Very interesting to see the quality and knowledge of the contributors to this thread and how some possible scenarios are emerging...
One area understandibly under focus by the AAIB will be the maintenance history of this aircraft.
Since entering GA after many years working in Airlines i have come to accept as a fact of life that the tech log never tells even half the story. In making this comment I am not suggesting the subject operator is any different to others..no better or worse.....but "putting it in the tech log" is generally regarded as treason ( unless parked up at a maintenance facility with the days work completed) and i have seen more than once "offenders" being managed out of the company at the first opportunity.
I nearly flew a small cessna jet into the sea due to a faulty glide slope receiver....exactly the same had happened previously but nothing had been put in the book for the above reasons. As a result my routine pre flight inspection of the tech log did not alert me to a possible issue...even if no fault had been found.
We used to put entries " for information purposes only" in the tech log but were told not to do so because such would need to be written off by an engineer before flight.
The result is that intelligence about history of grumbling niggles ( and a well used old aircraft like this will be full of them) is not disseminated in a readily accessible way. You can bet your bottom dollar that the true history of this aircraft will only be reconstructed by looking at long e mail threads and questioning pilots and engineers about verbal exchanges.
The relatively inexperienced captain had only been on line with the company a short while and I just wonder how far, if at all, the innate deficiency in dissemination of essential technical information through the tech log from one crew to another might have made its contribution to this disaster. ( as one of the many holes in the swiss cheese that all lined up on the fateful day)