EASA SIB NE-19-08: Lycoming Engines - Parallel Valve Cylinders and Head Assemblies

What to do

Operators should determine if their engines contain affected cylinders using Lycoming MSB No. 634 and perform visual inspections and compression checks if symptoms occur or during routine maintenance. Affected cylinders should be replaced at engine overhaul or if cracks or leaks are found, rather than repaired. Installation of cylinders affected by Lycoming MSB No. 634 is not recommended.

Summary

The FAA Special Airworthiness Information Bulletin NE-19-08 addresses cracking issues in certain Lycoming Engines equipped with Parallel Valve Cylinders and Head Assemblies shipped between September 1, 2013, and April 30, 2015. This bulletin applies to Lycoming engines excluding the 0-235 series and informs operators and maintenance personnel about the potential for cylinder cracking without mandating regulatory action. It highlights symptoms, inspection recommendations, and cautions against repairing affected cylinders.

What changed

This bulletin introduces awareness of cylinder cracking in specific Lycoming Parallel Valve Cylinders and Head Assemblies and provides guidance on inspection and replacement without issuing an airworthiness directive. It emphasizes that affected cylinders should not be repaired or refurbished but replaced, and it references Lycoming Mandatory Service Bulletin No. 634 as a source for affected parts and inspection procedures.

Why it matters

This information is critical for aviation professionals to maintain engine reliability and safety by identifying potential cylinder cracks early and avoiding unsafe repairs. Operators and maintenance organizations can prevent engine performance issues and reduce the risk of in-service failures by following the FAA's recommendations. Compliance teams benefit from understanding that while this bulletin is not mandatory, it provides essential safety guidance to avoid costly failures and maintain airworthiness.