Worker On The Ground Pulled Lifting Line Bringing It Into Contact With Rotor Blades

The Civil Aviation Authority (CAA) of New Zealand has released its preliminary report in a helicopter accident in November which was shown live on New Zealand television.

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According to the report:

"The helicopter operator was engaged by the rigging contractor for the purpose of erecting the 25 meter (82 foot) tall tower for the Auckland Christmas tree located at Auckland’s Viaduct Harbour.

"The plan was for two lifts to be conducted. "The first lift was to raise the tower from the horizontal into the vertical position using the Kevlar lifting line, the tower pivoting on two bolts in the base. Then, once in the vertical position, two more bolts were to be inserted into the base corners and three temporary cable stays would be applied to hold the tower in place. The lifting line would then be released from the helicopter’s hook and removed from the tower by a rigger. The second lift would follow to position the ‘star’ ornament onto the top of the tower.

"The first lift proceeded well, until it came time to release the lifting line from the helicopters hook. The pilot then descended the helicopter toward the ground. The pilot was in radio communication with the rigging supervisor who was standing underneath the helicopter. When the helicopter hovered at approximately five meters (16 feet) above the ground, the rigging supervisor was seen to jump up and grab the lifting line which was sagging below the helicopter.

"The act of pulling downwards on the lifting line to release it from the helicopter’s hook instantly tightened the lifting line, which was still attached to the top of the adjacent tower, and the strop came into contact with the main rotor blades. The force of the impact of the main rotor blades on the lifting line caused massive out of balance forces within the helicopter’s rotating components, which resulted in the loss of the structural integrity of the helicopter whilst in flight. The helicopter then fell to the ground. All parties managed to escape without injury."

TV New Zealand's ONE News reports that the pilot, Greg Gribble, said he had no idea why the rigging supervisor, Scott Anderson, grabbed the line during the procedure. For his part, Anderson told ONE News that Gribble should not have been hovering below the mast. He also said that the CAA had not spoken to him about the accident.

Gribble said that there had been a very detailed plan in place for the operation, but "unfortunately, it didn't go that way."

FMI: CAA Report