NTSB Identification: ATL04LA181.
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Accident occurred Friday, September 10, 2004 in Waynesboro, GA
Probable Cause Approval Date: 07/07/2005
Aircraft: Hughes HU-369-D, registration: N5211R
Injuries: 2 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The flight was contracted by Georgia Power Company to complete inspections and maintenance on a number of their transmission power lines. After completing a shield wire splice procedure, both the pilot and passenger heard a "pop" in the rear of the helicopter. The helicopter began to spin "hard to the right". However, to avoid hitting the shield wire, the pilot increased the collective pitch, which accelerated the turn. After clearing the shield wire and making the second turn, the pilot reduced the throttle to slow the spin, leveled the helicopter and collided with trees in a level flight attitude. The pilot did not report any mechanical malfunctions with the helicopter prior to the accident. Examination of the helicopter revealed the main rotor blades separated, the left skid separated, the windshield broken, upward crush damage along the bottom of the fuselage aft of the skid, the tail rotor assembly separated at driveshaft, crush damage along the sides of the tail section and the horizontal stabilizer detached from the tail. The tail rotor assembly and part of the tail rotor drive shaft were sent to the NTSB Materials Laboratory in Washington D.C. for further examination. The Materials Lab determined that the tail rotor assembly failed due to a fatigue fracture of the input gearshaft in the tail rotor gearbox assembly. This fracture led to jamming of the gearbox and the resulting overstress fracture of the tail rotor drive shaft, which was consistent with the engine driving the shaft at the forward end with the aft end stopped.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The tail rotor assembly failed due to a fatigue fracture of the input gearshaft in the tail rotor gearbox assembly, which resulted in a loss of tail rotor control and subsequent collision with trees. Full narrative available
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