Fluid (unburnt oil maybe) dripping from the hull

SixPapaCharlie

SixPapaCharlie

May the force be with you
Joined
Aug 8, 2013
Messages
16,414
Display Name
Display name:
Sixer
I have oil all down the belly of the Cirrus. 100 hours on the major overhaul so we are thinking normal but this is going on along time and it seems to come and go. Lots of conversations about potentially glazed cylinders "We're not running it hard enough" Honestly I can't get the cylinder temps above 360 degrees to save my life so we think something has gone wrong.

I land yesterday and it looks like this (I took off with 7 quarts and landed with 5.5 after an hour flight)20210319_184753.jpg


Today I go to the hangar because I am thinking maybe I didn't tighten the dipstick cap and perhaps it blew out the top.

I take the cowl off and the top is bone dry. There is what appears to be oil on the lower half of the engine mount and a couple doodads. The "oil" does not really smell like burnt oil it is kind of odorless. Stay with me, it gets weird. So there is definitely some oil under the motor bottom half center.

I go back to the empennage and notice something really weird. The front of the belly is got crap on it but the tail half is dripping wet.

Then I spot this:

20210321_143211.jpg


There are little holes in the belly, I presume for water to drain out of if the plane gets wet?

The "oil" appears to be coming OUT OF THESE drain holes.
Like it is oozing out and running down along the fuselage toward the nose (lowest point) and creating that streak.

Why would there be oil in the hull?

It is 100% NOT burned oil based on smell but I think it is oil. I stuck my phone in and its all over the place inside the hull. Little pools and puddles. Everything is coated in it as well.

20210321_143949.jpg

It is light brown and I think it is oil but if so why? How would it get in there?

So there is a LOT of something on the belly. Some portion of it appears to be leaking out of drain holes. There is a bit of fresh-ish oil that has dripped on the motor mount and I see a bit on the fuel pump. I guess some could have have blasted out of the blow by tube if there was too much oil in the engine but it is only wet toward the back. The front has a massive exhaust streak that is more powdery / dry.

My dad did fly the plane through heavy rain last week for a few hours but it never sat in the rain on the ground. Not sure if that is relevant in anyway but we have liquids and he flew through some but this isn't water...

So I think 2 things are going on but I have no idea what I am looking at here.

Any guesses?
 
Send photos to the guy who did the R & R and get his thoughts.

Clean all the oily residue out of the interior and exterior of the aircraft, working back to front to see where the leak is entering the fuselage at. May be somewhere near the oil pressure line and firewall.
 
1.5 quarts in an hour is excessive but since I rent, I don't know how fast it gets launched. It does take time for the oil to drain back into the sump after a flight it seems but that is usually maybe 0.25 to 0.5 quart max. The other thing to watch out for is the dip stick, make sure you have it turned so there is no resistance as it goes into the filler neck. If you feel resistance the stick can "tension up" and give a low reading. I've seen this before. So take a couple readings to make sure this isn't happening. It should slide easily into the engine with barely any resistance. If you get some, pull it back, turn it a little and try again.

That's my experience, worth what you paid for it..
 
I'll do my best to keep your mind off this ooey gooey mess...........

....what's that shmutz on the battery box on the right side? is that like ghostbuster ooozy slime?
 
eman1200 said:
I'll do my best to keep your mind off this ooey gooey mess...........

....what's that shmutz on the battery box on the right side? is that like ghostbuster ooozy slime?
Click to expand...

I don't know I had to open a inspection compartment to even get those photos and it's all right next to that parachute rocket so I really don't like being around that thing.

I'm going to assume it's something critical that needs to be there though
 
That would be a lot of blow by and oil usage. Seems at 100 since overhaul that the breaking in would be done. There is a leak somewhere. Talk to the folks that did the work on it last ...
 
Sure looks like you've got a serious oil leak somewhere. It could be coming out the breather but if so, that's a real serious problem.

If oil is leaking somewhere and sprays / spashes on the firewall, depending on how the fuselage skins are seamed and what the static pressure is inside the fuselage relative to the pressure inside the cowling, the oil could well get sucked inside, where it could run down to the back where it runs back out the drain holes.

Clean everything, make a short flight or ground run, and see where the oil first reappears.

Bad case seal, pushrod tube seal, crank seal, oil cooler hose fittings, lotsa places it could be coming from. Lotsa places it could be coming from, some more expensive than others.. hope it's still in the warranty period.
 
Not the same plane, but the SR-20 that I used to fly would get rid of anything above 6 quarts. And by get rid of, I mean it would puke it all over the inside of the engine compartment.
 
1.5 quarts in 60 minutes suggests a leak, not engine consumption. Pulling and inspecting the plugs would confirm it, if there's any doubt.

But the amount of oil you have sloshing around in the bilge suggests something unusual, perhaps a leak on the cabin side of the firewall.

Are there any oil lines that penetrate the firewall, such as the line to a bourdon tube oil pressure gauge? Also, many Hobbs meters use an oil pressure switch and I've seen those on the back side of the firewall behind the panel, usually on a tee off the oil pressure gauge line.
 
Last edited:
bflynn said:
Not the same plane, but the SR-20 that I used to fly would get rid of anything above 6 quarts. And by get rid of, I mean it would puke it all over the inside of the engine compartment.
Click to expand...

Yeah, the 22s do the same, but I've never seen one come back with that much oil on the bottom after 1.5 hours. Of course the place I rent from wipes the bottoms pretty much every day.
 
Pardon if this is silly... I only just quickly skimmed the thread so maybe I missed something....could there have been a spare bottle of oil in the baggage compartment that leaked back there?
 
Drain holes obviously aren’t working. Bore them out so it drains from the belly faster.
 
