19980417007059A

Heli experienced a power surge on approach, lost power, and landed hard causing the main rotor to cut off the tail (.4)during final approach, the pilot reported erratic engine and rotor RPM accelerations and droop. To arrest a high rate of descent, the pilot initiated a cyclic flare at 75 feet AGL and leveled the helicopter prior to touchdown. The helicopter landed 'hard' and the main rotor blades 'flexed' downward, separating the tail boom. Four passengers onboard thought the helicopter 'lost power.' The helicopter was within weight and balance limits for the flight. Examination of the engine and fuel system did not reveal any anomalies. Calibrated bench tests of the N1 tachometer, and the N2/rotor RPM dual tachometer showed that they were within limits. The fuel control, fuel pump, and power turbine governor were all found to be within overhaul specifications. Pneumatic lines were found intact. (-23) Mr. Breslin was interviewed and counseled by lamont williford, aviation safety inspector with the baton rouge flight standards district office. Mr. Breslin stated that he did not return to the oil platform that he had departed from because it was not suitable for an autorotative landing, if it became necessary to perform one. Therefore, he elected to divert to a Cameron, Louisiana, heliport, which was the closest suitable location for an autorotative landing. Upon arrival at Cameron, he made a steep approach angle from which an autorotation could be made. When he was at approximately 300 feet AGL, the engine surged to an overspeed condition. He increased collective pitch and reduced throttle in an attempt to control the RPM. The engine lost RPM and he reduced the collective in an attempt to control the RPM for an autorotative landing. Based on the information in the emergency procedures section of the Bell 206B flight manual for fuel control and/or governor failure, Mr. Breslin took the appropriate actions for the indications that he described.