In flight oil spill

SixPapaCharlie

SixPapaCharlie

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Flying a rented 172 on Sunday, everything seemed fine.
~2 hr flight and no issues to speak of.

My parents landed about 10 min before me.
I landed and my mom asks "What's all over the plane?"

I take a look and the entire left side and bottom of the plane are coated in a thick layer of oil. real thick.

My first thought was I forgot to put the oil cap back on.
I open the cowl and the cap is on nice and tight.

The entire inside of the cowl is coated in oil.

I grabbed the dip stick and it felt like it wasn't seated all the way.
Checked and it showed 3 quarts :yikes:

I filled it up to 6 prior to departing. Never had any indication of low oil pressure or temp issues.

I cleaned the plane up and filled it back up with oil and flew it back to its owner (15 min away) That flight, everything was normal as well.

I spoke to the owner and he said it needed an oil change anyway so they changed it, cleaned it up and so far, no leaks detected.

Couple questions.
The dipstick was in place but it is "in" but push harder and it goes in more.
Could a lose dipstick cause 3 quarts of oil to come out?

Should there have been some indication via gauges? pressure or temp?
I saw none. At what point do those start indicating an issue. I would have thought at 1/2 recommended level, I would have seen something.

Was it stupid to fill it back up w/ oil and fly it home (the 15 min flight)?

This is an older plane 1964 C-172 (E I think)
 
With that much oil loss I would have grounded the plane.
 
It would take a long time to lose 3 quarts to a loose dipstick typically, especially if it's on the high pressure side of the cylinders/baffle.
 
Losing half your max capacity of oil in a few hours is a sign of substantially bigger problems than a loose oil dipstick.

A possibility might be a backed-off oil filter. That might get changed with the oil.

I wouldn't fly an airplane like that until the leak was identified and neutralized. You could have been pouring out a crank seal. If you run out of oil, your engine gets big holes in bad places.
 
If that much oil actually blew out of a mildly loose dipstick, there are bigger problems. If that much oil didn't actually come out of the dipstick, there are even bigger problems!
 
MAKG1 said:
Losing half your max capacity of oil in a few hours is a sign of substantially bigger problems than a loose oil dipstick.

A possibility might be a backed-off oil filter. That might get changed with the oil.

I wouldn't fly an airplane like that until the leak was identified and neutralized. You could have been pouring out a crank seal. If you run out of oil, your engine gets big holes in bad places.
Click to expand...

Yup

That's quite the oil loss, Id want answers before I put that plane back up in the air.
 
That's not good. When I was part of a club we had a 1976 150. Two years ago I went to fly it right after a CFI and student came down. I checked the oil and it was low and I found Oil coating the engine and inside the Cowl. I told the club President and we grounded the plane. I cant remember what was wrong but the club couldn't afford to fix it and they sold the plane off. I felt bad that I downed it and they had to sell it. Oh well.. you made it back so all is good but I honestly would not have flown it.
 
<embarrassing mode on>
Back in my rental days, my wife and I were heading out for a long weekend in another state. +/-3 hr flight away. Lots of things went wrong that day. Was trying to beat a weather front, the hanger door was "off the track" and took a couple of hours to get my rental out, etc, etc. I added a qt of oil prior to takeoff, and had a spare quart in the rear of the plane just in case. (this was a 172 F, 145hp Continental)

Anyway, about 20-25 mins into the flight, I noticed a "fine mist" was appearing on the windscreen. Nothing bad...just enough to get my attention. Diverted to the nearest airport. Normal approach and landing and parked on the apron. When I got out, I just about "shat" myself. The entire lower left exterior cowling was COVERED in oil....blown back past the strut and on the door, not to mention the belly. It looked horrible. I opened the cowl and had that sick feeling in my stomach when I noticed the oil filler cap dangling from it's safety chain.....apparently after adding oil I either didn't replace, or didn't tighten correctly. There were no out of normal indications on either Oil Temps or Oil Pressure.

Got the local AP's help in removing the cowling and power washing everything. Dipstick says I only blew out about 2 qts. Placed a call to the mom & pop place I rented from and confessed. Got her buttoned back up, paid the AP, and went on my way. (watching the temps/pressure and windscreen ever so closely the rest of the way).

That was about a $200 lesson. Now that I own, my plane partners constantly complain that every time they fly after me, the damn oil filler knob (same as dipstick in my Cherokee) is tightened too tight. They have a hard time loosening it to check the oil. They can continue to *****.....I won't be bitten by that one again....
</embarrassing mode off>
 
Doubtful the dipstick caused that much oil loss unless you were flying the thing upside down. Something is wrong with it.

