NTSB Identification: DEN05TA113.
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Accident occurred Tuesday, July 19, 2005 in Loveland, CO
Probable Cause Approval Date: 04/25/2006
Aircraft: Hughes 369FF, registration: N530TJ
Injuries: 1 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
The helicopter was being used to support United States Forest Service (USFS) firefighting operations in the area and was attempting to deliver supplies via external load. Prior to the approach, the pilot overflew the intended landing location and was informed that the winds were from the west approximately 7 knots. The pilot performed a hover check approximately 1/2 mile east of the intended landing zone (LZ) over a valley. The pilot moved the helicopter west to the LZ at a speed just above effective translational lift and came to a hover with the load approximately 30-40 feet over the landing spot. The pilot checked the engine and operating instruments and all systems indicated normal. The pilot began looking down and outside the helicopter when he felt a yaw to the right. The pilot noticed that he was "depressing the left [pedal] more as I pushed on the left to stop a right turn." The helicopter then made an "uncommanded turn to the right and began spinning right." The helicopter made two to three rotations to the right; the pilot jettisoned the cargo portion of the long line and lowered the collective. The pilot attempted to regain control of the descent by adding power/pitch to the main rotor; however, the aircraft immediately started spinning again. The pilot lowered the collective and began a glide into the trees. Subsequently, the helicopter impacted trees and terrain and came to rest on its left side. Examination of the aircraft revealed no anomalies that would have precluded normal operation. Prior to the flight, the pilot incorrectly computed the performance and load calculations for the operation. The pilot's incorrect performance and load calculations were also not properly verified by the USFS helicopter manager. In addition, the USFS personnel miscalculated the weight of the external load, which was unknown to the pilot. A review of the rotorcraft flight manual revealed the maximum gross weight limitation was exceeded given the environmental conditions at the time of the accident. The calculated density altitude was 11,465 feet.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain aircraft control due to delayed remedial action during the encounter with the loss of tail rotor effectiveness. Contributing factors were the pilot's inadequate preflight performance planning, and the inadequate supervision by the US Forest Service personnel. Full narrative available
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