A HELI ROTOR DOWNWASH DAMAGED A PARKED ACFT DURING HOVER TAXI AT 5W15.

Narrative

I FLEW TO A FLY-IN AT MERRILL ARPT. AFTER ESTABLISHING COM WITH ARPT PERSONNEL ON 122.8; I ASKED THEM WHERE THEY WANTED ME TO PARK THE HELI. THEY WANTED ME TO PARK ON THE RAMP WHICH IS E OF RWY 34; AND TO LOOK FOR A GND PERSONNEL IN AN ORANGE VEST TO GUIDE ME IN. I SPOTTED THE PERSON AND CAME TO A HOVER IN THE GRASS AREA ON THE W SIDE OF RWY 34. I THEN PROCEEDED TO HOVER TAXI E ACROSS RWY 34 TO THE S TXWY WHICH LED IN TO THE RAMP. I CONTINUED IN TO THE RAMP WHEN THE GND PERSONNEL GAVE ME A WAVE-OFF SIGN. I WAS NOT IN RADIO CONTACT WITH THE GND PERSONNEL GUIDING ME IN (ONLY WITH ARPT PERSONNEL IN THE FBO SHACK) DUE TO HIS RADIO WAS INOP. AFTER RECEIVING THE WAVE-OFF SIGN; I LIFTED INTO A HIGH HOVER; THEN PROCEEDED TO FORWARD FLT TO THE DOWNWIND SIDE OF RWY 34. I CIRCLED SEVERAL TIMES IN THE DOWNWIND (E SIDE) OF THE ARPT WHILE STILL IN COM WITH ARPT PERSONNEL. I THEN LANDED N OF THE N TXWY; DEPARTED A CREW MEMBER TO GO TALK WITH THE GND PERSONNEL (IN THE ORANGE VEST) ON WHERE THEY WANTED ME TO PARK; WHICH WAS S OF THE N TXWY ON THE GRASS. AFTER SHUTDOWN; I WAS APCHED BY THE OWNER OF ACFT WHO WAS EXTREMELY ANGRY; STATING THAT I DAMAGED HIS ACFT WITH MY ROTOR DOWNWASH. HIS WINGTIP STRUCK THE GND AND HIS ELT ANTENNA ALSO BROKE. HIS ACFT WAS NOT TIED DOWN. IN THE FUTURE; I WILL ENSURE THAT ACFT ARE EITHER TIED DOWN OR A SAFE ENOUGH DISTANCE AWAY BEFORE I HOVER TAXI IN TO THE RAMP AREA. ALSO; A PREDESIGNATED LNDG AREA WOULD HELP TO AVOID THIS SIT. HENCE COORD WITH ARPT PERSONNEL PRIOR TO A FLY-IN ON WHAT IS NEEDED FOR A SAFE LZ AND ALSO SAFE INGRESS/EGRESS RTES TO THE LZ; WOULD HELP TO AVOID FUTURE SIMILAR SITS.