

2020-20-11 General Electric Company: Amendment 39-21267; Docket No. 
FAA-2020-0555; Project Identifier AD-2020-00615-E.

(a) Effective Date

    This AD is effective November 3, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all General Electric Company (GE) GEnx-1B64/
P2, -1B67/P2, -1B70/P2, -1B70C/P2, -1B70/75/P2, -1B74/75/P2, -1B76/
P2, -1B76A/P2, and GEnx-2B67/P model turbofan engines with:
    (1) a high-pressure turbine (HPT) rotor stage 2 disk, part 
number (P/N) 2383M86P02, having one of the following serial numbers 
(S/Ns): TMT18D6T, TMT18D6U, TMT18JC4, TMT18NGC, TMT1985C, TMT3UA34, 
TMT3UA55, TMT4CT46, or TMT4CT47, installed; or
    (2) a stages 6-10 compressor rotor spool, P/N 2628M56G01, S/N 
GWN10ECM, installed.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7250, Turbine 
Section.

(e) Unsafe Condition

    This AD was prompted by the detection of melt-related freckles 
in the billet, which may reduce the life limits of certain HPT rotor 
stage 2 disks and a certain stages 6-10 compressor rotor spool. The 
FAA is issuing this AD to prevent failure of the HPT rotor stage 2 
disk and stages 6-10 compressor rotor spool. The unsafe condition, 
if not addressed, could result in uncontained release of both the 
HPT rotor stage 2 disk and the stages 6-10 compressor rotor spool, 
damage to the engine, and damage to the aircraft.

(f) Compliance

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

(g) Required Actions

    After the effective date of this AD, before the parts accumulate 
the cycles since new (CSN) threshold listed in Table 1 to paragraph 
(g) of this AD, remove the affected HPT rotor stage 2 disk and the 
stages 6-10 compressor rotor spool from service and replace with 
parts eligible for installation.

[[Page 60900]]

[GRAPHIC] [TIFF OMITTED] TR29SE20.075

(h) Installation Prohibition

    After the effective date of this AD, do not install the affected 
HPT rotor stage 2 disks or the stages 6-10 compressor rotor spool 
identified in Table 1 to paragraph (g) of this AD on an engine.

(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) of this AD. You may email your request 
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 Mehdi Lamnyi, 
Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: 781-238-7743; fax: 781-238-7199; email: 
[email protected].

(k) Material Incorporated by Reference

    None.

    Issued on September 24, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-21450 Filed 9-28-20; 8:45 am]
BILLING CODE 4910-13-P

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