NYC83FA210

While on final apch to a heliport, the helicopter was at aprx 70 KTS & 100 ft AGL when the plt applied power to begin decelerating. As collective pitch was applied, he heard a series of banging noises which he described as similar to compress stalls. Simultaneously, he noted a decay of the eng power. The plt changed his course to minimize the distance to the landing area & raised the nose to further decelerate for a vertical descent. However, during touchdown, the tailwheel strut fairing hit a barrier at the edge of the heliport, separating the vertical stabilizer & fenestron. The separated component traveled upward & struck the main rotor blades. Reportedly, the low RPM warning horn sounded just before the compressor stall. Corrective action for a low RPM warning horn in this situation should have been to reduce the power demand by lowering the collective and/or reducing right pedal application. An eng check revealed it was capable of exceeding the max required torque, but it had slight fouling of the fuel injector wheel & compressor air flow