Lycoming 540 series engine [Credit: Lycoming Engines]
Key Takeaways:
The FAA has issued an airworthiness directive for certain Lycoming O-235, O-540, and IO-540 aircraft engines due to defective piston pins.
These defective thin-wall piston pins, produced with microcracks from manufacturing process changes, have led to metal particulate contamination and engine failures.
The directive mandates the replacement of affected piston pins and inspection of engine oil for metal particulates, impacting approximately 957 U.S.-registered engines and taking effect September 14.
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)
