Cold WX operations

Richard

Richard

Final Approach
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Ack...city life
Your plane is kept outside and subject to ambient air temp. In below freezing temps do you sump the fuel tanks? Why?

(For the sake of this thread, set aside the perception of foolishness of flying in temps blo freezing.)

Here is why I ask why: any water in the tank would be in a solid state, therefore would not be 'sumpable'. The absence of water in the sumped sample would not be an indication of no water in the tanks.

Now consider the same scenario except the plane is kept in a heated hanger. In this case, the water would be in a liquid state and be detected when sumping.
 
Richard said:
Your plane is kept outside and subject to ambient air temp. In below freezing temps do you sump the fuel tanks? Why?

(For the sake of this thread, set aside the perception of foolishness of flying in temps blo freezing.)

Here is why I ask why: any water in the tank would be in a solid state, therefore would not be 'sumpable'. The absence of water in the sumped sample would not be an indication of no water in the tanks.

Now consider the same scenario except the plane is kept in a heated hanger. In this case, the water would be in a liquid state and be detected when sumping.
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In vary cold weather ops here is what to do. Rent a heated hangar for a night or two, warm the aircraft, sump the tanks and add 12 oz of alcohol per 10 gallons of gas. drain all static low points.

buy a large funnel, and manufacture a chamos filter to go in the bottom of the funnel. use it every time you gas up, even from the truck or pumps, because the truck or below ground tanks could be delivering fuel that has water in it that will form balls of ice that will plug your fuel lines.

OBTW the alcohol will not harm you aircraft in a one time use.
 
Richard said:
Here is why I ask why: any water in the tank would be in a solid state, therefore would not be 'sumpable'. The absence of water in the sumped sample would not be an indication of no water in the tanks.
Click to expand...

Water can exist as a liquid in the atmosphere down to -20°C. I don't know if it could get that low as entrained or free water within fuel, but I wouldn't be surprised if it hit -10°C before it froze. See
http://en.wikipedia.org/wiki/Supercooling

Many gasolines have at least a tiny bit of alcohol present. Seems to me that for aircraft it must be less than 1% by volume but the Avgas MSDS doesn't mention it at all. Even a smidgen, if it's there, is going to mix with small amounts of entrained water and disperse it.

That said, I have seen "snow" in cold fuel, which is frozen entrained water. It does tend to settle into the sump, slowly, and if I see it I drain until the sample is clear. I can't remember ever finding the sump valve frozen shut by a gob of ice in the sump.

Dan
 
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I still want to sump to confirm the correct fuel color.
 
Ice crystals in fuel>engine compartment temps>h2o in liquid state

Larger ice crystals>fuel lines>starvation

It is a less than ideal situation. IMO, like Tom says, best to purge your fuel tanks of water the best you can once then do your darnedest to keep h2o out for the rest of the winter.

One concern is having your drains freeze open while checking. I've never had that happen and I imagine it is pretty rare and only possible in a narrow range of conditions.
 
most fuel tanks have a finger strainer as the fitting that the fuel line to your engine attaches to. this screen prevents ice from exiting the tank. any partical of ice that is small enought to get thru the screen, is small enough to go all the way to the carb bowl and be fed to your engine.

Your only hope of catching it is the gascolater's colessing screen.

but once in the carb it will melt and be fed to your engine as water and you will probably never know it went thru.
 
gprellwitz said:
How would you do that without creating a fuel spill?
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Well you're probably familar with the technique. There is one important modification and that is to locate the target visually rather than using your shins...:D
 
NC19143 said:
You should be checking the color when you are putting fuel into your tanks not after .
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How do I do that? all airports I've bought fuel at the past 3 years has a fuel truck. I check the signage on the truck as it pulls up to confirm the correct fuel type.

I agree it would be ideal to confirm what's in the truck is the correct fuel before it gets into the tank, but that's hard to do generally.
 
Another pice of advice.... When sumping the 23 sumps on a new 172 on a cold and windy winter day, make sure to be upwind of the quick drain. 100ll tastes bad, and makes a sub-zero windchill just that much worse :D.
 
high of 5 today, -2 tomorrow. I think I'll stay inside and bake cookies...
 
Ugh! Cold weather ops = rising at 05:15, snowblowing out the driveway and common drive so I can get out. The drive to the City's #2 hospital takes 30 minutes. Make rounds. Drive back across town to office. By the time the OR opens, I've already put in half a day.

Sigh.
 
bbchien said:
Ugh! Cold weather ops = rising at 05:15, snowblowing out the driveway and common drive so I can get out. The drive to the City's #2 hospital takes 30 minutes. Make rounds. Drive back across town to office. By the time the OR opens, I've already put in half a day.

