Oil Reservoir flooded with fuel?

[Animosity2k]

So I spoke with Arian and Roger about this yesterday and wondered if anyone else has experienced this. I have a 2014 CTLSi. I had an annual done in November, and flew maybe 10-15 hours after. I haven't taken the plane out or ran it since probably December. Yesterday I went to the Airport to go fly for the first time in forever. When I opened the door to the oil reservoir and took the dip stick out and laid it on a paper towel the oil level seemed fine and the oil was a nice brand new amber color. I burped the prop and walked back over to the side to take a measurement with the dipstick and to my surprise oil was flowing out of the canister, into my cowling, down my muffler and dripping all over my front tire fairing. Looking inside the reservoir with a flashlight revealed the oil level is literally 1" from the top of the reservoir. I know my AP didn't overfill the oil during the annual as I had flown several times after and never had this problem occur. 

Arian said he hasn't heard of this before given it's fuel injected but said that it's possible that over 6 months I had a very small amount of fuel leaking through the injectors that would have been pushed into the oil reservoir when I burped the prop. Roger also said that would make sense. I can assure you from here out I'll be shutting off my fuel every time I exit the plane. 

The remedy I have gone over with Roger is to drain my oil take maybe 6 oz. Put the drain plug back in, burp the prop a ton of times forcing whatever oil/fuel mixture I still have in the crank out back into the oil reservoir. Drain the reservoir completely, and do a fresh oil change. I plan to do this tomorrow morning and hopefully fly tomorrow. Has anyone else ever ran into this? I use 100LL. 

[Jim Meade]

When you say oil is flowing from the canister, do you mean the oil tank?  And by reservoir do you mean oil tank?  I just want to be sure I understand what you are describing.

Out of curiosity, how do you explain that at one point oil was flowing out of the top opening of the tank and later the oil level in the tank was 1 inch below the opening?  Do you have some thoughts on where the missing oil went - back down into the crankcase?

What is the reason for draining only part of the oil, swinging the prop, and then draining?  Do you expect that you need some oil in the tank so you develop the gurgling sound we associate with the oil being pumped out of the crankcase?  Otherwise, I'd think you could drain it all and swing the prop till you got no more oil draining.

As you can see, I am uncertain that I really understand your situation so if I made an inappropriate observation just correct me.

If I were in your shoes, I would absolutely call Brett Lawton of Leading Edge Air Foils in Wisconsin.  In my experience with Brett, he is a very competent Rotax engine mechanic who is highly trained and works at one of the Rotax repair stations in the US.

Good luck with your endeavors and please keep us posted.

[FlyingMonkey]

Do you smell fuel in the oil?  If yes then Arian's guess sounds plausible.  If not...maybe keep looking.

[Animosity2k]

8 hours ago, Jim Meade said:

When you say oil is flowing from the canister, do you mean the oil tank?  And by reservoir do you mean oil tank?  I just want to be sure I understand what you are describing.

Out of curiosity, how do you explain that at one point oil was flowing out of the top opening of the tank and later the oil level in the tank was 1 inch below the opening?  Do you have some thoughts on where the missing oil went - back down into the crankcase?

What is the reason for draining only part of the oil, swinging the prop, and then draining?  Do you expect that you need some oil in the tank so you develop the gurgling sound we associate with the oil being pumped out of the crankcase?  Otherwise, I'd think you could drain it all and swing the prop till you got no more oil draining.

As you can see, I am uncertain that I really understand your situation so if I made an inappropriate observation just correct me.

If I were in your shoes, I would absolutely call Brett Lawton of Leading Edge Air Foils in Wisconsin.  In my experience with Brett, he is a very competent Rotax engine mechanic who is highly trained and works at one of the Rotax repair stations in the US.

Good luck with your endeavors and please keep us posted.

yes I mean the oil tank. As to where the missing oil went causing it to recede back slightly below the opening ,  simple all over the ground and the cowling. 

the reason behind draining some before burping it again is simply so it doesn’t again overflow and cause a mess. Why not drain it entirely then burp it all out? I was told if you burp the empty oil tank it will suck air into the system and to never burp it empty. 

