pigboat,
If Dave and I are right about the particular gearbox ratio here, your answer is:
Prop speed = 0.093 * 14200rpm = 1320 rpm
pailot77,
Can't comment on the F27, but the issue here seems to have been the maintenance of the Dart powerplant - specifically the gearbox or the airscrew. My guess is that the sequence started with a propellor blade failure.
Can someone confirm if the blade anti-ice is electrical? In any case, the rubber layer on its leading edge can conceal cracks, as in the case of that DC6 accident quoted earlier on this thread.