>>>>
<excerpt>Both organizations (EAA and Petersen) offering Mogas (Autogas)
STC's in the US specify Regular 87 octane for the certified aircraft that
were originally certified on 80/87 Avgas. Petersen also offers STC's for
some aircraft that originally needed 91/96 octane. The mogas for that
STC is U.S. hi-test or 93 octane. That includes the Lycoming O-360, 180
hp. I am not familiar with the factory spec for the Rotax 912 just the
facts for Cessna 150, 172 and 182's.
According to Todd Petersen, ALL Continental and Lycoming engines
overhauled or built at the factory since 1983 have had the harder valves
and guides that do not need lead for lubrication. The reason both
Continental and Lycoming factories do not approve Mogas, according to EAA
fuels guru Harry Zeisloft, now retired, is that there was a General
Aviation Notice (GNOT)tacked onto the original EAA Autogas STC for the
Cessna 150 in 1982 that exempted Cessnas 150's from being using in a
commercial air charter (Part 135) operation. The idea was the FAA would
rescind the GNOT after a year or so of field experience with mogas.
(Field experience since 1982 has been EXCELLENT according to data filed
with the FAA.)
Unfortunately, through an oversight, EAA forgot to ask FAA to rescind the
GNOT until about 3 years ago. This the FAA has now done. According to
Harry Zeisloft, back in 1982 Continental and Lycoming brass were advised
by their lawyers (not the engineering departments which had fully
cooperated and helped EAA with their autogas testing) that since FAA had
not given 100% approval for ALL operations on the Cessna 150 STC (i.e.,
no Part 135 ops), they were not comfortable approving autogas because of
the remote liability question.
Also, according to Todd Petersen (and others), in Sweden an unleaded
version of 91 octane avgas has been available and used with their GA
fleet with no problems "as long as it was used with certain high-quality
oils". That means ANY aviation oil available in the US.
Kas Thomas, who publishes TBO Advisor magazine, also has had extensive
info on the auto gas and no-lead question. The world is going to loose
leaded av fuel some time in the not too distant future and substitute has
to be found for engines that truly need more than 91
octane. In the US the EPA is going to mandate unleaded av gas
eventually and rescind the lead exemption for aviation use in the USA.
US general aviation is now the largest polluter of lead in the
environment in the US.
Dee Whittington
Richmond, VA, USAg
Date: Wed, 16 Sep 1998 21:40:31 -0400
From: "Martin J.Tuck" <<102034.2747@compuserve.com>
Subject: Re: Mogas Octane
Re: Mogas Octane
Those of you flying on unleaded mogas (a previous question seemed to
indicate most of you) - unless you want an increase in the 'wear of the
valve seats and deposits in the combustion chamber' (Rotax 912 manual)
might like to answer a question.
What octane is recommended?
As an ex-pat I know I'll get a whole bunch of people replying '3-star'
or
'4-star' so before you do perhaps you could translate that to'
Americanese'
i.e '97', '98' or whatever.
Perhaps U.S flyers could chip in too with what they use.
The manual says 'EURO-SUPER RON 95 unleaded to DIN 51607, ONORM 1101'
which
caused a few raised eyebrows at my local QuikTrip - one even looked on
the
coffee can and asked if I meant decaf ....
Appreciate the help
Regards
Martin Tuck
Wichita, Kansas
N152MT
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