 

[Animosity2k]

3 hours ago, FlyingMonkey said:

Do you smell fuel in the oil?  If yes then Arian's guess sounds plausible.  If not...maybe keep looking.

No but I use 100LL and there’s not really a smell 

[FredG]

If the propeller is rotated with an empty oil tank air can enter the oil system.  If that happens then a purge of the oil system should be done.  

[Anticept]

I have only seen this happen with the carburated engine, never the injected one.

[Animosity2k]

5 hours ago, Anticept said:

I have only seen this happen with the carburated engine, never the injected one.

exactly what Arian said. I’m going to do a  complete oil change here in a few hours and see

[Anticept]

I am in my heavy renewal class right now and asked.

There was another flight design a while ago that had the same issue. The fuel pressure regulator went bad, and started allowing fuel into the manifold line, working its way into the intake and down through the oil system.

See attached.

[Animosity2k]

35 minutes ago, Anticept said:

I am in my heavy renewal class right now and asked.

There was another flight design a while ago that had the same issue. The fuel pressure regulator went bad, and started allowing fuel into the manifold line, working its way into the intake and down through the oil system.

See attached.

I'm not entirely sure it's fuel at this point. I drained a little out of the oil tank yesterday and then burped the prop 20 times to push whatever was in the lines and crank out back into the container. I then did a full oil change, burped the prop a few times and now have clean oil, at the right level and am getting 55pounds of pressure while running. 

I still chose to not fly after the oil change as I noticed I had two tires that were dry rotting so I ordered some from Desser and will hopefully fly next week some point to make sure everything is ok. I'll plan to keep an eye on the oil level and color every flight.

With Regard to what you had said Corey about the fuel regulator going bad and brining fuel into the oil.  Would that cause the oil to have some milky white color to it? I figured that would be indicative more of water / coolant then fuel. See the attached photo: 

[Anticept]

Milky color is either moisture that got into the oil, or you have coolant leaking somewhere and getting into the coolant. Either way, it's water that makes it look funky.

It's common to see a weird white cakey wet paste on the underside of the lid of the oil reservoir after shut down on a moist day and coming back the next day: the engine is cooling, and barometric breathing brings in that moist air across the cap.

Also, if you are not getting your engine to running temperature of 190F or higher for 10 minutes or more, then it cannot drive moisture from the oil very effectively. This is a serious issue and said moisture will compromise the oil and rust parts internally over time.

Re: dry rotting tires. Tire checking (the small cracks in the surface of the tires) is fine as long as you do not see cord or one long check. The cord is what provides structure to the tire, the rubber provides a buffer so that the cord is not damaged. Goodyear has a section on what is acceptable and what isn't. https://www.goodyearaviation.com/resources/pdf/aviation-tire-care-2020.pdf

[Roger Lee]

We’re thinking coolant right now and not fuel because of the milky color. He changed the oil so now he’s going to keep an eye on it every few hours.

[cdarza]

7 hours ago, Anticept said:

Re: dry rotting tires. Tire checking (the small cracks in the surface of the tires) is fine as long as you do not see cord or one long check. The cord is what provides structure to the tire, the rubber provides a buffer so that the cord is not damaged. Goodyear has a section on what is acceptable and what isn't. https://www.goodyearaviation.com/resources/pdf/aviation-tire-care-2020.pdf

Thanks for this - i noticed small cracks on my tires but overall they are still relatively new and not worn.  This info helps that i may not need to change them as early as i thought. 

[Roger Lee]

Howdy Cory,

if you have dry rotting tires you have no idea what is going on under the rubber and what condition the cord is in. They may be dry, weak and rotting too, but you can’t see it. In the Southwest US when you see dry rot on tires it usually means a weak tire that even the pressure could cause a failure so we change them out here and it’s what the tire Mfg’s recommend. We see many blowouts here on the roads and many of those have cracking. For what’s at stake for making the wrong choice and the expensive consequences it’s far better to error on the good side. No use rolling the dice and losing.

[Anticept]

That's not what the tire manufacturers say Roger.

The dry rot is callen oxygen checking, and the name reflects what is happening: oxygen and UV radiation are breaking the bonds in the **surface** of the tire.

