AD 2023-20-03 Prompted By Reports Of Piston Failures

The FAA is adopting a new airworthiness directive (AD) for certain Austro Engine GmbH Model E4 and E4P engines.

This AD is 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. This AD 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 is issuing this AD to address the unsafe condition on these products. This AD is effective December 11, 2023.

Background: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Austro Engine GmbH Model E4 and E4P engines. The NPRM published in the Federal Register on July 14, 2023 (88 FR 45118). The NPRM was prompted by European Union Aviation Safety Agency (EASA) AD 2022–0240R1, dated December 15, 2022 (referred to after this as the MCAI), issued by EASA, which is the Technical Agent for the Member States of the European Union. 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 (EASA AD 2022–0240), to specify repetitive oil analyses and 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 are unlikely to be found during subsequent oil analyses. As a result, EASA revised

EASA AD 2022–0240 and issued the MCAI 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.

In the NPRM, the FAA proposed to require initial and 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 is issuing this AD to address the unsafe condition on these products.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA–2023–1412.

FMI: www.regulations.gov