Avgas and Jet A Contamination Results

[overdrive148]

Avgas and Jet A Contamination Test Results (with pics and video)

Okay, so following the news of the Cessna 421 that went down in Las Cruces, NM due to being fueled with Jet A instead of 100LL (link to story here), I decided to do a few tests while sumping tanks at work to see what Jet A and Avgas looked like together.

Conclusions:

Visual test did not show any sign of contamination whatsoever.
You'd think the straw color of the Jet A and the blue color of the 100LL and their different densities would create a clear border and indication of contamination, but as you can see in the sunlight pictures, there's nothing at all. The only thing I detected with the visual test is a very slight lightening of the blue color (with the Jet A addition) and the incredibly clear border (in the water addition).

Smell test detected Jet A, but did not work as well as expected.
I could tell there was something off with the sample immediately, although the smell of Jet A was very subdued. I work around Jet A and Avgas all day at work, I know the smells and the differences pretty well. I'd take a whiff of your regular 100LL and just go by that. If it doesn't smell right, double check.

Feel test detected Jet A, but did not work as well as expected.
The slimy feel of regular Jet A wasn't exactly there, it was more watered down. Based on feel alone, I feel it's a bad test to detect contaminated fuel. However, I did do some tests in the YouTube video below based on evaporation of each fuel (100LL, Jet A, Contaminated) and found that if the fuel isn't gone off your hands in ~30 seconds, you've got Jet A on your hands. Pun semi-intended.

I had to wash my hands twice with soap and hot water after the Jet A test to even get the stuff off, it is very pervasive. The contaminated mixture did not show any sign of beginning to evaporate at 30s (which I believe is a good detector of Jet A contamination). You don't have to use your entire hand like I did, but I wanted it to be obvious on the video (which is at the bottom of this post, after the pics).

The paper test worked flawlessly.
This test requires a blank piece of paper. Put a drop or two of the fuel on your paper. If it evaporates and leaves nothing behind, you're good. If it leaves a halo or a oil spot behind, that's the sign there's Jet A in the fuel. I took the drops from my sample from about a nail's length under the surface of the contaminated fuel and it came up positive (result shown in picture form below). The only thing wrong with this test is that left for a long long time, the spot will be really hard to see. I left the sample in the FBO for like 30 minutes while I did airport stuff and came back and couldn't make out the halo anymore.

That being said, here are the pictures.

Bucket with 100LL only.

Bucket and Bottle with 100LL only.

100LL Bottle against sunlight.

Contaminated 100LL bucket with 50/50 mixture of Jet A. Bottle has 100% 100LL still.

Contaminated bucket and bottle - notice the amount of fluid in the bottle compared to 100LL only in the pic above.

Contaminated 100LL bottle against sunlight. Still has a blue hue with no clear border whatsoever.

Added water to the contaminated bottle. Droplets outside with water inside settling. The clear boundary at the bottom is water.

Contaminated bottle + water in shade for color observation. Still blue with no clear separation except for water in the bottom.

Jet A only bucket.

Jet A only bottle.

White Paper test (envelope). Halo visible on the top right corner of the paper from the contaminated Bottle, fresh 100LL was below but evaporated quickly.

Contaminated Plastic Bottle Test - used this instead of the glass to check for differences.

Plastic Bottle Test from above.

Contaminated Bottle from the side in sunlight. I let this sample sit for about 5 minutes. The horizontal line a few inches from bottom was VERY slightly showing the beginnings of a border, but it was very light.

And last but not least, here's a link to the full-resolution set of pictures for extra zoom and detail for extra scrutiny.

[Link]

If you look at any of them, be sure to take a look at the up close shots of the bottles against sunlight. Hard to believe there's any Jet A in it whatsoever.

As you can see, it's not hard at all to miss the signs of fuel contamination watch the line guys fuel your plane and make sure to really look (and feel and smell) your fuel. Let's learn something from that accident and try to prevent it from happening again

 

[Jim Logajan]

Excellent work.

