JvTonder wrote:Rotax Manuel states:
"AVGAS 100LL places greater stress on the valve seats due to its high lead content and forms increased deposits in the combustion chamber and lead sediments in the oil system. Thus it should only be used in case of problems with vapor lock or when other types of gasoline are unavailable."
I saw a gearbox after 800 hrs, it had to be redone completely, slipper clutch, bearings the lot. According to my AP if AVGAS is used this must be done every 1000hrs and the oil pump check as well. The oil that came out of the gearbox had a lot of lead sediments and it could be felt between your fingers.
So ones again stick to 95 for the 912 and 914 and 93 for the 582 ect.
Well, I am still not convinced... The reason you change the oil every 50 hours with AVGAS is to protect the engine from the "sludge", maybe the 800 hour gearbox owner did not stick to the 50 hour rule?
Personally I would rather believe Rotax than the local AP (sorry!!), Many Many strange stories heard from some "experts", often based on partial facts and some fiction
The official Rotax service schedule does not show ANY lower TBO, just the additional oil and plug changes. If you can feel the lead in the gearbox oil (remember on the 912 the engine/gearbox oil is shared) you have a real problem and I am SURE the oil was not changed every 50 hours!! Remember with AVGAS use you also need to flush/clean the oil reservoir on the 912/4.
It is important on the 912/4 to use the correct oil, the wrong oil will cause early failure of the slipper clutch and you should NEVER use full synthetic oil if you are EVER going to use AVGAS The Rotax manual is very specific about this (This is something some local AP's don't seem to know.... they should read the COMPLETE manual sometime
) Many guys say they will never use AVGAS, wait till they have to divert somewhere and need to fill up, at most airports you can only get AVGAS.
Having said the above, there are some real knowledgeable AP's out there, but just because he is an AP does not make him always right
I learned the hard way, if I am not sure I do some research and/or get a second opinion.
Why 93 octane for the 582? 95 is a better option according to Rotax.... I don't own a 582 but have flown many hours behind one, only ever used 95, like I use 95 in my 618.
Anyway, to each his own, don't know why anyone would use AVGAS unless they have no other option.....
Fly safe,
Rudi
