NTSB Identification: SEA98FA084.
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Accident occurred Tuesday, June 02, 1998 in SHOSHONE, ID
Probable Cause Approval Date: 01/10/2000
Aircraft: McDonnell Douglas 369FF, registration: N16031
Injuries: 1 Fatal,1 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

Witnesses reported that the helicopter had just released from positioning a fiber optic cable on top of a power pole. An external line is hung over the left landing skid, forward of the front leg, and a shoe is used to cradle the cable to lift and position it in place for permanent attachment. A lineman was on the pole and in the process of permanently attaching the cable to the pole when the pilot maneuvered the helicopter away and behind the lineman about five feet. Another lineman was standing on the left side landing skid and was then going to install vibration dampers on the cable. The lineman on the pole stated that everything was normal when he heard what sounded like a clicking sound or a sound like a card in a spoked wheel. The lineman on the pole stated that he knew that the helicopter was in the wires and saw pieces of the helicopter flying. The lineman ducked down on the pole, and when he looked up again, the helicopter had already gone through the transmission wires and was laying on its right side on the ground. Impact signatures of a cable strike were found on both tailrotor blades. The cable that the helicopter was positioned next to was severed. Further inspection of the severed cable noted that 19 of the 22 strands that make up the fiber optic cable received varying amounts of mechanical damage prior to failure. During the post-crash wreckage documentation and inspection, no evidence was found to indicate a mechanical failure or malfunction.

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

Failure to maintain clearance from wires. A transmission wire was a factor.

Full narrative available

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