On September 9, 2003, a Hiller UH12E (registration N9792C) was involved in an aviation accident near Kekaha, HI. Investigators recorded the probable cause as: the pilot's failure to maintain clearance with the wires due to an inadequate visual lookout. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter conducting aerial application operations collided with power lines at 500 ft MSL, impacting the top wire. The main rotor severed the wire and tail boom, leading to a right spin and autorotation.
Accident Overview
A helicopter struck power lines while returning for another load of chemicals during aerial application operations. The pilot was unaware of two power lines present at the top of a ridge at approximately 500 feet mean sea level.
Sequence of Events
While descending at 60 knots, the helicopter impacted the top wire about the middle of the bubble. The impact caused the aircraft to pitch forward. Subsequently, the main rotor blade cut the wire and then severed the tail boom in sequence. The helicopter began spinning to the right, prompting the pilot to perform an autorotation.
Pilot Response
The pilot successfully executed an autorotation after the loss of the tail boom and the onset of the right spin. No further details on the outcome of the autorotation are provided.