Sump the pump

Peter Ha

Peter Ha

Pre-takeoff checklist
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Nov 18, 2019
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Leadpan
Hey folks,
Yesterday spoke to local pilot who crashed due to engine stop at 200ft.
VERY lucky he survived. Among few injures (head trama, broken wrist,ribs fracture,broken-foot, busted-lips) the yoke broke off during impact and the broken shaft nearly PIERCED his heart.
There were several weeks of rains and the plane is parked outside without cover.
He said the problem was... water in tank.
Lesson learned: pre-flight and sump tank.

https://www.nbclosangeles.com/news/local/two-people-injured-in-corona-plane-crash/2348650/
 
Cessna tanks can hold onto a crapload of water. No guarantee he didn't sump. Plenty of anecdotes of people getting all kinds of water in the tanks.
 
Parked outside for 25 years. Water was common in my sumps, but never more than a tbsp. Not from rain. From condensation.

I was taught that even on floats in flowing water where preflighting is difficult you always sump the tanks and strainer and always check the oil.
 
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steingar said:
Cessna tanks can hold onto a crapload of water. No guarantee he didn't sump. Plenty of anecdotes of people getting all kinds of water in the tanks.
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Yeah, on the other thread about this I noted that my only emergency was a 150 ceasing to run after liftoff, due to water. A lot of water, too much to run. And I did sump the tanks, always do.
 
Maybe I am weird or perhaps even anal, but in addition to always sumping my tanks before flight (and I am in a hangar), I always do it again after refueling as well. It’s amazing to me to watch other pilots refuel who just jump in and go apparently without a thought there might be water in the fuel supply. I know the probabilities of that are low, but if it’s going to happen to anyone, it’s likely to be me.
 
Jumpmaster said:
Maybe I am weird or perhaps even anal, but in addition to always sumping my tanks before flight (and I am in a hangar), I always do it again after refueling as well. It’s amazing to me to watch other pilots refuel who just jump in and go apparently without a thought there might be water in the fuel supply. I know the probabilities of that are low, but if it’s going to happen to anyone, it’s likely to be me.
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i was taught to sump every time after refuel, i do see a lot of people, put fuel and jump in the plane and take off. out here in Bismark there was an accident (long ago i think, can remember) and the cause was crap load of water in the fuel. something else my primary CFI hammered in my head ... to check oil... whenever we stopped for anything at an airport. i still do it ...well most of the times :p
 
Wouldnt one need to let it set at least a short bit after fueling to be accurate?
 
Jumpmaster said:
Maybe I am weird or perhaps even anal, but in addition to always sumping my tanks before flight (and I am in a hangar), I always do it again after refueling as well. It’s amazing to me to watch other pilots refuel who just jump in and go apparently without a thought there might be water in the fuel supply. I know the probabilities of that are low, but if it’s going to happen to anyone, it’s likely to be me.
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Huckster79 said:
Wouldnt one need to let it set at least a short bit after fueling to be accurate?
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If I need to add fuel before a flight, I do it before the biological break. After the biological, and maybe a snack and a bottle of water, sump the tanks.
 
My primary instructor told me "Never skip an opportunity to check the fuel and the oil." I never do. And when you fuel, give it some time to settle before sumping.
 
In the Comanche world (Twin Comanche especially) a very common cause of engine failure -- sometimes temporary failure -- is water in the fuel. I give each tank a good ten seconds of sumping on the preflight, even though my plane lives in a hangar.
 
I pre-flight everything but NOT on flying day. I actually like pre-flighting. I take my time, and I don't have the distraction of someone with me or the time pressure to get up in the air because others are going to a lunch, etc.
On flying day, I sump the gas. Fortunately I am in a locked hangar. Works for me.
 
Adding a little MMO to the fuel serves to highlight any sumped water. The red dye in MMO binds to water. Try it sometime.

I’ve aways preferred the wider, shallower sump cups for checking fuel. It makes it easier to recognize water.

Wanna have some fun with a friend? Make a small note like you did in grade school and tuck it somewhere on your buddies plane where he should find it during a good preflight. See if he finds it.
 
I had an incident last year where my low-wing was parked outside on the ramp and refueled. I sumped as I always do, but it was ALL water. The problem with sumping 100% water is that there's no layer to see the separation. My old plastic tube had been dyed blue over time and who knows how many uses and the ramp air smelled like avgas in general.

I didn't see any layers, I smelled avgas, and I saw blue tint, so I took off.

Thank goodness it was only in one tank but wow...

I now use a glass mason jar that won't dye blue and I can stick my nose in the thing. Even though I'm in a hangar now, I still sump prior to every flight and refuel. I'm never making that mistake again.
 
