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Water in fuel tank


helidoc
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Anybody ever accidently get a small amount of water in their fuel tank (ie. accidently leaving the fuel cap open when spraying off the helicopter to clean it)? If so what did you do? Did it eventually all settle to the bottom and come out the inspection valve? Any fuel additives that will disperse the water into soluble form? Suggestions or experiences?

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I once sumped at least 2 cups of water out of each wing on a 152. It's typical to get a little bit, that's what the sump valve is for. The fuel tanks are vented to the atmosphere so you're going to get moisture in them no matter what.

 

And, yes, it will all settle to the bottom since water is much heavier than AvGas. As for jet fuel, its takes a while for it to settle.

 

A good rule of thumb is to wait 30-60 minutes per foot of fuel to sump it. The tank in the R22 or S300 is about 24in high, and they use AvGas, so wait an hour then sump it if you think you have water in it.

 

Keep in mind than .5 gallon of fuel is un-usable. Therefore you could have almost .5 gallons (8 cups!) of water in the fuel and the engine would still start and run.

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Sometimes it won't settle at all in jet fuel, it can stay suspended in the fuel and the fuel itself will be foggy instead of clear and bright. I've just seen this myself because we had this problem with a Jet-A truck at my work. It is less likely however, that this mix would make it into the aircraft because it still has to go through the filter on the truck and the filter at the end of the fuel nozzle, but I wouldn't want to rely on those working 100 percent of the time.

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  • 3 weeks later...

water in fuel is NOT good ! & @ 50-75 feet in the air its even werse !! One thing i learned wayyyyyyyyyyy back in my early days of flying, make SURE you see a separation of the fuel & the water, & IF ya dont? make sure what you are looking at is fuel, and NOT all water. AND Delorean? a 300 will use up just about EVERY last drop of fuel in the tank b4 it quits---unless that last 1/2 gallon is water !

Edited by pokey
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water in fuel is NOT good ! & @ 50-75 feet in the air its even werse !! One thing i learned wayyyyyyyyyyy back in my early days of flying, make SURE you see a separation of the fuel & the water, & IF ya dont? make sure what you are looking at is fuel, and NOT all water. AND Delorean? a 300 will use up just about EVERY last drop of fuel in the tank b4 it quits---unless that last 1/2 gallon is water !

 

 

Yeah, sorry, didn't mean to imply that the 300 has .5 gallon of unusable fuel......I forgot that I had reference it with the R22. And, by no means should you fly with ANY water in the tank that you know of. A few drops is not a reason to get worried though.

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Well the helo has been sitting for a few weeks now with the wheels up so there is a slight forward tilt to the aircraft. The pickup for the fuel is forward in a funnel like portion of the tanks. I have checked it and there is no water to be found after draining a pint of liquid. I am still uncomfortable with the thought of water hiding somewhere and my mechanic has suggested running the turbine for 30 to 40 minutes maybe practicing low hover manuevers (hopefully not hovering autorotations!). I have thought about draining the tanks but am not really sure that will answer the question of whether or not all the water would come out or could some be hanging up in the tank somewhere like on the foam baffling. I guess one could ask how much water in a tank becomes significant?

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A few years ago I had a memorable fuel incident.

 

I was flying a Soloy 12E in logging support. We were working ahead of the crew, supporting cutters, preparing the next sale. Because we were working on our own, we were fueling out of barrels, using a hand pump. It was February in Idaho.

 

One morning I was unable to get a fuel sample out of the sump. It was about 20 degrees below zero. I figured there must have been some condensation or a small amount of water that had frozen in the sump valve. No big deal.

 

Getting a 12E ready to fly in the winter included warming up the transmission with a big toro space heater aimed into a canopy that covered the head and tranmission area. So I took the toro and put it on the ground, aimed at the sump. After a little while I was able to work the sump and get a sample. It was about a cup of water. After another little while I got a jar of water. Then another jar. When all was finished we sumped about 2 gallons of water out of the fuel tank that morning.

 

We had been operating with what we thought was a go/no-go type filter. We also had been using Prist. It turns out that the filter was not the correct one, the fuel supplier had messed up.

 

Melted snow on the transmission deck or on top of the barrels was the likely source of water into the fuel supply. The 12E fuel port is recessed into the deck under the transmission. Any water pooling there could penetrate a weak seal on the fuel filler neck. The top of the barrels provided another potential pool with easy access to the pump attachment hole. The snow could not have melted that morning as I warmed the transmission, made its way into the tank and re-froze in that short time. It had to have been the day before. The aircraft had been flown and refuelled several times the day before. It is possible that we had been flying with 2 gallons of water in the tank, either in suspension or frozen in a block!!!

 

I still shudder when I think about that. We were flying over 150' - 200' trees in steep terrain. I had an angel that day.

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A few years ago I had a memorable fuel incident.

 

I was flying a Soloy 12E in logging support. We were working ahead of the crew, supporting cutters, preparing the next sale. Because we were working on our own, we were fueling out of barrels, using a hand pump. It was February in Idaho.

 

One morning I was unable to get a fuel sample out of the sump. It was about 20 degrees below zero. I figured there must have been some condensation or a small amount of water that had frozen in the sump valve. No big deal.

 

Getting a 12E ready to fly in the winter included warming up the transmission with a big toro space heater aimed into a canopy that covered the head and tranmission area. So I took the toro and put it on the ground, aimed at the sump. After a little while I was able to work the sump and get a sample. It was about a cup of water. After another little while I got a jar of water. Then another jar. When all was finished we sumped about 2 gallons of water out of the fuel tank that morning.

 

We had been operating with what we thought was a go/no-go type filter. We also had been using Prist. It turns out that the filter was not the correct one, the fuel supplier had messed up.

 

Melted snow on the transmission deck or on top of the barrels was the likely source of water into the fuel supply. The 12E fuel port is recessed into the deck under the transmission. Any water pooling there could penetrate a weak seal on the fuel filler neck. The top of the barrels provided another potential pool with easy access to the pump attachment hole. The snow could not have melted that morning as I warmed the transmission, made its way into the tank and re-froze in that short time. It had to have been the day before. The aircraft had been flown and refuelled several times the day before. It is possible that we had been flying with 2 gallons of water in the tank, either in suspension or frozen in a block!!!

 

I still shudder when I think about that. We were flying over 150' - 200' trees in steep terrain. I had an angel that day.

 

Wow! You really did have an angel flying with you!

 

Makes my situation pale in comparison. I did finally go flying this weekend without a problem and never did find a drop of water after draining about a gallon out of the tank.

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