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Help - Cloudy Fuel

B

bits

Member
Cloudy Fuel - Please Help

Has anyone seen anything like this. Sumped my left tank today...fuel blue and clear. Sumped my right tank...fuel was blue and cloudy/milky. I drained four 2oz cups, each one clearer than the last. The fourth sample was blue and clear. The aircraft (RV-6A) has been indoors, in my unheated hangar in NE Ohio. The temperature was about 35degF when I took the samples, but the overnight temperature was about 25degF. I am not the builder...it was built by Bob Barrett, in Clear Lake MN, completed in 2009. The wings were quick-build. My guess is that it's either ice crystals in suspension, or a substance breaking down in my fuel tank. Any thoughts?
 
Water can look murky/bubbly. Did you let the sample sit? if you let it sit for a few minutes the water will settle to the bottom.
 
I don't know about your case but we need to be especially careful of water/ice in the fuel in the winter.

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NTSB Identification: CEN14LA120
14 CFR Part 91: General Aviation
Accident occurred Thursday, January 23, 2014 in Ashland, MO
Probable Cause Approval Date: 09/24/2014
Aircraft: CESSNA 414A, registration: N414CJ
Injuries: 3 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot reported that, during the descent to the destination airport, the airplane?s left engine experienced a partial loss of power and that he attempted to troubleshoot the issue. Unable to restore the engine power, he secured the left engine, feathered the propeller, and advised air traffic control of the situation. Shortly after, the right engine experienced a partial loss of power and eventually only produced idle power. Unable to reach the destination airport, the pilot conducted a forced landing to a field. A postaccident examination of the airplane revealed ice buildup in the fuel manifold valves, the fuel strainer bowls, and the fuel strainer screens. The left fuel strainer bowl contained a 1 3/8-inch thick piece of ice. Fuel samples from both of the airplane?s fuel tanks and from the fuel supplier at the airport used to the fuel the airplane earlier in the day were tested, and no water contamination was found; the source of the water contamination could not be determined. It is likely that the loss of engine power resulted from water contamination and subsequent ice buildup in the fuel system.
 
Thank you for your advice. I'm going to take another sample tomorrow. I will let it sit a while and see if it separates out.
 
bits said:
Thank you for your advice. I'm going to take another sample tomorrow. I will let it sit a while and see if it separates out.
Click to expand...

Take two samples. Let one warm up and see what it does. 100LL has a certain capacity for water, so if the sample clears up on warming it maybe that the water has re-dissolved in the fuel. Think "ice beer" (remember that craze?). The alcohol in the beer was concentrated by freezing a portion of water out as ice crystals and then filtering them physically, Leaving a beer with higher alcohol concentration.

You might try using a coffee filter to strain a cold sample of the cloudy fuel and see what you get.

Alternatively, freeze the fuel even colder and see if crystals grow to visible size.

Ain't amateur chem lab fun?
 
Fuel

Better yet drain the fuel and put it in your snow blower and put fresh in your plane.It could have been the airport help not draining the filters or the bottom krud in the tank don't take a chance with bad fuel.
Bob
 
Well we finally had some cold weather last night. I took a couple 1oz fuel samples this morning and they were cloudy. I put the samples in a warm room, and looked for cloudy crystals to melt, and the water to separate out. Unfortunately, that didn't happen. Instead, the cloudy particles have remained cloudy and settled to the bottom of the samples.

Thinking it may be a plastic/petroleum based product breaking down in the tank, I called the Van's Builder Assistance line and talked to Scott. Scott was unaware of anyone having this issue. From our conversation, I've derived a list of petroleum based products in the tank to include the tank sealant, the fuel sensor float, and a white plastic grommet on the wing rib, all these items installed or applied at the Philippine factory. Items installed or applied by the builder are the inspection panel sealant, the brown rubber fuel cap O-ring, and the fuel drain O-ring.

My priorities now are to 1) determine what the cloudy substance is, 2) isolate the source, 3) replace the source, and 4) cleanse/purge the fuel system. My AMT will take the samples for analysis. Hopefully, that will help us narrow down the source. Any thoughts, considerations or advice would be appreciated.
 
I would drain the tank and then refill with new fuel and see if the new fuel becomes cloudy. This would tell you whether or not it is the tank, or something introduced in the fuel.
 
Build should not be the first suspect

If the other tank is clear I would drain the one in question via a strainer as suggested earlier. Don't think I would start with the build if the second tank is still clear days later. I would review my fuel stops though.
 
This is #2 Diesel just a little past cloudy :D Ever since the government changed to the ultra low sulfur fuel we have experienced serious problems with this new fuel. Back before they changed the chemistry the #2 would cloud around -15 F now we get complete filter blockage at 5 F. I hope that our LL or auto 91 does not do anything like this.

