Water in fuel tanks

AlanM

AlanM

Pre-takeoff checklist
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Needles
Just yesterday, I preflighted a C172SP in Florida (at a flight training school) and much to my surprise, there was actually WATER in the 100LL. Using a GATTS jar, it took about 5-6 samplings before all the water was gone.:yes: It wasn't just on one side, it was on both sides AND in the sumps under the engine.

The point here is: SAMPLE THE FUEL for your own safety. Every time you fly and after refueling. It is so important. I learned a dramatic safety lesson yesterday. WOW.
 
When was the last time it was flown? Was fuel contaminated or did water somehow get in from atmosphere and find its way into tanks. Did you fly it after you sumped all the water out?
 
If it took that much to clear the tanks,either people haven't been slumping the tanks,or you may have leaking caps. Or could be contaminated fuel. I'm sure you let the school know.
 
Yeah, leaking caps or contaminated fuel. I'm betting bad fuel...surely Cessna fixed their potential fuel cap issues by the time the SP model came out...surely...

Okay, maybe I'm being far too optimistic. :)
 
Gasoline can hold up to a teaspoon of water per gallon in solution. Yes, i mean the water is desolved into the gasoline. When temps get cooler it comes out of solution and settles to the bottom of the tank. Normally the small amount found in the tanks can be injected by the engine when running and you don't know it. Obviously, a large amount can cause a stumble, but it usually passes through without much problem, or maybe a stumble. This is normal and should not be a surprise to anyone that flies.

Water also comes from condensation from the humid air cooling inside the tanks this time of year. This should not be news to anyone flying airplanes. If it is your CFI sucks. This is why sumping your tanks once a flying day is a good idea.
 
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Geico266 said:
Gasoline can hold up to a teaspoon of water per gallon in solution. When temps get cooler it comes out of solution and settles to the bottom of the tank. Normally the small amount found in the tanks can be injected by the engine when running and you don't know it. Obviously, a large amount can cause a stumble, but it usually passes through without much problem, or maybe a stumble.

Water also comes from condensation from the humid air cooling inside the tanks this time of year. This should not be news to anyone flying airplanes. If it is your CFI sucks. This is why sumping your tanks before once a flying day is a good idea.
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In +35 years of aviation, owned 3 aircraft, some hangared and some tied down outside.....I've never seen this. :no:

I have, however, seen leaky fuel caps allow water to enter the tanks. :yes:
 
Checkout_my_Six said:
In +35 years of aviation.....I've never seen this. :no:

I have, however, seen leaky fuel caps allow water to enter the tanks. :yes:
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So condensation in your part of the world doesn't happen? Wow, the laws of physics and chemistry are suspended in your airplane?

You haven't been looking very hard, or don't understand how water can enter a fuel tank.
 
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Geico266 said:
So condensation in your part of the world doesn't happen? Wow, physics are suspended in your airplane?

You haven't been looking very hard, or don't understand how water can enter a fuel tank.
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I'm willing and able....just never seen it.

It hasn't stopped me from looking though....:goofy:
 
Larry,

I've done the math here. You can park the typical single engine airplane outside with tanks 3/4 empty, assume a full air exchange every day, assume 80% RH every day, assume 100% of the moisture condensates into the gas every day...for a month...and there's still not enough water to worry about. (And none of this will ever occur to the extremes used for the example.)

Condensation of moisture into fuel out of the atmosphere...even if the plane's parked in a feakin' rainforest is a myth.
 
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timwinters said:
Larry,

I've done the math here. You can park the typical single engine airplane outside with tanks 3/4 empty, assume a full air exchange every day, assume 80% RH every day, assume 100% of the moisture condensates into the gas every day...for a month...and there's still not enough water to worry about. (And none of this will ever occur to the extremes used for the example.)

Condensation of moisture into fuel out of the atmosphere...even if the plane's parked in a feakin' rainforest is a myth.
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It's not a myth that gasoline can hold water in solution. It's not a myth that water can condense on the inside of a fuel tank. :rolleyes:
 
Geico266 said:
It's not a myth that gasoline can hold water in solution. It's not a myth that water can condense on the inside of a fuel tank. :rolleyes:
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It is a myth that ENOUGH water can condensate out of the atmosphere to make a sh*t. Unless physics and chemistry are suspended in your mind!:goofy:
 
When I bought my Piper (which was based in Alabama and hangared), I had a pre-buy done in Winter Haven after which it was flown to me in Sarasota, so three hops. The very FIRST time I went to sump the tanks, there was water at all three sump points and even a few insects..eww.

