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Federal Register / Vol. 86, No. 153 / Thursday, August 12, 2021 / Proposed Rules
For service information identified in this NPRM, contact General Electric Company, GE Aviation, Room 285, 1
Neumann Way, Cincinnati, OH 45215;
phone: 513 5523272; 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.
FAA20210567; 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 2387236; fax: 781 238
7199; email: Stephen.L.Elwin@faa.gov.
SUPPLEMENTARY INFORMATION:

lotter on DSK11XQN23PROD with PROPOSALS1

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.
FAA20210567; Project Identifier AD
202100663E 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.
FAAs 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 721201 R01, dated April 28, 2021 GE90 SB 721201 R01, and
GE GE90100 SB 720857 R01, dated April 28, 2021 GE90100 SB 720857
R01. GE90 SB 721201 R01 specifies procedures for performing a one-time inspection of the TGB radial gearshaft for presence of burrs or rework on teeth chamfers on GE9076B, GE9085B, GE9090B, and GE9094B model turbofan engines. GE90100 SB 720857
R01 specifies procedures for performing a one-time inspection of the TGB radial gearshaft for presence of burrs or rework on teeth chamfers on GE90110B1 and GE90115B 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 721201 R01 and GE90100
SB 720857 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., APPENDIXA, Table 1
of GE90 SB 721201 R01 and GE90100
SB 720857 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
Action
Labor cost
Inspect TGB radial gearshaft

1 work-hour $85 per hour = $85

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Cost per product
Parts cost
E:FRFM12AUP1.SGM

$0

12AUP1

$85

Cost on U.S.
operators $10,710