R22B INSTRUCTOR AND STUDENT LOSE CTL OF ACFT DURING HOVER AND BLADES HIT GND CAUSING DAMAGE AT ZZZ.

Narrative

AN INDIVIDUAL CAME UP TO ME AT THE ZZZ AND ASKED IF I WAS A HELI CFI. AFTER I SAID YES HE WAS INTERESTED IF I WOULD DO A SHORT DUAL FLT WITH HIM. I DIDN'T SEE A PROB WITH THAT AND TOLD HIM WHEN I GOT BACK FROM ANOTHER FLT THAT I HAD TO DO; WE COULD GO. WHEN I WAS FINISHED WITH THE FIRST FLT AND I BOARDED THE ACFT (ROBINSON R22 HELI); I PERFORMED THE START UP AND TAXIED US TO A GRASS AREA SLIGHTLY OFF THE RAMP. I FACED US INTO THE WIND AND TOLD STUDENT THAT HE COULD PUT HIS HANDS ON THE CTLS WITH ME. WE PROCEEDED TO PRACTICE SOME HOVERING MANEUVERS; SIDE TO SIDE WITH SOME FORWARD AND BACKWARD. WE WERE APPROX 3-5 FT OFF THE GND. FROM THERE; THE STUDENT ASKED FOR ME TO SHOW HIM A HOVER ALSO; WHICH I DID. AFTER THAT HE WANTED ME TO SHOW HIM A QUICK STOP; WHICH I DID. I THEN ASKED IF HE WANTED TO TRY A QUICK STOP; WHICH HE DID WITH ME ON THE CTLS WITH HIM. FROM THERE WE PROCEEDED BACK TO THE RAMP AREA TO LAND. ONCE OVER THE LNDG SPOT; WE PROCEEDED TO SET THE ACFT DOWN. WHEN WE WERE APPROX 1 FT OR SO OFF THE GND; THE ACFT BEGAN A MOVEMENT TO THE L. I TRIED TO CORRECT THE MOVEMENT WITH R CYCLE BUT COULD NOT MOVE THE CTLS. I REALIZED THE STUDENT WAS 'FROZE UP' ON THE CTLS AND YELLED FOR HIM TO LET GO AND THAT I HAD IT. THE ACFT SWUNG AROUND TO THE L; CONTACTED THE L SKID ON THE GRASS AT THE EDGE OF THE RAMP. THE ACFT BEGAN A L ROLL UNTIL THE BLADES HIT THE GND WHICH CAUSED US TO FLIP AROUND THE NOSE ONTO THE R SIDE OF THE ACFT. I ASKED STUDENT IF HE WAS OK BEFORE I UNBUCKLED MY SEAT BELT AND CRAWLED OUT. I THEN TRIED TO HELP HIM GET OUT. BY THAT TIME SOME PEOPLE WHO WERE AT THE ARPT FBO; CAME RUNNING OUT TO HELP US. STUDENT HAD SOME RIPS IN HIS PANTS AND I HAD A SMALL CUT ON THE BACK OF MY HEAD. THAT WAS THE EXTENT OF OUR INJURIES. AS FAR AS CORRECTIVE ACTIONS; ALTHOUGH NOT VERY PROFESSIONAL; I MAYBE COULD HAVE ELBOWED STUDENT IN THE FACE OR BODY TO GET HIM TO LET GO OF THE CTLS. NOT SURE I HAD TIME TO DO THIS SINCE WE WERE ONLY A FOOT OFF THE GND FOR LNDG.