It seems 3 students were taking turns at hands-on flying under instruction, the ballast of a full aircraft making for some difference in handling, part of the initiation to an R44. The witnessed “spiralling” indicates a tail rotor malfunction or mast bumping, the latter a sadly not uncommon cause of the demise of these and other teetering rotor helicopters, carburettor icing being a common cause of engine flaming out. When I was doing al little R22 training, the flying school had a big block lettered notice stuck on inside “NO PUSHOVER MANOEUVRES!”. They had sadly lost one of their aircraft through a pushover when it was hired out. These aircraft don’t forgive mistakes, but aside from that they are in themselves fundamentally reliable.