Clean up the mess and confirm it is motor oil or determine what else it might be. I am not familiar with Cirrus, but oil in the tail cone seems a bit strange. If you are leaking that much oil in the engine compartment, it should not be difficult to find..oil filter seal, oil line, etc.
 
Clean and remove all oil residue. Then fly for a bit, then check. Could well be crankcase vent.
 
Advice from a guy who has chased down lots of oil leaks on airplanes. Clean all the oil up. Every last drop. Then add a UV die to the oil, run it for about 5 minutes, and inspect with a UV light. If you don’t see anything, add more time. You’ll find the leak quickly. You can pickup the die and UV light at any auto parts store.

Personally I would ignore the advice to clean it and fly it. Flying an engine with an unknown massive oil leak when you don’t have to is a great way to earn an NTSB report. This can and should be diagnosed and fixed on the ground.
 
Lemme axe you this....at some point after your last oil change did you find an empty quart of oil bouncing around the engine compartment?
 
jesse said:
Advice from a guy who has chased down lots of oil leaks on airplanes. Clean all the oil up. Every last drop. Then add a UV die to the oil, run it for about 5 minutes, and inspect with a UV light. If you don’t see anything, add more time. You’ll find the leak quickly. You can pickup the die and UV light at any auto parts store.

Personally I would ignore the advice to clean it and fly it. Flying an engine with an unknown massive oil leak when you don’t have to is a great way to earn an NTSB report. This can and should be diagnosed and fixed on the ground.
Click to expand...
Yes. Could not say it any better.
 
jesse said:
Personally I would ignore the advice to clean it and fly it. Flying an engine with an unknown massive oil leak when you don’t have to is a great way to earn an NTSB report. This can and should be diagnosed and fixed on the ground.
Click to expand...

I had a much smaller leak a few years ago and it took a bit to find it. I was told that I should just fly the plane as the leak was small and I wasn't losing very much oil. I declined as my reasoning was that I didn't know what the cause was. If I knew it was a leaky rocker cover that would be one thing but not knowing where it was coming from was quite another.

Turns out I had damaged the oil cooler during maintenance and it had a very small crack in it. Had I continued to fly the plane the possibility for the crack to split wide open and cause an engine failure in flight could have been very real. Yes, finding and fixing a severe oil leak is something that should be done on terra firma.
 
This might be helpful, but just saw a cirrus yesterday that had oil all over the bottom of the rudder. Or not helpful.
 
I’ve seen newly overhauled engines leak at the case halves seam. Also, Had an 0200 case crack between the oil journal and crankcase near the main bearing seal. Occurred during a tear down due to a defective main bearing failure at 100hrs since o/h. Oil usage in both instances was similar to yours.
You need a good mechanic give it a good looking over.
Somethings wrong.
 
Have you checked the breather hose/line? Mud Dauber makes a home or some other obstruction there and oil goes everywhere.
 
You may have been on the right track with your dipstick comment. If it is loose or the gasket has gone bed, air flows through the cowling and into the dipstick which can pressurize the crank case. From there, instead of seeing oil on the top of the engine, which you say you did not, you'll see it on the bottom as it will have flown through your vent tube which begins in the filler neck. Check the gasket, tighten the dipstick, clean and take another flight. I had this happen on my 310. Lost about three quarts in an hour, and this ended up being the problem. Another issue can be from the alignment of the rings on the pistons, let's hope this is all it was.
 
We figured it out. My father filled up the oil to seven and a half quarts and he was flying home from North Carolina.

There's a little metal plate behind the firewall on the belly of the plane and the oil coming out of the blow by tube got sucked up into there and so just a tiny puddle of oil was living there.

When we go flying, The air pressure would blow it all over the belly and some of it we get sucked up into those little drain holes and then after we land it would drip back out and run down the belly.

My mechanic literally got a pressure canister full of low-lead and sprayed it up in between the belly and that metal plate to wash it all out and it's been bone dry ever since.
 
SixPapaCharlie said:
We figured it out. My father filled up the oil to seven and a half quarts and he was flying home from North Carolina.

There's a little metal plate behind the firewall on the belly of the plane and the oil coming out of the blow by tube got sucked up into there and so just a tiny puddle of oil was living there.

When we go flying, The air pressure would blow it all over the belly and some of it we get sucked up into those little drain holes and then after we land it would drip back out and run down the belly.

My mechanic literally got a pressure canister full of low-lead and sprayed it up in between the belly and that metal plate to wash it all out and it's been bone dry ever since.
Click to expand...

Musta been a relief it was that easy. Did they reroute the blow by tube a little to keep it from happening again? Had it already moved from it’s original position to cause it to happen in the first place?
 
SixPapaCharlie said:
We figured it out. My father filled up the oil to seven and a half quarts and he was flying home from North Carolina.

There's a little metal plate behind the firewall on the belly of the plane and the oil coming out of the blow by tube got sucked up into there and so just a tiny puddle of oil was living there.

When we go flying, The air pressure would blow it all over the belly and some of it we get sucked up into those little drain holes and then after we land it would drip back out and run down the belly.

My mechanic literally got a pressure canister full of low-lead and sprayed it up in between the belly and that metal plate to wash it all out and it's been bone dry ever since.
Click to expand...

Used to fly a DA40 with an IO360, and for virtually the whole time I owned the aircraft, I missed a service bulletin from Lycoming requiring replacement of the OEM dipstick. The original dipstick underestimated the oil quantity by about a quart. Being a diligent (compulsive) pilot, I kept the oil topped off at the 8 quart max before IFR flights, but could never quite put together why there was so much oil on the belly between 7 and 8 quarts, but virtually none when the level was <7 quarts and I could never find a leak. The new dipstick fixed it.
 
You must log in or register to reply here.
Back
Top