20160112_144324%201_zpsdapj1iw2.jpg
 
bret said:
This is #2 Diesel just a little past cloudy :D Ever since the government changed to the ultra low sulfur fuel we have experienced serious problems with this new fuel. Back before they changed the chemistry the #2 would cloud around -15 F now we get complete filter blockage at 5 F. I hope that our LL or auto 91 does not do anything like this.
Click to expand...

Wow... you need some Power Service white! Was recommended by many TDI web forum members from Canada (eh?), and I never had a problem with fuel gelling or waxing when I owned my '96 Passat TDI, even in single-digit temps.
[/off topic]

Back on topic:
Drain the tank through a large coffee filter, and see what (if anything) gets filtered out. Refill the tank, and resample after a minimum of 24hrs to see if you get the same cloudiness.
As already suggested, store the "suspect" gas and use it for lawn mower, snowblower, and other non-critical outdoor equipment.
 
Quick Update

As suggested by forum users, I drained all the fuel from the tank through a coffee filter, flushed the tank a couple of times with about a quart of clean fuel, and refilled the tank. I let it sit for about 42 hrs, through temperatures ranging from 23deg F to 36deg F. I then took a sample; the fuel is now crystal clear. I plan to check the fuel filter screen, and clean the filter/lines as needed. After that, I'll give it a good long ground run. If all indications are normal, I'll take it up for a test flight above my home field.
 
bret said:
This is #2 Diesel just a little past cloudy :D Ever since the government changed to the ultra low sulfur fuel we have experienced serious problems with this new fuel. Back before they changed the chemistry the #2 would cloud around -15 F now we get complete filter blockage at 5 F. I hope that our LL or auto 91 does not do anything like this.

20160112_144324%201_zpsdapj1iw2.jpg
Click to expand...

Looks like the frame filter off a Ford 6-leaker - never had that happen in the 14 years and the 290,000 miles when I owned one.

On a more serious note - a friend of mine routinely fills his Cub at a nearby airport then drains out 5 gallons to have extra fuel on hand. Once he had 5 gallons turn from blue to white in the jug after a couple of weeks of sitting. We never figured out what caused it, needless to say it when it the H tractor and not the plane.
 
100LL turned clear

I put 100LL in clear plastic racing fuel tanks. After 4 months the fuel lost its blue color. Has anyone else experienced this phenomenon?
 
Safest bet would be to drain the ENTIRE fuel system, including the carb fuel bowl. Flush the system with clean fuel with the carb bowl plug removed, clean all screens and go from there.
 
Jpm757 said:
Safest bet would be to drain the ENTIRE fuel system, including the carb fuel bowl. Flush the system with clean fuel with the carb bowl plug removed, clean all screens and go from there.
Click to expand...

You are replying to a two year old thread.
 
Excerpt from avaition fuel handling handbook

"Water Contamination
? Water is the most common contaminant found in aviation fuel and falls into the following two categories
o Dissolved Water (Water in Solution)
 Does not present a risk to aircraft engine operation
 The amount of water that fuel can hold in solution is a function of the fuel temperature
 The higher the temperature of the fuel, the greater the potential concentration of dissolved water
 As fuel cools, it can hold less water in solution and the water condenses out of the fuel as free water.

o Free Water (Undissolved Water)
 Any water that is not dissolved in the fuel
 Accumulates at low points in fueling systems and settles to the bottom of tanks because it is heavier than fuel

Sources of Free Water
? Movement of ?water in solution? into ?free water?
? Introduced into the fuel from outside sources
o Condensation of water vapor (humidity) in any air space inside fuel storage tanks, piping and filter vessels

o Fuel handling equipment integrity issues (leaks in fittings, fill caps, manways, etc.)
o Water laden transport deliveries
1.1.2 Risks of Free Water
? A water slug reaching the engine could cause performance issues
? At high altitudes (colder temperatures) free water can form ice crystals which can plug aircraft fuel system filters and fuel control units
? Water enables microbial activity in fuel storage
? The presence of water in a storage tank can cause the FSII additive in jet fuel to migrate out of the fuel and into the water, at the fuel-water interface
1.1.3 Detecting Free Water
? Field Testing
o White Bucket Test ? Free water in fuel may be observed as a hazy/cloudy appearance, water droplets, or bulk water see Section 5.5 Fuel Quality Testing ? White Bucket Test
Note: Free water is typically not visible to the eye until it reaches levels greater than 30 parts per million (PPM)
o Free Water Test ? ATA Specification 103 recommends a maximum allowable limit of 15 PPM downstream of filtration"

Unquote...I suspect you are seeing dissolved water. I would keep your fuel tanks topped off after each flight so water does not condense from the airspace above the liquid level in your tanks if you don't already follow that practice.
 
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