Oil Leak 2nd (?) belly pan

[Stefanovm]

I went ouit this moring and saw a six inch oil puddle. It is coming from the area of the second belly pan, see photos. The brakes still work very good and so do the flaps. However, that is the only thing that comes to my mind. I carry a quart of oil in baggage right above the leak area, but it is still intact. The reason I mention this is that it is more of an aeroshell 100w type and color oil than the fluid used for brakes and flaps. Is the wheel retract gear box oil filled? Or is there another idea about the origin. I guess the belly pan will come off in the next hour or so. It is still dark and cold in the hanger.

[Piloto]

This is definitely a fuel leak. It looks like is coming from the wing inboard rib that faces into the fuselage. To further check take the pilot and copilot side panels out. You will see the fuel tank fuel lines and the fuel level transducer. If you are lucky the leak may be just coming from the fuel line hose or the fuel transducer. If not and is coming from the rib itself you will need to open the tank and reseal inside. Beware of possibility of fire hazard if the plane is not ventilated before engine start.

José

 

[DaV8or]

I'm going to assume the OP knows the difference between 100LL and oil and the first picture he posted looks a little more like oil to me than gas, although he definately has/had a fuel leak as well (in addition to a gear up in the past). I would theorize that he may have a major oil leak in the engine compartment and the oil is working it's way back under the first belly skin and then out on the second. Perhaps mixing with gas and making it worse. If it really does seem oily, I would recommend pulling the cheek panels off too and seeing where this leak is coming from. The gear actuator has no oil, it is electric only and the oil for flaps and brakes is usually red I think.

Sadly, I think this bird needs to see a A&P doctor.

[Gone]

Mark:

If your smell detector did not tell you that this was oil when you cleaned it up off the floor, then I tend to agree with the other posters' comments.  From the colour of stain on your belly panel, it looks like avgas.

Good luck with this one.  Hope you find it.

 

[carusoam]

I re-read Jose's post, and I tend to agree.

[1] Its blue.....and it's doing the chromatography trick.  (The color moves as far as it can until it's carrier evaporates)

[2] If it were red it would be flaps and brakes.

[3] Oil can't get to the belly pan in that quantity, without leaving the crank case very empty.

[4] There is probably a significant amount of fuel missing from the tank, it takes a fair amount  of evaporation to leave this much darkness.

[5] Since it is the belly pan area, the wing roots are probably worth taking a look at.  Check the cockpit floor near the wing roots for additional stains.  Things that like to leak in this area are the 40 year old fuel lines and the fuel senders. 

Since this comes as a surprise, the fix might be one of those things mentioned.  The expensive ones are the small leaks that turn into medium leaks that grow and grow over time....

Use caution working with and around fuel leaks.  100LL does not vaporize as easily as gasoline, but it does light up with a simple spark.  There is a picture of a crispy mooney on this board somewhere if you need a serious reminder.

-a-

[Stefanovm]

The fuel is 6 months accumulation as the blue/purple does not come off real easy. There is a recommendation for addressing fuel leaks in the airstream. My A&P says keep an eye on it as it will need addressing, but in the future. He does not believe it is coming from the side of the tank as that has been investigated and side tank leaks require immediate attention.

What was on the concrete floor was deinitely oil, not flap actuator hydraulic fluid. In addition it was very clean. It is still a mystery to me as engine oil running down 15'+ of belly internally with 20 hours on it would be far more discolored, even initially. The puzzling item was I thought that it was dripping from the seam aft of the air device. If it was, it was coming from somewhere other than inside the airplane.

Removal and replacement of the belly skins and inspection plates since my first post was very enlightening for me to watch. Everything appeared to be in good order with no oil or fuel accumulations internally.

Yes, it had a nose gear collapse about 3 years ago before I bought it. There is a long story to that, also. It is also why I have no prop AD with which to deal.

[carusoam]

 

Clean oil on the floor....?

Off the top of my head, the sources I am familiar with:

[1] When filling fresh oil into the fill tube, it is way too easy to miss the target.  Some amount of oil runs through the cowling and down the gear doors and collects on the ground.

