How much oil

LesGawlik

LesGawlik

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is acceptable on the windshield? I flew the 182 at night. When I landed, the oil mist really interfered with vision. It was hardly noticeable on the earlier flight during the day. The windshield was cleaned before the flight. When I went to clean it the next day, it didn't look like much at all.

I assume it's coming from the prop. I know one of the things you look for on run up is oil on the windshield. I can say I did not an would not notice it during the day, but after landing at night it was noticeable.

There isn't much on the top of the cowl that could allow oil mist to escape. Everything seems to seal well. There is no excessive oil consumption. Some oil on the belly.

What are the chances that it is the prop? What is acceptable?
 
Do you have goggles?
Does the window open wide enough to stick your head out?
Can you reach and manipulate the flight controls while imitating a Golden Retriever?
 
Anything over 2 quarts on the windscreen is a no-go for me.

/s.

:)
 
You should be looking at the windscreen when doing your runup prop check. I do three pulls, 1st pull, oil pressure drop. Second pull, rpm drop and mp rise. The third pull is to watch for oil spittle on the windscreen.
 
Bill said:
You should be looking at the windscreen when doing your runup prop check. I do three pulls, 1st pull, oil pressure drop. Second pull, rpm drop and mp rise. The third pull is to watch for oil spittle on the windscreen.
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Which is why I said what I said.

"I assume it's coming from the prop. I know one of the things you look for on run up is oil on the windshield. I can say I did not and would not notice it during the day, but after landing at night it was noticeable."

At worst, it is a fine fog not visible during the day. Nothing is visible on the prop pull. Nothing is visible in flight. Nothing is visible during the day at shutdown. If I hadn't flown at night I never would have seen it. As I said, when I went back the next day there was nothing visible on the windshield.

All the posts about quarts are appreciated. I needed the laugh.
 
It doesn't need to come from the prop. The airflow into the front of a cowling is often really messed up, not nice and straight and smooth like we imagine. The Super Cub is a famous example; it has had cooling problems right from the start. Someone did tuft testing on that inlet and found that air went in the outboard areas of the inlets and shot back out behind the prop from the inboard areas. Any small oil leakage from just about anything anywhere near the front of the engine will get carried out and blown back over the cowl. If you think about it, the air off the prop blades near the hub is next to nothing, while a few inches farther out it's a lot, and the centrifugal pumping effect of the hub and spinner can easily suck air out. If the cowl flaps are closed it can be much worse.
 
When there is more oil on the windshield than in the engine!
 
Dan Thomas said:
It doesn't need to come from the prop. The airflow into the front of a cowling is often really messed up, not nice and straight and smooth like we imagine. The Super Cub is a famous example; it has had cooling problems right from the start. Someone did tuft testing on that inlet and found that air went in the outboard areas of the inlets and shot back out behind the prop from the inboard areas. Any small oil leakage from just about anything anywhere near the front of the engine will get carried out and blown back over the cowl. If you think about it, the air off the prop blades near the hub is next to nothing, while a few inches farther out it's a lot, and the centrifugal pumping effect of the hub and spinner can easily suck air out. If the cowl flaps are closed it can be much worse.
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Now THAT was helpful, and addressed one of my concerns. I was wondering about the airflow around the cowl. The previous owner chased a few very small oil leaks. It was never a SOF issue, just a messy annoyance. I was wondering whether oil vapor from under the cowl could get sucked out and blown on the windshield, and it appears it can.

Thank you.
 
If you have oil bad enough that it showing up on the windshield from the propeller, you would also see oil streaking on the blades themselves. It’s pretty simple. Do you have any showing up?
 
Bill said:
You should be looking at the windscreen when doing your runup prop check. I do three pulls, 1st pull, oil pressure drop. Second pull, rpm drop and mp rise. The third pull is to watch for oil spittle on the windscreen.
Click to expand...

I always wondered why pilots milk the prop control 3x during runup.
 
Rgbeard said:
If you have oil bad enough that it showing up on the windshield from the propeller, you would also see oil streaking on the blades themselves. It’s pretty simple. Do you have any showing up?
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None at all. And I didn't know I had oil on the windshield until I taxied to park after landing at night.
 
None, out to the mechanic it would go, or if I was renting, I would say " Gimme another airplane, not flying this one today."
 
Rgbeard said:
so why are we talking about the prop if the blades are dry?

next suspect, please step forward.
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if the blades are dry and it's a 470 skylane, my next stop would be the crank flange seal.

I'd also be scrutinizing the case and spark plug bosses. There's some service letter IIRC that describes the common case crack locations.

...but if it's a rental, "give the keys back" sounds like the right answer, and putting the squawk in writing somewhere so they can't ignore it. :)
 
Any oil on the windshield is a prompt to investigate for the source of leakage, lest it get worse. Depending on how tight your cowl seals, oil can be coming from the engine compartment. This can originate almost anywhere, as oil gets blown around the engine compartment, and droplets can exit the cowling seams near the windshield.

