OS160FX crankshaft

[Karl G. Mueller]

Xavier,

Haven't seen one break on the 160. This used to be a problem in the
old .60 FSR. We also used to break the crankpins on those. This could
be from an inconsistency in the heat treating process, were one batch
would have a slightly higher Rockwell-Hardness number than the norm.
The inlet opening is the weakest point on the crankshaft and that is usually
one of the first places it will break, or the crank pin. If the engine has
been back-firing a lot in the starting process that might cause this type
of fracture as well.

Karl G. Mueller
kgamueller at rogers.com

----- Original Message ----- 
From: "Xavier Mouraux" <xavier.mouraux at sympatico.ca>
To: <discussion at nsrca.org>
Sent: Monday, May 17, 2004 8:27 PM
Subject: OS160FX crankshaft


> Hello guys,
>
> When I started the OS160FX on my Hydeout on Sunday morning, it stopped
right
> away. While turning the prop by hand, I noticed it was really stiff. I was
> going to replace the bearings this week but I didn't expected it would
> become that stiff all of a sudden. I removed the engine from the plane and
> opened the back plate but can't found anything wrong. I packed the Hydeout
> and took the other airplane out to practice.
>
> Once home, I dismantled the engine and was surprised to found the problem.
> The crankshaft is cracked radially from a corner of the inlet port to
about
> half way on the other side.
>
> The engine has been runnig very well since the beginning of the season for
> about 30 flights. It had approximatly 80 flights in another airplane in
the
> last 2 years. The engine is still under warranty so my hobbyshop will try
to
> get it fixed.
>
> Anyone had seen that before ?
>
> Xavier
>
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