sentences:  There had been two prior engine separation incidents with the 377, on January 24 and 25, 1950.In this case, investigators hypothesized that the propeller failure caused the engine to experience highly unbalanced loads and it eventually separated from the aircraft, precipitating an in-flight breakup.Debris from the propeller and engine may have contributed to the breakup by damaging control surfaces after being flung from the port wing during the failure.