Halifax HR910 of 405 Squadron took off from RAF Gransden Lodge at 14:10 hours for a cross country navigation exercise, estimated to last around 3 hours.
Shortly after passing Newcastle on the outward journey the starboard inner engine began to vibrate violently and about two minutes later, at around 15:30 hours, the engine came away and fell to earth.
The pilot, Flying Officer A.P. Campbell, aborted the flight and made a successful landing back at base, minus one of the four engines.
The engine, and part of a three bladed propeller, landed in a field at Hartburn near Morpeth.
The vibration was attributed to a fracture in the propeller hub causing one of the propellers to detach in flight. There had been previous similar instances of propellers detaching in flight but none so serious as to cause the entire engine to break away. The missing propeller was never found.