Two thoughts come to mind:
1. Pilot Error - Not one for believing in coincidence, why is the AW139 currently proving to be much more susceptible to accidents than other similar sized twins. Is it just down to crew training and selection as inferred, or is there also a cockpit ergonomics issue here?
2. Design - Is there any correlation between airframe serial numbers that have (or we suspect) suffered tail rotor blade separation and the 6400 and 6800 kilo weight certification?