 

[Hank S]

Would the Jet A mixture show up when either bottle was held up in front of a white panel? I hold mine up a couple of inches from the plane, although it's more cream than white, the blue is always very noticeable. I try to do it in direct sunlight, so the shadow is thrown behind the sample instead of looking toward the sun.

 

[FlyingMonkey]

An internet forum at its best. Well done and thank you so much.

 

[overdrive148]

Would the Jet A mixture show up when either bottle was held up in front of a white panel? I hold mine up a couple of inches from the plane, although it's more cream than white, the blue is always very noticeable. I try to do it in direct sunlight, so the shadow is thrown behind the sample instead of looking toward the sun.

Good question. I didn't have any shade above me to simulate a wing, but I did have a couple pictures (the step on the truck w/plastic bottle) and a bit of video (where I put a wrench behind it for contrast because I couldn't see anything with the white behind in full sunlight).

I can follow up and see if I can replicate that for you I don't work for a few more days though. Do you use a regular old plastic tester?

 

[PaulS]

Nice work, thank you....

 

[Matthew]

I just use a normal fuel tester, nothing quite so large or clear as a glass or plastic bottle.

On the contaminated sample, was the Jet A smell noticeable enough to indicate something was wrong? It sure didn't look contaminated.

Great work, by the way.

 

[overdrive148]

I just use a normal fuel tester, nothing quite so large or clear as a glass or plastic bottle.

On the contaminated sample, was the Jet A smell noticeable enough to indicate something was wrong? It sure didn't look contaminated.

Great work, by the way.

It was enough for me to detect it fairly easily, but it wasn't nearly as strong as regular Jet A. I'm guessing because the Jet A is more dense than the AvGas so the surface was mostly 100LL which blocked out a lot of the smell. That, or the fumes mixed and took the trademark sharp edge off the Jet A.

I think there's enough validity to the smell test to figure out if something is amiss, but if you're really worried, I'd just put some drops on paper and check for halos - the avgas evaporated away in under 30 seconds on my hand, I think about the same time for the paper as well.

It was about 75-80*F outside during the testing and winds were at a moderate clip too. Maybe the mid-range temps had something to do with the densities and fuel mixing? It was in the morning, so the fuel could have been cooled off overnight when I pulled it out of the tank.

It is incredibly worrying that there was no boundary whatsoever with the contaminated fuel, I've thrown out and flown on tests that were less intensive. The mixture was 50/50, halfway up the barrel ending at the neck. I wanted to use a bigger clearer container to show more fuel and hopefully a bigger difference but as you can see, there isn't one.

 

[ja_user]

Thank you for this testing.

 

[schmookeeg]

Dang, nice science. I can't wait to read the flurry of "dude, my bad" for the armchair QB types who roasted the guy for not sumping.

What I learned -- when I fly planes that the uninformed/uninterested/uncaring could mistake for something Jet-A burning, my best tool is one of these:

 

[asechrest]

Ok. I am now taking pre-orders for a new product, available through Sporty's in October of 2014:

Ultra-thin Reusable Aviation Fuel Contamination Tester - $39.95

For a limited time, you can also add the companion product for a discounted price:

Mark XVII Aviation Fuel Dual Aspirator and Applicator - $29.95

PM me if interested.

--

PS - Great work OP!

 

[schmookeeg]

Ok. I am now taking pre-orders for a new product, available through Sporty's in October of 2014:

Ultra-thin Reusable Aviation Fuel Contamination Tester - $39.95

Wahaha

I think you need to roll that paper into a cone shape and call it the GATTS Contamination Tester -- pour sumped fuel back in the tank -- saves fuel waste and helps the environment! (only $69.95 at Sporty's, comes with choice of free gift -- both choices are a Richard Collins video. Opting for neither is not a choice.)

