THE PILOT HAD POSITIONED THE HELICOPTER ON AN EASTERLY HEADING TO ALLOW THE PASSENGER TO PHOTOGRAPH A CEMETERY. ACCORDING TO THE PILOT, AS THE HELICOPTER SLOWED THROUGH TRANSLATIONAL LIFT, ADDITIONAL POWER AND LEFT PEDDLE WERE APPLIED TO MAINTAIN THE HOVER. WHILE HOVERING ABOUT 400 FEET ABOVE THE GROUND, THE HELICOPTER WAS HIT BY A STRONG WIND GUST, THE PILOT LOST TAIL ROTOR THRUST AND CONTROL OF THE HELICOPTER. EFFORTS TO ARREST THE UNCONTROLLABLE CONDITION FAILED. THE HELICOPTER LOST ALTITUDE AND COLLIDED WITH THE MULTI-FAMILY DWELLING. WESTERLY GUSTING SURFACE WINDS, MAX 19 KNOTS, WERE RECORDED AT THE THREE LOCAL AIRPORTS AT THE TIME OF THE ACCIDENT. THE WRECKAGE EXAMINATION FAILED TO DISCLOSE ANY MECHANICAL PROBLEMS. FLIGHT CONTROL CONTINUITY WAS ESTABLISHED FROM THE COCKPIT TO THE RESPECTIVE FLIGHT CONTROL SURFACES.