How much water???

[Boss_BlueAngels]

Here is a question for you... what's the highest amount of water you've seen sumped from a fuel tank before one of your flights... when you still decided to go up?

I heard a story from a fellow lineman who worked at an airport that he sumped about 6 "gats" jars fulll of water after rocking the wings and letting it settle several times. the lineman was told to do that before a customer comes to the plane so he would still fly it.  

So, what do you guys think?  The airplane had been sitting outside for about 2 weeks (if that) since its previous flight.

[Brett_Henderson]

This is a good topic. I've never not flown for finding water in the sump-cup. I just keep taking samples until there is no water. Of course, if I had to draw a ridiculous amount of water out.. I'd want to know why before flying.

It depends too, on how much fuel is in the tank. A mostly empty tank can have you drawing quite a bit out at the sump, and even after you get a clean sample, there can still be lots of water condensed on the tank's inner walls. If you're plannning on taking a weight sensitive flight, and topping off the tanks is not an option; then even "shaking" won't get all the water into the fuel and out the sump (unles you REALLY rock the wings and let it settle for a LONG time).

The biggest danger is not from having "some" water in the fuel (there will always be some), but from a concentrated amount working it's way to carb/throttle-body and starving the engine. Also.. when any part of the fuel lines have water only in them (like when that stuff in the bottom that you forgot to drain starts making its way through), it can freeze, if it's cold enough.

If a plane has sat for a long period of time... and nobody had the foresight to top the tanks off, you had best top them off yourself.. let the water settle and then drain it off. If it's that weight sensitive flight... then either go up and burn some of the fuel off.. or off-load it.

The biggest question about your lineman story would be... How full were the tanks ?

[beaky]

Never had to take more than two samples to get rid of it (and amounts I would call "trace"; very small), and when I do find water, I usually run it up just a little longer and maybe even rev it a little while holding short if possible. You never know...

I was once told a story about a similar scenario to what Boss describes: an old Aztec that had been sitting in a prolonged downpour, maybe more than a day... this pilot took a few samples, and was puzzled by the fact that although he saw no water/fuel separation line, the samples all looked very clear- not blue, as they should with 100LL. Same story on both sides... and the tanks appeared nearly full looking in the filler openings; more than enough for his planned flight.
He shrugged and decided it was just him- surely there couldn't be that much water in there...

Well, he got both engines started and run-up... everything seemed OK...but they both quit abruptly when was about to roll into position for takeoff. They would not restart. He had the tanks drained, and they contained almost all water. There had been just enugh fuel in the tanks, or perhaps just the lines between tanks and engines, for the run-up and some taxiing. the rest was water. Gallons and gallons of it. Leaky filler caps- the seals had most likely deteriorated.
He was very happy the engines quit when they did, and never made the same assumption again...

[Boss_BlueAngels]

Yeah, my buddy said the tanks were topped off about two weeks ago, right after its last flight.  It was a 182 so there was still a lot of fuel in those tanks... but still, that's nearly a gallon of water from a pretty short period of time.  Our school has a couple of planes in maintenance that have been out in the weather for months and only have a few drops of water in them.

[RitterKreuz]

yeah about 6 is the most i have seen, it was from a cessna 210 with bad gas cap seals after a light rain.