Sigh.
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I feel your pain no more. Lay in bed until 0820, get up, make coffee, climb stairs, in office by 0830. Pray for 2" of snow so driveway and sidewalk are plowed and shovelled for me.
 
Richard said:
Your plane is kept outside and subject to ambient air temp. In below freezing temps do you sump the fuel tanks? Why?

(For the sake of this thread, set aside the perception of foolishness of flying in temps blo freezing.)

Here is why I ask why: any water in the tank would be in a solid state, therefore would not be 'sumpable'. The absence of water in the sumped sample would not be an indication of no water in the tanks.

Now consider the same scenario except the plane is kept in a heated hanger. In this case, the water would be in a liquid state and be detected when sumping.
Click to expand...

Wouldn't the sump be the lowest place in the tank? If it is frozen would you get anything at all? If it is frozen and not obstructing the flow how would it get to the engine? It would be a block of water like a rock. I would be more worried about the plane sitting inside the heated hanger then going outside in freezing temps. (Water not frozen then once plane moves water moves towards the outlet then freezes.) In the winter I sump to check for flow and contaminates same as in the summer.

Dan
 
Richard said:
Your plane is kept outside and subject to ambient air temp. In below freezing temps do you sump the fuel tanks? Why?

(For the sake of this thread, set aside the perception of foolishness of flying in temps blo freezing.)
Click to expand...

I learned to fly in Wisconsin, in winter, and I've flown year-'round ever since. Some of the very best flying weather occurs in winter, when those giant bubbles of Canadian high pressure settle over the upper Midwest. The folks who park their plane in October and don't open the hangar until April are truly missing the very best flying of the year.

That said, it's -24 degrees Fahrenheit as I'm typing this -- the coldest I've ever seen in Iowa. Even I'm not crazy enough to fly today -- although I would, if I had a pressing need to be anywhere. The Pathfinder has an awesome heater, but the pre-flight can be brutal, so our brunch plans will have to wait.

We use car gas exclusively (well, except when we're on x-country flights, of course) and have never had any trouble flying in extreme cold. We, of course, pre-heat our engines (the Pathfinder has sump and cylinder-head heaters, while the Ercoupe only has a sump heater), but otherwise our winter ops are no different then in summer. Sump all four tanks, check for contamination, and go fly.

Ice crystals are always present in fuel -- avgas or mogas -- at extremely cold temperatures. When you hold the sump up to the sun you can see them reflecting the light, but they are extremely small and have never (yet!) presented any trouble. The notion of running 84 gallons of gas through a cheesecloth is...scary. The very real danger of static spark in the extremely dry air far outweighs the perceived danger of ice contamination, in my humble opinion.
 
vontresc said:
Another pice of advice.... When sumping the 23 sumps on a new 172 on a cold and windy winter day, make sure to be upwind of the quick drain. 100ll tastes bad, and makes a sub-zero windchill just that much worse :D.
Click to expand...

Exactly. I use the Sporty's tester with the little bowl to catch the spray, but it doesn't always work, especially with the winds we've been having in WI.

My cold Wx strategy? I had an IR flight scheduled last night at 0100Z, but told my instructor I didn't want to come out and play - minus 20 wind chill. The takeoff roll is dicy when you can't feel your fingers, though the 172 does warm up nicely at some point.
 
>though the 172 does warm up nicely at some point.

a 172 will warm up? sure, in the spring. :-/
 
Bob Noel said:
>though the 172 does warm up nicely at some point.

a 172 will warm up? sure, in the spring. :-/
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I don't know - last week I was sweating through a localizer approach with a 70 degree 35kt crosswind trying to stay within the PTS for my CFII. That little box of aluminum sure felt warm to me!
 
-40 wind chill. another day of sitting inside!
 
Bob Noel said:
>though the 172 does warm up nicely at some point.

a 172 will warm up? sure, in the spring. :-/
Click to expand...

I started my flight training in February (got chased back to the airport by a snowstorm on my intro flight, in fact!) and I don't recall the 172 being that cold. Yeah, it's cold until you get up in the air and get the engine working and the air moving, but it warms up very quickly after takeoff.

The 182's heater is actually good enough that if I leave it on high, the floor vents are hot enough to literally burn my feet through my shoes if I forget to turn it down. It also melted my IFR Flight File that was sitting in the side pocket.

Jay's right - The flying this time of year is awesome. Usually, the air is very smooth (no thermals at all), the exception being when winds are really bad (low-level mechanical turbulence) or there's a shear layer aloft, but an altitude change will fix that. Engines, props, and wings love the thick air. Visibility is phenomenal.

Wish I had some money sitting around, I'd go fly. :frown2:
 
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