Those mechanical failure figures are far higher than most accepted numbers. Most OEMs (Agusta, Bell, Eurocopter) quote Human Factors as being accountable for ~75% of causes, with inherent mechanical failures being attributable for less than 10% (if memory serves
Yes, this is pretty much the frame of reference I have had in mind for several years, and why I found the 407 data surprising. The numbers I cited are compiled by me on the basis of reading every NTSB accident report on the 407. Am I missing something?