Alan,
Good question and sorry to hear about your little fright.
I've been microlighting for about 20 years and all our machines are filled
---From petrol stations and jerry cans. We get water in our tanks in varoius
quantities. From my experience the most likely sources of water in the
tank are, in order of frequency:
1. Condensation in a (normally) metal container. If the container is not
airtight, and few are, and it is left partially full, then diurnal
temperature changes make the airspace above the fuel breath. Cooling draws
in air, warming expands it out. The temperature of the fuel is often lower
than the air temperature. If the fuel is below dew point, then moisture
---From the air will condense on the surface of the fuel and sink to the
bottom. Continuous cycling simply builds up the water lying on the bottom
of the container. The effect is exacerbated by the metal walls of a
container whose temperature drop also lags behind air temperature. A
filter will not remove this water. A chamois leather is said to do so but
the best solution is to keep it out in the first place. Keep containers
(including the aircraft's fuel tank), full, particularly if the fuel is
being kept for more than a few days, and particularly in cold moist
weather.
2. Contamination of the fuel at the filling station. Never take up fuel
while there is a tanker on the premises. The filling of the underground
tanks can disturb water normally lying on the bottom of the storage tank so
that it is brought up by the pumps.
3. Alcohol absorbs water and some unleaded fuels contain alcohol. However
I believe that UK fuel is mostly free of alcohol, but not so on the
continent.
4. Drips into the aircraft tank from a wet fuselage while filling.
1 and 2 are nearly level pegging for popularity.
Dave Simpson
PS - Don't tell the CAA - they're trying to ban all petrol station fuel
purchases for aeroplanes at the moment.
----------
> From: Alan D Stewart <alan.stewart@cableinet.co.uk>
> Subject: 'Water in fuel' incident.
> Date: 20 March 1999 20:51
>
>
> I've just returned from a day trip to the Isle of Wight, during which I
> had to make a
> precautionary landing due to rough running.
>
> Quite a lot of water was drained off from the bottom of the fuel tank
> (at least 20 ml).
>
> My Europa is a standard (Mark 1) 912.
>
> Has anyone else experienced this problem. Any thoughts as to the most
> likely source of the water
> contamination ?
>
> I always leave the tank full or nearly full.
> I always fill the tank from standard jerry cans, through a fine mesh
> filter.
> Sometimes the jerry cans are stored half empty for about a week.
> The a/c and fuel are housed inside a large metal hanger.
> I have been using a plastic 5 litre jug to calibrate fuel consumption,
> emptying fuel backwards and
> forwards from the jerry cans.
> The use of unleaded auto-fuel has been the subject of some discussion in
> the past. Does this contribute
> to a risk of condensation in the tank ?
>
> I think the main question I am asking is, what is the most likely cause
> of water in the fuel ? (both for my
> own benefit, and for others in the future).
>
> --
> Alan. D. Stewart
>
-
>
> 14 Goddard Way 'phone : +44 1245 264186
> Chelmer Village work : +44 1473 607571
> Chelmsford, Essex CM2 6UR email : alan.stewart@cableinet.co.uk
>
>
-
>
> office email : alan.d.stewart@bt.com
>
>
|