[Federal Register Volume 88, Number 114 (Wednesday, June 14, 2023)]
[Proposed Rules]
[Pages 38758-38759]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-12695]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 88 , No. 114 / Wednesday, June 14, 2023 / 
Proposed Rules  

[[Page 38758]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1401; Project Identifier AD-2022-01017-E]
RIN 2120-AA64


Airworthiness Directives; General Electric Company Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Proposed rule; withdrawal.

-----------------------------------------------------------------------

SUMMARY: The FAA is withdrawing a notice of proposed rulemaking (NPRM) 
that proposed to adopt a new airworthiness directive (AD) for certain 
General Electric Company (GE) CF6-80E1A2, CF6-80E1A3, CF6-80E1A4, and 
CF6-80E1A4/B model turbofan engines. The NPRM was prompted by a 
manufacturer investigation that revealed that certain compressor 
discharge pressure seals (CDP seals) and forward outer seals were 
manufactured from powder metal material suspected to contain iron 
inclusion. The NPRM proposed to require the replacement of the affected 
CDP seals and forward outer seals. Since issuance of the NPRM, the FAA 
has reviewed subsequent information received from the manufacturer and 
determined that the unsafe condition is not likely to exist or develop 
in other products of the same type design. Accordingly, the NPRM is 
withdrawn.

DATES: As of June 14, 2023, the proposed rule, which published in the 
Federal Register on November 4, 2022 (87 FR 66625), is withdrawn.

ADDRESSES: AD Docket: You may examine the AD docket at regulations.gov 
by searching for and locating Docket No. FAA-2022-1401; 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 AD action, any 
comments received, and other information. The street address for Docket 
Operations is Docket Operations, M-30, West Building Ground Floor, Room 
W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Alexei Marqueen, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
(781) 238-7178; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Background

    The FAA issued an NPRM that proposed to amend 14 CFR part 39 by 
adding an AD that would apply to certain GE CF6-80E1A2, CF6-80E1A3, 
CF6-80E1A4, and CF6-80E1A4/B model turbofan engines. The NPRM published 
in the Federal Register on November 4, 2022 (87 FR 66625). The NPRM was 
prompted by notification from the manufacturer of the detection of iron 
inclusion in a turbine disk manufactured from the same powder metal 
material used to manufacture certain CDP seals and a certain forward 
outer seal. Further investigation by the manufacturer determined that 
certain CDP seals and a certain forward outer seal made from billets 
manufactured using the same process may have reduced material 
properties and a lower fatigue life capability due to iron inclusion, 
which may cause premature fracture and uncontained failure.
    The NPRM proposed to require the removal of certain CDP seals and a 
certain forward outer seal from service and replacement with a part 
eligible for installation. The proposed actions were intended to 
prevent fracture and uncontained failure of certain CDP seals and a 
certain forward outer seal, which could result in uncontained debris 
release, damage to the engine, and damage to the aircraft.

Actions Since the NPRM Was Issued

    Since issuance of the NPRM, the FAA and the manufacturer have 
determined that the affected CDP seals have met their full Chapter 5 
life of 15,000 cycles and are not subject to the unsafe condition. 
Since there is only one affected forward outer seal, identified by part 
number and serial number, the FAA has determined that the unsafe 
condition is not likely to exist or develop in other products of the 
same type design. Therefore, the FAA has determined that this AD action 
is not appropriate. However, the FAA may publish a separate rulemaking 
to address the unsafe condition in the specified forward outer seal.
    Withdrawal of the NPRM constitutes only such action and does not 
preclude the FAA from further rulemaking on this issue, nor does it 
commit the FAA to any course of action in the future.

Comments

    The FAA received comments from three commenters. The commenters 
were Delta Air Lines, Inc. (DAL), GE, and an anonymous commenter. The 
anonymous commenter supported the NPRM without change. The following 
presents the comments received on the NPRM and the FAA's response.

Request To Remove CDP Seals From the Proposed AD

    GE requested the removal of CDP seals with part number (P/N) 
1669M73P02 and serial numbers (S/N) TMT1C0E1 or TMT1C0E2 entirely from 
the NPRM. GE stated that this P/N has been assessed to meet its full 
Chapter 5 life of 15,000 cycles and, therefore, will not result in 
premature fracture and uncontained failure and, accordingly, no unsafe 
condition exists for these CDP seals.
    The FAA agrees and is withdrawing the AD in response to this 
comment.

Request To Expand Applicability To Include Additional Engine Models

    DAL requested the FAA expand the applicability of the proposed AD 
by adding CF6-80C2B2F/B6F/B7F/B8F model turbofan engines because the 
CF6-80C2 Engine Illustrated Parts Catalog identifies affected forward 
outer seal P/N 1778M70P03 as a part installed on those model turbofan 
engines. DAL stated that it is possible that parts were intermixed 
across models during previous engine shop visits, necessitating a 
review of operator CF6-80C2 fleets for the affected serial number.
    The FAA disagrees. Providing both the P/N (1778M70P03) and S/N 
(NCU65340) of the affected forward outer seal is sufficient information 
to identify which engine model is affected since it is a single tracked 
part.

Request To Clarify Disposition of Removed Parts

    DAL requested that the FAA clarify the disposition of removed parts 
in

[[Page 38759]]

paragraph (g) of the proposed AD. The commenter stated that paragraph 
(g) of the proposed AD, Required Actions, states to remove the affected 
CDP seal or forward outer seal from service. DAL stated that there is 
no clear statement that the parts could not be returned to service, yet 
further commented that paragraph (i) of the proposed AD, Installation 
Prohibition, ensures that the parts may not be installed. DAL commented 
that requiring disposal of the affected parts will ensure the parts do 
not enter the materials market.
    The FAA disagrees. The FAA does not have the authority to require 
operators to discard parts to address an unsafe condition. Within the 
scope of an AD, removing parts from service and prohibiting 
installation is within the FAA's authority.

Request To Revise Definition of ``Piece-Part Exposure''

    DAL and GE requested that the FAA revise the definition of ``piece-
part exposure'' in paragraph (h)(2) of the proposed AD. DAL stated that 
paragraph (h)(2) of the proposed AD defines piece-part exposure as when 
the affected part is removed from the engine. DAL suggested this be 
specified as removal of the affected part from the mating structures 
instead. The commenter reasoned that the current wording could indicate 
that if the module an affected part is installed in is removed from the 
engine, replacement of the affected part is required. GE stated that 
the current definition of ``piece-part exposure'' is unclear and 
suggested clarifying paragraph (h)(2) of the proposed AD to read, ``For 
the purpose of this AD, ``piece-part exposure'' is when the affected 
part is removed from the engine and completely disassembled.''
    Because the FAA is withdrawing the NPRM, the clarification of 
paragraph (h)(2) of the proposed AD is no longer necessary.

Regulatory Findings

    Since this action only withdraws an NPRM, it is neither a proposed 
nor a final rule. This action therefore is not covered under Executive 
Order 12866 or the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Withdrawal

0
Accordingly, the notice of proposed rulemaking, Docket No. FAA-2022-
1401; Project Identifier AD-2022-01017-E which published in the Federal 
Register on November 4, 2022 (87 FR 66625), is withdrawn.

    Issued on June 8, 2023.
Michael Linegang,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-12695 Filed 6-13-23; 8:45 am]
BILLING CODE 4910-13-P


