2024-22064. Airworthiness Directives; Austro Engine GmbH Engines

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Oil analysis	1 work-hour × $85 per hour = $85	$0	$85	$30,345

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:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Replace engine core	35 work-hours × $85 per hour = $2,975	$15,524	$18,499
Replace pistons, piston rings, and con-rod assembly	65 work-hours × $85 per hour = $5,525	2,216	7,741
Replace pistons, piston rings, con-rod assembly, and crankcase	75 work-hours × $85 per hour = $6,375	4,141	10,516

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 ( print 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.

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.

§ 39.13

[Amended]

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.

Table 1 to Paragraph ( g )(1)—Oil Analysis for All Affected Engines

Engine group	Compliance time	Interval
Group 1 and Group 3 engines that do not have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Within 15 flight hours (FHs) from December 11, 2023 (the effective date of AD 2023-20-03)	Before exceeding 50 FHs since last oil analysis.
Group 1 and Group 3 engines that have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Within 15 FHs from the effective date of this AD	Before exceeding 50 FHs since last oil analysis.
Group 2 and Group 4 engines that do not have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Within 25 FHs from December 11, 2023 (the effective date of AD 2023-20-03)	Before exceeding 100 FHs since last oil analysis.
Group 2 and Group 4 engines that have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Within 25 FHs from the effective date of this AD	Before exceeding 100 FHs since last oil analysis.

Table 2 to Paragraph ( g )(1)—Affected ESNs Not Included in AD 2023-20-03

Engine group	ESN	ESN	ESN	ESN
Group 1	E4-A-06367	E4-A-06248
Group 2	E4-C-06249	E4P-C-06185
Group 3	E4-A-05072	E4-A-05074	E4-A-05075	E4-A-05078
Group 3	E4-A-05079	E4-A-05080	E4-A-05081	E4-A-05082
Group 3	E4-A-05083	E4-A-05084	E4-A-05085	E4-A-05086
Group 3	E4-A-05087
Group 4	E4-C-00559	E4-C-05089	E4-C-05090	E4-C-05091
Group 4	E4-C-05092	E4-C-05093	E4-C-05094	E4-C-05096
Group 4	E4-C-05098	E4-C-05099	E4-C-05100	E4-C-05101
Group 4	E4-C-05102	E4-C-05103	E4-C-05104	E4-C-05105
Group 4	E4-C-05106	E4-C-05107	E4-C-05108	E4-C-05109
Group 4	E4-C-05110	E4-C-05111	E4P-C-06073

(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 ( print 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.

Table 3 to Paragraph ( g )(5)—Replacement for Group 3 and 4 Engines

Engine group	Compliance time
Group 3 engines that do not have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Before exceeding 900 FHs since new, or within 15 FHs after December 11, 2023 (the effective date of AD 2023-20-03), whichever occurs later.
Group 3 engines that have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Before exceeding 900 FHs since new, or within 15 FHs after the effective date of this AD, whichever occurs later
Group 4 engines that do not have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Before exceeding 1,000 FHs since new, or within 25 FHs after December 11, 2023 (the effective date of AD 2023-20-03), whichever occurs later.
Group 4 engines that have an ESN identified in Table 2 to paragraph (g)(1) of this AD	Before exceeding 1,000 FHs since new, or within 25 FHs after the effective date of this AD, whichever occurs later.