Excerpt from Dennis Fetters post:

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Bill Phillips: 1. What about running the Rotax at 104% continuously?
Rotax itself does not warrant this engine in this application. The
manual states that the rpm for 104% should only be used for 5 minutes,
yet the Mini 500 will not fly with most people in it unless it's run
at
104%, which is nearly 6800 rpm. Rotax says maximum continuous is 6500
rpm. There is simply no margin left at 6500 rpm, and the engine is not
designed to be run at 6800 rpm for more than 5 minutes.

Ken Armstrong: RPM limits are usually related to the possibility of
overheating. In my Mini 500 flying--including extensive hovering where
the engine works hardest--heat was well within the green.

Dennis Fetters: Statement No. 1 is totally incorrect. First, Rotax
does
warrant the 582 engines used in the Mini 500 and always has. Next, the
Rotax manual mentioned is for airplane or propeller installations
only!
Helicopters are very different and use the power and rpm in a
different
manner. All helicopters run their engines at 100 to 104% rpm while
constantly changing the power settings.
So at 104% rpm at cruise flight, the power required and used is about
70%, a normal usage. Operating at 104% rpm will not hurt the Rotax
engine in the least bit. In fact, it works better running it at a
continuous rpm and varying the power level. This will result in more
stable exhaust gas temperatures, more constant engine running
temperatures, and less carbon buildup. To date, there has not been a
single Rotax engine failure in a Mini 500 due to the overexertion of
the
engine.

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The post above contains the statement "First, Rotax does
warrant the 582 engines used in the Mini 500 and always has."

Yet, the the following was entered by the NTSB investigating an
engine-out fatality in November 1998 which was 1 year previous to Mr.
Fetters statement.

https://extranet.nasdac.faa.gov/pls/..._BRIEF_REPORT?
EV_ID=20001211X11436&AC_VAR=FALSE&ENG_VAR=FALSE&IN J_VAR=FALSE
&FT_VAR=FALSE&OCC_VAR=FALSE&WTHR_VAR=FALSE&PNARR_V AR=FALSE
&FNARR_VAR=FALSE&CNARR_VAR=FALSE&NARR_VAR=mini%205 00

"Although the kit helicopter was built according to plans, the engine
manufacturer did not recommend several of the engine modifications
found on the accident helicopter. Additionally, the engine
manufacturer did not recommend the installation of this model engine
in the helicopter and published the following warning with the engine
manual: 'This engine, by its design is subject to sudden stoppage.
Engine stoppage can result in crash landings, forced landings or no
power landings. Such crash landings can lead to serious bodily injury
or death.'"

Is it normal for Rotax to "not recommend" an engine for a particlar
aircraft yet to also still "warrant" its use in that same aircraft ?

Thanks