Crankshaft failure data points - large bore continentals.

[Dave Taylor]

While at the Pecan Plantation fly-in yesterday, quite by happenstance I was seated next to a gentleman L-IV owner who told the group a story about having a crankshaft failure in his airplane last year over the Panhandle followed by a successful landing to a dirt road.
Because the exact same thing happened to me in 2020, I am always looking for similar stories and within those stories any information that can link our engines.
Both our engines were TSIO-550's assembled by Performance Engines.
P.E. has a previously well-described history on the chats regarding their products but I still had never heard of any work that they did which would explain a severed crankshaft.

Both ours broke in the space between cyls 1/2 and 3/4 - I forget the cheek number on mine right now.
Both of ours had a composite prop in use. I mention this because my first overhauler (who actually sat on the replacement engine for over a year) said he has seen crank and case failures in a disproportionately large number of 550s and 520s that had a composite prop and his theory (completely anecdotal, no supporting evidence) is that the lack of mass in the composite props was unable to absorb the acceleration/decelerations of each combustion event like a heavy metal prop would.