Document ID: FAA-2021-0567-0007
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2022-01-11T05:00Z

[Federal Register Volume 87, Number 7 (Tuesday, January 11, 2022)]
[Rules and Regulations]
[Pages 1343-1346]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-00049]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0567; Project Identifier AD-2021-00663-E; 
Amendment 39-21865; AD 2021-26-06]
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) GE90 model turbofan engines. This 
AD was prompted by two separate in-flight shutdowns (IFSDs) resulting 
from failure of the transfer gearbox (TGB) radial bevel gear (TGB 
radial gearshaft). This AD requires visual inspection of the TGB radial 
gearshaft and, depending on the results of the inspection, replacement 
of the TGB radial gearshaft. The FAA is issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective February 15, 2022.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of February 15, 
2022.

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: 
[email protected]; website: https://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. It is also available at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0567.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0567; 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: Stephen Elwin, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7236; fax: (781) 238-7199; 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 all GE GE90-76B, GE90-
85B, GE90-90B, GE90-94B, GE90-110B1, and GE90-115B model turbofan 
engines with a certain TGB radial gearshaft installed. The NPRM 
published in the Federal Register on August 12, 2021 (86 FR 44321). The 
NPRM was prompted by notification of two separate IFSDs resulting from 
the failure of the TGB radial gearshaft. After further investigation, 
the manufacturer determined that rework on the TGB radial gearshaft 
teeth chamfers during manufacturing may have caused local burrs and 
micro-cracks which led to high-cycle fatigue failure. GE subsequently 
issued service information to provide instructions for a one-time 
visual inspection of the affected radial gearshafts for the presence of 
burrs or rework on TGB radial gearshaft teeth chamfers. In the NPRM, 
the FAA proposed to require visual inspection of the TGB radial 
gearshaft and, depending on the results of the inspection, replacement 
of the TGB radial gearshaft. 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 5 commenters. The commenters were 
Air Line Pilots Association, International, The Boeing Company, FedEx 
Express, Japan Airlines (JAL), and United Airlines. The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Question on the Difference Between This AD and the Service Information

    JAL asked why there is a difference between the affected serial 
numbers (S/Ns) in this AD and the related service bulletins (SBs).
    The FAA notes that the applicable SBs include several populations 
of TGB radial gearshafts. The FAA determined that TGB radial gearshafts 
with S/Ns starting with prefix FIAAXXXX, FIA05XXX to FIA09XXX, or 
FIA0AXXX to FIA0NXXX are not subject to the

[[Page 1344]]

unsafe condition in this AD. Although this AD does not require that 
these TGB radial gearshafts be inspected and removed, operators may 
still elect to inspect these TGB radial gearshaft at the next scheduled 
engine shop visit.

Request To Clarify Engine Shop Visit Definition

    JAL requested that the FAA clarify disassembly of the compressor 
discharge pressure (CDP) seal joint in the definition of ``engine shop 
visit.'' JAL indicated that they understand that disassembly of the CDP 
seal joint is the same as disassembly of the CDP seal flange bolt, but 
not the same as removal of the CDP seal.
    The FAA notes that any disassembly of the CDP seal joint meets the 
definition of an engine shop visit.

Request To Clarify if Inspection Occurs During Quick Turn Workscope 
(QTW)

    JAL asked if the TGB radial gearshaft is required to be inspected 
during engine QTW. JAL indicated that GE GE90-100 Service Bulletin (SB) 
72-0857 R01, dated April 28, 2021 (GE90-100 SB 72-0857 R01), excludes 
the performance of the inspection during QTW. The proposed AD, however, 
did not reference QTW in the required inspection. JAL suggested that 
the FAA update this AD to either exclude QTW from the compliance 
requirement for inspection or clarify the difference between the 
service information and this AD.
    The FAA understands that the CDP seal joint, in some cases, may 
require disassembly during a QTW; however, in this scenario the 
appropriate provisions would exist to perform the required actions of 
this AD. A QTW that does not disassemble the CDP seal joint would not 
meet the definition of an engine shop visit, per this AD.

Addition of Interim Action Paragraph

    The FAA determined the need to add the Interim Action paragraph to 
this AD. The manufacturer is investigating if an additional population 
of TGB radial gear shafts are affected by the unsafe condition of this 
AD.