I've seen these little spatters on my windshield, with various sources subsequently identified:
  1. hardened pushrod tube seals (pretty common in older Lycomings)
  2. seeping gaskets on valve covers
  3. leaking dipstick tube gasket
  4. seeping oil sump screen plug (this one has bedeviled me since overhaul--finally fixed by removing case burrs around the plug hole and installing fresh crush gasket with maximum torque. No more drips...for now.)
Anywhere oil can leak, it can get out and may wind up on the windshield. When it gets blown all over the engine compartment, it can be difficult to trace to the source if it is a seep. Good luck finding the source.
 
In the automotive world, I'd put a little UV tracer in the oil, ground run it and come back at night with a UV light. Is that appropriate here?
 
None.

The only time I've ever seen oil on the windshield was when the cowl was off chasing another problem. About 20 seconds of that was maybe a 1/8 of a quart and it was everwhere.

The last, $%%# to clean residual of our oil leak still lightly streaks out the seam between the bottom cowl and the copilot side.

I definitely wouldn't fky again at night. Maybe a quick single lap around the pattern at the very very most to get it warmed up to troubleshoot. But something misting like that should be leaving some type of drip right after shutdown.

I would pull the top cowl right away and go on the hunt. Then pull the bottom cowl if it's not obvious. I think you'll find it within 1hr of careful looking.

Maybe run it up for about 1min with top cowl off then quickly inspect.
 
My old engine had one of those Hartzell bladder props. WIthout fail, I'd schedule a day to pull the prop off and replace the bladder, a full year before it was officially due, and it would start to leak the flight before. As Margy's flight instructor would say, oil is like blood. A little looks like a lot. The bladder probably didn't leak enough to make noticeable change on the dipstick, but it sure made a mess out of the windshield.

Any leak however needs to be figured out.

My other two big leaks was the time I forgot to put the filler cap back on the 170. Probably lost half a quart but spent the rest of the afternoon cleaning up the film from all over the aircraft.

The other was after the IO-550B came apart in flight on me. The amount of oil that was released at the time that happened (and the amount still pouring out of the breached case after I touched down, belies the fairy tale that Continental sold the NTSB on the teardown.
 
I think some of you in your answers are confusing grease with oil. Many props will sling a bit of grease and yes you will see it on the blade. I am not sure you will see a very small oil leak on the blades and certainly won’t if it’s coming through the cowl. Oil leaks on a aircraft are extremely hard to find because as others have mentioned airflow under the cowl can move oil all over. It’s a pain but you need to decowl it and clean the engine throughly. From there you can ground run it and inspect. Baby powder can be used to show leaks or some of the dye options. If it’s a really small leak you might never find it. Has there been any change in oil consumption?
 
Jeff767 said:
I think some of you in your answers are confusing grease with oil. Many props will sling a bit of grease and yes you will see it on the blade. I am not sure you will see a very small oil leak on the blades and certainly won’t if it’s coming through the cowl. Oil leaks on a aircraft are extremely hard to find because as others have mentioned airflow under the cowl can move oil all over. It’s a pain but you need to decowl it and clean the engine throughly. From there you can ground run it and inspect. Baby powder can be used to show leaks or some of the dye options. If it’s a really small leak you might never find it. Has there been any change in oil consumption?
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Some props use oil, not grease. Besides that, they're actuated by oil pressure from the governor and can develop leaks internally and let the oil out.
 
Don't listen to any of these guys, they're full of %$#&:

1. It "for sure" was the plane in front of you. This happened to me while racing all the time:cool:
2. That light oil prevents corrosion, see if you can get it to increase to prevent further corrosion:confused:
3. If you're flying west Texas, it's the oil wells crying sad oil tears for the current "green" attack:(
4, If it's serious, the propeller would've come to a standstill:eek:



*** Obviously joking for any PC folks that may be reading and didn't get the emojis ***
 
Dan Thomas said:
Some props use oil, not grease. Besides that, they're actuated by oil pressure from the governor and can develop leaks internally and let the oil out.
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I am 99% sure the prop he is using is greased where anything could migrate on the blades.
 
<<<. Check out my Profile Pic. That's a bit too much. :) That's :10 minuets without the oil-cap. (Never got below 10qts.)
 
LesGawlik said:
Do you agree that a leaking prop would sling oil on the blades?
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Maybe.

Wipe your windshield with a white rag, towel, paper napkin, whatever. You may see pink/red. Probably prop if it has dye for leak detection

Remove spinner and look for pink inside. Same for outside of hub.

Satisfy yourself with this bit of work and move to the next stuff inside the cowl. You may need/want an A&P to put the spinner back on (mark it so you or he/she can clock it the same way, in case it makes any difference for balance).
 
On a 182, a leak from the oil cooler can be pulled forward and over the cowling. In our case, it was a simple drain plug on the cooler that had a bad seal, and was a relatively painless fix, after we found it. The catch was, there was hardly any oil at the plug, compared to the mess it made all around, so figuring out the source was some trial and error.
 
If you pull the spinner, have a few of those thin paper discs available. Sometimes there aren't enough and its slowly wearing the spinner thin from the inside out.
 
I had a similar problem and upon investigation we found a hairline crack in the engine case. Given that the engine was at 1400 hours (TBO 1900) I elected to have it fully overhauled.
 
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