Do you sump your gascolator?

[F1R]

Originally Posted by FireMedic_2009

And according to DanH, small amounts of water are not a problem for FI unlike for carbs where water can collect in the bowl.

There have been more than 1 or 2 Piper Aztecs (IO 540 x2 ) and other FI twins and single engine AC fail to stay in the air when small amounts of water in the fuel form ice crystals which restrict flow by progressively blocking fine mesh filters and even finger strainers at the servo body inlet. At altitudes (and latitudes) where air temps are below freezing for long enough ice crystals are bad news. Water contamination in any fuel system is to be prevented as much as possible and eliminated by all means available.

[robert@jonesrv10.net]

I don’t have a gasalator on my RV10. I have an Airflow Performance FM300 throttle body and the Airflow Performance electric fuel pump with the huge corrugated screen just prior to the fuel pump. I sump my tanks every time and have never found any water, not even a drop when the aircraft has been in heavy rain outside on a road trip. I keep the tanks full almost all the time, and the aircraft is hangered at HND in the desert when I am home. 400+ hours since finished in 2020. I make sure the fuel caps are adjusted to be snug and I will replace the O rings if I find the slightest imperfection. Condensation is a big problem in the midwest and southeast, which is why I always refuel as soon as I land. No air in the tanks, no condensation.

A friend of mine put a gasalator in his RV6 with a very fine ceramic filter. The lead in the gas plugged it up.

[Roadjunkie1]

Originally Posted by robert@jonesrv10.net

Condensation is a big problem in the midwest and southeast, which is why I always refuel as soon as I land. No air in the tanks, no condensation.

It would be a little difficult to get ALL the air out of a tank. Even a little air can cause the water to condense out. Great to hear you have not had a problem.

A friend of mine put a gasalator in his RV6 with a very fine ceramic filter. The lead in the gas plugged it up.

Huh. Interesting. That would be removing the lead on a molecular level. THAT would be a very fine filter! How did they determine it was lead that was the problem? Curious minds want to know.....

[Snowflake]

Originally Posted by FireMedic_2009

I keep hearing the only way to suck water into the gascollator is by using a fuel pump which must be insinuating an electric fuel pump since all aircraft engines have a mechanical fuel pump. If the engine driven fuel pump is drawing fuel from the tanks it will also draw water as well. So what makes an electric fuel pump any more efficient to pull water into the fuel system than the engine driven fuel pump? The electric fuel pump is a back up in case the mechanical fuel pump fails.

This may just be a misinterpretation. On the ground before flight you can't sump a gascolator on a TW RV because there's no pressure in the system to push out a sample. You might get a few dribbles but that's it. So you have to turn on the electric pump to pressurize the system. Sump the tank first, to be sure there's no water in it, and then sump the gascolator, to get any water that may have been brought there on a previous flight (and you're right, that could be from either the electric or the engine-driven pump).

I can’t imagine anyone not having an in-line fuel filter at the very least which has way more filter area than a gascolator to filter out way more debris.

A gascolator can hold a lot more debris in the bottom than a filter can in its folds, and not restrict the flow in the process. A filter will ultimately become a plug once it's picked up enough debris, and cleaning it requires disconnecting your fuel lines and trying not to spill fuel everywhere. A gascolator is designed to be cleaned easily.

[SwimmingDragonfly96]

Thanks for all your replies. A little more confused than I was before I posted this and I’m guessing the non sumpers are under represented so they’re not shamed. I’m going to work on a way to make sumping mine a practical part of my pre flight, but still curious as to why there’s disagreement about the low point in the system. Also, why’s the gascolator included in plans without the corresponding infrastructure to make it a practical part of the pre flight?

[MacCool]

Originally Posted by SwimmingDragonfly96

Thanks for all your replies. A little more confused than I was before I posted this and I’m guessing the non sumpers are under represented so they’re not shamed. I’m going to work on a way to make sumping mine a practical part of my pre flight, but still curious as to why there’s disagreement about the low point in the system. Also, why’s the gascolator included in plans without the corresponding infrastructure to make it a practical part of the pre flight?

I periodically fly a 172M. It has a pull-knob just inside the oil door...when you pull it, it expels a stream of gasoline onto the ground thereby "sumping" the gascolator. It's a routine part of the preflight.

I was surprised to hear that Van's doesn't call for an accessible gascolator with drain. My -9A has one at the lowest point and I thought that they all did. I'm sure that they have a rationale...I just don't know what it is.

[gmcjetpilot]

The Gascolator is also for filtering, straining particles. sediment as well as a water separator. It is suppose to be the lowest point, but regardless it will catch water at some point. The gascolator is it's own low point. Once the fuel is flowing it will go through the gascolator regardless of location it still filters particles out and separates water out, if any water got that far. The gascolator is a "how goes it" from the last flight.

The logic of draining tank first and foremost is sound, and if no water found no water should be in the down stream fuel system. However it still does not clean out anything the Gascolator that may have collected from the last flight, including a little water and any dirt, sediment if you don't drain it.

Where does water come from? It comes from the fuel tank. Hew does water get in tank? Heavy rain and leaky gas gap? Biggest fear is refueling and getting a big slug of water from the fuel truck or underground fuel tanks.

As pointed out some planes have preflight procedures that does not require you to collect a gascolator sample, but you do pull a cable to spit gas out the gascolator bowl onto the ramp. This clears the bowl of stuff. RV builders could so something similar. I get crawling on the ground with a sample cup is no fun. We all have drained fuel from tanks and "gascolators" for decades and rarely if ever found water. So we might get complacent.

There are massive threads about fuel system design. One topic is to install a gascolator or not. Some builders substitute in-line filter or filters that are not drainable, unless you break the fuel line and remove them. The nice part of a gascolator is you can drain it and remove the bowl for inspection easily without breaking the fuel line. Pulling the bowl every other oil check and condition inspection is a good idea. It is a fuel filter. There is a lot of freedom in building but somethings should be kept standard and as simple as possible.

[gasman]

Originally Posted by SwimmingDragonfly96

Thanks for all your replies. A little more confused than I was before I posted this and I’m guessing the non sumpers are under represented so they’re not shamed. I’m going to work on a way to make sumping mine a practical part of my pre flight, but still curious as to why there’s disagreement about the low point in the system. Also, why’s the gascolator included in plans without the corresponding infrastructure to make it a practical part of the pre flight?

Take a tape measure or laser measure and measure from the ground to the wing tank skin at the petcock drain. Then, try to find a lower spot in the fuel system.

[Snowflake]

Originally Posted by gasman

Take a tape measure or laser measure and measure from the ground to the wing tank skin at the petcock drain. Then, try to find a lower spot in the fuel system.

It's not that you're looking for a lower spot. It's that you're looking for a low spot in the system that can trap water that you can't remove until it moves to a spot with a drain in it.

[Dan 57]

Nope. Neither do I sump the tanks.

PS
My baby stays put in a heated hangar, and is flown 1-2 times a week as a minimum. I'll sump the tanks if she stays outside, in rainy weather, whilst on a trip.