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 the ADDRESSES section. Include “Docket No. FAA-2024-2318; Project Identifier MCAI-2023-00981-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 Morton Lee, 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 2023-20-03, Amendment 39-22562 (88 FR 76104, November 6, 2023) (AD 2023-20-03), for certain Austro Engine GmbH Model E4 and E4P engines. AD 2023-20-03 was prompted by an MCAI originated by the European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union. EASA issued EASA AD 2022-0240R1, dated December 15, 2022 (EASA AD 2022-0240R1), to address reports of piston failures.

AD 2023-20-03 requires repetitive engine oil analysis for aluminum content outside the acceptable limits and, if necessary, replacement of the pistons, piston rings, con-rods assembly, and crankcase or as an alternative, replacement of the engine core. The FAA issued AD 2023-20-03 to prevent piston failure, which could result in loss of oil, loss of engine power, and reduced control of the airplane.

Actions Since AD 2023-20-03 Was Issued

Since the FAA issued AD 2023-20-03, EASA superseded EASA AD 2022-0240R1 and issued EASA AD 2023-0163, dated August 18, 2023 (EASA AD 2023-0163) (also referred to as the MCAI). The MCAI states that a manufacturer investigation into reports of piston failures determined that certain batches of pistons were manufactured with a dimensional deviation in the piston pin bore and in the piston diameter, which could cause piston failure, with consequent loss of oil, loss of engine power, and reduced control of the airplane. To address the unsafe condition, EASA issued EASA AD 2022-0240, dated December 6, 2022, to specify repetitive oil analyses and ( printed page 79475) replacement of the pistons, piston rings, con-rods assembly, and crankcase, or as an alternative, replacement of the engine core. EASA AD 2022-0240 also prohibited release to service of an airplane until receipt of the results for each oil analysis.

Since EASA AD 2022-0240 was issued, the manufacturer determined that aluminum levels outside of the acceptable limits would be found during the first oil analysis and would be unlikely to be found during subsequent oil analyses. As a result, EASA revised EASA AD 2022-0240 and issued EASA AD 2022-0240R1 to allow release to service of airplanes for a limited number of flight hours immediately after the second and subsequent oil samples are taken for analyses.

Since EASA AD 2022-0240R1 was issued, the manufacturer identified errors in the lists of affected engine serial numbers in the service information and issued Mandatory Service Bulletin No. MSB-E4-039/2, Revision 2, dated July 31, 2023, to revise the list of affected engine serial numbers, which prompted EASA to supersede EASA AD 2022-0240R1 with EASA AD 2023-0163, dated August 18, 2023. Since EASA issued EASA AD 2023-0163, the manufacturer revised the service information again and issued Mandatory Service Bulletin No. MSB-E4-039/3, Revision 3, dated November 22, 2023, to amend the labor efforts section.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2024-2318.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/3, Revision 3, dated November 22, 2023, which identifies affected engine serial numbers and specifies procedures for oil analysis and replacement of the pistons, piston rings, con-rods assembly, crankcase, and engine core.

This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

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 and material 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 retain all of the requirements of AD 2023-20-03. This proposed AD would also add compliance times for additional affected engine serial numbers and remove certain engine serial numbers from the applicability of the existing AD, as specified in the material already described.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 357 engines installed on aircraft of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

The FAA estimates the following costs to do any necessary replacements that would be required based on the results of the proposed inspection. The agency has no way of determining the number of engines that might need these replacements:

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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 ( printed page 79476) 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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

2. The FAA amends § 39.13 by:

a. Removing Airworthiness Directive AD 2023-20-03, Amendment 39-22562 ( 88 FR 76104, November 6, 2023); and

b. Adding the following new airworthiness directive:

Austro Engine GmbH: Docket No. FAA-2024-2318; Project Identifier MCAI-2023-00981-E.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by November 14, 2024.

(b) Affected ADs

This AD replaces AD 2023-20-03, Amendment 39-22562 (88 FR 76104, November 6, 2023) (AD 2023-20-03).

(c) Applicability

This AD applies to Austro Engine GmbH Model E4 and E4P engines with an engine serial number (ESN) listed in Tables 1, 2, 3, and 4 of Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/3, Revision 3, dated November 22, 2023 (Austro MSB-E4-039/3).

(d) Subject

Joint Aircraft System Component (JASC) Code 8530, Reciprocating Engine Cylinder Section; 8550, Reciprocating Engine Oil System.

(e) Unsafe Condition

This AD was prompted by reports of piston failures and the determination that certain batches of pistons were manufactured with a dimensional deviation in the piston pin bore and piston diameter. The FAA is issuing this AD to prevent piston failure. The unsafe condition, if not addressed, could result in loss of oil, loss of engine power, and reduced control of the airplane.

