I don’t believe in this condensation thing. It’s as with many other things in aviation: just because a phenomenon is explainable in theory, does not mean it really (noticeably) takes place.
In 16 years, have never drained a single drop of water from the SR22. MAYBE it is somewhat specific to the aircraft type or the conditions it is stored in. But I still believe 99% of all water that is ever (globally) found in aircraft tanks is either entering via the fuelling process or via rain.
boscomantico wrote:
I don’t believe in this condensation thing.
Let’s estimate an amount of condense water. We are in an extreme climate, 40 °C hot day, 0°C cold night. At 40 °C one liter of air can hold 0.05 ml of water. Now assume you keep it outside and every day the whole amount of water condenses and flows into the fuel. Of course, through the vent of the tank or anything moisture from outside has to enter again the next day in order to accumulate water in the fuel.
Let’s assume we’re talking about a 120 liter tank filled with 20 liter of fuel. So 100 liters of air may hold 5 ml of water in total. If we do this for, say, 10 days, we have 50 ml of water in the tank.
So in theory, water accumulation through condensation is possible. But on the other side, water accumulation in cars (where fuel tank is also vented) is no problem at all, and lots of cars are not babied at all.
So I do not think that condensation leads to any significant amounts of water accumulation. However, when an aircraft is left outside, draining sounds reasonable for several reasons.
boscomantico wrote:
I don’t believe in this condensation thing. It’s as with many other things in aviation: just because a phenomenon is explainable in theory, does not mean it really (noticeably) takes place.
You may be right, I think think it’s always important to check.
Water might have gotten in because of rain. (Even if hangered can you be 100% sure nobody moved your aircraft outside for any reason and it happened to rain at that point)?
It might have gotten in because of contaminated fuel.
It might have come about due to condensation (even if it’s not normal and just a small amount, but there may have been unusual conditions weather conditions).
It might have been maliciously added.
Personally, I’m not willing to bet my life on the fact that there is no water in the tank, especially when there is an easy and quick way to check for it.
dublinpilot wrote:
Personally, I’m not willing to bet my life on the fact that there is no water in the tank, especially when there is an easy and quick way to check for it.
I agree completely.
If there is water in the tank, then knowing that is primary and how it got there is secondary. I can just imagine trying to explain that to an accident investigator …. “I didn’t check for water because the aircraft was in the hangar and I don’t believe this condensation hocus-pocus.”
dublinpilot wrote:
You may be right, I think think it’s always important to check.
Oh, definitely!
dublinpilot wrote:
Personally, I’m not willing to bet my life on the fact that there is no water in the tank, especially when there is an easy and quick way to check for it
The point was not about the value of checking but more explaining where water drained from the aircraft comes from? I am more inclined to think if condensation/rain are key drivers then it’s high likely condensation/rain in the pump fuel tank than condensation/rain in some hangared aircraft fuel tank, after all the fuel pumps are spending way more time outside not moving under lot of rain water flow & air humidity with load of temperature deltas…
Condensation in fuel tanks is well worth a read.
It’s an interesting little dance with an empty 5L water bottle to check all 6 tanks in PA30 for water. Easier with a second person lying on a creeper to spot the contents of each tank as you drain it. It’s one aeroplane that likes to live in a hangar, you won’t change my mind on that.
I know how important it is… because I got badly caught in my old one, with water in the fuel. Not a nice place to be. You wouldn’t get a credit card between the cheeks of your ass when it starts to splutter in mid-air.
My previous aircraft lived in a hangar and would mysteriously have water in the tanks on occasions.
After quite some time we discovered that maintenance would sometimes push her outside to use the hangar space and it would get rained on. obviously the tank seals were not as they should have been.
My current ride lives outside and in 4 years, I’ve never sumped a drop.
I have 6 drain points and another from a lever in the engine bay.
That all takes 1 whole minute for 1/2 litre in total drained. As an environmental effort, I tip it back in to the lowest tank.
I don’t recall ever flying the first sortie of the day or after fueling, without sumping the fuel.
It’s straightforward to do on most aircraft and thus is a big safety check for relatively little effort.
It’s been said that the engines can consume water, and I agree. but if your engine goes super lumpy and spluttery at 500ft are you going to ride it out and see, just because it may be a bit of water, or are you going to revert to training and put her in a field, maybe as a total hull loss, when another minute at splutter (loosing an insignificant 100 to 200ft alt ) will see you soaring again.
At 500ft, I’m closing the throttle and managing the arrival.
I don’t want to do that because I didn’t sump the fuel.
WilliamF wrote:
It’s an interesting little dance with an empty 5L water bottle to check all 6 tanks in PA30 for water.
Cessna 172 R and S aircraft have 13 (!!) drains. 5 under each wing and 3 under the engine.