The last "major" oil leak I had on my Flybaby occurred flying home from Airventure last year. I had oil from the cowling literally all the way back to the end of the elevator on both sides. The oil sump tank was cracked.

Working on fixing the oil leak on my mags now..Slow going though since I can't find an exploded parts diagram that shows orientation..and when I do decide I need a new part it takes weeks to get. Taking my time....since my life counts on it. Spending lots of time looking at each piece with a magnifying glass to see how it has worn to confirm I'm putting it back in correctly.
 
Mess a dipstick can provide quite readily, huge mess, usually at a rate of less than a quart an hour. It's amazing how much mess a little bit of oil can make. 3 quarts is a lot to be down.
 
What is the mechanism of oil loss when the dipstick is loose or has a poor seal?
 
Saw 3 quarts immediately after shutdown? Probably a quart still in the engine that hadn't drained into the sump yet. IRRC 4 quarts is minimum on an O-300.

The dipstick on an o300 will make a hell of a mess since it is on the LOW pressure side of the baffling.



You all may find this interesting

Oil capacity --- 8; 7.46 usable at 5° nose-up and ---5.6 usable at 5° nose-down; 7.76 usable at 10° nose-up and 3.77 usable at 10° nose-down attitudes

http://www.luscombeassoc.org/tc/Continental/E-253 O300A.pdf

Cessna says do not operate with less than 6 quarts. I believe a while back I was reading an O-300 operators manual which said 4.
 
FORANE said:
What is the mechanism of oil loss when the dipstick is loose or has a poor seal?
Click to expand...

Crank windage spraying it up, and depending on location, you can also get pressure differential that will either blow it out the vent or out the dipstick tube by ventilating the oil mist out of the crankcase.
 
I wonder if I didn't have the oil cap tight enough.
It seemed snug and I took it off and put it back on 3 times during the trip while preflighting.

The flight was 2.4 hours (checked) and the oil was as Terry describes.
It was even on the under side of the horiz. stab.

I double checked w/ the owner and he has 6 hours on it since w/ no issue.

Still curious if anyone has any idea at what point the gauges would have shown an issue.

This is also the 145 hp continental.
 
SixPapaCharlie said:
I wonder if I didn't have the oil cap tight enough.
It seemed snug and I took it off and put it back on 3 times during the trip while preflighting.

The flight was 2.4 hours (checked) and the oil was as Terry describes.
It was even on the under side of the horiz. stab.

I double checked w/ the owner and he has 6 hours on it since w/ no issue.

Still curious if anyone has any idea at what point the gauges would have shown an issue.

This is also the 145 hp continental.
Click to expand...



Should have pulled the top cowl. It's pretty painless on those old things.


There's isn't much to leak. Oil pressure line. No oil cooler. May not even have an oil filter adapter.
 
SixPapaCharlie said:
I wonder if I didn't have the oil cap tight enough.
It seemed snug and I took it off and put it back on 3 times during the trip while preflighting.

The flight was 2.4 hours (checked) and the oil was as Terry describes.
It was even on the under side of the horiz. stab.

I double checked w/ the owner and he has 6 hours on it since w/ no issue.

Still curious if anyone has any idea at what point the gauges would have shown an issue.

This is also the 145 hp continental.
Click to expand...
Likely would see increasing oil temp and decreasing oil pressure around 2 qts.
 
bnt83 said:
There's isn't much to leak. Oil pressure line. No oil cooler. May not even have an oil filter adapter.
Click to expand...

Famous last words before oil starts leaking out of every crevice.
 
SixPapaCharlie said:
I wonder if I didn't have the oil cap tight enough.
It seemed snug and I took it off and put it back on 3 times during the trip while preflighting.

The flight was 2.4 hours (checked) and the oil was as Terry describes.
It was even on the under side of the horiz. stab.

I double checked w/ the owner and he has 6 hours on it since w/ no issue.

Still curious if anyone has any idea at what point the gauges would have shown an issue.

This is also the 145 hp continental.
Click to expand...

You would start seeing oil temps go up around 2 quarts, at that time you need to reduce power. A loose oil cap will lose a lot of oil.
 
jesse said:
Famous last words before oil starts leaking out of every crevice.
Click to expand...


This ain't oil ebolia


My guess would be filter or crank seal.

