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Weird Fuel Issue


AH-1 Cobra Pilot

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Two weeks ago, I took a trip to a nearby airport.  They have the cheapest gas around, so I always fill the tanks there.  The operator put in about 15 gallons in the left tank, when the truck ran out.  I left to do some business, and he refilled the truck and finished filling my plane sometime after.  I returned to the airport a few hours later, paid for the 51 gallons, and left.

On departure, after climbing a few hundred feet, I noticed a definite decrease in power.  I was still able to climb pretty well, so I climbed within gliding distance of the airport.  I checked all my systems, (mags, fuel pump, switched tanks, prop, mixture), without any positive change in the output.  Since there are airports every 8-10 miles all the way home, I could glide to one if the engine quit, so I decided to take the plane directly to my primary mechanic.  I made it without issue, but on the roll to taxi, (throttle mostly/all the way retarded), the engine quit.

We immediately started checking the obvious things.  Removing the fuel lines from the injectors: plenty of output.  Sumped the fuel: no water or contamination; it smelled and looked right.  We tried to restart the engine, but it would not start.  My mechanic drained some fuel from the tanks and gascolator and kept it on the side, then checked screens, etc. and found no obstructions.  He sent some of the fuel system into Central Cylinder for evaluation, and checked the mags/electrical system; it was good.

After about 10 days, he noticed the fuel.  As you can see from the pictures, the first drain looks clear and has something growing in it.  The more recent sample still looks appropriate, except it now has some white, biologic-looking sediment.

My mechanic drained my tanks and left the fuel sit in a container.  It still looks like fuel, but does not smell as strong as I think it should.  He tried burning samples of the samples and some fresh gas from his own pump, but did not notice any obvious difference.  He also mixed some 100LL and Jet A just to see what that would look like, but it is green.  (He also tried to light the Jet A, but to no avail.)  We called the FBO that had filled my tanks, and he said nobody else has reported any problems.  He also said the trucker who delivers his 100LL only hauls 100LL.

Has anyone ever experienced anything similar to this?

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14 minutes ago, RobertGary1 said:

that’s interesting. I’ve never seen anything grow in 100LL but it’s a common issue in jet A without Prist. 
 

-Robert 

Yeah, I was going there as well.  When I read the OP, and got to the part about the engine quitting...and then looking at the pics, I thought for sure someone pumped JetA.  Was then thinking either "someone" forgot to put the blue dye in the fuel, or it came from a severely-contaminated tank.

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The blue jar looks like 100LL...

The clear jar with water in the bottom? Doesn’t look like 100LL at all...

If the clearer stuff is auto fuel... The lower octane May cause pre-ignition... Under high power settings...

Got any JPI data to share from that flight?

That would be interesting to review...
 

PP thoughts only, not a mechanic...

Best regards,

-a-

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Really odd.  I hate being the person who hits the bottom of the tank.  Most contaminants would congregate there.  I wonder where the fuel truck pick-up is in relation to that.  The right sample is very suspicious.  Can you explain what the left sample is vs the right sample.  Not sure I am correlating the two to your wrote up.  In either case, I suspect your power issue is related to some sort of contamination of that tank of gas.  

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15 hours ago, takair said:

Really odd.  I hate being the person who hits the bottom of the tank.  Most contaminants would congregate there.  .  

Shouldn’t. Just like airplanes fuel trucks have an amount of unusable fuel to collect that. Also like airplanes they have drains to test the fuel.  
 

 

-Robert 

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On 9/4/2020 at 10:53 AM, Ah-1 Cobra Pilot said:

Two weeks ago, I took a trip to a nearby airport.  They have the cheapest gas around, so I always fill the tanks there.  The operator put in about 15 gallons in the left tank, when the truck ran out.  I left to do some business, and he refilled the truck and finished filling my plane sometime after.  I returned to the airport a few hours later, paid for the 51 gallons, and left.

On departure, after climbing a few hundred feet, I noticed a definite decrease in power.  I was still able to climb pretty well, so I climbed within gliding distance of the airport.  I checked all my systems, (mags, fuel pump, switched tanks, prop, mixture), without any positive change in the output.  Since there are airports every 8-10 miles all the way home, I could glide to one if the engine quit, so I decided to take the plane directly to my primary mechanic.  I made it without issue, but on the roll to taxi, (throttle mostly/all the way retarded), the engine quit.

We immediately started checking the obvious things.  Removing the fuel lines from the injectors: plenty of output.  Sumped the fuel: no water or contamination; it smelled and looked right.  We tried to restart the engine, but it would not start.  My mechanic drained some fuel from the tanks and gascolator and kept it on the side, then checked screens, etc. and found no obstructions.  He sent some of the fuel system into Central Cylinder for evaluation, and checked the mags/electrical system; it was good.