 

[asechrest]

Wahaha

I think you need to roll that paper into a cone shape and call it the GATTS Contamination Tester -- pour sumped fuel back in the tank -- saves fuel waste and helps the environment! (only $69.95 at Sporty's, comes with choice of free gift -- both choices are a Richard Collins video. Opting for neither is not a choice.)

 

[jfrye01]

Ok. I am now taking pre-orders for a new product, available through Sporty's in October of 2014:

Ultra-thin Reusable Aviation Fuel Contamination Tester - $39.95

For a limited time, you can also add the companion product for a discounted price:

Mark XVII Aviation Fuel Dual Aspirator and Applicator - $29.95

PM me if interested.

--

PS - Great work OP!

This made me laugh out loud!

 

[sourdough44]

So if it's hard to find the Jet A in avgas, I guess it's back to monitoring fueling operations?

 

[Jaybird180]

Great stuff. Perhaps its my phone but at first I thought the bucket was blue and I was thinking, "Why did he use a blue bucket on blue AvGas?" Then I saw the bucket in later photos and saw it was light tan.

I think I'll watch the youtube now...

Glad you did this

 

[FlyingMonkey]

Thinking about this in the context of flight school operations, where as a student or renter you frequently show up and the plane has full tanks. You rarely get to monitor the fueling for your flight. Until I get my own plane I am probably going to do the paper test every preflight.

 

[Jaybird180]

So basically, if there is any chance the ground crew could screw up, supervise!

That's my takeaway.

 

[Jaybird180]

Thinking about this in the context of flight school operations, where as a student or renter you frequently show up and the plane has full tanks. You rarely get to monitor the fueling for your flight. Until I get my own plane I am probably going to do the paper test every preflight.

Consider the environment. The two airports I frequent do not have Jet-A so the paper test would be a waste of time and fuel.

 

[jsstevens]

Thanks for doing this. Very good useful stuff.

The flying club I belong to has the fueling done by the FBO who hosts our schedule book and key, etc. I've only supervised the fueling a time or two when somebody has not had the tanks topped off after a flight. This gives me a bit of pause, although in the 10 years I've been flying with them (two clubs, same FBO) I've never heard of any issues with contaminated fuel.

Hmmm.
John

 

[Capt. Geoffrey Thorpe]

So, like, if you dump the sample on the ground and it evaporates right away, it's gasoline...

 

[Matthew]

Is there a trend in contaminated fuel incidents?

Is the larger problem:

1) Ramper simply gets in wrong truck or grabs wrong hose?
2) Ramper thinks aircraft takes the wrong fuel and puts in what he thinks is correct?
3) Fuel in the truck/tank farm is bad? (This would be very bad for a lot of people.)

 

[JeffDG]

I'm speculating, have done no real experimentation or research on this...so this and some cash will get you a coffee.

The lack of visible border actually makes sense. There is the clear border with water. The old story of "oil and water don't mix" is true, in that water will not dissolve oil (or its distillates). That means that they will separate out clearly from each other when they are put into a common container.

The issue is, both Jet-A and 100LL are "oil", and oil does mix with oil. Given enough time the Jet-A might settle out due to being more dense, but I have no idea how long that might take. Then again, they might simply remain together as a combined fluid with an intermediate density...again, no real research or testing done on my part.

 

[JohnF]

Bravo! Science is cool. (said the obviously biased scientist)

Despite the fuel gauge indication, I stick the airplanes I rent just to make sure the fuel gauge is reasonable. The stick in the citabria I rent looks to be mahogany, which may or may not matter. If I doddle the fuel will evaporate before I see the level on the stick.

I bet this test may work with a stick.

 

[Capt. Geoffrey Thorpe]

The issue is, both Jet-A and 100LL are "oil", and oil does mix with oil. Given enough time the Jet-A might settle out due to being more dense, but I have no idea how long that might take. Then again, they might simply remain together as a combined fluid with an intermediate density...again, no real research or testing done on my part.

