rocketbob
Well Known Member
Over the last several years I've been using push lock fittings for pitot/static connections. On a few occasions I've had these fittings leak and last night I examined a leaky tube and fitting closely under magnification to determine why. These fittings use a small conical washer with tabs to embed into the plastic tubing to retain them. During insertion the washer can scratch the tubing which causes an imperfect seal against the o-ring. Normally when used in higher pressure applications the oring seals work fine because they get compressed. The simple solution is to use a tiny amount DC4 silicone grease on the tube end during insertion which helps prevent the tube from being scratched and helps with the oring seal.