Parts Source: KNOTS2U

[JAG]

Steve and all,

More info on o-rings than you probably want. You hear terms like Viton, fluorocarbon and Buna-N...well, I am not here as an expert, but sharing my experience with o-rings over the years. If I am incorrect in any of these statements cause my memory is poor - just be kind in how you correct me.

MS29513 or rings are Buna-N, and designed for fuels (jet fuel, etc). These o-rings are great for cold temperatures (I mean really cold, not just "have to wear a jacket" cold). I believe they have shelf life, which tell you that they do not age as well.

MS28775 / M83248 and old NAS 1593 are made of Fluorocarbon. They are similar to Viton o-rings (Viton is trademark of Dupont), in that they have similar properties. Fluorocarbon o-rings tend to stand-up better to the constant immersion in the fuel for a primer. That is why I use the MS28775-012 in my primers (I knew I would remember why). I think McFarlane kits use the M83248/1-012 - which cross references to the NAS1593-012 (which Cessna calls for) and the MS28775-012. Fluorocarbon is not as good as Buna-N in extreme cold, but I can tell you from experience from working in the high Arctic maintaining aircraft, I did not see a problem between the two types....

So, in summary...there are a few options of o-rings, and as near as I can tell, most Cessna aircraft (150-210 and the 337) use the same primer.

Jeff