NTSB Probable Cause

THE PILOT'S IMPROPER EMERGENCY PROCEDURES BY NOT FEATHERING THE LEFT ENGINE AFTER IT LOST POWER AND/OR WAS SHUT DOWN, AND HIS FAILURE TO KEEP THE AIRCRAFT AT OR ABOVE THE MINIMUM CONTROL AIRSPEED (VMC), WHICH RESULTED IN A LOSS OF AIRCRAFT CONTROL. A FACTOR RELATED TO THE ACCIDENT WAS: AN UNDETERMINED PROBLEM CONCERNING THE LEFT ENGINE THAT CAUSED IT TO LOSE POWER OR PROMPTED THE PILOT TO SHUT IT DOWN.