Can temps around 0 cause a fuel leak...

cowman

cowman

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This is on my 78' Piper Archer II...

After a fiasco of getting stranded away from home due to a failed left mag and no-start due to the cold, I plugged my pre-heater in overnight with the intention of starting up warm and leaving the next morning. It was fairly windy and temps were around 0F. This was outside on the ramp- no hangar available.

As I did my preflight I noticed a little gas around the fuel sump quick drain. I then looked closer and found some fuel dripping from inside the cowling somewhere. Apon further investigation the selected left tank was almost 1gallon low(although some of that was undoubtedly missing from attempts to get it started with a bad mag previously). I turned the fuel selector to off aborted the flight until the mechanic could come out and take another look at it. He wouldn't come out until it warmed up above 20.... I don't blame him but :mad2:

When the mechanic came out there was no fuel leak. Turned the selector back on, ran the boost pump, started the engine/ran it up. No more fuel dribble to be found. He said it was probably just due to the cold and was fine. I flew it home, fuel consumption was normal. Aircraft performance was stellar... probably due to the nice cold dense air.

Is this a common thing? It appears to be fine but that answer bugs me. I've had it parked in the hangar and tried to fly on days that cold(my hangar is not heated) and I've never seen a fuel leak like that before. Any reason to worry about it?
 
Not typical in my world. Did you try to drain the sumps and gascolator? That's a bad idea in sub-freezing temps. Any ice will get stuck and prevent the drain from seating. If you sumped then yes, I'd blame the cold.
 
Not common, but a water droplet may have frozen at the base of the sump, wedging itself when the quick drain valve was actuated and preventing the valve from completely seating. After working the valve it eventually reseated itself. Sometimes mechanical stuff doesn't work so well when it's really cold.
 
Stewartb said:
Not typical in my world. Did you try to drain the sumps and gascolator? That's a bad idea in sub-freezing temps. Any ice will get stuck and prevent the drain from seating. If you sumped then yes, I'd blame the cold.
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+1......
 
I have a car like that. 0 and below it leaks fuel at the clamped hoses. Today it is -5 and it leaks. One of these days the remote starter will blow it up in the parking garage :-)
 
The colder "O" rings and other rubber like seals get, the less flexible they get.
The metal contracts and the seals don't adjust to it. May not be what happened to you but we see it all the time on the fuel trucks. Age of the seal material also contributes to its loss of flexibility.
 
doesn't sound like it applies to your situation, but fuel leaks are more noticeable in the winter due to it not evaporating as quickly
 
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Graueradler said:
The colder "O" rings and other rubber like seals get, the less flexible they get.
The metal contracts and the seals don't adjust to it. May not be what happened to you but we see it all the time on the fuel trucks. Age of the seal material also contributes to its loss of flexibility.
Click to expand...

I've seen 20 gallons disappear over a few weeks. The only evidence was a large blue ring residue under the airplane. It was fine till it got super cold outside. The orings were so old in the gascolator they just cracked when removing them (the one on the plunger shaft). The fuel selector and firewall valve were the same way.
 
I have a fuel leak on the drain bowl of the fuel filter on my truck right now.
Old O-rings + cold weather = leak.

New O-rings are on hand. I'll change them this week.
 
IMO fuel leaks due to cold weather are natures way to telling you to fix a looming problem, old hoses, o-rings, seals, whatever. I would deal with it vs. chalking it up to cold and ignoring it.
 
Brad Z said:
Not common, but a water droplet may have frozen at the base of the sump, wedging itself when the quick drain valve was actuated and preventing the valve from completely seating. After working the valve it eventually reseated itself. Sometimes mechanical stuff doesn't work so well when it's really cold.
Click to expand...

Now that you mention that, everything on the plane was stuck from a little ice. When I tried to remove the gas caps, open doors, etc... just a really thin bit of ice in the gaskets that had it all stuck. I also had to push pretty hard against the quick drain valve on the sump to get it to move.... that might have been the case.

Today it's -15F at home. Maybe I should go up to the hangar and look and see if it's leaking again. Maybe this was cold + me pushing on things?
 
So you did sump? What did you expect to find? Ice cubes don't flow through quick drains. If you accidentally do it again a can of isopropyl will fix it but it'll take a little time. In fact being that you proved you have moisture in the tanks you ought to run some isopropyl to eliminate it.
 