What amazes me is ever since that day, every time I go sump the plane I have not once, seen a repeat of that situation. And there have been some whopper storms here in FL lately, plenty of opportunity for insects, water or both to reappear.

I can only guess that either the plane wasn't sumped at any of those locations when I got it (unlikely), or that there was some fuel contamination along the way.

During my whole private pilot training I sumped C172's and C162's, never saw water or anything like what I saw the first time I sumped my new plane, so although I heard about what to look for, seeing it was quite a different experience.

It is VERY obvious when water is in the fuel, I was expecting something more subtle, but man, it's hard to miss those big clear drops at the bottom of the sampling container.

Good job on conducting a thorough pre-flight and catching it. Could have been fuel, or condensation, or if it is a school plane, a poor job by previous renters/students that kept the water there.

I sump everytime I fill up or before any flight (even if I haven't gotten fuel). The last thing I want is to become a statistic due to fuel contamination.

It's shocking to me to watch other pilots get fuel or just hop in the plane and go without even checking what is in the tank (some don't even do a walkaround). Makes me glad I'm not flying with them.
 
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Caramon13 said:
It's shocking to me to watch other pilots get fuel or just hop in the plane and go without even checking what is in the tank (some don't even do a walkaround). Makes me glad I'm not flying with them.
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It takes quite a while for water to settle down and make it's way to the sumps after fueling.
 
I have never sumped water from either of the two airplanes I've owned. But I still do it before every flight.
 
Anymouse said:
It takes quite a while for water to settle down and make it's way to the sumps after fueling.
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:yes:

Sumping right after a flight or fueling isn't really a accurate indication of the absence of water.

I've also gotten into the habit of rocking the wings, if I can, before sumping.
 
The CFI who trained me on the Mooney told me that sumping after fueling is useless, since even if there was water in the fuel it would be in suspension for some time due to all the churning during fueling. I have now owned three airplanes, one kept exclusively outdoors for years. I've never seen water in the fuel, not even after hellacious rain storms.
 
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steingar said:
The CFI who trained me on the Mooney told me that sumping after fueling is useless, since even if there was water in the fuel it would be in suspension for some time due to all the churning during fueling. I have now owned three airplanes, one kept exclusively outdoors for years. I've never seen water in the fuel, not even after hellacious wind storms.
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Why I fuel after a flight not before. I have found water in my fuel a few times. Just this year it has happened twice. Not a lot maybe an ounce or so. I use auto fuel without ethanol 92 octane purchased from a new store just built a year ago.

I know people who wash thier fuel.

Tony

P.S. My airplane never sits outside.
 
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Anymouse said:
It takes quite a while for water to settle down and make it's way to the sumps after fueling.
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I've gone a week without flying after filling the tanks up (with many rainstorms in between) and still nothing as bad as that first time. I think the plane sat for maybe a day or two after it was delivered before I took ownership and flew it.

How long would "quite a while" be do you suspect?
 
I did fly into a fly-in the other day and needed fuel after landing. As I was fueling the thoughts of water kept entering my mind. But I did not sump, for I believe it would take some time for the water to separate. But I should have sump the tank or checked it.

In my hangar if I believe water is in the fuel I run it through one of those funnels that removes the water. I have yet to find water in my fuel jugs from sitting in the hangar.

Yes we store fuel in our hangars as most who fly these little airplanes do.
 
Caramon13 said:
I've gone a week without flying after filling the tanks up (with many rainstorms in between) and still nothing as bad as that first time. I think the plane sat for maybe a day or two after it was delivered before I took ownership and flew it.

How long would "quite a while" be do you suspect?
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Put some fuel in a glass jar. Add water and shake. Watch and see how long it takes. I have no idea and might do this myself.
 
Geico266 said:
So condensation in your part of the world doesn't happen? Wow, the laws of physics and chemistry are suspended in your airplane?

You haven't been looking very hard, or don't understand how water can enter a fuel tank.
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It's not hard to bound just how much water you can get from that, given a temperature difference, humidity, and tank level.

It's also not hard to figure out you haven't done so, and have just accepted the OWT.

It's leaky caps or contaminated fuel. Most likely the latter.
 
We've had a lot of rain in Florida over the last few weeks what with the tropical storms in the Atlantic. I just took the fuel caps apart on my Piper Arrow to clean them and I realize why I get water in the fuel; it's due to the design of the vents that there's just no way that a driving rain would not push water into the fuel tanks regardless of the condition of the gaskets.
 
Caramon13 said:
I've gone a week without flying after filling the tanks up (with many rainstorms in between) and still nothing as bad as that first time. I think the plane sat for maybe a day or two after it was delivered before I took ownership and flew it.

