@Winch-control
"I would suggest 7 days, 10 at the most is adequate. If the AIB need 12 months plus to resolve the reasons for any accident/incident I would suggest they are sadly very lacking, and not fit for service."
Having served my time in the incident investigation sector, I would ask you to think again. In root cause analysis (the way of stopping similar things happening again, rather than just pointing the finger at someoner) we always start with the incident statement. What happened? What are we investigating?
That can be hard enough to decide. In this case you'd think it was obvious: helo crashed, people died. I'd suggest it's not so obvious, and a good investigation would start with: helo fell through building roof; people died.
Then you draw up a list of everything that needs to be looked at. Then a provisional timeline. Then a list of all the factors that could be involved (you'll probably want to use the TOP-SET method at this point). Then another list of all the things you need to examine, all the things you need to simulate, all the people you need to talk to... oops; your 7 days is up.
Ah well; Pilot Error it is, then...
Isn't that exactly what we DON'T want? A quick headline, and probably blame pinned on the last bod to touch the controls?
In other words, it's a long, meticulous business. And it has to be, if investigation's ever to be of any use. Your or my desire for a quick answer isn't worth squat compared with the need for the truth of what happened. (And sometimes, as every investigator knows, you have to accept the fact that you'll never find the whole answer.)
Nobody's dragging their feet. But a team of investigators shouting "Coo gosh wow chaps let's go with MY hunch!" is about as much use as a chocolate teapot.