After about 10 days, he noticed the fuel.  As you can see from the pictures, the first drain looks clear and has something growing in it.  The more recent sample still looks appropriate, except it now has some white, biologic-looking sediment.

My mechanic drained my tanks and left the fuel sit in a container.  It still looks like fuel, but does not smell as strong as I think it should.  He tried burning samples of the samples and some fresh gas from his own pump, but did not notice any obvious difference.  He also mixed some 100LL and Jet A just to see what that would look like, but it is green.  (He also tried to light the Jet A, but to no avail.)  We called the FBO that had filled my tanks, and he said nobody else has reported any problems.  He also said the trucker who delivers his 100LL only hauls 100LL.

Has anyone ever experienced anything similar to this?

Did it look or smell strange after you sumped it before taking off?

I'm not being sarcastic by asking that, and I know hindsight is 20/20, but after an incident 20 years ago I have not missed sumping after a re-fuel. I had a Piper Mirage at the time and I was on a tight schedule to get back home. I sumped it on pre-flight and knew right away that I wouldn't make it home that night. The smell was different and the appearance told me that something was wrong. The lineman that refueled it wasn't there, but the girl at the desk called him and let me speak with him. He remembered the airplane and I asked him what type of fuel he put in it. Immediately he said Jet-a of course. It turns out that there was a JetProp conversion at the field that he fueled often. The next day the FBO drained all of the fuel and flushed the tanks. They reimbursed me for my hotel and rental car and apologized profusely. Before this incident I would sump most of the time, but not all of the time. After this I have never missed sumping the airplane, no matter what I have flown. 

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Update:  The second jar has also lost its blue color.  (Unfortunately, I do not have an updated picture.)  It took much longer to change, but it also has more sediment than it had in the pictures posted above.  It would appear that the biological contamination was more concentrated in the sample taken 10 days earlier, right after I landed.  Both of the samples came from all three drain points, so it is not possible to tell if the contamination was only in one tank.

I did not sample the tanks before take off, since it had no time to settle and since I watched the first 15 gallons go in.  The same guy refuels my plane every time I am there, so I had no concern about him putting in something besides 100LL. 

Unfortunately, I believe the first 15 gallons went into the left tank, but I do not remember which tank fed the engine on takeoff.  I switched the selector at least once trouble-shooting, so there is no telling where it was.  If that first 15 gallons from the bottom of the truck had biological contamination, it may have concentrated in the bottom of the left tank before putting in the rest of the fuel, so if I had run the left tank on takeoff, perhaps it partially plugged the filter screen.  My mechanic disassembled the fuel system, and could not find anything obvious in any of the filters.

I am still waiting for the injectors and other parts to be returned from testing.  If they show no dysfunction, we will reassemble and see how it runs.  I am also thinking about adding some anti-biologic poison to the fuel system.  Any recommendations?

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4 hours ago, Ah-1 Cobra Pilot said:

Update:  The second jar has also lost its blue color.  (Unfortunately, I do not have an updated picture.)  It took much longer to change, but it also has more sediment than it had in the pictures posted above.  It would appear that the biological contamination was more concentrated in the sample taken 10 days earlier, right after I landed.  Both of the samples came from all three drain points, so it is not possible to tell if the contamination was only in one tank.

I did not sample the tanks before take off, since it had no time to settle and since I watched the first 15 gallons go in.  The same guy refuels my plane every time I am there, so I had no concern about him putting in something besides 100LL. 

Unfortunately, I believe the first 15 gallons went into the left tank, but I do not remember which tank fed the engine on takeoff.  I switched the selector at least once trouble-shooting, so there is no telling where it was.  If that first 15 gallons from the bottom of the truck had biological contamination, it may have concentrated in the bottom of the left tank before putting in the rest of the fuel, so if I had run the left tank on takeoff, perhaps it partially plugged the filter screen.  My mechanic disassembled the fuel system, and could not find anything obvious in any of the filters.

I am still waiting for the injectors and other parts to be returned from testing.  If they show no dysfunction, we will reassemble and see how it runs.  I am also thinking about adding some anti-biologic poison to the fuel system.  Any recommendations?

This is a fascinating and somewhat terrifying issue with which I was unfamiliar until I just started reading about it.  I learned that the anerobic bacteria and fungi need a water-fuel interface to grow.  They float at that interface and once the water is removed they cannot survive.  So as long as your tanks remain dry I doubt you'd have a recurring problem.  Even if a little water gets in your tank at a later date, the relevant microbes from this contamination should be dead after they were deprived of water.  The issue is much more common for Jet-A than for 100LL, but is very possible with the latter - auto gas stations have to deal with it too.  It seems very clear here that there was significant sediment, either organic and/or inorganic in nature, that was stirred up into suspension a bit above the level of the unusable fuel at the bottom of the tank not long before the last usable bit was dispensed to you.  It's not surprising that others did not experience the same contimation in fuel dispensed from the same tank. I'm not sure what's going on with progressive loss of the blue dye but there is clearly some chemical interaction between the dye and a component of the sediment.  

