Document ID: FAA-2020-0592-0008
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2020-12-16T05:00Z

[Federal Register Volume 85, Number 242 (Wednesday, December 16, 2020)]
[Rules and Regulations]
[Pages 81378-81381]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-27628]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0592; Project Identifier AD-2020-00251-E; 
Amendment 39-21352; AD 2020-25-10]
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 all 
General Electric Company (GE) 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 model turbofan engines with a certain high-
pressure turbine (HPT) rotor stage 2 disk installed. This AD was 
prompted by a report of the potential for undetected subsurface 
anomalies formed during the manufacturing process that could result in 
uncontained failure of the HPT rotor stage 2 disk. This AD requires an 
immersion ultrasonic inspection (USI) of the HPT rotor stage 2 disk 
and, depending on the results of the inspection, replacement of the HPT 
rotor stage 2 disk with a part eligible for installation. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective January 21, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of January 21, 
2021.

ADDRESSES: For service information identified in this final rule, 
contact General Electric Company, GE Aviation, Room 285, 1 Neumann Way, 
Cincinnati, OH 45215; phone: (513) 552-3272; email: 
aviation.fleetsupport@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 at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2020-0592.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2020-0592; 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, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7743; fax: (781) 238-7199; email: 
Mehdi.Lamnyi@faa.gov.

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 all GE 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 model turbofan 
engines with a certain HPT rotor stage 2 disk installed. The NPRM 
published in the Federal Register on June 12, 2020 (85 FR 35816). The 
NPRM was prompted by a report of the potential for undetected 
subsurface anomalies formed during the manufacturing process that could 
result in uncontained failure of the HPT rotor stage 2 disk. In the 
NPRM, the FAA proposed to require an immersion USI of the HPT rotor 
stage 2 disk and, depending on the results of the inspection, 
replacement of the HPT rotor stage 2 disk 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 six commenters. The commenters were 
Air Line Pilots Association, International (ALPA); The Boeing Company 
(Boeing); Cargolux Airlines International S.A. (Cargolux); GE Aviation; 
United Airlines (UAL) Engineering; and Qantas Airways Limited (Qantas). 
One commenter requested that the FAA update the Affected ADs paragraph 
of this AD. One commenter requested that the HPT rotor stage 2 disks be 
replaced instead of inspected. One commenter requested that the FAA 
update the Definitions paragraph of this AD. Two commenters requested 
adding credit for previous action. Three commenters supported the AD. 
The following presents the comments received on the NPRM and the FAA's 
response to each comment.

[[Page 81379]]

Request To Update Affected ADs

    UAL Engineering requested that the FAA update paragraph (b), 
Affected ADs, of this AD to note the impact of the reduced life limits 
imposed by AD 2020-20-11 (85 FR 60898, September 29, 2020) (AD 2020-20-
11) when complying with this AD. UAL Engineering reasoned that multiple 
HPT rotor stage 2 disks are affected by both rules, and leaving 
paragraph (b) blank creates ambiguity for operators generating 
compliance documentation for the dual-affected disks and engines.
    The FAA disagrees. Paragraph (b) of this AD identifies superseded 
or revised ADs, or other ADs if the requirements of those ADs are 
affected (i.e., terminating actions). This AD does not meet any of 
those conditions. Although this AD affects certain HPT rotor stage 2 
disks that also affected AD 2020-20-11, the ADs address separate root 
causes and have different compliance actions and times. To comply with 
this AD, the affected HPT rotor stage 2 disks must be inspected and 
replaced if a rejectable indication is found. If, in accordance with AD 
2020-20-11, an affected HPT rotor stage 2 disk has already been removed 
from service, then no further action is necessary to comply with the 
requirements of this AD.

Request To Replace Certain HPT Rotor Stage 2 Disks

    GE Aviation requested that HPT rotor stage 2 disks with serial 
numbers TMT3UA34, TMT3UA55, TMT4CT46, or TMT4CT47, be replaced instead 
of inspected. GE reasoned that AD 2020-20-11 supersedes this AD, and 
the disks should be replaced in accordance with AD 2020-20-11.
    The FAA disagrees. AD 2020-20-11 does not supersede this AD. Both 
ADs address separate root causes and have different compliance actions 
and times. AD 2020-20-11 requires replacement of certain HPT rotor 
stage 2 disks before accumulating a specified number of cycles since 
new. This AD requires a USI of certain HPT rotor stage 2 disks and, 
depending on the results of the inspection, replacement of the HPT 
rotor stage 2 disk. This AD may require replacement of an HPT rotor 
stage 2 disk prior to the required compliance time specified in AD 
2020-20-11. If, however, an HPT rotor stage 2 disk is removed from 
service per AD 2020-20-11, then the affected turbofan engine would no 
longer have an affected HPT rotor stage 2 disk installed and would fall 
outside of the applicability of this AD.

