Help with constant prop and oil in the fuel tank

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Corsario

Filing Flight Plan
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Corsario
Hi all,

Recently picked up my Commander 112A from ADSB upgrade and when I wanted to set cruise settings, the prop leveler wont stay and will go forward.
Now, on the preflight, I noticed oil in my left tank fuel sump. Engine fuel sump and right tank sump were clean.
Didnt noticed the issue on runup because when I cycle the prop y dont leave it in any back position as it "cycles"

During the flight I had to keep the leveler in position with my left hand while using my thumb to add/remove power. If I tried to set the prop in cruise, it will slowly return to full possition.
Noticed the same while taxiing after landing as I was trying to understand if it was something while flying or permanent.

Is it possible that the governor has a leak? but how will the oil end up in the fuel tank? Unless it is from somewhere else but only the brake lines are close...

With the engine off, I pulled the leveler and stayed in the position I left it, so definitely it is not any spring.

Any clue?

Thank you!
 
Looks like oil, in the sump probe it stay at the bottom the fuel (like water), it has the color of oil and when slowly dumped in the floor, these bubbles looks like oil and the sump probe now looks like someone poured oil on it.
The brake fluid will be red and having the problem with the prop leveler (which also uses oil) is what tells me something is related, at least in my logic.
 
Someone more experienced than I will come along but in my opinion, oil would be held in suspension in the fuel and not separate to the bottom of the sump.

I have no idea how the two would mix unless oil was deliberately added to the tank

contaminated fuel is a question as well
 
Thank you, now trying to understand what the technician did to cause that. It had no problem when flying from Ohio to Florida and then to the shop to add the ADSB
 
Timbeck2 said:
Someone more experienced than I will come along but in my opinion, oil would be held in suspension in the fuel and not separate to the bottom of the sump.

I have no idea how the two would mix unless oil was deliberately added to the tank

contaminated fuel is a question as well
Click to expand...
This is correct. Oil and gasoline are miscible. Once upon a time, people used gasoline to remove grease and oil from parts. You have dirty water in your gasoline tanks.
 
why I think it is not water?
I drained the "dirty water" on the preflight, so when I dumpled fuel, it was coming out fuel only. After the flight, did the same and the sump had "dirty water" again. Also the sump probe looks oily now.
 
Tomorrow I will do the same, sump fuel until clean, taxi the plane, run-up, check for the prop to feather, then check the fuel sump again
 
As 455BU said, you have two separate issues. Cycling the prop won’t fix your fuel issue.
 
not looking to fix it but looking to troubleshoot and use logic:

Tonight I cleaned the fuel drain, then tomorrow:
if-> fuel drain clean then it is because happen during operation, if dirty, then it is something dumping that thing in the tank.
If-> fuel drain clear then cycle prop, check fuel drain
If-> fuel drain dirty then clean, retry without cycling the props, checl fuel drain
if-> fuel drain dirty then is not prop related but engine operation related
 
Okay, will run the test to make sure.

About the prop leveler not staying back? what do you think? Governor?
 
Jet fuel and/or water in the fuel system? Possible your shop messed up the prop cable during transponder install.
 
Last edited:
Prop problem first check should be to see if the friction lock for the control has been backed off and allowing complete freedom of movement. Found a few throttles where that had happened.
 
When you say the prop is “not staying back” do you mean rpms increase, but the knob is in the same place, or is the knob moving and rpms?

water in a tank might reappear any time you shake the aircraft. Starting the engine shakes the aircraft. Sometimes you can simulate this by rocking the plane as much as you can from outside. It is almost impossible for the prop governor to put something into your fuel tank.
 
Clip4 said:
Jet fuel and/or water in the fuel system? Possible your shop messed up the prop cable during transponder install.
Click to expand...

Jet Fuel could be, before noticing it, I asked to top off the tanks... would be some st*** operator putting Jet Fuel on a Commander 112A but wouldnt be the first time. My concern is, because I drained all the "dirty water" from the sump, after the flight, there was more of it. Was thinking maybe the hydraulic flud is getting in the tank? But in that case the landing gear wont operate.
About the cable, do you think if they messed up the cable, while the engine is off, the leveler will have the same problem? because in that case, if the engine is not operating the leveler can stay in the position I set
 
Salty said:
When you say the prop is “not staying back” do you mean rpms increase, but the knob is in the same place, or is the knob moving and rpms?

water in a tank might reappear any time you shake the aircraft. Starting the engine shakes the aircraft. Sometimes you can simulate this by rocking the plane as much as you can from outside. It is almost impossible for the prop governor to put something into your fuel tank.
Click to expand...

What I meant with the prop control not staying back is that:

During engine operation. I pull the control back (decreases RPM) as soon as I release the control, it will slowly move to the forward possition and increasing RPM.
Seems the cable is fine as RPM increase/decrease when I operate the control, but the control will not stay in the position rather than full forward.

While flying RPM was all the time in 2500 because of it, so I had to hold the control with my left hand on a lower setting to allow RPM to drop to 2,000 as soon as I removed my hand from the control it will move forward and increase RPMs
 
Corsario said:
What I meant with the prop control not staying back is that:

During engine operation. I pull the control back (decreases RPM) as soon as I release the control, it will slowly move to the forward possition and increasing RPM.
Seems the cable is fine as RPM increase/decrease when I operate the control, but the control will not stay in the position rather than full forward.

