NTSB Identification: ANC06LA137.
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Accident occurred Saturday, September 23, 2006 in Port Alsworth, AK
Probable Cause Approval Date: 08/30/2007
Aircraft: Aerospatiale SA319B, registration: N119PH
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
During a Title 14, CFR Part 133 flight, the commercial certificated pilot was transporting a previously crashed 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. While flying about 60 knots, and about 2,000 feet above ground level (agl), the pilot felt the load shift, becoming light, or unloaded, and he 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. The pilot released the external load from the belly of the helicopter and entered an autorotation. About 1,000 feet agl, the pilot 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 did not determine the cause of the external load shift.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to adequately secure the external load rigging of an airplane that was suspended from the helicopter, which resulted in a load shift during cruise flight, producing an abrupt nose-down attitude, and the severing of the tailrotor drive shaft by the main rotor blades. Full narrative available
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