Rotax 582 rod big end failures

[Beaver Shaver]

I'm curious if anyone has experienced or might have some insight as to
why the Rotax 582 (blue head) seems to be prone to bearing failures on
the connecting rod big end. I have examples of this occuring on three
engines, all of which have about 250 hours on them. These engines have
been carefully maintained and followed the factory service
recomendations to the letter.

The failures have been occuring on the magneto-end cylinder and seem to
be initiated by a failure of the thrust washer on the rod big end. The
exact same thrust washer failed on all the engines. (The one that fails
is the thrust washer on the mag-end cylinder, PTO side of the rod.) When
the washer fails, the rod gets hot enough to severely distort it and
lock the engine. There is no indication on any of the engine gauges
(CHT, EGT, water temp) that anything is wrong unitl the engine begins to
loose power and then locks up a few seconds later. There is no
indication of a lubrication failure either (all the engines are oil
injected).

The problem has me stumped. Any ideas?

[GTH]

When
> the washer fails, the rod gets hot enough to severely distort it and
> lock the engine. .... There is no
> indication of a lubrication failure either (all the engines are oil
> injected).

Overheating big end, hmm ?
What makes you think this is NOT a lubrication issue ?

Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr

[Beaver Shaver]

GTH wrote:
> When
>
>> the washer fails, the rod gets hot enough to severely distort it and
>> lock the engine. .... There is no
>> indication of a lubrication failure either (all the engines are oil
>> injected).
>
>
> Overheating big end, hmm ?
> What makes you think this is NOT a lubrication issue ?
>
> Regards,
> Gilles Thesee
> Grenoble, France
> http://contrails.free.fr

Because there is no indication of friction burns on the cylinder walls
or piston skirts. Also, you can still feel the oil film on the cylinder
walls when breaking down the engine for inspection.

It's possible that the cylinders are getting lubrication, but not the
crank. If so, it's a design problem with the 582.

From what I've gathered (off the record) from some of the rotax
service centers is that the 582 crank is having problems when used in a
training environment such as ours. It seems the high number of landing /
take off cycles at high throttle settings may be causing the premature
crank failures. Rotax claims the crank is rated for 300 hours. The
longest we've had one last is 236 hours.

Incidently, you might be able to spot this problem before it goes
catastrophic by examining the pulse line hose (assuming you are using a
clear urethane hose). The hot air produced by the failure turns the
first couple of inches of the pulse line black.