View Full Version : water in fuel
04-11-2004, 02:53 PM
Is it really necessary to use a water removing funnel. The gas station claims that they are tested on a regular basis for contaminants and water volume.
Why cut corners? In my book it is 100% mandatory to check and double-check every single fuel-related item. The vast majority of aero incidents are fuel related, and the vast majority of those could have been prevented had the pilots been rigorous regarding fuel checks.
Quite apart from good airmanship, consider the following:
It is the responsibility of oil companies to ensure that no contaminant is of any sort of present in their product at time of delivery to the holding tanks of the gas station. When fuel is uplifted from the holding tanks, the oil companies responsibility ceases and from then on it is up to the gas station to ensure that no contamination occurs.
The most common contentment is water. In spite of the best efforts of the oil companies water can leak into ground fuel tanks.
Water can also get into the tanks through the fuel caps of aircraft if they are not properly secured or have worn seals. Even with good caps properly secured there have been occasions when water has entered tanks after the aircraft has been parked outside in wet conditions.
Fuel, and the air in the space above it in an aircraft tank, naturally contains a small amount of water. A drop in ambient temperature (ie overnight) can cause this moisture to condense and contaminate the fuel system, blocking the fuel passages in the carby, and resulting in engine failure.
Since water is more dense than fuel it will tend to gather the low points in the aircraft fuel system. Not doing a fuel drain before every flight is to court disaster. It should be part of every preflight regime, no excuses, no ifs, no buts.
My person preflight check includes six separate fuel checks, as follows:
(1) visual level check of fuel contents (ie dipstick)
(2) the fuel drain (the one you seem to have doubts about doing)
(3) fuel cock check (make sure it is open)
(4) fuel pump check (is it on?)
(5) fuel pressure check (is it sufficient?)
(6) fuel gauge check (does it agree with the visual level check)
This is followed by a manual entry in my flight log as follows:
Fuel contents: 120 litres, Safety: 25 litres, Safe flight duration: 3h10min
Now obviously the checks I perform in my aircraft might be suited only to my aircraft, not to yours. But the point here is that the single most important factor related to aircraft safety in-flight is fuel and fuel management, and to even consider skipping such an important check as you have mentioned would seem to me extremely ill-advised.
04-11-2004, 04:28 PM
I was on the same track as you as I come from GA backround prior to joining the gyro world and I was also wondering about the length of time a tank of gas can sit for. I have an oil injected 2 stroke and I let my fuel sit for 7-10 days max.It is good to re-confirm , for this I thank you . Dave
Glad to be of some help. I was half afraid that my message would be construed as too forceful or even arrogant (I have just been chided for sounding arrogant on this forum :( ) Oops...
04-11-2004, 09:32 PM
That's alright, Duncan. If they were able to put up with me for numerous years on the old forum, I'm sure we will all be able to put up with you. :p
04-12-2004, 07:37 AM
After a while you will get to know who will respond and what triggers them.
As long as what you meant to say is factual, f... e'm let them wring their hands and be judgemental about your attitude.
By the way have you ever seen that Catalina in N.Z. that belongs to the group that flys it all over N.Z. at airshows?
04-12-2004, 09:27 AM
Hey, you old, dumb fart. There's no Catalina in New Zealand, it's an island off the coast of Southern California. Don't you know anything, you curmudgeon? You been forgetting to turn on your oxygen at altitude again? :D
04-12-2004, 09:40 AM
Don't be a smartass Kenny, we floated that Island over to N.Z. a week ago.
So go pound salt peter.
04-12-2004, 01:10 PM
Guy's , What about the fuel!
Its simple Dave.....
One....are you willing to bet your life that the fuel is safe WITHOUT checking it?
Because thats what your doing.....
Second....does act of checking the fuel present some hidden danger that you would not be exposed to had you not checked it?
Both answers seem pretty friggin obvious to me....and what to do seems like a no brainer.....but maybe Im just a genius and dont realize it.....
04-12-2004, 01:33 PM
yes I too have heard you are a genius, but it is easy to check the fuel , I have 3 fuel tanks and I will put in fuel check valves in all of them this week, my original question was is it necessary to use the water funell at the gas station, I do use it. Dave
04-12-2004, 02:18 PM
I fill my cans straight from the pump. But nothing goes in the gyro without a Mr. Funnel ! Although I still worry about what else they put in their "gasoline" .
04-12-2004, 02:43 PM
I use a home made pump , so I need the filter at the gas station. I will try to post a picture it is very cool.I can not insert a picture it says file to large and I do not know how to make it smaller, if you have e-mail I can send pics there.
