Here is a closer look. Just guessing this was the
front end of the crank based on the remaining piece (probably welded) into the
main bearing. It is more common for the shaft to fail ahead of the main bearing
because of over tightened belts fatiguing the shaft in
bending.
This looks like either an over speed that took out the
front main bearing or just an oiling failure that welded the shaft into the
bearing shell. Both would have allowed the damage on the iron where the rotor
tips dragged along being badly misaligned.
In an over speed, the crank takes on an "S" shape that
lets the rotor tips drag on the irons.
13-B rotors are nearly 10 pounds each.
This is only a problem for folks who shift above
10,000 RPM without lightened rotors.
It is typical to remove .010" from the sides of the
rotors to allow extra room for this kind of activity.
The over tightened belt trick works at much lower RPM.
There are tension load figures for belts that must be observed. This is not a
typical failure in a rotary engine. Lycoming makes cranks with this failure
mode if you need one.
Lynn E. Hanover
In a message dated 8/20/2013 10:06:57 P.M. Eastern Daylight Time,
cbarber@texasattorney.net writes:
I lifted
this from the Rotary Aviation Facebook page. Holy smokes, I have never even
heard of this happening.
Chris