Service Instruction No. 1290F DATE: July 24, 2009 WEBSITE PUBLISH DATE: June 17, 2025 due to frequent requests. MODELS AFFECTED: All Lycoming wide cylinder flange engines identified by the suffix “A” or “E” after the engine serial number and incorporating body-fit thru-studs such as: O, IO, AIO, AEIO and LIO-320 series engines O, IO, AIO, AEIO, HIO, LIO, TO and TIO-360 series engines O, IO, AEIO...