Loctite 515 Gasket Eliminator – Makes flexible gaskets for rigid machined flanges with less than a .050 gap. Flexes with flanges that move in service. Loctite 515 is an approved option for sealing Lycoming crankcases. Use 515 instead of silk thread. See Lycoming Publication No. 60294-7, revision 10 dated January 2007. Can also be used as an alternate to TCM 646942 per SIL99-2 Rev. B.