Problem with sumping just after you fuel is the water is all churned up. Can take upwards of a half hour to settle, or so I've been told. I usually don't sump just after fill up, but instead wait until the aircraft has sat awhile. I used to find a bit of water here and there on my 150. Found water once in the Cherokee. So far not a drop out of the Mooney.
 
AU_James said:
I had an incident last year where my low-wing was parked outside on the ramp and refueled. I sumped as I always do, but it was ALL water. The problem with sumping 100% water is that there's no layer to see the separation. My old plastic tube had been dyed blue over time and who knows how many uses and the ramp air smelled like avgas in general.
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See post Sump the pump above, and follow the link to that thread. I pulled ~25 samples of pure water before I started getting gas. My old crusty CFI taught me when in doubt, pour the sample across your fingers. Water dries clear but takes a while, avgas dries quick and leaves white residue on your fingers, jet A doesn't really dry and feels oily.
 
Stewartb said:
Adding a little MMO to the fuel serves to highlight any sumped water. The red dye in MMO binds to water. Try it sometime.

I’ve aways preferred the wider, shallower sump cups for checking fuel. It makes it easier to recognize water.

Wanna have some fun with a friend? Make a small note like you did in grade school and tuck it somewhere on your buddies plane where he should find it during a good preflight. See if he finds it.
Click to expand...

Wow, i didn't know this. Been using MMO for few months; but didn't know it binds to water!
Thanks for info!
 
Jumpmaster said:
Maybe I am weird or perhaps even anal, but in addition to always sumping my tanks before flight (and I am in a hangar), I always do it again after refueling as well .
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As do I. Even If I just did it, and called for fuel I re sump it to make sure that its not Jet A or H2O in there. I dip the finger rub it, feel for evap, or greasy, and than a quick waft to see if I smell something different.
 
Bill Jennings said:
See post Sump the pump above, and follow the link to that thread. I pulled ~25 samples of pure water before I started getting gas. My old crusty CFI taught me when in doubt, pour the sample across your fingers. Water dries clear but takes a while, avgas dries quick and leaves white residue on your fingers, jet A doesn't really dry and feels oily.
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Water that's been in a tank for a long time can take on the blue color and smell like avgas. One really needs to look after his airplane, and when just going to the airport to check that it's OK it doesn't hurt to sump the tanks, especially if it's tied down outside.
 
Jeremy Billeaudeaux said:
As do I. Even If I just did it, and called for fuel I re sump it to make sure that its not Jet A or H2O in there. I dip the finger rub it, feel for evap, or greasy, and than a quick waft to see if I smell something different.
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Your fueller should have water-stop filters on his pumps. Those things have been available for many years already. They simply won't pass water, and when they're full of it, the fuel flow stops. The filter media absorbs and holds water, swelling in the process.
 
WannFly said:
... i do see a lot of people, put fuel and jump in the plane ....
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I fuel AFTER landing and sump prior to flight, gives the water time to settle ... on trips, I fuel and then pay, then head to the restroom, then snacks/fluids then sump just to give it at least 20-30 minutes.
 
steingar said:
Problem with sumping just after you fuel is the water is all churned up. Can take upwards of a half hour to settle, or so I've been told.
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I have heard that, and even said that to students, many times in the past. However, when showing samples of a fuel/water mixture in sealed glass jars, no matter how hard I shake them, they always settle almost immediately. I have never had one take long, let alone the standard "15 minutes" for the separation to occur...

:dunno:
 
smv said:
I have heard that, and even said that to students, many times in the past. However, when showing samples of a fuel/water mixture in sealed glass jars, no matter how hard I shake them, they always settle almost immediately. I have never had one take long, let alone the standard "15 minutes" for the separation to occur...

:dunno:
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Even if it settles immediately, how quickly does it run down the bottoms of the tank to the sump valve?
 
Bill Jennings said:
Even if it settles immediately, how quickly does it run down the bottoms of the tank to the sump valve?
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It is water, not molasses. :D

Here's a way to visualize the process without jeopardizing aircraft safety. Get a paint roller tray, a quart or so of AVGAS, and a cup or two of water. Shore up the paint roller tray to approximate the angle on the bottom of your fuel tank. Dump the liquids into a large glass jar and shake them real well. Pour the mixture into the upper part of the paint roller tray and see how quickly it separates and for the water to end up at the bottom. Likely you will see some bits of water hanging out in the "washboard" recesses. This can simulate the undulations found in the bottom of some fuel tanks. Give the roller tray a jiggle to simulate shaking the wing to force the water off the bumps. See how much it takes to shake it loose and how long it takes to move to the bottom.
 
Bill Jennings said:
True, but it’s water moving in a fluid much more viscous than air.
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It is AVGAS, not molasses. :rofl:

Sure, it will not accelerate at 32/fps/s as it would in a vacuum, but it still moves pretty quick.

Dribble some water into a clear container of AVGAS and watch how quickly it settles.
 
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