How long would "quite a while" be do you suspect?
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It's been a long time since it was brought to my attention (20 years or so??), but I'm thinking that I was told 30-60 minutes at least.
 
I'm a relatively low-time pilot and have found water in the tanks a couple of times. Both times, the plane had recently been flown and the likely cause was contaminated fuel. Regardless, it's been a bit of a surprise to see it that often. When I was a student, I assumed that these were very low frequency events. But because the consequences were so high, we had to check every flight. Now I'm learning that in addition to severe consequences, it happens more often than I thought. It's a good reminder to do a thorough preflight. Things happen.
 
How about carrying one of those funnels that remove water from fuel and using it when refueling at an unfamiliar airport?
 
Have never found an issue, but still always sump.

Here's something to get the debate going... what about the winter when it's below freezing?

Personally I still always sump (since it's more than just water I'm checking for), but I've been told off for doing so by more than one northerner with something along the lines of:

"If there's water in there it's frozen and now you've just dislodged it so the ice can clog an intake. Never sump if it's below freezing out."

My usual response is "show me where it says that in the PoH" (it doesn't)... but I'll admit the logic seems plausible. Anyone else ever hear this?
 
I've seen water before in 172N or 172M (can't remember) and it was due to old/leaking caps, once the caps were replaced the "issue" was solved.
 
Here's a credible reference showing the solubility of water in aviation gas and jet A and JP-8 at different temperatures as volume %: https://books.google.com/books?id=J...lubility water in "aviation gasoline"&f=false

Given 40 gallon tanks, it looks like a few (1 to 3) teaspoons could come out of solution going from 40° C (very warm, even hot) day to 20° C (nice comfortable day) assuming I did my calculation correctly.
 
You can get water to separate from fuel with temperature and altitude. While flying the engine cough, spudder, or completely die. Within a few minutes of landing the water will absorb back into the fuel and you will stand around scratching you're head. Some planes that fly at higher altitudes actually have to add a fuel treatment like dry gas or something. I read that **** in a magazine yo, Aopa 4 life homies!!
 
Condensation in fuel tanks happens in my planes. Cars, snowmobiles, chainsaws, too. I can demonstrate it on most of my flights. But I routinely run on quarter tanks and park outdoors. Because you've never experienced it doesn't mean it doesn't happen.

I love the contaminated fuel argument when the condensation topic comes up. I have 100LL in clear plastic containers that's stored for long periods. Filled and sealed they have never had even a trace of water in the bottom of the containers. Leave one open and half full in a shed and water appears. My fuel is a known entity purchased from an above ground tank and dispensed Ito my own tank. I maintain my water filters very well. My plane sits in the rain for days without having water appear in the fuel so the leaking cap assumption is incorrect. You nay-Sayers should provide your preps as you understand them and let others do the same.
 
Checkout_my_Six said:
now that's insane.....:yikes::D
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Crazy isn't it! ;)

Anymouse said:
It takes quite a while for water to settle down and make it's way to the sumps after fueling.
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I've heard this said many times but I'm not sure if it's accurate. The reason I suspect it's not is that when I check autogas for ethanol...I do it by putting one inch of water in a rain gage, then 4" of gas on top of it, then cork it and shake it vigorously.

The water settles back out in about 5 seconds. Sure, this is a very small sample but, I'd suspect that If you fill up and then go take a pee, things will have settled out by the time you return.

But I don't know...I'd like to!

This is my ethanol tester:

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Checkout_my_Six said:
another reason not to buy a Florida plane.....:yikes::D:ohsnap:
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I have owned and flown my aircraft for 3 years in Florida, sump before every single flight. Have not seen water in the tanks ever, up to now. :nono:

Cheers
 
80*F out, water is about 50*F out of the fridge.

I'd go bigger but my boss probably wouldn't approve of me watering 40gal of 100LL for the internet
 
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So how do you even get past the run up without the engine dying?
 
The C172 had about 1/4 fuel in each tank....per the reliable gauges. We then went to the fuel farm to refuel. I'll bet that the water came from the huge fuel tanks that were there.

During the run up, the initial mag drop on the left mag was about 500 rpm. The CFI said anything within 300 was ok, but the POH says 150. Even after the sumping, we spent about 10 minutes trying to purge the water from the system by doing full power run-ups.....I've never seen that done. With a 500 rpm drop, boy, was the airplane shaking.

I'm glad to hear all the war stories posted above. Based on my experience with water and all the postings, I cannot understand why anyone would just jump in an a/p and go. PS: I also rock the wings after a refuel and wait about 10 minutes so that the water can settle to the low points in the system.

Thanks for all of your comments.
 
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