Water Contamination
 

Would any water in fuel that is not visible, ie only detectable using capsules, cause a problem for turbine engines?

I was told by a Shell refueller that it would not and that the syringe/capsule test was overkill for turbine helicopters. Not sure I'd stake my life on it though.

Could the suspended water form droplettes in the tank after a change in temp/atmospheric pressure?

It is possible to get molecular suspension in fuel and if you go high enough and/or are flying in cold enough conditions it is possible for the water to begin to build as ice in the filters.
I was on a C-130 back in 1982 that suffered an engine failure and a partial loss of power on a second due to icing in the filters following molecular suspension.

I'm more than surprised that a Shell refueller advised that the syringe/capsulre test is an overkill for turbine engines.
A positive test for water in suspension does not necessarily mean that engine problems will occur, but it warns that the concentration is sufficiently high to enable water to condense out of suspension should the conditions alter. i.e change in temp/pressure etc This could give rise to a sufficient amount of water in the fuel lines to cause power loss or complete shut down.
Leaving an aircraft overnight in conditions where daytime temps are in high 30degs plus and night temps drop substantially can cause such a problem.

Daily sump testing and checking fuel supplies before and after delivery are essential for longevity..........

Whether you think it is suitable for use or not.
CAP 748 Chapter 4, page 2 states that fuel should be considered unfit for use in aircraft if a visual examination shows a positive reaction to a water finding paste,paper or chemical

CAP 748

Chuck it:D

I can't imagine that very fine droplets of water would affect the actual engine, they would go straight through the relatively large fuel jets. I suppose a large proportion of suspended water must by definition cause a reduction in power output but I'm sure this would be an extreme case and would be visible to the naked eye.

However, suspended water MAY affect the contents gauge readings where capacitance type sensors are used, a gauge over-read would occur due to the water content.

I also understand that the presence of suspended water gives more of a storage problem because bacterial growths can occur in it.

Of course in the old 206L we used to inject water to help us out! (the alcohol in it was to prevent freezing not aid power as some think)

There is always water in suspension in jet fuel. The stuff you have to worry about is that which collects together and forms an entity of itself.

Phil

I would not start up without having the A/C tanks checked, also the tank farm and filters.
Probab;ly doesn't harm the engine as such, but does the FCU no good at alll, seen a few FCU changes due to contaminated fuel, some engines may have a higher tolerance than others, but daily checks is the only way to go.

As said earlier, the problem is mainly icing in filters and in controls ie FCU etc. However as also said earlier it can cause other problems internally in FCUs with regard to corrosion, especially on older mechanical systems.

I'm surprised the question was asked to be honest!

:confused:

water solubility in Jet A
 

the problem arises from the decreased solubility of water in Jet as the temp drops. Similar to loading too much sugar in a coffee or tea. It can only dissolve so much then precipitates out into visible water. As the fuel chills off in flight the water can be sufficiently cooled to cause precipitation. Can also happen in drums moved to a cold area after filling.

Water detecting paste ( green stuff that goes purple ) only works on water you can basically see and should only be used on avgas. Shell water detector or similar should always be used including on daily's

How much water can put the fire out in an Allison????????

Cheers

Re: Water Contamination
 

We had a blue spot(no bigger than a pinhead) on the detector capsule with the daily sample from the bowser. Tried again with another capsule and it was clear. Tried a fresh sample and that showed clear, as did the aircraft sample. Just wondering that's all.

Opinions seem to be divided, as always with these things. Ice particles are not a problem for us, we never get into really low temps, plus we have FSII added.

Re: Water Contamination
 

Suspended water in fuel and operating in cold climates can it seems cause ice build up in airframe fuel filters as indicated above. I am not sure on the tec stuff? But I understand that parts per million water content (we used the Shell detector kit went green at 60 PPM) relating that to fuel burn rate and size if fuel/ice filter. The old 61 in cold climates could sometimes show a filter light if the filter was starting to block, this in cold weather was an indication of ice rather than fuel contamination (good fuel quality and handling procedures). As mentioned once the filter started to by-pass this allowed the ice crystals to reach the FCU inlet filter and this was when it became worrying as it could affect engine performance.
The later AS 332’s I think did away with ice filters and increased the size of the fuel filter bowl thus allowing a greater capacity for ice collection. Least that what the French chap on the refresher course seemed to imply. I am sure that the experts will be able to expand on the complicated theory stuff.
outhouse

Re: Water Contamination
 

The TSO for fuel icing call for a horrendous amount of suspended moisture, and the screen areas are consequently very large, or heated with recirculated fuel as a result. While it is possible that for some helos with very cold environments and saturated fuel to get a fuel system icing problem, some dissolved water in fuel is no great concern, as long as there is no liquid water pumped in with the fuel.