While flying RPM was all the time in 2500 because of it, so I had to hold the control with my left hand on a lower setting to allow RPM to drop to 2,000 as soon as I removed my hand from the control it will move forward and increase RPMs
Click to expand...
If it’s not a vernier control, then perhaps you just need to tighten the friction lock.
 
Look at the governor arm and make sure nothing is putting pressure on it or interfering with its travel. Give a look to the cable behind the panel. It wouldn’t surprise me if the radio guy pushed the cable behind another to keep it out of the way. To the fuel thing? Add isopropyl to clear the water. One 12oz jug per 10 gallons of avgas.
 
Thank you everybody for the replies and good ideas to check
 
Salty said:
If it’s not a vernier control, then perhaps you just need to tighten the friction lock.
Click to expand...
Dont know the type of control it is but this weekend I will check the control friction lock.
 
Corsario said:
Dont know the type of control it is but this weekend I will check the control friction lock.
Click to expand...
If you can spin it left and right to make fine adjustments, then it's a vernier, if you can only pull and push on it then it's not a vernier. Most prop controls are vernier. I guess some verniers also have a friction lock so either way you should find out if it does.
 
Salty said:
If you can spin it left and right to make fine adjustments, then it's a vernier, if you can only pull and push on it then it's not a vernier. Most prop controls are vernier. I guess some verniers also have a friction lock so either way you should find out if it does.
Click to expand...

Then not venier control, it moves forward/backward like the image

5kjFQDwvg_HSgCzhQ9yFilRTJW6FqZbcnAAymXfBqlCDG8nsSmiUgJr56IhpMd51TV_wdz4mjTZeaZ23sr0HjlXH4FxgVDfkejI5_RfkB_Q
 
Clip4 said:
Jet fuel and/or water in the fuel system? Possible your shop messed up the prop cable during transponder install.
Click to expand...
Corsario said:
Jet Fuel could be, before noticing it, I asked to top off the tanks... would be some st*** operator putting Jet Fuel on a Commander 112A but wouldnt be the first time. My concern is, because I drained all the "dirty water" from the sump, after the flight, there was more of it. Was thinking maybe the hydraulic flud is getting in the tank? But in that case the landing gear wont operate.
About the cable, do you think if they messed up the cable, while the engine is off, the leveler will have the same problem? because in that case, if the engine is not operating the leveler can stay in the position I set
Click to expand...
Jet fuel is miscible in gasoline, too. It's just another hydrocarbon.

Cessna lost a lawsuit because a single drain apparently didn't allow all the water to be drained from a tank.
Moving the plan can dislodge water:
https://www.aopa.org/training-and-safety/students/presolo/skills/checking-fuel-samples
https://generalaviationnews.com/201...on-water-contamination-and-cessna-fuel-tanks/

Stewartb said:
Look at the governor arm and make sure nothing is putting pressure on it or interfering with its travel. Give a look to the cable behind the panel. It wouldn’t surprise me if the radio guy pushed the cable behind another to keep it out of the way. To the fuel thing? Add isopropyl to clear the water. One 12oz jug per 10 gallons of avgas.
Click to expand...
I'd prefer to drain the water. Some "isopropanol" is 70% water.

As for the prop issue, I'm not commenting as I don't know much about those systems; I do know they are separate from the fuel system.
 
Corsario said:
Then not venier control, it moves forward/backward like the image

5kjFQDwvg_HSgCzhQ9yFilRTJW6FqZbcnAAymXfBqlCDG8nsSmiUgJr56IhpMd51TV_wdz4mjTZeaZ23sr0HjlXH4FxgVDfkejI5_RfkB_Q
Click to expand...
ah, that type will have a friction lock. Learn how to use it.
 
Salty said:
ah, that type will have a friction lock. Learn how to use it.
Click to expand...

I checked the manual, should be on the right. But if that is the problem, shouldnt affect the mix and throttle too?
 
Corsario said:
I checked the manual, should be on the right. But if that is the problem, shouldnt affect the mix and throttle too?
Click to expand...
Each one should have it's own adjustment for friction I would think, but I don't know that plane. Maybe the prop control just needs a little more friction than the others. At any rate, the operation of the friction locks on that aircraft is something you should fully understand before flying it.
 
There is 1 friction control and was disengaged, moved it to half way forward and the controls are better now. Thanks!.
As per the dirt in the tanks there was just 2 or 3 drops of that red/brownish thing. I will flush the entire tank but first will use a probe with a camera and see if there is something going on inside the tank
 
I am surprised your instructor did not teach you about friction locks. Always check them after maintenance, mechanics like to loosen them. As far as the crud in your tank inspect/replace the seal on the fuel caps.
 
Corsario said:
There is 1 friction control and was disengaged, moved it to half way forward and the controls are better now. Thanks!.
As per the dirt in the tanks there was just 2 or 3 drops of that red/brownish thing. I will flush the entire tank but first will use a probe with a camera and see if there is something going on inside the tank
Click to expand...

I have seen a kind of red/brownish fungus like material from tanks that have sat for a long time. I usually keep draining samples till clear but some will usually show up a bit the next flight. Seems to takes quite a while (number of fill ups) to flush all of that out. Been a number of years since I have seen this, and may be bit more likely in planes that use Mogas. I dont’ recall ever seeing it come from the Gascolator only from the tank drains. Mechanics have always just told me to keep flushing it till clear and it will eventually go away, but have never had anyone explain to me exactly what it is.

Brian
 
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