(f) Compliance

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

(g) Required Actions

(1) For all affected engines, within the applicable compliance times specified in Table 1 to paragraph (g)(1) of this AD, perform an oil analysis in accordance with paragraph 2., Technical Details, Engine Oil Analysis of Austro MSB-E4-039/3, and do not return the engine to service until the results of the oil analysis have been determined.

(2) Thereafter, repeat the oil analysis required by paragraph (g)(1) of this AD before exceeding the applicable interval specified in Table 1 to paragraph (g)(1) of this AD.

(3) Following each repetitive oil analysis, the engine may be returned to service for no more than the applicable interval specified in Table 1 to paragraph (g)(1) of this AD, until receipt of the oil analysis result.

(4) If the result of any oil analysis required by paragraph (g)(1) of this AD indicates the aluminum content of the oil is greater than the limit specified in paragraph 2., Technical Details, Engine Oil Analysis, Table 5—Oil ( printed page 79477) check analysis—Aluminum PPM allowable; of Austro MSB-E4-039/3, before further flight, replace the pistons, piston rings, con-rods assembly, and crankcase, or replace the engine core in accordance with paragraph 2., Technical Details, Engine core replacement; or Pistons, piston rings, crankcase and con-rod assy replacement; as applicable, of Austro MSB-E4-039/3.

(5) For Group 3 and Group 4 engines, within the applicable compliance times specified in Table 3 to paragraph (g)(5) of this AD, replace the pistons, piston rings, and con-rods assembly, or replace the engine core in accordance with paragraph 2., Technical Details, Engine core replacement; or Pistons, piston rings and con-rod assy replacement, as applicable, of Austro MSB-E4-039/3.

Note 1 to paragraph (g)(5): FHs since new indicated in Table 3 to paragraph (g)(5) of this AD are FHs accumulated by the engine since first installation on an airplane or since last overhaul as of December 11, 2023 (the effective date of AD 2023-20-03) for Group 3 and 4 engines that do not have an ESN identified in Table 2 to paragraph (g)(1) of this AD, or as of the effective date of this AD for Group 3 and 4 engines that have an ESN identified in Table 2 to paragraph (g)(1) of this AD.

(h) Terminating Action

(1) Replacement of the pistons, piston rings, con-rods assembly, and crankcase, or replacement of the engine core, as specified in paragraph (g)(4) of this AD, constitutes terminating action for the repetitive oil analysis required by paragraph (g)(2) of this AD.

(2) Replacement of the pistons, piston rings, and con-rods assembly, or replacement of the engine core, as specified in paragraph (g)(5) of this AD, constitutes terminating action for the repetitive oil analysis required by paragraph (g)(2) of this AD.

(i) Definitions

For the purpose of this AD:

(1) Group 1 engines are engines having an ESN listed in Table 1 of No. MSB-E4-039/3.

(2) Group 2 engines are engines having an ESN listed in Table 2 of No. MSB-E4-039/3.

(3) Group 3 engines are engines having an ESN listed in Table 3 of No. MSB-E4-039/3.

(4) Group 4 engines are engines having an ESN listed in Table 4 of No. MSB-E4-039/3.

(j) Credit for Previous Actions

(1) You may take credit for the actions required by paragraph (g)(1), (4), or (5) of this AD, if you performed those actions before December 11, 2023 (the effective date of AD 2023-20-03) using Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/0, dated October 24, 2022.

(2) You may take credit for the actions required by paragraph (g)(1), (4), or (5) of this AD if you performed those actions before the effective date of this AD using Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/2, Revision 2, dated July 26, 2023.

(k) No Return of Parts/Reporting Requirement

Although the service information specifies returning certain parts and submitting certain information to the manufacturer, this AD does not include those requirements.

(l) Alternative Methods of Compliance (AMOCs)

(1) The Manager, International Validation 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 International Validation Branch, send it to the attention of the person identified in paragraph (m)(1) of this AD and email to 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.

(m) Additional Information

(1) For more information about this AD, contact Morton Lee, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (860) 386-1791; email: morton.y.lee@faa.gov.

(2) Material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (n)(3) of this AD.

(n) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise.

(i) Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/3, Revision 3, dated November 22, 2023.

(ii) [Reserved]

(3) For Austro Engine GmbH material identified in this AD, contact Austro Engine GmbH, Rudolf-Diesel-Strasse 11, A-2700 Weiner Neustadt, Austria; phone: +43 2622 23000; website: austroengine.at.

(4) You may view this material at 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.

(5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/​federal-register/​cfr/​ibr-locations or email fr.inspection@nara.gov.

89 FR 79474