Request To Update Definition of Engine Shop Visit

    Qantas requested that the FAA update the definition of an ``engine 
shop visit'' to exclude engines with 2,000 or fewer cycles since new 
(CSN) that install the new retaining clips for the HPT stage 2 nozzle 
assembly (retaining clips) introduced in GEnx-1B Service Bulletin (SB) 
72-0398 during a ``Quick Turn'' shop visit. Qantas reasoned that the 
definition of an ``engine shop visit'' in the NPRM would require the 
removal and inspection of an affected HPT rotor stage 2 disk during 
their planned low-time engine elective ``Quick Turn'' shop visit for 
installation of the new retaining clips. Qantas concluded that 
additional disassembly, cost, and engine shop turn time will 
significantly affect the viability of the GE retaining clip ``Quick 
Turn'' program.
    The FAA disagrees with excluding low-time engines that install the 
new retaining clips for the HPT Stage 2 Nozzle Assembly during a 
``Quick Turn'' shop visit. Changing the definition to exclude the 
``Quick Turn'' shop visit would possibly postpone the immersion USI of 
the HPT rotor stage 2 disk required by this AD until a subsequent shop 
visit. As a result, the risk of failure of the HPT rotor stage 2 disk 
would increase. Qantas did not provide documentation to show that 
excluding the ``Quick Turn'' shop visit from the definition of an 
engine shop visit offers an acceptable level of safety. The FAA, 
however, will consider requests for alternative methods of compliance 
if submitted documentation supports an acceptable level of safety.

Request To Add Credit for Previous Action

    Cargolux and GE Aviation requested credit for previous performance 
of the immersion USI of the HPT rotor stage 2 disk using GE GEnx-1B 
Cleaning, Inspection and Repair Manual (CIR) 72-53-41, Special 
Procedure 001, or GE GEnx-2B CIR 72-53-41, Special Procedure 001. 
Cargolux reasoned that GE GEnx-2B SB 72-0402 R00, dated November 20, 
2019, refers to GEnx-2B CIR 72-53-41, Special Procedure 001.
    The FAA disagrees. This AD does not require the use of GE GEnx-1B 
CIR GEK112862, CIR 72-53-41, Special Procedure 001, Rev 31, dated 
January 31, 2020, or GE GEnx-2B CIR GEK114120, CIR 72-53-41, Special 
Procedure 001, Rev 24, dated January 31, 2020, to perform the immersion 
USI of the HPT rotor stage 2 disk. The CIR are referred to in the 
service information referenced in paragraph (i), Credit for Previous 
Action. Therefore, if an operator performs the actions using the CIR, 
the operator is performing the action using the service information and 
has complied with this AD. The FAA did not change this AD.

Support for the AD

    ALPA, Boeing, and UAL Engineering expressed support for the AD as 
written.

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.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed GE GEnx-1B SB 72-0463 R01, dated January 6, 2020, 
and GE GEnx-2B SB 72-0402 R01, dated January 8, 2020. This service 
information describes procedures for performing an immersion USI of the 
affected HPT rotor stage 2 disks on GEnx-1B and GEnx-2B model turbofan 
engines, respectively. 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.

Costs of Compliance

    The FAA estimates that this AD affects 276 engines installed on 
airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
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USI of HPT rotor stage 2 disk.........  8 work-hours x $85 per                $0            $680        $187,680
                                         hour = $680.
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[[Page 81380]]

    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
required inspection. The agency has no way of determining the number of 
aircraft that might need this replacement:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Remove and replace the HPT rotor stage 2 disk.  2 work-hours x $85 per hour =           $458,900        $459,070
                                                 $170.
----------------------------------------------------------------------------------------------------------------

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:

2020-25-10 General Electric Company: Amendment 39-21352; Docket No. 
FAA-2020-0592; Project Identifier AD-2020-00251-E.