04-13-2004, 03:56 AM
I've been thinking about getting a larger container with pump like the big boys. I had a hard enough time finding decent 5 gal cans, with the new laws. Ended up getting some nice racing cans from JEGS. I don't understand why you can't pump through a filter funnel though. Send a pic. CLS447@aol.com
04-13-2004, 04:51 AM
Chris ,I did send an e-mail , I hope you get it, if not please let me know. Dave
04-13-2004, 06:51 AM
I would also like a picture of your home made pump. If you don't mind sending me a picture, I will resize it and post it for everyone to see.
04-13-2004, 01:06 PM
Darren ,It is on it's way. thanks Dave
04-13-2004, 01:14 PM
04-13-2004, 01:16 PM
Dave Eisler home made pump.
04-13-2004, 01:16 PM
Another pic of Dave Eisler home made pump.
04-13-2004, 01:52 PM
Note , behind the gas can is an old airplane battery, you can see one of the alligator clips , All I do is connect and pump, you could also use your gyro battery, I use a cheap trickle charger once in a while to keep it going. I can also use a much larger gas can. it will pump 12 GPH without spilling a drop and the large filter on the top trap water too.The use of the hand truck really makes it portable.
04-13-2004, 03:47 PM
12 GPH or 12 GPM ?
04-13-2004, 04:56 PM
I like the set up a lot of the guys use who train. They use a plastic drum disposed from car washes and strap them to the hand dolly. Then they get a simple hand pump - some go round and round and some go in circles - and then the nozzle goes into a Mr Funnel and then into your tank. Simple and cheap should be less than 100$ for Everything you would need.
04-13-2004, 05:17 PM
Robert , you are correct GPM, GyroRon I too like the simple and cheap method, in fact what you said is what I had before the northeast winter blues got me tinkering in the garage. Dave
04-13-2004, 06:20 PM
Holy cow, Dave, make sure you're in a well-ventilated area when you hook up that alligator clip! Might be better to add a sealed switch somewhere in the circuit, so you can hook up the clip without drawing the spark, then turn on the switch.
04-13-2004, 08:39 PM
Let me know if anyone's interested in this hangar dust-gatherer. We started having fire inspections every couple years, so I can't use it. It's a small trailer with 2, 50 gallon plastic barrels on it. It has a gas station type pump handle, a car battery, and a huge glass filter system. The trailer is road legal with tail, stop and side marker lights. I'll sell it cheap, but it has to be picked up in San Diego. Would be great for a bunch of off-roaders who head for the desert and don't want to take a jillion 5-gallon cans also.
04-14-2004, 05:26 AM
Paul, It could be a hazard, but it is grounded with a 3rd wire just like in general aviation when the fuel truck connects to the airplane. There is no question that this pump is way more than any of us need and for a lot less you could devise pump.As I have with my first pump. But as I said earlier I made this for one reason, winter tinkering blues, I had all the parts in my shed and a warm shop. Thanks Dave.
Just a factoid here...and its one of those things alot of people know or learned and it something that some unlucky people were never told or learned..or learned a long time ago and forgot it...
One source of water in fuel, particularly old fuel that has sat around in the humid southeast for awhile is water vapor in the air...
Now, if you have a fuel tank that is mostly empty....it will "breathe"....during the day it will get hot and fuel vapors will be expelled.....then as it cools during the night, it will drawn in some air (that contains water vapor) and not surprising some of that water vapor will be "dissolved" in the fuel....
So, one trick to minimize this daily cycle of water vapor is keep the fuel tank as full as possible without it being so full that it is a safety hazard....that or the fuel system is so "air tight" that it cant breathe ...but that brings on other engineering/safety issues that must be addressed...
And another consideration.....how much water gasoline can hold in solution (vs little water droplets at the bottom) is a function of its temperature ......and if i recall correctly the warmer the fuel gets....the less water it can contain....
So, lets say you go out one cold morning and check your tanks....there is some water in the bottom of them.... (which means that most likely the fuel in the tank is holding as much water in solution as is possible ....ie its saturated)...so you drain out that water and all is well...
You keep flying all day....and it keeps getting warmer and warmer...if that fuel was saturated with water in solution...as it gets warmer it will be over/supersaturated and NEW little water droplets will form...
So, just because you checked the fuel that morning....isnt a good reason to not check it again throughout the day....as well as the consideration you might have had a big water bubble trapped somewhere else and it finally breaks loose....
