Sub-zero gas sumping

labbadabba

labbadabba

Pattern Altitude
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Lawrence, KS
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labbadabba
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KIXD, KLWC
If there is residual water settling into to sump in sub-zero temps, will it freeze?

I could see this being an issue if so...
 
No problem. It's colder at altitude so it'll stay frozen in place and not cause any trouble.

Just don't fly south.
 
So, if we're not using an alcohol-based fuel treatment, how cold is too cold to check the sumps? The idea of clogging the gascolator with slush doesn't appeal to me but neither does the idea of jamming the drains open due to ice in the sump.
 
When it is cold enough to freeze water, I won't sump. If there is a problem, it will show itself during the warm up and run up.

Don't ask me how I learned to not sump when everything is frozen.....
 
Water freezes at 32* F. That's a pretty good threshold for sumping/not sumping. My quick drains are frozen solid from October until April.
 
Stewartb said:
Water freezes at 32* F. That's a pretty good threshold for sumping/not sumping. My quick drains are frozen solid from October until April.
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I mean, duh, water freezes below 32*. I did my initial training at KHPN and live in KS where we definitely have winter and I've not heard this from my CFIs. We always just checked the sumps as normal. The only real cold-weather consideration was cold engine start procs.

What you're saying makes total sense, but just trying to figure out with the myriad of CFIs I've had over the years, I've not once had one tell me not to sump the gas below 32*.
 
Pure water freezes at 32. The freezing point is depressed in proportion to the molecular weight of the solute. I've seen people try to work quick drains in colder weather only to find that the freeze while open.

Frankly, I'm happy to have a heated hangar now.
 
labbadabba said:
but just trying to figure out with the myriad of CFIs I've had over the years, I've not once had one tell me not to sump the gas below 32*.
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Lack of experience on the instructors? I never had an instructor tell me not to sump below 32 degrees, not until I went to Alaska.
 
This whole topic has me concerned too. I have yet to meet someone at the airport or a CFI who was like "Don't sump that tank!!!!...its below freezing." And we're the nut jobs who want to fly when its like -10F. Yet many here are quite adamant and have actual experience with this.

So lets say we bypass sumping the tanks and the lowest level sump under the engine. What are the odds the engine would run during warm up, run-up and taxi but fail on take off due to water in the fuel? Can isopropyl be added? Will it wreck fuel bladders? Do the North Korean's get Netflix? ...too damn many questions for a newbie pilot :eek:

flyingron said:
I'm happy to have a heated hangar now.
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:mad: ...that really is the answer though.
 
Remember to put the EPA fast response team on "speed dial" if you want to sump below freezing.
 
So here's one for ya....if all goes well I will do my PPL checkride sometime soon this winter. It will most likely be somewhere between 5F..20F. Do I sump or not when the DPE is monitoring the pre-flight?????????????????????????
 
If you do happen to have a brain fart and have a quick drain stick and drip? A blow dryer works to thaw the ice and allow the drain to seal. That's a pirep. We learn from our mistakes. ;)
 
Sinistar said:
Do I sump or not when the DPE is monitoring the pre-flight?
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I don't recall being "monitored." I'm pretty sure I did the whole preflight and gathered up all the logbooks prior to his arrival. After the oral was completed he said "let's go fly" (which is secret code for "you're about to be a pilot") and when we got to the plane he asked a couple of questions about what I had done for preflight but he didn't have me re-do it.
 
Ravioli said:
I don't recall being "monitored." I'm pretty sure I did the whole preflight and gathered up all the logbooks prior to his arrival. After the oral was completed he said "let's go fly" (which is secret code for "you're about to be a pilot") and when we got to the plane he asked a couple of questions about what I had done for preflight but he didn't have me re-do it.
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From my experience they do watch and ask questions as one preflights. Be able to explain what you are checking and for what. Know which antenna does what, stuff like that.
 
Stewartb said:
If you do happen to have a brain fart and have a quick drain stick and drip? A blow dryer works to thaw the ice and allow the drain to seal. That's a pirep. We learn from our mistakes. ;)
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Thats a no-go too! Hair dryer motors like vacuum motors, will light off the fuel vapors! -Skip
 
Blow dryers blow the fumes the other way. Like I said....pirep.
 
mscard88 said:
From my experience they do watch and ask questions as one preflights. Be able to explain what you are checking and for what. Know which antenna does what, stuff like that.
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Interesting. So the message to @Sinistar is to talk with your CFI about how your DPE will be doing things. They'll be able to answer much better than SGOTI.
 
Ravioli said:
Interesting. So the message to @Sinistar is to talk with your CFI about how your DPE will be doing things. They'll be able to answer much better than SGOTI.
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SGOTI?

It depends on individual DPEs also. But I imagine even if they're not out with a student watching the preflight, they're somewhere else watching, maybe while enjoying a cup of coffee. :D
 
Sinistar said:
So here's one for ya....if all goes well I will do my PPL checkride sometime soon this winter. It will most likely be somewhere between 5F..20F. Do I sump or not when the DPE is monitoring the pre-flight?????????????????????????
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If he want you to do a pre-flight then Yes Sump.
But most of the time you pre-flight before he gets there.

Good Luck with your test!!!
 