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How is ice/moisture getting under the aircraft and up into the sump valve unless water is in the tank? I would find a warm hangar for a day or two, really sump it out good, and figure out how this happened so I could fix it. This is nothing to screw around with IMO.
 
The moisture is inside the tanks. If you ever go to the airport or even to your car and find frost on the surfaces you can bet that your half empty fuel tanks have similar frost on their surfaces. Fill it up and slosh some fuel around and that frozen moisture will come loose and settle into your sumps where it will ultimately coagulate into a lump of ice. Warm the plane and you can sump it but the next time you go out in the cold the tanks will frost again, and since they aren't exposed to moving air they can frost when nothing on the exterior will. Most people in the north will try to keep tanks full to prevent it but we all get it. Isopropyl is common for us. I buy it by the case.
 

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I store my aircraft with the tanks full 99% of the time, on this occasion they were basically full except the left wing being a gallon low from previous starting attempts/the leak. However, it had been parked on the ramp for about a week... I normally am in a T hangar.

So for the isopropyl, do you guys just use the generic HEET stuff available at any auto parts store or does it need to be special aviation grade stuff?
 
Sumping in cold weather is a guaranteed way to make your quick drains seep. It'll stop with a little applied warmth or some isopropyl. Iso Heet in the red container is 100% isopropyl. There are several other brands, too. Don't use the standard Heet in the yellow bottle. Lycoming and TCM both allow isopropyl but you might want to see what your airframe POH says.
 
cowman said:
This is on my 78' Piper Archer II...

After a fiasco of getting stranded away from home due to a failed left mag and no-start due to the cold, I plugged my pre-heater in overnight with the intention of starting up warm and leaving the next morning. It was fairly windy and temps were around 0F. This was outside on the ramp- no hangar available.

As I did my preflight I noticed a little gas around the fuel sump quick drain. I then looked closer and found some fuel dripping from inside the cowling somewhere. Apon further investigation the selected left tank was almost 1gallon low(although some of that was undoubtedly missing from attempts to get it started with a bad mag previously). I turned the fuel selector to off aborted the flight until the mechanic could come out and take another look at it. He wouldn't come out until it warmed up above 20.... I don't blame him but :mad2:

When the mechanic came out there was no fuel leak. Turned the selector back on, ran the boost pump, started the engine/ran it up. No more fuel dribble to be found. He said it was probably just due to the cold and was fine. I flew it home, fuel consumption was normal. Aircraft performance was stellar... probably due to the nice cold dense air.

Is this a common thing? It appears to be fine but that answer bugs me. I've had it parked in the hangar and tried to fly on days that cold(my hangar is not heated) and I've never seen a fuel leak like that before. Any reason to worry about it?
Click to expand...

Cold causes many problems.
 
N801BH said:
Especially if you wear tennis shoes when it is -20 out...:redface::(
Click to expand...

Last time I flew somewhere where it was -20 out I was bundled like the Michelin man and the 310 had Tanis heaters, sleeping bags, and an extra set of batteries from an F-550 Powerstroke 7.3 just in case.

Started on the 2nd blade, both sides. Didn't need the extra batteries.
 
I like it the way I have it. My airplanes have survived outside just fine. All it takes is a little prep and a little know-how. Not a big deal. Life is good.
 
Airplanes are built to withstand temperature's at both extreme's, but 0 CAN cause anything mechanical to have issues. Lot's of good advice above though on more likely culprits.
 
The water (ice) has been pumped into your fuel system when refueling. It is not from air & venting, as the amount of water contained in an air exchange is extremely small in low temperatures.

Fuel comes out of the ground fully saturated with water at maybe 40 degF which is probably the coldest it has ever been. Then you chilled it to 0 degF in your tanks. From that temperature change, much of the dissolved water in the fuel will come out of solution as you chill the fuel, as snow that can plug your gascolator or your quickdrains from a refreeze.

Yes you need a small amount of isopropyl alcohol to keep water dissolved in the Avgas. I wrote more about this in Dec 1986 Sport Aviation after I had a scary takeoff incident.

If you are going to fly in temperatures that cold, read up on the effects of dissolved water in gasoline.
 
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