I'd document everything very carefully here, and the FBO should be on the hook for your trouble and expense.  Given the amount of liability they face related to fuel contamination, I'd think they'd be VERY interested in your troubles and want to address any issue with sediment at the bottom of their tanks ASAP.  It also seems like their insurance company should be covering your repairs including thorough cleaning of your tanks and fuel system.  

 

 

 

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When fuel is known to be 100LL, it is blue...

Any fuel lacking color, is not 100LL... it may be... or might be... or could be... Or may have been 100LL..?

If it was Jet-A... the piston tops probably would have melted by 1000’ AGL... A side affect of pre-ignition...
 

The aroma of Jet-A is hard to miss...

 

So... we know what it wasn’t...


I had so much rain water in my tanks once... it looked a lot like the near clear jar... Sump attempt after sump attempt I go the same color... ready to believe I got car fuel or something like that... I spit in the sump device... the spit spread across the sample like it was landing in water...   so it was... 

 

When it comes to fueling... trust but verify... simple mistakes, turn into deadly results, incredibly easy...
 

If something has washed / extracted out the blue dye... did it take any of the other additives like lead with it?

This is a really weird fuel situation, for us as pilots... that a fuels engineer will probably be very familiar with...
 

Now... is it the same blue fuel in the jar has gone clear?

Did the blue dye plate out on something? Did it sink to the bottom? Where did it go?

This would give a hint to what needs to be cleaned....

Does MS have a fuel guy?
 

Best regards,

-a-

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On 9/12/2020 at 12:09 PM, Ah-1 Cobra Pilot said:

I did not sample the tanks before take off, since it had no time to settle and since I watched the first 15 gallons go in.  The same guy refuels my plane every time I am there, so I had no concern about him putting in something besides 100LL. 

We are all very happy that you landed safely and that the engine waited to quit until you were on the ground.

When I use self serve I have no concern about me putting in something besides 100LL, but I still sample every time. Contamination is almost always going to be heavier than 100LL so it gets to the sump pretty quickly.

In 35 years of flying I haven't often found contamination when I sample, whether it's water or something else, but every few years I do. Mainly it's been a little water here and there. Thinking about this I remember another time when I found metal slivers after sampling. As many samples as I took the slivers were still there. It was my home base at the time, so I did not start up the airplane. I tied down the airplane instead of putting it in the hangar and went the next morning to show the FBO the sample. It turns out their pump was coming apart and metal shavings were somehow making it past the filters in their fuel system. Needless to say they took care of draining all of my fuel and cleaning out my fuel system. They did that with other airplanes also.

I look at sampling every time like cutting the oil filter open on every oil change. You hardly ever find anything, which makes you happy. But every few years when you do find something it makes you even happier that you cut it open instead of skipping it. If I skip sampling the fuel, I'm cutting a corner on the checklist. How many items I can skip and still stay accident-free I don't want to find out.

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My common mission is a two hour flight.  I always replace the fuel I use AND tanker extra fuel (so I am at same level I departed).  I fuel upon arrival and ALWAYS sump before I depart as well as visually confirming fuel quantity in tanks.  I have sumped and found water before.  I learned about the “spit” trick here on Mooneyspace as well as smell test.  This “event/scenario” could happen to anyone and surely reinforces the importance of sumping  and visual inspection every time.  Glad it worked out with no off airport event.  No doubt the FBO “running dry” gave you some “gunk”.  They should remedy and make you feel confident in your planes entire fuel system.  The “Nobody else complained” reply is no bueno...

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Does this fuel have an odd smell? I had an incident last year where the 100LL smelled like piss; almost like ammonia. Never found out what it was. The FBO that filled it from the 100LL truck flows a ton of fuel too. It never came back after using it up and diluting it.
Maybe we can get a comment from a lurking petroleum chemist or engineer.

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1 hour ago, tigers2007 said:

Does this fuel have an odd smell? I had an incident last year where the 100LL smelled like piss; almost like ammonia. Never found out what it was. The FBO that filled it from the 100LL truck flows a ton of fuel too. It never came back after using it up and diluting it.
Maybe we can get a comment from a lurking petroleum chemist or engineer.

I did not smell anything out of the ordinary.  If anything, it may have seemed to smell a little less strongly of fuel, but that is so subjective it is easy to dismiss.

More and more diesel pumps have DEF, (Diesel Exhaust Fluid), colocated.  It is basically liquid urea for cleaning the particulate filters in the exhaust system.  With fuel delivery having to account for that, now, I could see some getting mixed into other products, including 100LLL.

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