It's a thing that's been understood for decades, and people freak out about it on cars for good reason due to the thinner radial ply design being much weaker in the sidewalls and the rubber being a critical part of the structure. Aircraft tires are an overbuilt bias ply and work very, very differently in how the plys are bonded together and carry the loads. Dry rotting is only a surface condition, flat out period.

I had linked the goodyear tire maintenance and care guide because it goes over this, and it applies to tires on all aircraft, small and big, civil and military, because there are tire standards at minimum that all manufacturers have to comply with. It also details when there are limits to the checks.

If there's a problem with the cord underneath the rubber to the point of being an actual problem, it will manifest in something a lot more noticeable than a little bit of cracking at the surface.

We don't use bias ply tires on cars because they aren't as smooth of a ride.

Sorry, am a bit passionate on this one, its an argument that people keep having with me when they don't understand how bias ply works. These cords are EXTREMELY strong and rigid, and are designed to support the loads without any rubber on the outside at all. Some tires even prescribe how much cord you can wear through before replacement is required, and it's funny seeing fighter jets with what look like cotton balls stuck to their landing gear.

Replacing a tire because it looks dry rotted isn't even a conservative safety margin, it's just straight up replacing a tire for no good reason at all. If there are problems with the cord, you will see more than just oxygen checking.

Edit: michelin's tire care guide says the same thing. https://aircraft.michelin.com/wp-content/uploads/sites/15/2018/01/2016_CSM_Print.pdf

[Roger Lee]

Ozone also does it and constant exposure to dry heat like in the Southwest. Dry rot causes weakening of the tire. Tires aren’t like that right away. It usually takes years and in the southwest US you see these many times with blowout’s. Out here people don’t drive on those tires especially on trailers. It is a sign of deterioration and there is no way to determine how bad it is under the rubber. Why gamble.
I have articles too.

https://palmbeachgarage.com/tire-dry-rot/

https://www.wetrytires.com/tire-dry-rot/

https://worldtirereview.com/tire-dry-rot/

[Anticept]

Those are car tires, I am specifically talking about aircraft tires (distinction was made above) which are built differently, and don't suffer the same way.

Car tire sidewalls are, as mentioned, much thinner and weaker. Plus, they are at high speed for a long time, giving lots of time to heat up.

Aircraft tires are only briefly and very suddenly turned, hence a big reason for their bias ply, stronger wheel beads, and because of the biased ply, all of the mesh has to also cross the sidewall overlapping.

The two just arent comparable, you can literally run an aircraft tire without a rubber case on it (not for long but it will work).

[Roger Lee]

Car tires and aircraft tires use the same tire technology in manufacturing. Dry rot is dry rot on either. Aircraft tires aren’t anything magical over car tires. 

Your choice is pay $250 - $500 when this happens  for tires and tubes or pay big bucks if you’re wrong and you’re stranded with a flat or trashed wheel pant or plane.

The first is cheaper and easier. 

[Animosity2k]

I wasn't trying to start any arguments.  I ordered tires & tubes when I saw the cracking. 

[KentWien]

Survey:

 

Anyone blow a tire on a CT that WASN’T caused by spinning the under-inflated tire and breaking the stem?

That’s the usual culprit in tire failure on a CT. Keep the tires inflated. 
 

Mike Busch addressed tire checking on the “Ask the A&Ps” podcast. I checked with two other mechanics I know. All said it was fine.  Doesn’t look very pretty, so for that reason I’d change it at the next annual for cosmetic reasons. 

[Anticept]

1 hour ago, Roger Lee said:

Car tires and aircraft tires use the same tire technology in manufacturing. Dry rot is dry rot on either. Aircraft tires aren’t anything magical over car tires. 

Your choice is pay $250 - $500 when this happens  for tires and tubes or pay big bucks if you’re wrong and you’re stranded with a flat or trashed wheel pant or plane.

The first is cheaper and easier. 

They are different roger, and not by a small amount. This is why I get passionate about it, because people in the field are getting this *incredibly* wrong.

