Re: Northwest Airlines Icing related problem IAD Jan 27 6:30

Date:         31 Jan 97 14:29:24 
From:         "Peter Mchugh" <PMCHUGH@mail.hq.faa.gov>
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>2 - How long does the Jet A take to evaporate and not be a hazard if
>some other airplane comes by. (Hazard as in take an airliner takes in
>the air mixed with kerosene into its cabin air inlet as well as a small
>airplene like mine flying through it and perhaps injesting it into the
>reciprocating engine and having a detonation problem)

You'd be surprised how much kero a recip can burn with little obvious
change in operation.

A couple of years ago, on the left side of the continent, a major
refinery distributed avgas blended (unintentionally) with jet fuel
(kero).  At two airports the resulting mixture serviced into GA
aircraft was determined to be approximately 30% contaminated and to
lesser degrees at four other airports...nearly 1000 aircraft probably
received fuel from these airports, and most got new engines from the
refiner, but there was no report of engine failure or even, to my
knowledge, of much other than higher cylinder head temps noted by
owners/operators.

The refiner did, IMHO, the honorable thing in every case, honoring
claims from operators who could show that fuel was purchased at any of
the airports during the period contaminated fuel was dispensed.

Tear down revealed very little...FAA had inspectors look at a number
of the engines that were removed from aircraft...and most had very
limited damage.

So, the moral of this story is NOT to blend your avgas with kero or
jet...and TO be conscious of changes in cylinder head temp and funny
noises originating in the engine compartment...but flying through a
fuel dump pattern may produce more risk in the cockpit than in the
cylinders of your engine...

And for the jet jocks...Boeing has a very interesting memo in
distribution about the levels of tolerable contamination in jet
juel...related to EPA and IRS dyes leeching into jet fuels during
distribution in pipelines...virtually any red or blue color observed
in jet fuel is sufficient to require defueling...and perhaps purging
of filters etc...but if memory serves, the memo suggests that a 01-02%
contamination of jet with home heating oil or dyed diesel would
present so low a level of dyes as to be unobserved...and by default
acceptable for use within the current fuel specification which
requires that jet fuel be "water white" in a white bucket test.