Raven Over Our Shoulders

[Ira Heilveil]

I recently read an accident report in which a pilot lost power on the rollout, and then when he heard the engine surge back to life, resumed his takeoff. Just after leaving the ground, the pilot retracted the landing gear, the engine quit again and the pilot died attempting to make the 180-degree turn back to the airport.

 

In a matter of a very few seconds, the pilot had some important decisions to make. If he had made the decision to abort the takeoff the first time his engine lost power, he would likely be alive enough today to have learned that his fuel was contaminated with water. But perhaps buoyed by the engines roaring back to life, he decided instead to climb out. That was his first bad decision. The second bad decision was to retract his landing gear before reaching the end of the runway. The third was his attempt to turn around rather than find a place to land in front of him. That was the one that sealed his fate. http://cftblog.com/the-raven-over-our-shoulders/

 

 

[Spooks]

Funnily enough I did my pre-flight ground school last week where the instructor emphasised the importance of checking for contaminated fuel prior to each flight. I guess it is easy to become complacent :(

 

 

[facthunter]

It's an easy way to die too. You always check fuel on loads, especially from drums which is only legal in aviation terms if the drum has the original seal. Condersation (water) can settle in the bottom of a tank as well from the air in the tank space.. Some aero clubs had a policy of filling all tanks to the brim before putting them away in the hangar each night.Nev

 

 

[poteroo]

It's an easy way to die too. You always check fuel on loads, especially from drums which is only legal in aviation terms if the drum has the original seal. Condersation (water) can settle in the bottom of a tank as well from the air in the tank space.. Some aero clubs had a policy of filling all tanks to the brim before putting them away in the hangar each night.Nev

All of which is sound too. Water often doesn't get pulled through to the filter until the engine is close to full power. Hence, the engine runs quite smoothly during the run up and power checks - but falters after a few secs at takeoff power. One lesson learned in the tropics was to stand on the brakes and run it to full power for at least 30 secs. This only after the engine had been started, run for 5 mins, and fully pre-takeoff checked. The principle was that you'd be off the strip and well airborne in 30 secs so if things were ok on the ground - than it was ok to go. There are a few limitations on full power runups - but it used to work for us. happy days,

 

 

[Ada Elle]

Funnily enough I did my pre-flight ground school last week where the instructor emphasised the importance of checking for contaminated fuel prior to each flight. I guess it is easy to become complacent :(

Every flight? I was always taught first flight of the morning, and after refuelling. The logic being that dew is most likely first thing in the morning, otherwise you can't get water in unless you refuel (or you left the top open and are flying in the rain!)

 

 

[Spooks]

I think it was on the basis of others who may have used the aircraft or 'done the checks' earlier, but failed to check the fuel. For what is a ten second job, I don't see much point risking it.

 

The aircraft I was learning on had a few minor issues which should have been reported on the checking out sheet but had not. I don't know whether this was a setup to ensure I think "oh eck, I'd better do all the checks!" or that the people using the aircraft before hadn't bothered to check it correctly.

 

 

[ayavner]

My take on the "before the first flight and after refuelling" thing is that it is fine if it is your plane and you are the only one who uses it and are comfortable that you know everything that has gone on since the last time you flew. I'm with Spooks - no idea if the last person did or not, so may as well. Easy to make it a habit if you don't have to qualify it each time.

 

 

[facthunter]

The requirement is (if my memory serves me correctly) to drain after each fueling episode, and prior to first flight, but some systems have numerous drain points making procedures a bit complicated. Some people argue the agitated fuel needs time for the water to settle. Some are poorly designed in so much as the water may be retained in some places even though the drain is clear of water. Shake the plane or taxi it and more water may come out from drains. You should also test the fuel in the container to identify it that it hasn't been contaminated by so much water that there is no fuel in the testing sample. There have also been quite a few instances of Avtur being added to planes with Turbo on the cowl which usually results in destruction of the engine on take of due detonation. I do a drain any time I take over a plane in recreational type aviation Nev

 

 

[Ada Elle]

Are the dyes in fuel water soluble? ie, if it was pure water, would it still be a fuel colour?