[2] The only other source of oil that goes into the cabin is from the oil pressure sensor, but that would leave a huge mess in the cabin, and would be discolored to match what is in the engine.

[3] The least probable would be from the "whiskey" compass.  It is filled with kerosene and would have emptied itself completely.  It smells strongly of kerosene.

[4] The last thing I can think of... Check the seal on the spare bottle of oil that was in the back that may have spilled?  The plastic bottle/induction seal that they are made of probably don't stay sealed in the low pressure environment that 10,000' msl creates.  The rug must have some tell tale signs.

best regards,

[Hank]

Quote: carusoam

Clean oil on the floor....?

Off the top of my head, the sources I am familiar with:

[4] The last thing I can think of... Check the seal on the spare bottle of oil that was in the back that may have spilled?  The plastic bottle/induction seal that they are made of probably don't stay sealed in the low pressure environment that 10,000' msl creates. 

[Stefanovm]

Thanks for the suggestions.

[1] I have done this several times. If it were closer to the engine compartment, it would be my best answer. It is possibly this, but I cannot imagine how it happeend as oil has not been added in a week. I flew it since then, did not push back through it, or run through it coming back into the hanger. What a delayed reaction if this is it.

[2] Agree. No mess and still too far away.

[3] Vertical card, too much oil, over carpet not showing signs, wrong viscosity, and still too far away

[4] This was my first guess, but no easily visible carpet mess. Also I keep the baggage area bottle in a plastic tray, so it would catch most, if not all, of it. However, my wife suggested a lost bottle under the pasenger seat, which is the best guess location wise. I still need to look there and check the carpet. Maybe I did lose a quart under the seat, but it has not spread horizontally from underneath the seats. This is still the most likely possibility. Carpet damage would be a small price for the wondering that I have done for the last few days.

[Piloto]

The stain on the ground looks like a mix of oil and fuel. This is not rare since the inside of the belly panels is commonly coated with engine oil. If the nose wheel doors are clean you don't have an oil leak to worry about.

José

 

[Stefanovm]

Thanks. After the weekend flurry of activity to investigate and this forum, I am starting to feel a bit less concerned. By the way, when I dipped finger into puddle and smelled, there was no fuel smell at all. Not a scientific test, but that with no dye color leads me to beleive very little if any fuel in it. However, I appreciate the different insight and can believe it. Oil use is 5 to 8 eight hours per quart, so not much from the engine to confirm a major leak. The inside of the inspection plates and pans were completely cleaned to compare at the next opening during the upcoming 2011 annual. Most of what was cleaned produced a much darker residue.

[DaV8or]

Quote: Stefanovm

Thanks. After the weekend flurry of activity to investigate and this forum, I am starting to feel a bit less concerned. By the way, when I dipped finger into puddle and smelled, there was no fuel smell at all. Not a scientific test, but that with no dye color leads me to beleive very little if any fuel in it. However, I appreciate the different insight and can believe it. Oil use is 5 to 8 eight hours per quart, so not much from the engine to confirm a major leak. The inside of the inspection plates and pans were completely cleaned to compare at the next opening during the upcoming 2011 annual. Most of what was cleaned produced a much darker residue.

[Stefanovm]

That is the plan now. They were all cleaned. Probably Thursday for test flight. Maybe reinspect that day.

It only took 3 ounces of AS 100W to duplicate what was on the floor. AS 100W is what I use and appears to match what was on the floor closest.

[DaV8or]

Did you ever look under the back seat for a lost bottle of oil?

[mjc]

Another possibility might be oil from the filter. Did you change the oil recently? If so, did a bunch spill down the firewall? If not, have you checked around the filter for leaks recently? As you noticed, even a little oil makes a very big mess, and if the airplane sits for a while in the cold, it'll be a a while before the oil makes it down the firewall and either drips out on the nosewheel or makes its way into the belly panels.

[Stefanovm]

[Stefanovm]

Photo try again. Got it to attach earlier, but when tried to attach a better copy it lost it and I cannot seem to be able to re-attach it. Got it now, I think.