Squawk Box

June 1999 Issue

Piston Plug Mystery

Spotty failures continue to plague Lycoming piston plugs

The following information is derived from the FAA’s Service Difficulty Reports and Aviation Maintenance Alerts. Click here to view "Airworthiness Directives."


The FAA has issued a Special Airworthiness Information Bulletin addressing Textron Lycoming piston plug wear. The bulletin aims to help identify abnormally worn piston pin plugs and describes appropriate inspection/maintenance actions.

Lycoming engines have plugs that center the piston pin in the cylinder, which ensures that the piston is centered within the cylinder barrel. The plugs, by design, experience some wear on the plug face, which contacts the cylinder barrel. This...

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