Talking relevance - top of page 5 latest AAIB report, the cracks started and grew to failure in areas of the shaft that had not nor were required to be surface hardened.
The shaft on the CHC machine was it would seem from the latest AAIB report likely to be the highest time shaft on any 225...
That and the question mark on the use and function of HUMS which is now something of focus - EC don't look the smartest frankly.