When is leaking oil "OK"?

kimberlyanne546

kimberlyanne546

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Kimberly
So during my pre-flight I noticed a very small spatter of oil on the front wheel pant of the 1975 Cessna 150. I asked the person at the front (who is a pilot and flies that same plane) why it was there.

He said it had always been there, but on my other flights, he / the line crew had taken the time to wash up the plane / fill it with gas / get it ready, and that was the only time they haven't cleaned it. So they clean it off before every flight.

I told my CFI, since I know this place is well known for its good maintenance and nice planes. They do the "optional" 50hr as well as the required 100hr on all rentals.... she too said it was no big deal.

The explanation was the older style oil cap, you check the oil during preflight, and no matter how hard you screw it on a little bit of oil comes out I guess during flight (hence the spatter and no leaks when it is simply parked on the ramp)

The oil cap is flat, round, wide, and orange or yellow. I can't even grab it and noted it is different from the 1978 152 and the 1980 172s which have the newer style.

Is this a known issue? I'm going to bring "extra" oil with me (2 instead of 1 container) for my 400nm round trip if they will give me an extra, but I don't know how much leaves the plane each flight.
 
That little oil leak is commonly known as Continental corrosion preventive. (yeah that's a joke.)

A small amount of oil on the nose wheel pant will be
ok, If you noticed the 150 has a 0-200, the 152 has a lycoming 0-235 different engines, different oil sticks.

never launch with less than 4 qts in the sump. 5 is pretty normal.

clean it up, and check before each flight until you get to know the aircraft, and check to see if it really isn't coming from the crank case vent tube.
 
Some planes, I'd be more worried if they didn't leak. Took me 2 years to get all mine plugged up.
 
Tom, I would say check before every flight, not "until you get to know the aircraft." On a rental, who knows how long since the last flight?
 
gprellwitz said:
Tom, I would say check before every flight, not "until you get to know the aircraft." On a rental, who knows how long since the last flight?
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Yeah I forget some still rent..

but preflight by the POH and you'll be OK.
 
Tom-D said:
Yeah I forget some still rent..

but preflight by the POH and you'll be OK.
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Yeah. As one of those who still rents, no matter how well maintained the aircraft, I still check the oil levels. If in doubt, I carry an extra quart (or two!)
 
To answer Kimmy. What is minimum oil capacity for 'go fly'? If present indication is more than...go fly.

I don't know about the previous posts but maybe someone is 'topping off' the oil capacity and what you see dripping is the breather tube dripping onto the wheel pant.

I know it is kinda frustrating that when you ask a direct Q you expect but don't get an direct A.

The basic anser is if you pull the oil dipstick and the oil quantity indicates more than the minimum oil capacity you go fly. As a renter you will become more familiar with each aircraft (s/n and type) that you fly.

I have observed some pilots (mx included) will fill the oil to the maximum limit. Most Cessnas will throw overboard the excess. That will show up as drips on the wheel pant or on the cowling.

Bottom line, what is minimum oil capacity? If you have that and absent any anomalties, go fly.
 
gprellwitz said:
Yeah. As one of those who still rents, no matter how well maintained the aircraft, I still check the oil levels. If in doubt, I carry an extra quart (or two!)
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While still a private, after landing on the outbound leg of a night dual cross country, I noticed a drip on the nose gear. Upon further inspection I found the O-ring for the dipstick tube had come unseated. My CFI at first thought nothing of it. Then when, under flash light, I held the whole dipstick and tube afore his eyes he became a believer that **** happens.

Thank God for carrying those extra qts.
 
The question is not where the oil is, but where it came from. If it's a little spatter from the breather, that's one thing. If it's coming from where the fuel pump is bolted onto the gear box, that's another. If you can't tell where it's from, get the cowl removed and find out.
 
I do NOT miss my TSIO 360 engine. That thing blew so much oil out the breather tube that it would make a horrible mess on the underside of the airplane and I would sometimes have to clean it almost every flight.
 
If you are ever dealing with a radial engine, just remember, it is NOT leaking....it is marking its territory.
 
Kim, if the oil were leaking only in flight you would never see a spot on the wheel pant. The airflow would have it all over the belly first! Do check, but the most likely source is the crank case vent tube, aka the breather tube, as Tom suggested. If it is, and the plane does not use oil abnormally, just carry a rag to wipe the spot before the flight and then go fly... no worries here.

-Skip
 
Ron Levy said:
The question is not where the oil is, but where it came from. If it's a little spatter from the breather, that's one thing. If it's coming from where the fuel pump is bolted onto the gear box, that's another. If you can't tell where it's from, get the cowl removed and find out.
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I think you best take a another look at the back of a 0-200.
 
