On the morning of 19 November 2008, the pilot of a McDonnell Douglas 369D helicopter, registered VH-PLJ, and two lineworkers were conducting airborne joint-testing operations on an electricity transmission line between Mannum and Mobilong, South Australia. Joint testing involves closely approaching the transmission line to check joints in transmission wires. At about 1150 Central Daylight-saving Time, when about 13 km north of Murray Bridge, the helicopter's main rotor blades contacted a transmission line conductor. The pilot lost control and the helicopter impacted the ground. One lineworker was fatally injured, the other lineworker received minor injuries and the pilot received serious injuries. The helicopter was seriously damaged.

The investigation found that the crew was not aware before the flight that there were transpositions (changes in the relative positions of individual wires) in the line and that they did not detect such a transposition during the approach for the joint test that led to the accident.

Following the occurrence, the helicopter operator amended the guidance for conducting joint-testing and expanded training and supervision of new crews. The powerline owner reviewed the risk profile of its airborne operations and revised a number of hazard treatment options. The powerline maintenance provider made a number of operational changes and contracted an external auditor to examine its operation. All of the recommendations from that audit were adopted by the maintenance provider.

In response to the failure of the recording lineworker's shoulder harness, the shoulder harness repair facility has upgraded relevant repair equipment and provided a replacement program for any incorrectly-stitched harness in the operator's helicopter fleet. In addition, the Civil Aviation Safety Authority took action to have a number of seat belt harnesses recalled and examined. No issues were found with any of the seat belts that were examined and they were able to be re-released without further rework.

Preliminary report released 5 January 2009

At about 1115 Central Daylight-saving Time on 19 November 2008, a pilot and two linesmen were operating a McDonnell Douglas 369D helicopter, registered VH-PLJ, to test a high-voltage powerline between Mannum and Mobilong, SA. While manoeuvring to test a conductor joint, the helicopter's main rotors struck a conductor and impacted the ground. One linesman was fatally injured and the other sustained minor injuries, while the pilot sustained serious injuries.