NTSB Identification: LAX05LA288.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Saturday, September 03, 2005 in Trona, CA
Probable Cause Approval Date: 02/26/2007
Aircraft: Goodlett Safari, registration: N912TT
Injuries: 1 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 experimental helicopter impacted terrain after experiencing a failure of a flight control connecting rod. According to the pilot, he was maneuvering the helicopter about 50 feet above the ground when he heard a loud bang followed by a whirring or buzzing noise. The helicopter rolled to the left, which the pilot was unable to counter with control inputs, and impacted terrain on the left side. A post-accident examination of the helicopter by the pilot/builder revealed that a 27.875-inch aluminum control rod was fractured near the middle of the rod. The control rod was connected between the collective-cyclic mixing assembly and a walking beam that connected to the stationary swash plate of the left side (pilot side) of the helicopter. The break in the control rod was perpendicular to the longitudinal axis of the rod. Examination of the control rod by a metallurgical laboratory revealed the failure was a result of a fatigue crack that had propagated through nearly 75 percent of the control rod. A portion of the break was polished indicating that the crack had been present for quite some time. The pre-existing crack in the control rod reduced its strength to a point that allowed the flight control forces to fail the remaining material. According to the pilot/builder, a break in the control rod would result in flight characteristics consistent with that experienced by the pilot during the accident flight. The control system has been redesigned by the kit manufacturer as a result of this accident and now incorporates steel control rods as opposed to aluminum ones.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the in-flight fatigue failure of a control system connecting rod, which resulted in a loss of helicopter control. Full narrative available
Index for Sep2005 | Index of months