Sumping fuel in the desert/preflight checklists?

BillTIZ said:
Sounds like an older Cherokee 6. I'd have to find my old checklist, but I think draining each tank for a minute, move fuel selector, drain again, was the key to the 6.
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First year Comanche.
 
Gilbert Buettner said:
Which is worse, having the fuel evaporate into the atmosphere, or burning it and having it go into the atmosphere?
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100LL becomes hazardous waste when not burned in an engine or contained in a fuel tank. The lead additive is corrosive to ramp surfaces and carcinogenic to humans.

Florida takes an especially dim view of dumping slumped fuel on the ramp and you can be fined for doing so.
 
expensive as avgas is, it's going right back in the tank.
 
Zeldman said:
Then again, winter in Alaska we never sumped. Why.?? Because ice may get stuck in the sump when it is open, and drain the fuel out.

What did we do.??

We added isopropyl alcohol into the fuel while fueling up.
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In winter in the Midwest growing up, we'd always have a bottle or two of HEET when the car started running poorly. Winters were often full of wet snow. What is this mystery thing called HEET? 99% Methanol
Probably would have been cheaper to use Isopropyl, but was easy and convenient enough to use HEET.
 
Another source of water for those dealing with sub-freezing temperatures - Years ago, I had a warm 172H engine fail immediately after liftoff at KFCM in bitterly cold weather. I ended up tear dropping to a parallel runway landing down wind, never having left the boundaries of that airport.

A 1 qt fuel sample, would show tiny number of ice crystals appearing as "snow" which had plugged the gascolator screen apparently during the immediately previous 1 hr flight.

Conversations with Amoco uncovered some dissolved water charts from the 1930s for various hydrocarbons. The amount of water that could be fully dissolved varies with temperature. Chilling fuel reduces the amount of water that can be held in solution. Comparing this relationship with the Minnesota FBO's underground tanks suggested that our aircraft's fuel had been chilled in our unheated hangar, such that enough water had come out of solution to create the snow crystals and blocked the gascolator screen. In summary.....

Beware of fuel that has been severely chilled since it was refined. A small amount of deicer immediately before flight should help take care of this source of the problem.WaterSolubilityInGas.JPG
 
Gilbert Buettner said:
Which is worse, having the fuel evaporate into the atmosphere, or burning it and having it go into the atmosphere?
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long chain HCs and that wonderful tetraethyl-lead or H2O, CO2, CO, various NOx, PBOx and fewer long chain HCs....hmmm.
 
Water’s not the only thing you sump for… so yes, sump in dry enviros.
 
I sump before every flight, even a lunch stop because you never know where water may migrate to and it may not make it to the low spot until sloshing around in flight. I once discovered jet fuel in the tank during a preflight, so agree with the above post, it's not always about water contamination...
 
Gilbert Buettner said:
Which is worse, having the fuel evaporate into the atmosphere, or burning it and having it go into the atmosphere?
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A question to keep the greenies busy. :D

One is unburned hydrocarbons, one is CO2. :D

One other issue with dumping on the ground is that is seep into the ground instead of evaporating and contaminate the water table. If I sump without a GATS jar, I fling it, so most evaporates before it hits the ground. This is also better for the asphault.
 
I guess one could always flare it off like they do at the oil wells …..
 
I always sump on first flight of the day, and by that I mean my first flight. I once had 2 tubes of water in one tank on a Cherokee that I watched an instructor land 10 minutes before. I asked him if had switched tanks at any point. He said no. I don't know if it's leaky gaskets on the filler, or just that it's so humid around here all the time, but I've had water more than a few times, in different planes.

In the winter here, we don't sump either. Then I start, taxi, and run up on the same tank, and I do my first tank switch high over an airport. But I'm a big baby when it comes to most things.
 
It only takes 1 time of not sumping + 1 time of water.

Better to have sumped 1000 times and not found anything, than to have not sumped that once and wishing you had…

As for the enviro, if I had water in the sample and it’s not going into the tank, that one time going on the ground or in soil is no big deal in the grand scheme. If I worried about it that much, then I shouldn’t be running this lead burner. Take commercial or drive. My career is enviro.
 
When I had my harrowing winter ice experience, it was with a warm airplane that someone else had just flown for the previous hour. We did refuel from underground tanks at the resident FBO - and that's where I would guess the water/snowflakes came from. When confronted with a flaky sample after surviving our engine failure, the FBO had already sampled their underground tank again and confirmed no visible water separation. Of course this fuel was probably still at 45 degF, as cold as it had ever been since being refined in Texas. Our airplane was stored in an unheated Minnesota hangar.

