NTSB Identification: CHI05CA147.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Thursday, May 19, 2005 in Twin Brooks, SD
Probable Cause Approval Date: 09/13/2005
Aircraft: Bell 47G, registration: N8505F
Injuries: 1 Minor.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The helicopter collided with power lines during an aerial application flight. The pilot reported that he saw the power lines just prior to contacting them. He stated the lines hit the bubble then they traveled over the top of the helicopter contacting the main rotor shaft. He stated the helicopter then settled in a level attitude onto the tracks. The pilot stated he was spraying for the purpose of weed control along the Burlington Northern Santa Fe railroad when the accident occurred. The pilot stated he was about 2.75 miles into the 3 mile run when the helicopter contacted the lines. The pilot reported that he saw a pole to his left, but it was off in the distance. The pole on his right, which he did not see, was nestled in a group of trees. The pilot reported he was flying at an altitude of 15 to 20 feet above the tracks at an airspeed of 43 to 45 miles per hour. He stated the bubble was clean and the sun was to his back as he flew to the east.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's inadequate lookout and his failure to maintain clearance with the power lines. A factor was the low altitude at which the helicopter was operating.

Full narrative available

Index for May2005 | Index of months