Possibly another of those missing rubber main gearbox drive belts, you know, the one that wasn't actually fitted to the helicopter.
"Exclusive- Helicopter accident caused by missing rubber belt".
Examination of the aircraft was made by a local farmer, who spoke to someone in the pub and was overheard by someone's aunty's cousin, and passed it on to a chap in Woolworth's, who knows our aviation correspondent. There was no sign of a rubber belt between the engine and the transmission. Safety experts are now to call for rubber belts to be fitted to all helicopters
Seriously, I hope Dave and his good lady have recovered from their fright.
P.S. No doubt there will be an official announcement soon.