(a) Effective Date

    This airworthiness directive (AD) is effective January 21, 2021.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to all General Electric Company (GE) GEnx-
1B64/P2, GEnx-1B67/P2, GEnx-1B70/75/P2, GEnx-1B70/P2, GEnx-1B70C/P2, 
GEnx-1B74/75/P2, GEnx-1B76/P2, and GEnx-1B76A/P2 model turbofan 
engines that have a high-pressure turbine (HPT) rotor stage 2 disk, 
part number (P/N) 2383M86P02, and a serial number (S/N) listed in 
paragraph 4, Appendix--A, Table 1, Table 2, or Table 3, of GE GEnx-
1B Service Bulletin (SB) 72-0463 R01, dated January 6, 2020, 
installed.
    (2) This AD applies to all GE GEnx-2B67/P model turbofan engines 
that have a HPT rotor stage 2 disk, P/N 2383M86P02, and a S/N listed 
in paragraph 4, Appendix--A, Table 1, Table 2, or Table 3, of GE 
GEnx-2B SB 72-0402 R01, dated January 8, 2020, installed.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by a report of the potential for undetected 
subsurface anomalies formed during the manufacturing process that 
could result in uncontained failure of the HPT rotor stage 2 disk. 
The FAA is issuing this AD to prevent failure of the HPT rotor stage 
2 disk. The unsafe condition, if not addressed, could result in 
uncontained HPT rotor stage 2 disk 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 GE GEnx-1B engines, at the next engine shop 
visit after the effective date of this AD, or before the HPT rotor 
stage 2 disk has accumulated 6,500 cycles since new (CSN), whichever 
occurs first, perform an immersion ultrasonic inspection (USI) of 
the HPT rotor stage 2 disk using paragraph 3.B.(1) of GE GEnx-1B SB 
72-0463 R01, dated January 6, 2020.
    (2) If, during the USI required by paragraph (g)(1) of this AD, 
a rejectable indication is found, before further flight, remove the 
HPT rotor stage 2 disk from service and replace it with a part 
eligible for installation.
    (3) For affected GE GEnx-2B engines, at the next engine shop 
visit after the effective date of this AD, or before the HPT rotor 
stage 2 disk has accumulated 6,500 CSN, whichever occurs first, 
perform an immersion USI of the HPT rotor stage 2 disk using 
paragraph 3.B.(1) of GE GEnx-2B SB 72-0402 R01, dated January 8, 
2020.
    (4) If, during the USI required by paragraph (g)(3) of this AD, 
a rejectable indication is found, before further flight, remove the 
HPT rotor stage 2 disk from service and replace it with a part 
eligible for installation.

(h) Definitions

    (1) For the purpose of this AD, an ``engine shop visit'' is when 
a major engine flange is separated for purposes other than the 
removal of the fan for transportation.
    (2) For the purposes of this AD, a ``part eligible for 
installation'' is:
    (i) An HPT rotor stage 2 disk that does not have an S/N listed 
in paragraph 4, Appendix--A, Table 1, Table 2, or Table 3, of GE 
GEnx-1B SB 72-0463 R01, dated January 6, 2020, or GE GEnx-2B SB 72-
0402 R01, dated January 8, 2020; or,
    (ii) An HPT rotor stage 2 disk that has successfully passed the 
immersion USI required by paragraph (g)(1) or (3) of this AD, or 
passed the immersion USI using GE GEnx-1B SB 72-0463 R00, dated 
November 20, 2019, or GE GEnx-2B SB 72-0402 R00, dated November 20, 
2019, before the effective date of this AD.

(i) Credit for Previous Action

    You may take credit for the immersion USI of the HPT rotor stage 
2 disk required by paragraph (g)(1) or (3) of this AD if you 
performed this inspection before the effective date of this AD using 
GE GEnx-1B SB 72-0463 R00, dated November 20, 2019, or GE

[[Page 81381]]

GEnx-2B SB 72-0402 R00, dated November 20, 2019.

(j) 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 Related Information. You may email your request to: 
ANE-AD-AMOC@faa.gov.
    (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.

(k) Related Information

    For more information about this AD, contact Mehdi Lamnyi, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7743; fax: (781) 238-7199; 
email: Mehdi.Lamnyi@faa.gov.

(l) 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 (SB) 
72-0463 R01, dated January 6, 2020, and
    (ii) GE GEnx-2B SB 72-0402 R01, dated January 8, 2020.
    (3) For GE service information identified in this AD, contact 
General Electric Company, GE Aviation, Room 285, 1 Neumann Way, 
Cincinnati, OH 45215; phone: (513) 552-3272; email: 
aviation.fleetsupport@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 (781) 238-7759.
    (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 fedreg.legal@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on December 3, 2020.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2020-27628 Filed 12-15-20; 8:45 am]
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