Stewartb said:
Blow dryers blow the fumes the other way. Like I said....pirep.
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And suck air in from the other end, but yes, I have seen mechanics in Alaska use a heat gun on fuel sumps in a closed hanger.....but I only watched them for a second before I felt a strong need to go outside and look at the stars.....:loco::lol:
 
Zeldman said:
And suck air in from the other end, but yes, I have seen mechanics in Alaska use a heat gun on fuel sumps in a closed hanger.....but I only watched them for a second before I felt a strong need to go outside and look at the stars.....:loco::lol:
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Just have a pilot breathe on it. The hot air should thaw it in no time... :)
 
Who has a hangar? No freeze problems in those heated spaces. I park outside and preheat (or blow dry) using a generator. Anyone here ever use a Red Dragon pre-heater? Literally a propane flame thrower with a 12v fan to blow the air into the cowl. Guys use those all the time. Me? I watched a Red Dragon start my Cessna on fire once. Never again. A blow dryer to thaw a quick drain? That's pretty simple to do safely.
 
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Stewartb said:
If you do happen to have a brain fart and have a quick drain stick and drip? A blow dryer works to thaw the ice and allow the drain to seal. That's a pirep. We learn from our mistakes. ;)
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Sure, run a cheap, sparky motor in close vicinity of gasoline fumes. Kaboom!!!
 
49XW77_AS01
 
When you live long enough where crap freezes up? You find ways to deal with it. Me? I don't touch my sumps in cold weather. Isopropyl in the fuel works better. But if I need to apply heat..... ;)790C4CDA-02FA-4CBD-80B8-F09218574C4C.jpeg
 
So, back to the topic.

If water is frozen inside the sumps, does that pose an operational hazard? Or will it simply remain frozen? Could slushy water end up in the gascolator or fuel lines and cause problems?
 
It should stay frozen. It usually starts as ice crystals in the fuel and settles out into a layer of rime ice around the sump. In some cases you may get some ice in the finger screens and even into the strainer. I've never had fuel restriction myself but once you see it? Isopropyl sounds like a really good idea. Unless you do a good enough engine compartment preheat to warm the strainer that might be better left alone, too. There was another thread about it about a week ago with some good info and less BS.
 
A frozen quick drain suggests that there was water in the fuel that had melted for whatever reason & migrated to a quick drain location. If the initial a/c tank water was in the form of dissolved water in delivered fuel that was chilled, a small amount of isopropyl alcohol should keep it in solution so that it will pass thru the gascolator screen.

If the water simply leaks in through crappy fuel tank filler seals that's another case and the amount of water that could be present is much greater. If that water freezes next to a quick drain, it probably won't plug the gascolator. I don't want to go there except to fix the filler seals ASAP.

Each case may be different. Our case (described in another thread) the gascolator definitely plugged with ice crystals forcing the failed takeoff. In that case the airplane had been stored in an unheated -20 degF hangar yet the quick drains were free. After the incident, in cooler weather we started adding a few tablespoons full of isopropyl alcohol after every refueling. Sometimes we would get a few drops of liquid alcohol/water out the quick drains nut otherwise we never experienced frozen ones.

To me, iced quick drains suggest the need for a review of alcohol additive procedures. It doesn't normally take a lot, unless you have leaky caps or are pumping in water.

The very best is to cool the fuel as much as possible before filtering and adding it to an airplane. Q - stewartb from AK, are you fueling from an overhead/exposed tank?
 
I carry a 100 gallon avgas tank in my pickup. My own tank is double filtered. The bulk tank where I buy fuel is above ground and double filtered. It doesn’t rain much in Alaska in winter plus I use wing covers so no water gets to my fillers yet I ALWAYS have ice in the quick drains. I explained why in the other thread. That’s why I use 12 oz of isopropyl fuel deicer per 10 gallons of fuel for winter ops and occasionally in the warmer seasons, too.
 
What happens if you dont sump and take the plane to somewhere warm? Some planes with tip tanks could easily take off from say Chicago which is -5 right now, and not stop until Texas-type place. Would the ice melt upon descent and cause issues, or would it be used as the fuel is being drained during flight?
 
I think It depends on the temperature history of the fuel. If it was refined & delivered to the FBO always above say freezing, put in your tank & flown at -5 degF, moisture in the fuel will come out as snow crystals which could at some point plug your gascolator screens. A few gurgles of isopropyl alcohol added before flight would keep the ice crystals in liquid solution where they would successfully pass thru your gascolator.

All bets are off if the fuel cap seals on your tanks previously allowed rainwater to leak in. And if the FBO has water in the bottom of his tanks the fuel will become saturated with water at that temperature. My contention is that the fuel/water system will behave like a small weather system, precipitating water, ice or ice crystals as it is chilled.

This all assumes there is no water or frost accumulation from atmospheric breathing into the fuel vents. At cold temperatures (less than 32 degF) the amount of water present (i.e. the absolute humidity) in air is very small, and there is little opportunity for it to condense inside your tank.

Later - liquid water doesn't create my type of problem as a small amount will pass through the engine with only a burp. It is ice crystals that permit a minute amount of ice to plug a gascolator and stop the show. Note the pictures from the FAA of the collapsed fuel filter from the Bonanza in my article referred to in the other postings. By the time the picture was taken, engine heat had melted the evidence.
 
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(THX for bstewart's posting.) I wonder though, where his water that freezes in his quick drains is coming from? He is using what I think of as a massive amount of isopropyl alcohol.
 
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