Heres my 2 bob worth......
Sunfish,
Operating procedures would not really be an issue these days as the 524 and GE engines are controlled by an EEC or FAFC. Most of the failures (excluding bird strikes or FOD ingestion) originate from an internal failure in my experience.
There is the odd failure induced by defects in other systems, but again usually due to a component failure, even in those instances.
Powerplant engineering monitor performance trend data and occasionally call out in situ " tweaking" to optimize perfomance.
There seems to be a general quality issue with the engines supplied from MRO's. I believe this would account for a majority of the increased incidents that reflect in the Fed Sec statistics.
Cheers