Are you tired of leaking crankcases? So were we - that's why we decided to do something about it. Our proprietary O-ring modification is available with STC approval for Lycoming applications, and is available for experimental Continental applications as well. Our Haas CNC machine performs a test run with a special pen to verify the correct cutting path. Once accuracy is confirmed, it cuts a specially shaped groove in one half of the case to retain the sealing material. This modification lasts the life of the crankcase and the material can be easily replaced on each overhaul. Leaking cases will be a thing of the past! See our download page for a copy of the Kitplanes article on this process.