Lycoming 540 series engine [Credit: Lycoming Engines]
Key Takeaways:
The FAA has issued an airworthiness directive (AD) for specific Lycoming O-235, O-540, and IO-540 aircraft engines due to defective thin-wall piston pins.
These piston pins were found to have microcracks and inclusions from manufacturing process changes, leading to metal contamination and a risk of engine failure.
The AD mandates the replacement of the faulty piston pins and requires oil inspections for metal particulates to prevent potential in-flight engine failure and loss of control, affecting around 957 U.S. engines with an estimated compliance cost of over $2,200 per engine.
The FAA has issued an airworthiness directive for certain Lycoming O-235, O-540, and IO-540 aircraft engines due to defective piston pins that could cause engine failure.
According to the agency, AD 2026-17-10 was prompted by multiple reports of piston pin failure resulting in metal particulate contamination of the engine oil and, in some cases, engine failure.
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Meg Godlewski has been an aviation journalist for more than 24 years and a CFI for more than 20 years. If she is not flying or teaching aviation, she is writing about it. Meg is a founding member of the Pilot Proficiency Center at EAA AirVenture and excels at the application of simulation technology to flatten the learning curve. Follow Meg on Twitter @2Lewski.
![Lycoming 540 series engine [Credit: Lycoming Engines]](https://www.flyingmag.com/wp-content/uploads/2014/03/httpswww.flyingmag.comsitesflyingmag.comfilesimport2014sitesallfiles_images20140150engines-lycoming-540-series.jpg)
