Oil separators

[maxmotoring]

What is the general thinking regarding best practice relating to oil separators used on aircraft? Is it acceptable to route the collected oil back into the sump, or are there good reasons not to? Discuss! All opinions welcome.

Thanks, David

[mike newall]

It depends on what you are doing with the aeroplane.

If you are using it for aeros and the separator is in constant use, then you would normally return the oil to the sump.

If it is tourer and the sep fills over a period of time, I would likely dump it as you will have gunk and crud in there from condensation.

We have an Andair separator in the RV7, it gets plenty of use and returns to the sump. It also has a condensation trap which gets emptied manually every couple of months - that is usually full of milky crud.

[maxmotoring]

Thank you Mike, it seems then that it is best not to put it back in the oil tank, so I’ll route it to a collector tank for removal periodically. The engine is a Walter Mikron that tends to breathe a lot so I was hoping to not lose too much oil by recycling. Aeros will not be performed. Looking at the Aircraft Spruce Catalogue, there are many separators for sale so was influenced by that into thinking it would be a good idea!
David

[mike newall]

Andair is fine, and British.

What aeroplane ?

[maxmotoring]

Chilton

[mike newall]

As you said, do not return to the sump.