Excessive oil loss during aerobatics?

[Diana]

Today I lost almost three quarts of oil doing aerobatics; most of which now covers the Citabria. It was dripping off of the airplane like rainwater after a downpour. Yesterday I did five hammerheads and barely lost any oil and hardly any on the airplane. Today I did seven hammerheads. We can’t figure out what’s going on. There is no oil splashed in the engine compartment, so it seems like it’s all coming out the breather tube. Any ideas?

The hammerhead maneuver seems to cause the most oil to be tossed out of any of the maneuvers that I do. I still don’t really understand why the oil comes out in the first place.

 

[bbchien]

Is the inside of the exhaust still a light charcoal grey to a finger swipe?

 

[Diana]

There's a six hammerhead limit before the engine upchucks?

I think she was just doing it to get attention.

How much oil are you starting with?

It was at 6 1/2 quarts this morning before I flew.

A perusal of the net revealed the O-360 in the Slick-360 has a different recommended oil capacity for aerobatics vs. cruise... so I suspect a certain amount of oil loss is expected.

The computer I'm on won't open that one up. Is it the same for the O-320?

I usually lose the most oil during the hammerhead, but never 3 quarts in 30 minutes. I''m glad I was over the farm and didn't have to fly for long before I landed. Wonder how much of it dropped on the corn?

 

[gismo]

Dunno, I was just trying to locate some quantified documentation on the net for other airplanes that exhibited the same behavior. Not being an expert on aircraft engines, aerobatics, or just about anything else, I can only suspect the volume of oil loss is possibly a function of the time a non-inverted oil system experiences a -G condition, which can vary for a given manuever depending on the skill of the aerobat.

Btw, I've read that people who love aerobatics also enjoy having a lit match under their toenail.

You know Diana, I think you ought to add an inverted oil system to your Citabria and be done with all of this. Not only will you spend less time cleaning up and adding oil, your engine will be much happier. I don't know exactly what's required on the Citabria, but IIRC you can get the whole thing done for $1000-1500 and possibly less if you do some of the work and/or pick up the system used.

Take a gander at:
http://musclebiplane.org/htmlfile/invert.php

 

[Diana]

You know Diana, I think you ought to add an inverted oil system to your Citabria and be done with all of this. Not only will you spend less time cleaning up and adding oil, your engine will be much happier. I don't know exactly what's required on the Citabria, but IIRC you can get the whole thing done for $1000-1500 and possibly less if you do some of the work and/or pick up the system used.

Take a gander at:
http://musclebiplane.org/htmlfile/invert.php

Thanks for the site Lance. Interesting. I guess you get an STC with it?

 

[Diana]

I can only suspect the volume of oil loss is possibly a function of the time a non-inverted oil system experiences a -G condition, which can vary for a given manuever depending on the skill of the aerobat.

You may have hit on something with the "skill" part. I did four hammerheads today (didn't fall over on my back) and didn't lose any oil at all. None on the airplane either.

Called my mechanic last night. He said not to worry and to try to do the hammerheads correctly and that should take care of the problem.

 

[gismo]

Thanks for the site Lance. Interesting. I guess you get an STC with it?

Sure thing. An STC is pretty much required for anything not already on the type certificate that affects important systems like engine lubrication (on a certified airplane). And most (if not all) STC's are aircraft serial number specific so if you find a good deal on a used product, make sure you find out how to obtain the STC for your airplane before buying.

 

[Ken Ibold]

You know Diana, I think you ought to add an inverted oil system to your Citabria and be done with all of this. Not only will you spend less time cleaning up and adding oil, your engine will be much happier. I don't know exactly what's required on the Citabria, but IIRC you can get the whole thing done for $1000-1500 and possibly less if you do some of the work and/or pick up the system used.

Take a gander at:
http://musclebiplane.org/htmlfile/invert.php

A thousand bucks buys a lot of oil ...

While a 3-qt loss is extreme (I had a 2 qt loss happen to me once and never did figure out why), the vast majority of the time you are talking on the order of a few ounces. Messy, yes, but not dangerous.

The service information I've been able to find on minimum oil level has been spotty. I know of a POH for a Lycoming IO-360 that specifies a minimum operating level of 2 qts. Anyone know what the min is for a Lyc O-320 B series?

 

[gismo]

A thousand bucks buys a lot of oil ...

While a 3-qt loss is extreme (I had a 2 qt loss happen to me once and never did figure out why), the vast majority of the time you are talking on the order of a few ounces. Messy, yes, but not dangerous.

True, but 30 seconds of high power running with little or no oil flow to the main bearings can be awfully hard on your engine. The payback with inverted oil is longer TBO and less mess to clean.

 

[Diana]

While a 3-qt loss is extreme (I had a 2 qt loss happen to me once and never did figure out why)

Ken, was this while doing aerobatics?

 

[Ken Ibold]

Ken, was this while doing aerobatics?

Yup. And there was a mess to clean up as well. As I recall, I was doing slow rolls that day.

 

[Ken Ibold]

True, but 30 seconds of high power running with little or no oil flow to the main bearings can be awfully hard on your engine. The payback with inverted oil is longer TBO and less mess to clean.

Yes, that's true.

Of course, the simple thing to do would be to stick to positive g acro in a 7GCAA. But we're not interested in simple, necessarily. B)