FAA Mandates Inspections for Lycoming Engines Over Piston Pin Cracking

The Federal Aviation Administration (FAA) has issued a final rule requiring immediate inspections and maintenance for nearly 1,000 piston engines produced by Textron Inc. subsidiary Lycoming. The directive affects specific O-235, O-540, and IO-540 series engines utilized in general aviation aircraft and follows reports of metal particulates discovered in engine oil and two engine failures.

Under the airworthiness directive, which becomes effective in 17 days, operators must conduct oil changes and filter inspections to check for metallic debris. The FAA determined that “thin-wall piston pins” installed in the engines are susceptible to cracking due to manufacturing anomalies. According to the agency, the component supplier altered honing and tooling processes, resulting in micro-cracks and base metal inclusions that compromise the structural integrity of the pins.

The regulation estimates that 957 engines installed on U.S.-registered aircraft are subject to the compliance order. The safety concern involves piston pins manufactured between January 7, 2021, and December 15, 2025. If inspections reveal the presence of metal in the oil system, operators are required to replace the affected pins before further flight. For other engines within the scope of the directive, oil changes and inspections must be performed within five hours of service time.

Lycoming initially addressed the manufacturing flaw in a Mandatory Service Bulletin issued in March, which provided instructions for replacing pins and inspecting engines. The company followed up with additional documentation regarding overhaul frequencies in April. The FAA noted that it typically solicits public comment prior to finalizing such rules but bypassed that procedure due to the designation of an “unsafe condition,” opting instead to accept feedback post-ruling.

The implicated powerplants are widely used across the general aviation fleet. The six-cylinder O-540 and fuel-injected IO-540 models power airframes such as the Robinson R44 helicopter and the Britten-Norman BN-2 Islander, while the four-cylinder O-235 is found on aircraft like the Cessna 152.

What to watch

• Compliance costs and service volume impacts for Textron Aviation’s aftermarket network.
• Updated service bulletins or further regulatory action if additional affected engine serial numbers are identified.
• Upcoming earnings reports for commentary on maintenance, repair, and overhaul (MRO) trends.

Source: original release