They are overlapping mixes of hydrocarbons - they won't separate any more than the individual fuels will separate into the various components.

More than you wanted to know here: https://www.cgabusinessdesk.com/document/aviation_tech_review.pdf

 

[Dr. O]

Jaybird - so the semi tanker pulled away 20 minutes before you arrived and the plane was filled up 10 minutes before you arrived and you think there is zero chance of contamination.
We have engines ruined and crashes due to the wrong fuel being put into the airport tank.
Not a high risk, but so are lightning strikes low risk, yet they happen.
Dip a finger, put a drop on the wing and wait 30 seconds - or not (shrug)

 

[overdrive148]

Just remember that this was -made- by a ramp rat :wink2: Not all of us are bad or lazy or don't care. That being said though, I don't care if you stand there and watch me fuel your plane, or you ask if you can do it yourself, or when you walk up to the front desk and you fly a standard 172 and you ask for 100LL specifically. It's all about safety - no offense will be taken. I may even ask you about what fuel you're looking for just to make sure on the way out, "100LL to the tabs right?" and that extra confirmation doesn't bother me in the least. I've heard stories of ramp rats doing stupid things and stories of past employees though, so don't trust me implicitly. If I was in your shoes getting fuel, you can be sure that I'd watch! Heck, if you were concerned about fuel contamination and you were curious if you could have a quick look at a bit of sumped Jet A to have something to go on, I'd probably do that for you too.

Thinking about this in the context of flight school operations, where as a student or renter you frequently show up and the plane has full tanks. You rarely get to monitor the fueling for your flight. Until I get my own plane I am probably going to do the paper test every preflight.

It's scary because when I was learning to fly, all I really knew was look for a clear border because that shows water (and look for particles). Nothing about Jet A or other contamination and I think those are way more dangerous and harder to detect. 30 seconds for added insurance seems like a wise investment to me.

So, like, if you dump the sample on the ground and it evaporates right away, it's gasoline...

That'd work too (I was taught in training to throw samples on the ground) but I've heard more about the EPA frowning about that sort of thing. All the fuel I sump goes into barrels or containers.

Is there a trend in contaminated fuel incidents?

Is the larger problem:

1) Ramper simply gets in wrong truck or grabs wrong hose?
2) Ramper thinks aircraft takes the wrong fuel and puts in what he thinks is correct?
3) Fuel in the truck/tank farm is bad? (This would be very bad for a lot of people.)

As for the first one, the trucks at my airport are different - manual and automatic. Different key locations, different look, different quirks. Kind of helps affirm the fuel types to me. Not all places have that though, so on to nozzles.

This one is the 100LL nozzle, it's alone on the Avgas truck. I used my fingers as a size comparison since I didn't have a measuring tape or anything. Pretty small, fits close to fully into C150/C172/C182 fuel ports. Enough that I have to pull it out part-way or fully to see how much fuel to add in.

This one is on the Jet A truck. Apparently the only reason we have this one is because the police (and maybe the medivac) heli uses it. The diameter is way bigger than the avgas one, and it wouldn't fit into any of the small plane fuel ports. That being said, I've seen some Bonanza's with huge fueling ports that would probably accomodate this and maybe even the duckbill Jet A nozzle too.

And this one is the infamous duckbill nozzle, also Jet A. You can see the big round one in its holder on the left.

Of the 3, #2 is more likely, I almost always ask what kind of fuel a customer wants if it's something other than a 172 or other small common planes. I always always check the labeling around the nozzles which usually says 100 or 100LL. There's a third nozzle on the Jet A truck but it's a single point fuel nozzle and it's huge, heavy, and locks onto a special port so I doubt that'd be ever used for contamination.

I'm speculating, have done no real experimentation or research on this...so this and some cash will get you a coffee.

The lack of visible border actually makes sense. There is the clear border with water. The old story of "oil and water don't mix" is true, in that water will not dissolve oil (or its distillates). That means that they will separate out clearly from each other when they are put into a common container.

