i used work for an outfit that used to fly 500 D's and the 530 doing production external load work. never flew the 600, although we had one at the time and after i left, the 600 shed its tailboom killing the pilot. while i was there, we did have problems on both the 500 and 530 with m/r blades cracking and before my sentence began with the same company, they had a blade part company with the machine injuring the pilot pretty badly. he was lucky at that. one might think that the a/c were abused but that was not the case.
The 600 is a nightmare, that's why there are so few in Canada. The accident in BC last year was a combination of pilot error and 600 error. It's a typical chop and cut engineering job, and it flies like it.
The accident you are referring to with the blade departure is almost exclusively due to abuse of the machine and blades, the pilot it happened to will tell you as much... All five were cracked, and after many thousands of hours in the 500's I've only ever seen one, it was abuse no doubt. He was young and doing work with almost no supervision while trying to keep up to the experienced guys, classic scenario.
RH