If you don’t have one, you probably don’t need one. You should figure out what’s actually wrong.

By Erich Rempert
A&P Consultant

Highlights from Erich’s article in the June issue of Cessna Owner Magazine.

Well, if you don’t have a wet vacuum pump you shouldn’t need one. Dry vacuum pumps (the vast majority of those in service today) have graphite vanes and do not require any lubrication at all. In fact, moisture in the pump usually leads to catastrophic failure, i.e. the vanes shattering and destroying the pump.

So why do you still hear about airplanes that have AOS? Well, the theory is that they recover any oil blown out the breather tube and thus the engine only loses the oil it burns, meaning they are used as a means to reduce oil consumption.

So, I ask, does your engine use a lot of oil? If it does, why does it use oil, and how is it losing oil? If the oil is lost through combustion, an AOS will do absolutely nothing to solve that problem. If your engine is blowing excess oil out the breather, an AOS may prevent you from losing that oil, but really at best it’s a band-aid for some other issue.

It only takes a couple of hours to install and I recommend it highly.

By Scott Sherer
COO Forum Moderator

Highlights from Scott’s article in the June issue of Cessna Owner Magazine.

The instructions on oil changes for my airplane say to fill my Continental TSIO-360-EB’s with eight quarts of oil. Within about five hours of flight after the oil change, my oil level was about five quarts without the separator. It doesn’t take the intellect of Albert Einstein to know that three quarts of oil has to go somewhere, right? It certainly isn’t in the engine and it hasn’t blown by my piston rings.

So where was it? It blew out of the oil breather and all over the belly of my airplane. Additionally, I had to add one quart of oil for every 8-10 hours of flight after that. And you know where that oil goes, too, right? Right! All over the belly of my airplane.

So what does an air-oil separator do? … Once you install an air oil separator, this doesn’t happen anymore.

Read more in the June issue (read the digital issue here) and discuss the topic in our forum here.

What do you think?