Police helicopter crashes onto Glasgow pub

[Munnyspinner]

Eye witness statements can be quite unreliable and for a variety of reasons. I would discount the suggestion that there was no sound simply because in any situation such as this the brain tends to go into an overdrive situation which results in the impression that time slows down. This tends to create a mismatch between visual and aural perception.
The post crash evidence is that the blades were not turning under power otherwise they would have been damaged more extensively. After the initial impact it does appear that the cab settled into the building. The disc would have been relatively clear of obstruction until that happened and when a still turning rotor impacted something solid. The tail boom and fenestron appear to have broken off at initial impact.