THE PILOT (PIC) AND AN FAA INSPECTOR (CHECK PLT) WERE ON A COMBINED FLT INSTRUCTOR & FAR PART 135 CHECK FLT. THE CHECK PLT INSTRUCTED THE PIC TO EXECUTE A SIMULATED FIXED-TAIL ROTOR FAILURE; THE CHECK PLT SIMULATED THE FAILURE BY HOLDING THE RGT PEDAL SLIGHTLY IN, WHILE THE PIC REMOVED HIS FEET FROM THE PEDALS. THE PIC INITIATED A RUN-ON LANDING WITH AN ESTIMATED 10 DEG RGT YAW. HE RPRTD THAT JUST BEFORE LANDING, AT ABOUT 5 MPH & 2 FT AGL, THE HELICOPTER BEGAN TO YAW FURTHER TO THE RIGHT. HE RETARDED THE THROTTLE TO ALIGN THE HELICOPTER WITH THE GND TRACK & INCREASED THE COLLECTIVE TO CUSHION THE LANDING. THE HELICOPTER TOUCHED DOWN FIRMLY. NO PROBLEM WITH HELICOPTER WAS NOTED AT THAT TIME; HOWEVER, AFTER THE FLT, WRINKLES WERE NOTED ON THE TAIL BOOM, SIMILAR TO THOSE DEPICTED IN BELL OPNS SAFETY NOTICE (OSN) 206-84-13.