NMAC.

Narrative

I WAS INSTRUCTOR PLT OF HELI (HUGHES 500D) PERFORMING AN EMER PROC TO RWY 11; LITTLE RIVER ARPT; CA. WE HAD BEEN USING THE ARPT FOR MORE THAN 1 HR; HAD BEEN IN RADIO CONTACT WITH THE UNICOM OPERATOR AND 2 OTHER ACFT ON CTAF 122.7. AS WE WERE ON DOWNWIND TO RWY 11 WE NOTICED A SINGLE ENG CESSNA TAXI DOWN THE PARALLEL TXWY WITHOUT MAKING A RADIO CALL. WE CONTINUED OUR BASE AS THE CESSNA TAXIED TO THE RWY HOLD LINE AND TURN W AS IF DOING A CLRING TURN. WE TURNED A HIGH FINAL APCH (CALLED BOTH BASE TURN AND FINAL ON CTAF) AND PROCEEDED WITH OUR SIMULATED EMER (STUCK L PEDAL). WE PASSED 2/3 OF THE RWY ABOUT 120 FT ABOVE THE SURFACE WHEN THE CESSNA UNDERFLEW US BY 75-80 FT RESULTING IN A NEAR MISS. THE CESSNA PLT DID NOT ANNOUNCE HIS INTENTIONS OF DEPARTING. AFTER UNDERFLYING US THE CESSNA PLT PULLED UP ON A STEEP DEP AND CONTINUED EBOUND. WE FEEL THAT THIS WAS A DELIBERATE DEP UNDER US THAT UNNECESSARILY PUT 3 PEOPLE AT RISK. I CONFIRMED THE IDENT OF THE ACFT (CESSNA) AND THE OWNER'S NAME AND IF HE HAD RADIOS IN THE ACFT. THE FBO CONFIRMED THE ACFT HAD RADIOS. IF THIS HAD BEEN ACCIDENTAL; THE CESSNA COULD HAVE MOVED OFF THE CTRLINE EITHER L OR R TO CLR US INSTEAD OF UNDERFLYING US. WE WERE ABOUT TO INCREASE OUR RATE OF DSCNT AT THE TIME OF THE NEAR MISS. HAD THE CESSNA TRIED THIS SOME 8-10 SECONDS LATER; YOU WOULD HAVE HEARD ABOUT THIS ON CNN.