Document ID: FAA-2021-0567-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: General Electric Company Turbofan Engines
Posted Date: 2021-08-12T04:00Z

[Federal Register Volume 86, Number 153 (Thursday, August 12, 2021)]
[Proposed Rules]
[Pages 44321-44324]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-16758]

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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]
RIN 2120-AA64

Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain General Electric Company (GE) GE90 model turbofan engines. 
This proposed 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 proposed AD would 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 proposing this AD to address the unsafe condition on these 
products.

DATES: The FAA must receive comments on this proposed AD by September 
27, 2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

[[Page 44322]]

    For service information identified in this NPRM, contact General 
Electric Company, GE Aviation, Room 285, 1 Neumann Way, Cincinnati, OH 
45215; phone: (513) 552-3272; email: aviation.fleetsupport@ae.ge.com; 
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.

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 NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.

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: 
Stephen.L.Elwin@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2021-0567; Project Identifier 
AD-2021-00663-E'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
this proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
https://www.regulations.gov, including any personal information you 
provide. The agency will also post a report summarizing each 
substantive verbal contact received about this NPRM.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to 
Stephen Elwin, Aviation Safety Engineer, ECO Branch, FAA, 1200 District 
Avenue, Burlington, MA 01803. Any commentary that the FAA receives 
which is not specifically designated as CBI will be placed in the 
public docket for this rulemaking.

Background

    The FAA was notified 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 gearshaft teeth chamfers. This condition, if not 
addressed, could result in failure of one or more engines, loss of 
thrust control, and damage to the aircraft.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

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 GE GE90-100 SB 72-0857 R01, 
dated April 28, 2021 (GE90-100 SB 72-0857 R01). 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require visual inspection of the TGB radial 
gearshaft and, depending on the results of the inspection, replacement 
of the TGB gearshaft.
    Differences Between this Proposed AD and the Service Information
    GE90 SB 72-1201 R01 and GE90-100 SB 72-0857 R01 identify affected 
TGB radial gearshafts with serial numbers (S/Ns) listed in paragraph 
4., APPENDIX--A, Table 1, and with serial numbers starting with prefix 
FIAAXXXX, FIA05XXX to FIA09XXX, or FIA0AXXX to FIA0NXXX. This AD 
applies only to TGB radial gearshafts with S/Ns listed in paragraph 4., 
APPENDIX--A, Table 1 of GE90 SB 72-1201 R01 and GE90-100 SB 72-0857 
R01. The FAA determined that TGB radial gearshafts with S/Ns starting 
with prefix FIAAXXXX, FIA05XXX to FIA09XXX, or FIA0AXXX to FIA0NXXX are 
not required to be inspected and removed as part of this AD. However, 
operators may still elect to inspect the TGB radial gearshaft with 
these S/Ns at the next scheduled engine shop visit.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 126 engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
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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[[Page 44323]]

    The FAA estimates the following costs to do any necessary 
replacement that would be required based on the results of the proposed 
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

    The FAA determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would 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 Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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:

General Electric Company: Docket No. FAA-2021-0567; Project 
Identifier AD-2021-00663-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by September 27, 2021.

(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 the Accomplishment Instructions, paragraph 
3.A.(3)(a)1 through 3, of GE90 SB 72-1201 R01 or GE90-100 SB 72-0857 
R01, as applicable.
    (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 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

    (1) 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: Stephen.L.Elwin@faa.gov.
    (2) For service information identified in this AD, contact 
General Electric Company, GE Aviation, Room 285, 1 Neumann Way,

[[Page 44324]]

Cincinnati, OH 45215; phone: (513) 552-3272; email: 
aviation.fleetsupport@ae.ge.com; 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 (781) 238-7759.

    Issued on July 9, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-16758 Filed 8-11-21; 8:45 am]
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