I suspect from reading incident/accident reports that some fuel/carb icing problems may be due to that very effect....your carb is darn cold, but the air isnt in the accepted range of temp and humidity for carb icing to supposedly be a danger....but then here comes that little newly formed water droplet....it hits a nice COLD small metal part/passageway in the carb and freezes up...and a tiny one in the wrong place could cause alot of trouble...and since that droplet is deep in the carb...the procedures you use for carb ice arent going to work as fast as they typically do..
Of course this may be all theorectical and I could have it all backwards....anybody else have a clue on this?
04-14-2004, 08:58 AM
Bill, You are correct and to add to that, In general aviation, pilots will check the fuel at every pre flight and they do a pre flight before every engine start up, no matter how many times a day that may be. Also carb ice is known to be present at temps as high as 70F. Dave
04-14-2004, 09:38 AM
Ok, I thought I knew it all, well I was wrong. Here is what I learned last week when I ran my mouth.
Go to a good gas station. Sunnoco, Chevron, Ammoco. They have the best super out there. If you are a cheap bastard then go ahead an run mid grad but under NO circumstances do I recommend regular. Octane, water, etc. regular unleaded is maybe good for the lawnmower but nothing else.
WHEN YOU FILL UP:
They also have a device called a VEEDER ROOT. It measures water and other contaminates in the big tanks. You can ask the cashieer for a veeder root printout before you pump. It will give you the total number of gallons of fuel and number of gallons of water (if any) if out of 20,000 gallons of fuel it says 1 gallon I guess it would be ok but you have to wonder where that pocket of water IS sitting in regards to the tank pickup for the pump.
#2. I have always recommended the use of a MARINE type water / fuel separator. CPS sells a good one that you can see the bottom of the filter and it has a drain. Its made by raycor & complete part number is 8513 .
Now here is where I learned something.
3. Maxie always says to use a MR funnel. Why ? well over time even if you are using sealed airtight fuel storage containers water can accumulate in the fuel over filling cycles. now the pickups in most seat tanks and saddle tanks have a barb fitted with a rubber bushing to secure it. The pickup is anywhere from 3/8 to 1/2 from the bottom off of the tank floor. Now if you get a bunch of water sloshing around in a low tank you might be ok and then all of a sudden a bunch of water can get sucked into fuel intake and drown or overcome the capacity of your water filter and stall your engine.
Thats why you use a good filling station, sealed storage tanks, a MR funnel, and a water filter/separator. On top of using fresh fuel within 3 to 4 days in your UNPRESSURized fuel tanks on your aircraft. The good stuff in the fuel will boil off at atmospheric pressures within that time or sooner ! , Hence all the evap controls on modern autos will keep 1 to 4 psi of pressure to keep the vapor pressure in the tank. Clean out your fuel tanks once a year to make sure nothing is building up inside. Do not try to cap off or close off the vents in the plastic tanks on your aircraft. They do not have the strength to withstand the pressure and will buldge out with enough vapor pressure on a hot day. Honda/Acura does make a simple evap vent that is calibrated for about 1-4 psi with a vacuum function to allow for venting but I just dont see the benefit in it. Store idle fuel in a storage container, fly your fuel in your craft when you are ready to.
Which brings me to my last point in this long winded post. After a morning of training I was emptying the fuel tanks on the machine and discovered on full flow emptying in to my storage can I was getting air in the intake part of the fuel system. One of my fuel lines had become porus and was allowing a small amount of air to get sucked in and air bound my pumps and filter. Now I dont know how much it would take to foam my fuel at max throttle as compared to the free flow with no pump head but I repaired the lines and its ok now.
If all this seems too much or you think I am nuts thats fine, just dont say you were not told. There are too many unexplainable wrecks and I strongly suspect they were fuel related. The cost of fuel has gotten to the point where it is going to get watered down somewhere along the food chain so its best to minimize your exposure to any problems.
Do your best. its your tush in the seat.
04-14-2004, 01:05 PM
Johnathan, Very well put and so very important , I ordered the water/fuel seperator. what a great visual tool. One more thing should be added to your list and at a cost of about $8 or 10 bucks and only takes a few minutes to install, A drain valve to drain a few ounces before each flight and check for water. Dave
04-14-2004, 01:14 PM
Dave, the CPS water/fuel separator has a drain on it.
04-14-2004, 02:57 PM
Personally, I do not like using Mr. Funnel. Instead, install a gascolator on the machine and use the drain after refueling and before each flight. Downstream of the gascolator should be a seperate fuel filter.
I burned hundreds of gallons in the RV-6 and my other flying machines by using this setup.
04-14-2004, 05:27 PM
Johnathan , I meant to put a drain on the bottom of the tank and then test it at every pre flight. this is what I had before you told me about the gasolator and now I have both.
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