DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-2002; Project Identifier MCAI-2023-00176-E]
RIN 2120-AA64

Airworthiness Directives; GE Aviation Czech s.r.o. (Type
Certificate Previously Held by WALTER Engines a.s., Walter a.s., and
MOTORLET a.s.) Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede airworthiness directive (AD)
2021-13-07, which applies to all GE Aviation Czech s.r.o. (GEAC) (type
certificate previously held by WALTER Engine a.s., Walter a.s., and
MOTORLET a.s.) Model M601D-11, M601E-11, M601E-11A, M601E-11AS, M601E-
11S, and M601F engines. AD 2021-13-07 requires recalculating the life
of critical parts and, depending on the results of the recalculation,
replacing these critical parts. AD 2021-13-07 also requires replacing a
certain compressor case. Since the FAA issued AD 2021-13-07, the
manufacturer published the airworthiness limitations section (ALS) of
the existing engine maintenance manual (EMM), which includes the
calculations for the life of critical parts addressed by AD 2021-13-07
and prompted this proposed AD. This proposed AD would continue to
require the replacement of a certain centrifugal compressor case. This
proposed AD would also include an additional part number as an option
for the replacement and would limit the applicability of the proposed
AD, as specified in a European Union Aviation Safety Agency (EASA) AD,
which is proposed for incorporation by reference (IBR). The FAA is
proposing this AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this NPRM by December 11, 2023.

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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2023-2002; 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, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
street address for Docket Operations is listed above.
Material Incorporated by Reference:
For service information identified in this NPRM, contact
EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221
8999 000; email: ADs@easa.europa.eu; website: easa.europa.eu. You may
find this material on the EASA website at ad.easa.europa.eu. It is also
available at regulations.gov under Docket No. FAA-2023-2002.
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.

FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: (781) 238-7146; email: barbara.caufield@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-2023-2002; Project Identifier
MCAI-2023-00176-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
the 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
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
Barbara Caufield, Aviation Safety Engineer, FAA, 1600 Stewart Avenue,
Suite 410, Westbury, NY 11590. 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 issued AD 2021-13-07, Amendment 39-21612 (86 FR 31601, June
15, 2021) (AD 2021-13-07), for all GEAC Model M601D-11, M601E-11,
M601E-11A, M601E-11AS, M601E-11S, and M601F engines. AD 2021-13-07 was
prompted by an MCAI originated by EASA, which is the Technical Agent
for the Member States of the European Union. EASA issued EASA Emergency
AD 2021-0125-E, dated May 7, 2021 (EASA Emergency AD 2021-0125-E) to
address an unsafe condition identified as the manufacturer finding
errors in the ALS of the existing EMM, including errors in the formula
to determine the consumed equivalent flight cycles of critical parts
and errors with certain part numbers. The manufacturer also determined
that the life limit of a certain compressor case installed on Model
M601E engines is not listed in the ALS of the applicable EMM.
AD 2021-13-07 requires recalculating the life of critical parts
and, depending on the results of the recalculation, replacing critical
parts. AD 2021-13-07 also requires replacing a certain compressor case.
The FAA issued AD 2021-13-07 to prevent the failure of the engine.

Actions Since AD 2021-13-07 Was Issued

Since the FAA issued AD 2021-13-07, EASA revised EASA Emergency AD
2021-0125-E and issued EASA AD 2021-0125R1, dated January 30, 2023
(EASA AD 2021-0125R1) (referred to after this as the MCAI). The MCAI
states that the manufacturer published the ALS, which incorporates
certain requirements addressed by EASA Emergency AD 2021-0125-E, and
that EASA published EASA AD 2023-0020, dated January 23, 2023 (EASA AD
2023-0020), which requires accomplishment of the actions specified in
the ALS. The MCAI limits the applicability to M601E engines with a
centrifugal compressor case having part number M601-154.61 installed
and removes the requirements that have been incorporated in the ALS.
The FAA is addressing the actions specified in the ALS concurrently in
a separate AD action.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2023-2002.

Related Service Information Under 1 CFR Part 51

The FAA reviewed EASA AD 2021-0125R1, which specifies procedures
for replacing the centrifugal compressor case, limits the applicability
to certain M601E engines, and removes the requirements that have been
incorporated in the ALS.
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.

FAA's Determination

These products have been approved by the aviation authority of
another country and are approved for operation in the United States.
Pursuant to the FAA's bilateral agreement with this State of Design
Authority, it has notified the FAA of the unsafe condition described in
the MCAI referenced above. 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.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in the MCAI described previously, except for any differences identified
as exceptions in the regulatory text of this proposed AD and the
``Differences Between This Proposed AD and the MCAI.''

Differences Between This Proposed AD and the MCAI

The MCAI applies to GEAC Model M601E engines, and this AD does not
because they do not have an FAA type certificate.

Explanation of Required Compliance Information

In the FAA's ongoing efforts to improve the efficiency of the AD
process, the FAA developed a process to use some civil aviation
authority (CAA) ADs as the primary source of information for compliance
with requirements for corresponding FAA ADs. The FAA has since
coordinated with other manufacturers and CAAs to use this process. As a
result, the FAA proposes to incorporate by reference EASA AD 2021-
0125R1 in the FAA final rule. This proposed AD would, therefore,
require compliance with EASA AD 2021-0125R1 in its entirety through
that incorporation, except for any differences identified as exceptions
in the regulatory text of this proposed AD. Using common terms that are
the same as the heading of a particular section in the EASA AD does not
mean that operators need comply only with that section. For example,
where the AD requirement refers to ``all required actions within the
compliance times,'' compliance with this AD requirement is not limited
to the section titled ``Required Action(s) and Compliance Time(s)'' in
EASA AD 2021-0125R1. Service information required by the EASA AD for
compliance will be available at regulations.gov by under Docket No.
FAA-2023-2002 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 13 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs

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 that the 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

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]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive 2021-13-07, Amendment 39-21612 (86
FR 31601, June 15, 2021); and

b. Adding the following new airworthiness directive: