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I have followed the
discussion of fuel contamination, and how to detect it, with great interest,
having been burned by Jet Fuel contamination once before. A few detection
methods were suggested both on-line and in the recent SA article. I wanted
to see how effective these methods really are. Keeping in mind, of course,
that for a test to be effective it must be simple enough that pilots would
be willing and able to do it at every fill-up.
My goal was to
see if low level contamination could be detected by the methods recently
discussed: Smell, feel, and evaporation on paper, etc. Based on the
fuel contamination incident in which I was involved, it was determined
that 5% jet fuel in an O360 is enough to cause serious damage, but not immediate
engine failure. 12% is enough to cause engine failures on turboed or high
compression engines.
I acquired my sample
of Jet A from the wing of a King Air, with permission of course. I took
100ml of 100LL and started adding Jet A.
The smell
test:
Even at low levels
1-5% a faint smell of diesel or Jet A is detectable. I am not sure
however, how successful this would be without the control sample of pure
Avgas. I can see false positives when one starts to imagine faint hues of
Jet fuel odor in the fuel sample that are not really there. Pure jet fuel
is very obvious, but low level contamination is not quite so
obvious.
The feel
test:
Here again the fine
shades of grey make the transition from zero contamination to light
contamination difficult to detect. Even with a pure 100LL sample between
two fingers in one hand and a mildly contaminated sample in the other, I
could not tell an obvious difference. Once again pure jet fuel is
easy to detect.
The evaporation
test:
I was hoping this
one would be the answer and provide a black and white finding.
Unfortunately, even at 10% contamination, the sample dried completely
without any visible residue. At 100% jet fuel of course the stain was
obvious. A glimmer of hope however. Smelling the paper after
evaporation offered perhaps the best detection method. If any
Jet A was present there was a faint smell detectable, even down to
1%.. If none was present, there was no smell whatsoever, just clean
paper.
FWIW
full resolution
photo at:
Chris
Zavatson
N91CZ
360std
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