Support for the AD

    Air Line Pilots Association, International, The Boeing Company, 
FedEx Express, and United Airlines 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. 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 GE90 Service Bulletin (SB) 72-1201 R01, dated 
April 28, 2021 (GE90 SB 72-1201 R01), and GE90-100 SB 72-0857 R01, 
dated April 28, 2021. GE90 SB 72-1201 R01 specifies procedures for 
performing a one-time inspection of the TGB radial gearshaft for 
presence of burrs or rework on teeth chamfers on GE90-76B, GE90-85B, 
GE90-90B, and GE90-94B model turbofan engines. GE90-100 SB 72-0857 R01 
specifies procedures for performing a one-time inspection of the TGB 
radial gearshaft for presence of burrs or rework on teeth chamfers on 
GE90-110B1 and GE90-115B model turbofan engines. 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.

Interim Action

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

Costs of Compliance

    The FAA estimates that this AD affects 126 engines installed on 
airplanes of U.S. registry.
    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
----------------------------------------------------------------------------------------------------------------
Inspect TGB radial gearshaft..........  1 work-hour x $85 per                 $0             $85         $10,710
                                         hour = $85.
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    The FAA estimates the following costs to do any necessary 
replacement that would be required based on the results of the 
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
----------------------------------------------------------------------------------------------------------------
Replace TGB radial gearshaft..................  60 work-hours x $85 per hour =           $24,520         $29,620
                                                 $5,100.
----------------------------------------------------------------------------------------------------------------

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

[[Page 1345]]

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:

2021-26-06 General Electric Company: Amendment 39-21865; Docket No. 
FAA-2021-0567; Project Identifier AD-2021-00663-E.

(a) Effective Date

    This airworthiness directive (AD) is effective February 15, 
2022.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) GE90-76B, GE90-
85B, GE90-90B, GE90-94B, GE90-110B1, and GE90-115B model turbofan 
engines with a transfer gearbox (TGB) radial bevel gear (TGB radial 
gearshaft) serial number listed in paragraph 4., APPENDIX--A, Table 
1 of GE GE90 Service Bulletin (SB) 72-1201 R01, dated April 28, 2021 
(GE90 SB 72-1201 R01) or paragraph 4., APPENDIX--A, Table 1 of GE 
GE90-100 SB 72-0857 R01, dated April 28, 2021 (GE90-100 SB 72-0857 
R01).

(d) Subject

    Joint Aircraft System Component (JASC) Code 7260, Turbine Engine 
Accessory Drive.

(e) Unsafe Condition

    This AD was prompted by two separate in-flight shutdowns 
resulting from the failure of the TGB radial gearshaft. The FAA is 
issuing this AD to prevent failure of the TGB radial gearshaft. The 
unsafe condition, if not addressed, could result in failure of one 
or more engines, loss of thrust control, and damage to the aircraft.

(f) Compliance

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

(g) Required Actions

    (1) At the next engine shop visit after the effective date of 
this AD, perform a visual inspection of the affected TGB radial 
gearshaft using Figure 1 to paragraph (g)(1) of this AD.
[GRAPHIC] [TIFF OMITTED] TR11JA22.000

    (2) If, during the visual inspection required by paragraph 
(g)(1) of this AD, discrepancies are found that meet the criteria in 
the Accomplishment Instructions, paragraph 3.A.(4)(a) or 3.A.(4)(b), 
of GE90 SB 72-1201 R01 or GE90-100 SB 72-0857 R01, before further 
flight, replace the TGB radial gearshaft with a part eligible for 
installation.

(h) Definitions

    (1) For the purpose of this AD, an ``engine shop visit'' is when 
the compressor discharge pressure seal joint is disassembled.
    (2) For the purpose of this AD, a ``part eligible for 
installation'' is a TGB radial gearshaft that does not have raised 
material or rework on the teeth chamfers as described in the 
Accomplishment Instructions, paragraph 3.A.(4)(a) or 3.A.(4)(b), of 
GE90 SB 72-1201 R01 or GE90-100 SB 72-0857 R01.

(i) Credit for Previous Actions

    You may take credit for the inspection of the affected TGB 
radial gearshaft required by paragraph (g)(1) of this AD if you 
performed the inspection before the effective date of this AD using 
GE GE90 SB 72-1201 R00, dated January 5, 2021, or GE GE90-100 SB 72-
0857 R00, dated January 5, 2021.

(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 paragraph (k) 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.

(k) Related Information

    For more information about this AD, contact Stephen Elwin, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7236; fax: (781) 238-7199; 
email: [email protected].

(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) GE90 Service Bulletin (SB) 72-
1201 R01, dated April 28, 2021.
    (ii) GE GE90-100 SB 72-0857 R01, dated April 28, 2021.
    (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: 
[email protected]; website: https://www.ge.com.
    (4) You may view this service information at FAA, Airworthiness 
Products Section, Operational Safety Branch, 1200 District Avenue, 
Burlington, MA 01803. For

[[Page 1346]]

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: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on December 9, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2022-00049 Filed 1-10-22; 8:45 am]
BILLING CODE 4910-13-P