The International Cessna^® 170 Association

Howdy, the previous owner on our 170 installed a Walker Air/Oil Separator from a 180/182 on our bird and never did the field approval to do so. Walker never did a STC for the 170. There is one however for the 172 with an O-300D2 but it shows the oil return line via an exsisting line to a rocker cover. Ours was installed using the accessory case for the return line.

The question, has anyone done a 337/field approval for this? I know there is one on at TIC170A but it is for a Franklin engine.

Can this be done as a follow on STC based on the exsisting 172 STC?

Thanks for the advise.

I really want to get this done and get it legal.

I admire you for wanting to get the paperwork legal. You might get a copy of the STC for the similar installation on that engine in a 172 and submit it on a 337 for field approval.
I personally am intrigued by all the interest in air/oil seperators on these airplanes that don't have vacuum pumps. The orginal intent for these devices was to seperate the air/oil on the discharge side of vacuum pumps (which can be considerable oil pumped overboard without one.) But with a venturi system, the only overboard vent is the crankcase vent, and that oil loss is negligible.
But the water vapor that can condense in a seperator can be considerable, and I certainly wouldn't want to condense water and then drain it into my crankcase.
If you don't have a vacuum pump, I'd encourage you to remove it and sell it.

George, thanks. It does have a WET Vacumn pump that is plumbed into the Air/Oil Separator.
I was hoping that someone had already done a 337/field approval and we could use that as an example.