NTSB Probable Cause

FOR OCCURRENCE #1 - INADEQUATE SUPERVISION BY THE OPERATOR IN LAUNCHING A HAZARDOUS MISSION WITHOUT AN ADEQUATE SLING/HARNESS, THE PILOT'S POOR JUDGEMENT IN ACCEPTING AND CONTINUING THE MISSION INTO LOW LIGHT CONDITIONS, AND THE CREWMEMBER'S INADVERTENT RELEASE OF HIS HOLD OF THE NYLON STRAP. FOR OCCURRENCES #2-4 - FAILURE OF THE TAIL ROTOR DRIVE SHAFT AS A RESULT OF ENTANGLEMENT OF AN UNSECURED NYLON STRAP.