Why do my engines throw out the first quart of oil?

My Partenavia P68C is throwing out the first quart of oil. If I fill it to eight quarts it very quickly dumps the first quart or so and the oil level settles at somewhere around six and a half. After that it doesn’t use any more oil.

When it dumps the first quart, it leaves oil on the wings and flaps. Once the oil is cleaned up, the area stays clean unless I add oil.

This happens to both engines. They are both 1,260 hours from new but time expired as the aircraft is a 1985 model.

Rod Robertson
Queensland, Australia

A Partenavia P68C.

A: Rod, I’ve got to say this is not the first time this subject has come up. This is not an unusual occurrence for most Lycoming engines and from your information, I’d say this is quite typical.

This is something that each operator will encounter and this is where good operational records become very important.

As an operator, you should learn the peculiar quirks of each engine and in your situation, you’ve experienced what happens when you fill each engine with the oil sump capacity of eight quarts.

Through normal operation your engines blow the first quart overboard ending up on the wing and the flaps. I could tell you that this was a design by Lycoming in an effort to prevent corrosion in those areas, but that wouldn’t play very well, so we won’t even go there!

The fact is, this is pretty much normal and is nothing to worry about unless you know that your engine has a history of excessive oil consumption. As an example, the maximum allowable oil consumption for your engines is probably between 3/4 to one quart per hour at rated power.

The risk, as I see it, is if the engine has excessive consumption, theoretically you could run out of oil before exhausting your fuel on

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