I've been in classes where we compared the differences and went over the technology that goes into aircraft tires. Very little is the same. They are *purpose built* to withstand a lot of damage and still continue to be used, it's absolutely insane. For example, kevlar is used for some of the plies. The rubber is not the same chemistry either, they use different rubbers and additives. The construction is radically different. This is also why retreads are so possible on aircraft tires while road tires have problems.

The amount of actual cord failure that can occur before the tire is even at risk is insane too, as outlined in the two aircraft tire documents I provided.

Just about the only thing in common between aircraft and car tires is they both touch the ground. To say aircraft and car tires are similar is like saying a lycoming is the same thing as a rotax.

The chance of a tire failing because of oxygen checking is effectively zero, and any damage to the actual cord of the tire will manifest in more than just a dry rotted look.

Now granted, I don't mind if someone likes to be extra conservative anyways. That I will give you a thumbsup on. But please don't tell people they're the same as car tires.

[Roger Lee]

Numerous articles from aircraft Mfg’s and credited experts on the internet say if the checking goes down to the cords it should be replaced. They all said if it was more superficial and you could not see the cords then at that time it was okay.

[Anticept]

I agree, if it goes to cord, replace it. That's also covered in the documentation that I linked.

But don't throw it out just because you see cracking in the rubber, take a moment to investigate. I keep the tire guides handy because they have great pictures to use. Here's some pictures from said tire guides, which points out they are acceptable, yet I have had people insist that the tire needs replacing:

 

Both of these are perfectly fine, unless the cracks go to cord, or it starts crossing under tread (cracks that go under tread make it possible for a large part of rubber separation during a high stress event).

Please don't misunderstand, I don't intend to convey that people should ignore when cord is showing; just that it's insane how much tires are built up that they COULD run on cord for a limited time... meanwhile a dry rotted look on the outside of a tire is so far within acceptable limits, assuming no other irregularity in the tire, that it's a non issue, you can continue to use it.

Goodyear notice on cord exposure:

Quote

Return to Base Limits
In order to return to a maintenance base, Goodyear tires can remain in service with top ply cord visible, but only as long as the cord is not worn through or exposed for more than 1/8 of the circumference of the tire or not more than 1 inch wide at the fastest wearing location. Tires within these limits can continue in service no longer than necessary to return to a maintenance base and be replaced. (This applies to the proper tires for the aircraft as specified in its aircraft manual.) For all other circumstances, normal removal criteria are still recommended as per the rest of this manual. This does not apply to military tires with Maximum Wear Limits marked on the sidewall.
NOTE: Further use of tires beyond return to base limits may render a tire unsafe or unretreadable.

Here's the Michelin one:

Quote

NORMAL REMOVAL WEAR LIMIT: Remove the tire when the wear
level reaches the bottom of any groove at one point or up to 1/8 of the
circumference (Figure 504)
NOTE: When the NORMAL REMOVAL limit is reached, the tire should be replaced.
If it is necessary to continue the tire in service beyond the normal wear limit,
the tire should be removed either at the next maintenance base or upon reaching
the RETURN TO BASE WEAR LIMIT (Exposed Cord Limit), whichever occurs fi rst.
At the RETURN TO BASE LIMIT(Exposed Cord Limit), the tire should be removed
and replaced. In such a case however, the subject tire might not be
suitable for retreading.
7.4.2 RETURN TO BASE WEAR LIMIT (Exposed Cord Limit): Remove the tire if either the protector
ply (radial) or the reinforcing ply (bias) is exposed at any location over the tread surface (Figure
505). Continued operation of a tire after the top belt plies (radial) or top casing plies (bias) have
been exposed, increases the possibility of chunking of the tread and rib stripping.

Finally: here's a good photo on how an aircraft tire is built. There's a reason that quite a bit of rubber damage is acceptable. (pictured is an airline tire which has more buildup than a GA tire, but the concept is the same, there's several layers).

 

Meanwhile, your car tire looks like this:

 

[airhound]

Any inner tube suggestions?

[Towner]

Desser sells a heavy duty tube that has been repeatedly recommended on this site. I have the small tires and ordered these tubes. It seems everyone has said to make sure to buy the heavy duty tubes, not standard. I’ll see if I can find the part number.