From the AAIB report, it would appear that the engine on this respective aeroplane failed due to accessory gear failure.
As I mentioned before, this is a known problem area with these TCM engines.
Every operator I personally know who operate aeroplanes fitted with these geared Continental engines (Cessna 404, 411, 421 and AeroCommander 685) are well aware of the requirments of critical service bulletin 94-4D (starter adapter shaft gear and crankshaft gear inspection) and perform regular repetative inspections as called for in the CSB. If any legal action should be initiated due to this accident, I surely hope that the aeroplane maintenance records reflect the proper mandated inspections.
Continental designed these engines a long time ago, and if properly operated and MAINTAINED, are quite reliable.
But, it ain't cheap, just like everything in aviation...you pay now, or you pay later...but you will pay, one way or another.