THE PLT WAS ON A MISSION TO TRANSPORT COMPANY PERSONNEL & HAD LANDED ON A BARGE THAT WAS BEING USED AS A HELIPAD. THE BARGE WAS ABOUT 250 FT LONG & 75 FT WIDE. AFTER ARRIVING, THE PLT PARKED THE HELICOPTER WITH THE TAIL BOOM AS CLOSE TO THE EDGE OF THE BARGE AS POSSIBLE. HE THEN REDUCED THE POWER TO IDLE & SIGNALED FOR THE 3 PASSENGERS (WAITING BEHIND A ROPE LINE) TO APPROACH THE HELICOPTER IN ACCORDANCE WITH ESTABLISHED OPERATING PROCEDURES. AS THE PASSENGERS APPROACHED THE RIGHT SIDE OF THE HELICOPTER, THEY MOVED OUT OF THE PLT'S LINE OF SIGHT. WHILE 2 WERE BOARDING, THE 3RD PASSENGER WALKED TO THE REAR OF THE ACFT, DUCKED UNDER THE HORIZONTAL STABILIZER & WALKED INTO THE TAIL ROTOR. THE VICTIM WAS TREATED & TAKEN TO A HOSPITAL, BUT SUCCUMBED LATER DUE TO HEAD & SHOULDER INJURIES. A TRAINING PROGRAM HAD BEEN INSTITUTED TO EDUCATE THE PASSENGERS CONCERNING HAZARDS ASSOCIATED WITH ROTATING COMPONENTS OF THE ROTOR SYS & OFF-LIMIT AREAS. THE PASSENGER HAD BEEN BRIEFED ON 3 OCCASIONS & HAD BEEN A PASSENGER NEARLY EVERY DAY FOR 6 WEEKS.