The issue is, both Jet-A and 100LL are "oil", and oil does mix with oil. Given enough time the Jet-A might settle out due to being more dense, but I have no idea how long that might take. Then again, they might simply remain together as a combined fluid with an intermediate density...again, no real research or testing done on my part.

I think that it was beginning to settle out after the 5 min plastic bottle test. If you look closely in the videos in the bottle test, you can kind of see movement in the fuel like strands or lines. There was the beginning of a border but it was so weak at the 5 min mark...and besides who waits for 5 minutes for a fuel sample? I might leave one sample out for a while and see if it ever makes a border just for science.

Nice work, beautiful documentation, and your methods ensure reproducibility...impressive. As a chemist, I have used index-of-refraction (light-bending) to characterize liquids. In the laboratory, we use a refractometer...it's about the size and shape of a small microscope (way too much to carry in a flight bag). I know the wine-makers use refractive index to analyze sugar content in fermenting barrels with a much simpler and portable device, though I have no specific knowledge or experience with them. Perhaps someone on this forum has access to a small, portable refractometer and offer a comment on its utility for fuel-testing. I'll try to find published data on Jet-
a and 100 LL refractive indicies to see if they are even useful in this application. Blessings

Ok. I am now taking pre-orders for a new product, available through Sporty's in October of 2014:

Ultra-thin Reusable Aviation Fuel Contamination Tester - $39.95

For a limited time, you can also add the companion product for a discounted price:

Mark XVII Aviation Fuel Dual Aspirator and Applicator - $29.95


PM me if interested.

--

PS - Great work OP!

...both choices are a Richard Collins video. Opting for neither is not a choice.

Double

Bravo! Science is cool. (said the obviously biased scientist)

Despite the fuel gauge indication, I stick the airplanes I rent just to make sure the fuel gauge is reasonable. The stick in the citabria I rent looks to be mahogany, which may or may not matter. If I doddle the fuel will evaporate before I see the level on the stick.

I bet this test may work with a stick.

Now that you mention it, I've refueled the skydiving plane on the airport a million times and he uses a wooden dipstick. I noticed offhand that it dries very quickly and he has to take multiple readings. Not sure what it's made of but that could be a good test alternative to the paper. The only thing I can think of is residue being left behind after a while which wouldn't happen with the clean paper.

They are overlapping mixes of hydrocarbons - they won't separate any more than the individual fuels will separate into the various components.

More than you wanted to know here: https://www.cgabusinessdesk.com/document/aviation_tech_review.pdf

Nice link.

"While immiscible liquids normally separate if they have different densities and/or surface tensions, an emulsion can persist for a long time. The mixture is stabilized by surfactants that congregate at the surface of the droplets, preventing them from coalescing."

 

[Z06_Mir]

Is there a trend in contaminated fuel incidents?

Is the larger problem:

1) Ramper simply gets in wrong truck or grabs wrong hose?
2) Ramper thinks aircraft takes the wrong fuel and puts in what he thinks is correct?
3) Fuel in the truck/tank farm is bad? (This would be very bad for a lot of people.)

Number 2 would be the most likely. Avgas trucks and Jet trucks are really different. Although where I worked for awhile we had a 3,000 gallon 100LL truck that our brand converted from a Jet truck and sold to us. It was awesome! People loved it but often got a lot of "Is that 100LL?? Looks too big and there are two hoses!". Loved that truck. We kept our 100LL truck(s) separate from the Jet trucks and they worked differently, reels were in a different place etc.

Now, let's say you've got a fairly new guy. He's spent most of his early career fueling the airlines because that's where new guys go first where I worked. Suddenly a Conquest comes in.. he says hmmm it has props but it's smaller than a King Air and I swear I just did one like that in Av... That's how an issue starts.