 

 

[ayavner]

Are the dyes in fuel water soluble? ie, if it was pure water, would it still be a fuel colour?

That's a good question! I know the few times i have seen a large amount of water in the sample, it did not seem to have taken on any of the blue.

 

Which brings up a point. i think it would be a good idea for instructors to demonstrate this by putting some water in with the fuel in the sample cup so you can really see what it looks like. All during my training, it never came up so I just kinda assumed I'd know what it looked like. It happened for real once, and it stood out very plainly. It looks like this:

 

 

So i would say probably not Ada, even if the tanks were half full of water, the result would be the same, ie the water would not mix with the fuel and pick up the dye. There is also the smell, which would be much fainter.

 

As you are somewhat of a scientist about things, give yourself a few more data points and try it out. It's pretty cool to see, and i know i feel much more comfortable now that I know what it looks like for sure!

 

 

[facthunter]

I check the containers (drums if using a number of them). Tip some into your hand and smell. Some two stroke pre mix have dye which changes the fuel colour, but not very precise. Better to let the fuel evaporate and see if some oily feel there. ( or mix it yourself at the time.). Nev

 

 

[Ada Elle]

Which brings up a point. i think it would be a good idea for instructors to demonstrate this by putting some water in with the fuel in the sample cup so you can really see what it looks like. All during my training, it never came up so I just kinda assumed I'd know what it looked like. It happened for real once, and it stood out very plainly. So i would say probably not Ada, even if the tanks were half full of water, the result would be the same, ie the water would not mix with the fuel and pick up the dye. There is also the smell, which would be much fainter. As you are somewhat of a scientist about things, give yourself a few more data points and try it out. It's pretty cool to see, and i know i feel much more comfortable now that I know what it looks like for sure!

I'm not putting water in my tanks to see!

 

The standard test for ethanol in the fuel is to put water in to the test container to a set line, then fill with fuel and see if the water line increases. So I've seen that, but my question was more if the dye was a little bit water soluble, could you have a colour that looks like shandy (the pale green you get when you mix avgas and mogas). You'd have to get a jerry can of avgas with a bit of water in the bottom and start pouring a jarful out at a time.

 

 

[Ada Elle]

And with a bit of googling, the blue dye is Solvent Blue 98, which is essentially insoluble in water. so you will never get blue in an all-water sample.

 

 

[ayavner]

Well, i got solvent blue 35 with my googling, but the technical data sheet says Blue 1,4 dialkylamino anthraquinone - so whatever the "friendly name" it appears we have discovered it is in fact insoluble in water, by design.

 

 

[ayavner]

also, no one said anything about putting water in your tanks to see... quote: "demonstrate this by putting some water in with the fuel in the sample cup". If anyone wants to see for themselves, no reason the results would be any different on a smaller scale in the sample cup..

 

 

[Ada Elle]

also, no one said anything about putting water in your tanks to see... quote: "demonstrate this by putting some water in with the fuel in the sample cup". If anyone wants to see for themselves, no reason the results would be any different on a smaller scale in the sample cup..

I've done that, to check for ethanol in the past. However, if the dye had a reasonably low oil-water partition coeffficient (so 10:1 soluble, say - related to how hydrophilic it is) and a low diffusion coefficient (so it didn't mix very quickly - related to the size of the molecule) adding water to the cup might not let it sit long enough to diffuse into the water in 5-10s. Shaking it would improve the mixing. Especially if it precipitated out of solution onto the sides of the tank, you might not see a potential blue colour unless you let the water sit there for a long long time. (This is with a hypothetical blue dye that had these particular nasty qualities - and in that case, why would you use it in aircraft fuel?)

 

 

[ayavner]

Hey look, its blue... better check!!

 

 

 

[bexrbetter]

You guys would be shocked if you knew how much water sits on the bottom of ALL fuel tanks, especially inground ones (99% of servos). I hate to take business away from small operators, but the fact is the very busy big servos have the least water due to turnover.

 

1/2 cup of metho in your tank occasionally does wonders to clean the water out, especially if you've just gotten fuel from a little used place.