In the H-3 helos, when we didn't see oil on the airplane, we were scared because that meant it was out of oil. I think that was mainly the transmission that leaked though.
 
bartmc said:
Some planes, I'd be more worried if they didn't leak. Took me 2 years to get all mine plugged up.
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For example, with the big radial engines that used to be common, I've been told that "If there's no oil under it, there's no oil in it!"
 
All you need to know and more about the C-series and 0-200 Continental engines.

Note page 5 figure 2. http://www.pj260.com/Continental/O-200 Manual.pdf
when pilots pull the filler cap they see a 3/8" wide dip stick attached to the bottom side of the cap.

They turn it sideways and look to see where the oil level is, and shove it back in, in doing that they scrape about 1/4 tea spoon full of oil off the dip stick which drains down the out side of the filler neck onto the sump, and down and off the drain valve on to the cowl, and wheel pant.

Most times the pilot will believe the drain valve is leaking, when all it is, is a mess they created by being sloppy about how they check the oil quantity.
 
Palmpilot said:
For example, with the big radial engines that used to be common, I've been told that "If there's no oil under it, there's no oil in it!"
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Not true, we used to have the cowl open when the fuel truck got there, and after fueling we wash each engine by hosing it off with 115/145.

My Warner doesn't leak a drop. and uses no oil between changes.
 
Good that you noticed and asked the question.

While there are a number of engine types that will throw oil out the crankcase vent, sometimes an oil leak (even a small one) can be a symptom of something more. Like a cracked case (BTDT - looked like the seal at the case seam, but turned out to be a cracked case. One night it produced a fine film of oil on the windscreen - fortunately I was quite close to home port.) Or hydraulic fluid leaking from the strut/shimmy dampener (red in color, but a thin film may look like oil).

I'd rather figure out where the oil is coming from before flight.
 
I squawk the airlines when they stop leaking because then they're out of oil...
 
Inverted said:
I squawk the airlines when they stop leaking because then they're out of oil...
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Many years ago I was flying a B-727 from MIA to SJU. While we were being loaded I walked around the airplane with the FE and we noticed a puddle of oil underneath #1 engine. I went to find a mechanic and report it. When he came out I was informed not to worry about it, it probably happened during service. I asked for him to look it over, but he insisted it wasn't anything to worry about, and besides we were coming up on departure time.

We left, and about an hour out of San Juan my Engineer advised me #1 oil quantity was decreasing. When the oil got down to the minimum quantity as prescribed in the Abnormal procedures we shut the engine down.

After landing and pulling up to the gate, the SJU mechanic met me under the #1 engine, which was now soaked with engine oil. He went up an inspection stand and opened the cowling and as more oil poured out he found the problem, a part had backed off the engine accessory case.

Lesson learned after that was to always have a look inside the cowling when there's oil puddling and question things when they don't look right.
 
Ya, I have learned the hard way as well, to not accept a mechanic's "its ok" response. A break fire later and we all have learned lol...
 
kimberlyanne546 said:
.

The explanation was the older style oil cap, you check the oil during preflight, and no matter how hard you screw it on a little bit of oil comes out I guess during flight
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Please don't be one of the people that torques down on on the dipsticks so hard that you have to find a pair of pliers to get the stick out. Just make it snug - it's not going anywhere.
 
Arbiter419 said:
Please don't be one of the people that torques down on on the dipsticks so hard that you have to find a pair of pliers to get the stick out. Just make it snug - it's not going anywhere.
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Doing that can also make the plastic filler tube crack and cause a real problem.
 
Palmpilot said:
For example, with the big radial engines that used to be common, I've been told that "If there's no oil under it, there's no oil in it!"
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True for radials, I used to lightly spray down the belly of the Yak 55 after each flight with a 2 gallon garden sprayer loaded with mineral spirits to keep her clean and then give her a quick wipe down. Rag recycling thru the wash was routine. Oil was purchased by the 55 gallon drum and metered out into 1 gallon containers. Pretty common for radials.

On the front wheel of a Cessna it could be coming from almost anywhere if its running down the cowling and simply exiting at the first convenient outlet. FBO probably logs when each quart of oil is added with should give an idea of the severity of the problem if any.
 
Arbiter419 said:
Please don't be one of the people that torques down on on the dipsticks so hard that you have to find a pair of pliers to get the stick out. Just make it snug - it's not going anywhere.
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Amen! I hate it when I have to dig the Leatherman out of the bag so I can check the oil. Not necessary.
 