It's not really possible in modern fuel tanks to fill a Jet truck with 100LL or the other way. The connections from the large storage tanks are different.


OP, nice work. I would have thought the smell would be the definitive thing. I think in time Jet would settle more, but we're talking an hour or two. I'm surprised to see one of your nozzles on the Jet truck is the standard round.. None of ours were like that, all were the "Hoover" nozzle. Personally I think all Jet should be single point, life would be so much easier!

 

[Matthew]

When I used to stick our 150, we used a wooden ruler. On hot, windy days it would dry fast enough you couldn't get a reading. We switched to the FuelHawk dip tube so we can verify color and quantity at the same time.

 

[Bob T]

Ok. I am now taking pre-orders for a new product, available through Sporty's in October of 2014:

Ultra-thin Reusable Aviation Fuel Contamination Tester - $39.95

For a limited time, you can also add the companion product for a discounted price:

Mark XVII Aviation Fuel Dual Aspirator and Applicator - $29.95

PM me if interested.

--

PS - Great work OP!

Only $7.95 additional for shipping!

 

[Jim Logajan]

The issue is, both Jet-A and 100LL are "oil", and oil does mix with oil. Given enough time the Jet-A might settle out due to being more dense, but I have no idea how long that might take. Then again, they might simply remain together as a combined fluid with an intermediate density...again, no real research or testing done on my part.

I think that it was beginning to settle out after the 5 min plastic bottle test. If you look closely in the videos in the bottle test, you can kind of see movement in the fuel like strands or lines. There was the beginning of a border but it was so weak at the 5 min mark...and besides who waits for 5 minutes for a fuel sample? I might leave one sample out for a while and see if it ever makes a border just for science.
[...]
"While immiscible liquids normally separate if they have different densities and/or surface tensions, an emulsion can persist for a long time. The mixture is stabilized by surfactants that congregate at the surface of the droplets, preventing them from coalescing."

The solubility question has come up before on PoA - about a year ago. A general rule of solubility of organic compounds, like those in Jet-A and 100LL, are that if they are chemically similar they are therefore miscible, so are not going to "settle out." Relevant quote from Linus Pauling's "General Chemistry" in this older thread: http://www.pilotsofamerica.com/forum/showthread.php?p=1227702#post1227702

 

[petrolero]

Excellent work by the OP! Thank you. *This* has been a very productive and informative thread. Easily one of the best I have seen on this board.

Questions:

1. Would a paper towel work as well as a piece of notebook paper? Seems like the Jet A should still leave behind an oily ring.

2. If I requested it, would a fueler drizzle a little fuel into a clear container for me? Maybe a 2-liter bottle with the bottom cut off. Or something fancier - whatever. Is there some rule requiring you/them to dispense only into fuel tanks or 'approved (red) containers'?

If you are able to run more experiments...

3. Does an unagitated mixture ever form a phase boundary if left to sit? (I think you said you're going to test this anyway)

4. What happens if the fuel mixture is well-agitated as it might be during high-rate fueling? I'm curious to what degree the Jet A is actually soluble in 100LL such that, after a few minutes of agitation as would be typical, it might not ever separate because one fuel dissolved in the other. To my thinking, they are both hydrocarbons and should be soluble or at least partially so in the time it takes to fuel an small airplane.

Comments on the smell test:

The vapor pressure of 100LL is so much higher than Jet A that even at 50-50 volume mix with Jet A at the surface I suspect 100LL would dominate the nostrils because it flashes to vapor so much quicker. Jet A still might be detectable if one knows its smell since it has a very distinctive smell.

General BS:

Most of us have been taught that we can detect misfueling by using color or some kind of phase boundary (which works well with water) or even smell.

Clearly color has been shown to be unreliable and this has been a big eye-opener for me and I intend to add the paper test to my checklist and possibly even have the fueler dispense a small amount of fuel into a clear container before putting it into my tanks.

Undetected misfueling is a frighteningly-plausible accident chain.