That's when I contacted Amoco and received the graph in post 45 above. I then started to experiment with MoGas on the back porch (this was before Ethanol laced fuels), and found that yes, there were a number of ice crystals in MoGas delivered fuels that could be trapped with a simple screen, IF the fuel was severely chilled. The amount of water required to block fuel flow is much much less if it is in the form of snow. It gets trapped in the screen - not as a blocking slug at the bottom of the gascolator cup.

This was about 1972. The local GA Accident Prevention Specialist noted "there are some things about water-in-fuel we just don't understand". He already had investigated an earlier Bonanza crash that showed a lot of evidence of similar gascolator icing.

Again I suggest a small amount of fresh deicer before flight at sub freezing temperatures.
 
Clip4 said:
The lead additive is corrosive to ramp surfaces and carcinogenic to humans.
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The lead is not the problem with ramp surfaces. Unleaded fuels have the same issues.

Asphalt is small stones held together with tar. Gasoline softens and damages the tar.
 
It ain’t what you don’t know that gets you into trouble.

It’s what you know for sure that just ain’t so.
 
i learned the isopropyl alcohol trick as Zeldman mentioned. nothing worse than a stuck fuel drain .
 
BravoCharlieFoxtrot said:
Howdy y'all,

Did all of my training out of Ohio. I was trained to and have always properly sumped the aircraft before every flight. Even with weeks of no rain, I've caught water out of the tanks right after fueling - pretty sure it came from the fuel truck.

I recently moved out west to a really dry area, and went up with an instructor for a flight review/rental checkout. I have almost 300 hours and am working on commercial now.

When we get out to the aircraft (172), the instructor was eager to show me his no-checklist preflight "flow," which already rubbed me the wrong way. I understand having a flow can be valuable, but not using a checklist (even just to check things off after the "flow") as an instructor for a first flight, from a rental company/flight school, seems bizarre. At the end of his preflight demonstration, I noticed he hadn't bothered to sump anything. When I asked about it, he looked around and pointed out how dry it was, but said that I could if I wanted to (I did).

Just wanted to gather opinions on preflight flows vs. checklists as well as fuel sumping practices.
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He's an idiot and is a poor reflection of competent flight instruction. And then we wonder why people take off with sediment in tanks, control locks in place, etc. What a disgrace!

For what it's worth, I love having a flow, but, always back it up with a check (read, not a TO DO) list
I always sump before a flight.. it's not just water, it could be sediment, deteriorating rubber items in the tank you find, and it's a great way to visually see the fuel level. Plus, you deviate from your flow once, and habitualize it, then one day your not flying in the desert and you skip the sump and you have an accident.

Find someone else to fly with, or even a different club.. this is not a great reflection on the club in my opinion.
 
EdFred said:
I'm not gonna lie. I don't sump. I haven't sumped in 14+ years. Why? Because the only place to sump the fuel requires sliding under the plane on my back, opening up a hatch on the belly, and then getting to the sump.
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been a while since I quoted a post of yours! Our club Comanche is the same. To me, it's worth the hassle. I'm less worried about water, and more about other "crud" that could get jammed up in the fuel system somewhere. I agree the sumping is a hassle, and it is also problematic on the Aztec and twinkie. But I still sump.

For the OP; if individual owners want to develop their own flows, that's their own choice to make. For a CFI at a plane checkout in a new club to a new renter.. I think it shows a terrible example
 
EdFred said:
I'm not gonna lie. I don't sump. I haven't sumped in 14+ years. Why? Because the only place to sump the fuel requires sliding under the plane on my back, opening up a hatch on the belly, and then getting to the sump.
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I'd wager most people in a low wing don't sump at the most important point, which in many cases is going to be in a location like you described. Sumping at the tanks isn't going to catch everything.
 
Salty said:
I'd wager most people in a low wing don't sump at the most important point, which in many cases is going to be in a location like you described. Sumping at the tanks isn't going to catch everything.
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My C150 had an aftermarket quick-drain valve installed under the belly, I believe at the fuel shutoff valve. The aircraft came from the factory with a rubber plug at this location, which is slightly lower than the gascolator. Guess where I always found water...

I don't believe Cessna put quickdrains at this point in any of their aircraft until the restart 172 R and S models.
 
Our 172M when new had only a pipe plug drain on the fuel selector too. Wonder how they got by with it for so many years? Replaced with a quick drain.
 
Salty said:
I'd wager most people in a low wing don't sump at the most important point, which in many cases is going to be in a location like you described. Sumping at the tanks isn't going to catch everything.
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The Cherokee had an easy to reach low point. I sumped every time.
 
EdFred said:
The Cherokee had an easy to reach low point. I sumped every time.
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Ed:

Lost one friend to an un-sumped Comanche; rather never lose another.

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