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: 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 a long cross-country flight. Keep in mind that I said excessive oil consumption and I’m certain that you would notice that and would have taken the proper corrective action.
My suggestion is for you to make certain you always have a minimum of six-and-a-half quarts in the engine at all times.
It’s important to note here that you should keep very close track of the engines’ actual oil consumption, making an engine logbook entry each time any oil is added, including the engine hours and the quantity of oil added.
There may be another contributing factor here also. The age and the total hours on these engines may just — through normal operation over the years — have reached a point that there is more blow-by between the piston rings and the cylinder walls.
Again, I do not think you need to be concerned if the information you supplied is accurate.
The CAA Technical Manual 107, Aircraft Powerplant Handbook, 1949, explains the ‘oil system tank requirements’ , on page 198.
[ vs some of the dumb, lame comments].
The only free version I found.
https://www.scribd.com/document/34191354/Aircraft-Power-Plant-Handbook-CAA-No-107
You will need to scroll thru Oil system from page 185 to 202.
Guilty as charged
So now you know how the oil capacity was set….
My engine has a 10 qt. capacity, but anything over 7 qts gets dumped overboard, and all over the belly..ugh.!
The handbook is only $6 , used. I have 2 copies.
I have found that there are as many engine installations good versus bad, (meaning the oil dip stick)
The dip sticks vary in length and markings set by the airframe mfr. and or the builder. Lycoming has various dipstick filler neck lengths to help clear the cowling but also the dip stick lengths. Tail draggers are different from nose dragger and most twins have rolled the engines inward via wing dihedral. A few degrees makes a difference. Cessna had two distinct p/n’s for their dip sticks after 1965. So, when you introduce the oil to the dry engine count how much is added and then insert the dip stick to see if it is accurate. I have seen amateur built acft. that were way off. Lycoming dip sticks can be shortened from the top end at the cap. I prefer to run 1/2 to one quart low of maximum and that keeps the down the airframe spray. Also look at the crankcase ventilator tube for obstructions and fitment out of the cowling.
The total oil of aircraft engines is based on the time (hours-minutes) the aircraft can fly in cruise and burn (and maybe some leakage). So, lets say 4 hours of cruise at 3/4 of a quart burn.
8 quarts in sump minus 3 quarts burn the sump has 5 quarts of oil for lubrication at the end of the 4 hours..
Example, 8 quarts in sump allows the crankshaft and rods to dip into the sump and throw it into the cylinders and pistons. This causes excessive oil, that the oil rings can not handle, and see how that works out..
Leave one quart out. Race car engines have a dry sump. Little oil in sump and more engine horsepower because no oil thrown against moving parts near sump.
0-360 Mooney, cylinders honed and new rings..
287 hrs, zero oil consumption w/ 8 qts.
I see many questions about acceptable consumption and someone references manufacturer’s specifications. Consider their “acceptable level” is conditioned to their warranty. The lower that number, the more warranty rerings they’d be on the hook for.
Consumption is in the eye of the beholder and doesn’t neccesarily indicate an upcoming failure, other than fouled plugs, hence fine wires.
I understand there is a fix for Continental engines. At overhaul there is opportunity to install a scoop inside the engine at the breather …that traps the oil the engine will throw out. When the engine oil is lower no scoop is needed…but at least you don’t lose a quart or two.
It’s an interior extension to the oil breather, brazing a short tube to extend the breather into the engine so the oil isn’t thrown directly out.
For the 150’s O-200, you can get the Aerobat crankcase breather which has the extension on it. Brazing an extension on yourself isn’t legal on a certified engine. It is done all the time on O-200s in Experimental category.
The “official” Aerobat extension is brazed and pinned, so it won’t ever come loose. Now I know that FAA inspectors don’t have X-ray vision (are you sure?) so they’ll never know this mod has been made unless it comes apart and the noise stops because of it (“foreign object came loose in crankcase”), then you have a couple of problems.
Incidentally, if you send the crankcase out for work, you MUST remove the breather elbow or you will never see it again and you will get to buy a new one, and for a simple plumbing elbow, they are amazingly pricey. Same goes for magneto drive gears – don’t EVER let them out of your sight or you will pay, big time.
I worked line service for more years than I care to say. Everybody kept oil 1 quart down. Monitor your oil whenever you refuel and preflight. Make sure you use the correct oil for the engine. Your good.
Yeah, thanks anyway, guys, but I was just trying to throw a little humor in. All possibilities have been accounted for, and this engine is good to go. Now if only I were this lucky with the REST of the airplane…😢
Mark, I like our similar last names…. I too fly a 182😊😁
I have a Mooney with 180 HP Lycoming. Fill to 6.5 quarts. When a cold engine pre-flight shows 5.9 quarts, I add .5 quarts to 6.4 quarts. Repeat as necessary; my consumption is one quart every 12 hours.
I’m afraid that something is terribly wrong with my engine. It’s a Continental O-470U in my 182, and at every oil check or change it has the same amount of oil that was originally put in. I haven’t added a single quart in the three years I’ve owned it. Can someone please recommend a good mechanic who can install the standard oil leaks?
If you’d like, as a friendly gesture from one aviator to another, I could send you some oil leaks from my 0-200.
Actually, an engine that uses ZERO oil needs a look. If the rings were fitted too tightly, that will make a difference. If you live in a humid area where the temperature swings up and down, there could be condensation in the crankcase, and the added water gives the illusion of not needing any oil – the engine may very well be using the correct amount of oil, but the water plus the remaining oil keeps the level on the dipstick about the same. When you do an oil change, do you look in the bucket for brown foam (water in the oil)? Maybe do an oil analysis next oil change.
Then again, you could install a reversible pitch propeller and MAKE oil!
If this were mine, I’d poke around a bit and find out why the engine seems to be using zero oil. Sumpin’ ain’t right . . .
I got my airplane from Plane Silly and as he said if you never put in any oil you never have to replace the oil ;-o
In recognition of this, I never fill my engine to the maximum quantity. After each oil change I fill to 7 quarts, as the last quart won’t stay in there anyhow. I fill to 7 and add a quart at 6. When I had a 12 quart 6 cylinder, I filled to 10 and added at 9.
WELL SAID!
1 qt low Jerry