Article: 2913 of rec.aviation.owning
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From: lpmeditor@aol.com (LPM Editor)
Newsgroups: rec.aviation.owning
Subject: To ALL Re: Jet-A Contamination
Date: 29 Jun 1994 18:50:01 -0400
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I actually got to do the serial dilution tests with Jet A and avgas
today. The results were interesting. It turns out that at low
concentrations (below about 13% jet-A in avgas), the sniff test
becomes quite unreliable. We put two noses on the job and we both had
trouble detecting by scent.
However, the paper test also proved troublesome, though valuable if
you understand its limitations. We were able to detect jet-A down to
about five percent (5%). The big problem is that the solvent
properties of aviation alkylate causes some apparent evaporative
entrainment of the jet fuel. Thus, if you let the paper sit too long
before examining it, the contaminated fuel evaporates, leaving no
residue.
Our tests showed that under hazy sunlight at 80 degrees F, the 5% jet
fuel sample took more than twice as long to dry as pure avgas. Pure
avgas would evaporate entirely in 30 seconds or less, while the
contaminated sample drop hung around for a minute and a half (5%) to
10 minutes (10% to 13.2%).
So, the paper test works, but the user must be cognizant of the time
limitations.
I'll be doing a writeup on this for the Aviation Consumer, and I'll
put a blurb in LPM so everyone will know how to get the most out of
the blotter test.
Meanwhile, I got Chevron on the blower today. Ray Phillipini tells me
that Chevron is "going to stand tall on this." They've got the check
books out and they're ready to pony up the dough for anyone who got
bit. Nice to hear about at least one company that doesn't want to
shuck it all off on the consumer.
JL
LPM Editor