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.