Ether way I wouldn't put it in the air till I had it sorted out.
 
SixPapaCharlie said:
I wonder if I didn't have the oil cap tight enough.
It seemed snug and I took it off and put it back on 3 times during the trip while preflighting.

The flight was 2.4 hours (checked) and the oil was as Terry describes.
It was even on the under side of the horiz. stab.

I double checked w/ the owner and he has 6 hours on it since w/ no issue.

Still curious if anyone has any idea at what point the gauges would have shown an issue.

This is also the 145 hp continental.
Click to expand...

Hard to believe.....:rolleyes:
 
SixPapaCharlie said:
The entire inside of the cowl is coated in oil.

I grabbed the dip stick and it felt like it wasn't seated all the way.
Checked and it showed 3 quarts :yikes:


Couple questions.
The dipstick was in place but it is "in" but push harder and it goes in more.
Could a lose dipstick cause 3 quarts of oil to come out?
Click to expand...

I don't believe you did enough to minimize your risk prior to flight based on the info provided.

I seriously doubt there's an o300 out there that hasn't had this happen.

Look at the dipstick. There is a notch in the side and a ramp to it where a spring lock catches it.
 
Last edited:
MAKG1 said:
No oil gallery plugs or crank seals? Really?
Click to expand...

Oil galley pugs ?:rolleyes2:


I watched a guy fly a cardinal in, a nice fine mist of oil on the windshield. Found the crank seal actually spinning with the crankshaft. Not a lot of oil either. Just enough to make a mess.

That was on a 177B with CS prop too.
 
bnt83 said:
Stretching it dude. Everything leaks, even $1m engines do.
Click to expand...

James331 said:
This ain't oil ebolia


My guess would be filter or crank seal.

Ether way I wouldn't put it in the air till I had it sorted out.
Click to expand...

It was a joke related to the "there isn't much to leak" line. There's plenty of places small amounts of oil can leak that are incredibly annoying..and the moment you think you're leak free another one will pop up.

I do agree that there aren't many places 3 quarts of oil could leak out that wouldn't be obvious.
 
jesse said:
It was a joke related to the "there isn't much to leak" line. There's plenty of places small amounts of oil can leak that are incredibly annoying..and the moment you think you're leak free another one will pop up.

I do agree that there aren't many places 3 quarts of oil could leak out that wouldn't be obvious.
Click to expand...

If the cap was on tight......

My money is on a loose oil filter or leaking oil cooler, or oil line...
 
Terry L in KY said:
That was about a $200 lesson. Now that I own, my plane partners constantly complain that every time they fly after me, the damn oil filler knob (same as dipstick in my Cherokee) is tightened too tight. They have a hard time loosening it to check the oil. They can continue to *****.....I won't be bitten by that one again....
Click to expand...

That Cherokee's Lycoming has an entirely different oil cap/dipstick mechanism. It's not the same as Continental's, and overtightening it is a common problem. It doesn't have to be tight to stay put. Period. The O-ring on it should be soft, not hardened by age and heat, and that will contribute enough friction to stop the cap from creeping out. That cap also screws into an extension, usually plastic, that can be damaged by repeated overtightening and can also be pulled loose when someone has to use force to undo it. The extension will back off from its seat in the case, sometimes break the lockwire or at least stretch it, and now you have a leak at that joint. Overtightening gained nothing except added expense and maybe an oil leak. We used to have to keep telling students to not tighten it so much.

The dipstick in the OP's Continental might also be in a metal extension tube held by an Adel clamp at its outer end and a short bit of hose and a couple of clamps at the crankcase. Those clamps can back off, or the hose gets old and worn, and the extension can be pulled out a little way and create a bad oil leak. He might have reseated the extension in the hose when he fooled with the dipstick, but it soon enough could come out again.

Dan
 
Step #1 Deep breath cool off

Step #2 Find cellphone and get someone's attention who knows more than you

Step #3 Text pictures to that person

Step #4 ......
 
I made a oil dipstick mistake early on in my ppl training days. I didn't tighten the dipstick enough. Oil everywhere in the cowl. I was flying with a CFI at the time and no indication of high temp or pressure loss. This was a 2 hour cross country trip. I not sure how much oil was lost. I will never make that mistake again.
 
N801BH said:
If the cap was on tight......

My money is on a loose oil filter or leaking oil cooler, or oil line...
Click to expand...

I'm betting on a loose cap, Occam's razor and all that. Not uncommon in the least.
 
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