As mentioned above, the O-200 is notorious for spitting oil out the breather, look at the belly of any 150 that has not been washed for a while :redface:.
The problem is partially due to the design of crankcase breather. The fitting is flush with the crankcase wall inside the crankcase. The oil droplets and mist inside the engine contact the crankcase wall, travel down the wall, and the oil that travels down right near the breather fitting simply gets pushed out the breather due to the positive pressure within the crankcase. The 150 Aerobat's breather has a short extension tube on the inside so that the draining oil goes around the vent and not out. Kinda hard to explain in words...
If you are concerned, do bring it up with the club mechanic, they will know more than me.
 
The 150 I fly also leaks out of the breather- onto the front wheel pant. Does the hour log for the plane have notes if oil was added before the previous flight? On our club planes we would add a note in the log.
 
Aeric said:
As mentioned above, the O-200 is notorious for spitting oil out the breather, look at the belly of any 150 that has not been washed for a while :redface:.
The problem is partially due to the design of crankcase breather. The fitting is flush with the crankcase wall inside the crankcase. The oil droplets and mist inside the engine contact the crankcase wall, travel down the wall, and the oil that travels down right near the breather fitting simply gets pushed out the breather due to the positive pressure within the crankcase. The 150 Aerobat's breather has a short extension tube on the inside so that the draining oil goes around the vent and not out. Kinda hard to explain in words...
If you are concerned, do bring it up with the club mechanic, they will know more than me.
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That is a good fix for the problem, and cheaper than 4 new ECI cylinders.
 
If the mechanic is like me he will want to hear about it.

And if he's like me he might tell you not to worry.

Oil makes a HUGE mess for not a lot of oil. My plane is leaking about a quart in 10 hrs but looking at the belly after flight you'd think some one shot a jug off or something.
 
Tom-D said:
That is a good fix for the problem, and cheaper than 4 new ECI cylinders.
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Here's the culprit on the right, the solution on the left. Unfortunately this little piece costs over $300 :yikes:, so using a quart every 6-8 hours just doesn't seem too bad.
 

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Rotor&Wing said:
Many years ago I was flying a B-727 from MIA to SJU. While we were being loaded I walked around the airplane with the FE and we noticed a puddle of oil underneath #1 engine. I went to find a mechanic and report it. When he came out I was informed not to worry about it, it probably happened during service. I asked for him to look it over, but he insisted it wasn't anything to worry about, and besides we were coming up on departure time.

We left, and about an hour out of San Juan my Engineer advised me #1 oil quantity was decreasing. When the oil got down to the minimum quantity as prescribed in the Abnormal procedures we shut the engine down.

After landing and pulling up to the gate, the SJU mechanic met me under the #1 engine, which was now soaked with engine oil. He went up an inspection stand and opened the cowling and as more oil poured out he found the problem, a part had backed off the engine accessory case.

Lesson learned after that was to always have a look inside the cowling when there's oil puddling and question things when they don't look right.
Click to expand...

That mechanic probably went to work for Eastern at MIA and was the one who left the oil drain plugs out of the 1011 that almost killed 160 or so innocent pax and crew..:yikes:..
 
Tom-D said:
Not true, we used to have the cowl open when the fuel truck got there, and after fueling we wash each engine by hosing it off with 115/145.

My Warner doesn't leak a drop. and uses no oil between changes.
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Do you fill with the required 8 quarts or are you satisfied with the engines normal 6 1/2 quarts? Mine, 8 quarts out of oil change, 6 1/2 normal within the first 10 hours, and not a drop until the next oil change.
Mechanic also said "If there's only a quart left, you should be okay to fly." I suspect there's a caveat there but under 6, I want more.
 
silver-eagle said:
Do you fill with the required 8 quarts or are you satisfied with the engines normal 6 1/2 quarts? Mine, 8 quarts out of oil change, 6 1/2 normal within the first 10 hours, and not a drop until the next oil change.
Mechanic also said "If there's only a quart left, you should be okay to fly." I suspect there's a caveat there but under 6, I want more.
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The subject was an 0-200- they have a max capacity of 6 qts, and the manual says the min safe take off is 4 qts.
 
Unfortunately (I think I've mentioned this before), the CFI who has done my two check outs is one of those "helper" types (aka does things for you before you can even do them like transponder, flaps, etc... frustrating!!!!).

This means she has taken the oil cap off. I haven't soloed the airplane yet (but will soon now that I'm checked out). I could not get the cap off both times and she told me that was because it was supposed to be put on tightly due to that oil leak thing. She also said I have to push down and then twist. I'll try it this weekend or next weekend, when I fly. I will also look at the wheel pant and then climb underneath with a white paper towel and flashlight on the cement to investigate where it is coming from.
 
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