On September 23, 2006, about 1630 Alaska daylight time, a wheel-equipped Aerospatiale SA319B helicopter, N119PH, sustained substantial damage during an emergency landing following an in-flight loss of control while in cruise flight, about 62 miles west-southwest of Port Alsworth, Alaska. The helicopter was being operated as a visual flight rules (VFR) cross-country external load operation from a remote area under Title 14, CFR Part 133, when the accident occurred. The helicopter was operated by Last Frontier Air Ventures Ltd., Sutton, Alaska. The commercial certificated pilot and the one crewmember aboard were not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated from the area of the Mulchatna River, and was en route to Port Alsworth. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 24, the pilot/owner, who also is the director of operations, reported that he was transporting a previously crashed Piper PA-18 airplane on a 100 foot external load line. The external load line was attached to a spreader bar that was attached to the wing structure of the airplane. The wings had wing covers designed to spoil lift. The pilot said he was flying about 60 knots, and about 2,000 feet above ground level (agl), when he felt the load shift. He indicated that it felt as if the suspended airplane became light, or unloaded, and he immediately began to slow the helicopter's airspeed. The helicopter then suddenly pitched nose-down about 45 degrees. The tail boom of the helicopter was struck by one or more main rotor blades, severing the tail rotor drive shaft, and one or more of the main rotor hub spacing cables broke at their frangible bolt attach points. The pilot said when he released the external load from the belly of the helicopter and entered an autorotation, the helicopter descended with a severe lateral vibration in the main rotor system. The pilot said that about 1,000 feet agl, he shut the engine off, and performed a touch-down autorotation. During the landing on soft tundra, one of the main landing gear wheels dug into the terrain, and the helicopter's tail boom was struck by the main rotor blades, severing about two feet of the aft end of the tail boom. The pilot reported that after the external load was released, the suspended PA-18 airplane sustained extensive damage when it struck the ground. The pilot did not determine the cause of the external load shift.