Thanks again for the excellent post.

 

[MAKG1]

There are general prohibitions against dispensing fuel into unapproved containers. The glass bottles shown above, if left that way, are otherwise known as Molotov cocktails.

All you need is a strip of notebook or similar paper to dip half into the tank. You don't want to know what's in the truck. You want to know what's in the tanks. The airplane could have been auto-fueled with 10 gal of Jet A when you were away, especially if the airplane is shared and another pilot was trying to be nice.

 

[Clark1961]

2. If I requested it, would a fueler drizzle a little fuel into a clear container for me? Maybe a 2-liter bottle with the bottom cut off. Or something fancier - whatever. Is there some rule requiring you/them to dispense only into fuel tanks or 'approved (red) containers'?

If you are able to run more experiments...

3. Does an unagitated mixture ever form a phase boundary if left to sit? (I think you said you're going to test this anyway)

4. What happens if the fuel mixture is well-agitated as it might be during high-rate fueling? I'm curious to what degree the Jet A is actually soluble in 100LL such that, after a few minutes of agitation as would be typical, it might not ever separate because one fuel dissolved in the other. To my thinking, they are both hydrocarbons and should be soluble or at least partially so in the time it takes to fuel an small airplane.

I agree - good work and nicely presented

Addressing your questions:

2. do not routinely dispense fuel into unapproved containers - the risk is small but it isn't worth it (lots of folks disagree but this is one you don't want to learn the hard way)

3. Avgas and jet fuel are miscible in all proportions

4. Avgas and jet fuel are miscible in all proportions

 

[Geico266]

So if it's hard to find the Jet A in avgas, I guess it's back to monitoring fueling operations?

I never let anyone fuel my airplanes unless I am present.

 

[TulsaWeather]

Great work, and fascinating.

I wonder what effect the cooler blue wavelength of an LED flashlight vs. incandescent flashlight would have?

 

[overdrive148]

Excellent work by the OP! Thank you. *This* has been a very productive and informative thread. Easily one of the best I have seen on this board.

Questions:

1. Would a paper towel work as well as a piece of notebook paper? Seems like the Jet A should still leave behind an oily ring.

2. If I requested it, would a fueler drizzle a little fuel into a clear container for me? Maybe a 2-liter bottle with the bottom cut off. Or something fancier - whatever. Is there some rule requiring you/them to dispense only into fuel tanks or 'approved (red) containers'?

If you are able to run more experiments...

3. Does an unagitated mixture ever form a phase boundary if left to sit? (I think you said you're going to test this anyway)

4. What happens if the fuel mixture is well-agitated as it might be during high-rate fueling? I'm curious to what degree the Jet A is actually soluble in 100LL such that, after a few minutes of agitation as would be typical, it might not ever separate because one fuel dissolved in the other. To my thinking, they are both hydrocarbons and should be soluble or at least partially so in the time it takes to fuel an small airplane.

Comments on the smell test:

The vapor pressure of 100LL is so much higher than Jet A that even at 50-50 volume mix with Jet A at the surface I suspect 100LL would dominate the nostrils because it flashes to vapor so much quicker. Jet A still might be detectable if one knows its smell since it has a very distinctive smell.

General BS:

Most of us have been taught that we can detect misfueling by using color or some kind of phase boundary (which works well with water) or even smell.

Clearly color has been shown to be unreliable and this has been a big eye-opener for me and I intend to add the paper test to my checklist and possibly even have the fueler dispense a small amount of fuel into a clear container before putting it into my tanks.

Undetected misfueling is a frighteningly-plausible accident chain.

Thanks again for the excellent post.

I can give the paper towel a try, sure. As for if a fueler would do that for you, personally I would. But I'm not all fuelers, and the residue left behind with the Jet A is kind of dangerous I think. That being said, you put fuel in your fuel tester all the time, so that might be a better alternative. It'd be the first time anyone asked me to do it

I can test two samples, pour the first and set it, stir the second and set it. I don't know how long to do it for though (I actually DO work most of the time ). Maybe 30 mins? I'd like to do a timelapse if I had the equipment and wasn't afraid of leaving open fuel and my phone for pictures unattended. The vapor thing is probably true concerning flash point. I could still tell it wasn't 100LL though.

I'd probably add the paper test if you smelled anything off (or were just being cautious, 30s isn't that much time off anything). If you wanted some of the gas from the fueler, maybe get some from in your tester. That or pull it out of your wings - if it mixes this well in a bottle, I bet it'd mix that well in your wings.

There are general prohibitions against dispensing fuel into unapproved containers. The glass bottles shown above, if left that way, are otherwise known as Molotov cocktails.

All you need is a strip of notebook or similar paper to dip half into the tank. You don't want to know what's in the truck. You want to know what's in the tanks. The airplane could have been auto-fueled with 10 gal of Jet A when you were away, especially if the airplane is shared and another pilot was trying to be nice.

I'm not actually sure on the rules, I just picked two clear containers to try it with to show the best details. I usually use the bucket but lately I've been looking for something clear that I can see from the side for water contamination.

I agree - good work and nicely presented

Addressing your questions:

2. do not routinely dispense fuel into unapproved containers - the risk is small but it isn't worth it (lots of folks disagree but this is one you don't want to learn the hard way)

3. Avgas and jet fuel are miscible in all proportions

4. Avgas and jet fuel are miscible in all proportions

Just the once for the demonstration of course. As for the miscible part, I guess that's why I saw the stringy looking flow in the youtube plastic bottle test video. I didn't see any of that in the glass bottle test. I was always under the assumption that the two wouldn't mix and that there would be clear boundaries and different colors - kind of a shock that it's so easy to overlook on the visual only test.

 

[Clark1961]

Just the once for the demonstration of course. As for the miscible part, I guess that's why I saw the stringy looking flow in the youtube plastic bottle test video. I didn't see any of that in the glass bottle test. I was always under the assumption that the two wouldn't mix and that there would be clear boundaries and different colors - kind of a shock that it's so easy to overlook on the visual only test.

The sad thing for me is that I believed the jet fuel contaminated avgas will be clear story told by my CFI. I should have known better because I know hydrocarbon chemistry (but know nothing of the die).

Thanks again for sharing the demonstrations and always be careful with fuel - it's easy to get complacent when you work with it every day. I've been told the plastic buckets could be a spark hazard but have not seen the behavior so dunno. It's likely material dependent and I don't know how to tell good material from bad.

 

[petrolero]

There are general prohibitions against dispensing fuel into unapproved containers. The glass bottles shown above, if left that way, are otherwise known as Molotov cocktails.

All you need is a strip of notebook or similar paper to dip half into the tank. You don't want to know what's in the truck. You want to know what's in the tanks. The airplane could have been auto-fueled with 10 gal of Jet A when you were away, especially if the airplane is shared and another pilot was trying to be nice.

Well I agree you also want to check the tank too, especially if your airplane is operated by multiple people.

But I am imagining standing there waiting for the aircraft to be fueled. I certainly want to know what is about to go into my tank off the truck, especially when I am at an unfamiliar field. At my field I know the 100LL truck but either way I could still check to be 100% sure. Hence the idea of dispensing a little into a jar or some other clear container before it hits my tank. Dropper a little on paper if you see anything weird. If it passes muster then I dump the jar into my tank.

My airplane is owned and flown only by me, but I see no reason not to do the paper test every time I stick the sumps because it is so easy to do.

 

[Kiddo's Driver]

Well, it looks like specific gravity won't help much.
100LL is .68-.74 (@60F)
Jet A is .82 (@60F)

About the only way it would work would be to sample your tank before adding fuel and sample what comes out of the pump before it goes in the tank.

It would be easier to just fuel the plane yourself.

Jim