The ATSB is considering a number of factors that could have contributed to a Robinson R44’s main rotor blade striking the helicopter’s fuselage in flight as part of its ongoing investigation into a 2 December 2020 collision with terrain accident east of Goulburn.
Wreckage examination indicated that the main rotor struck the helicopter’s fuselage in flight. The uncontrollable aircraft subsequently collided with terrain, fatally injuring the trainee pilot and instructor on board, an ATSB preliminary report details.
“As we move forward with the investigation we will consider a number of factors that could have contributed to a rotor blade impacting the fuselage in flight, such as turbulence, pilot input, engine issues and aircraft controllability,” said ATSB Director Transport Safety, Stuart Macleod.
The training flight had departed Goulburn Airport shortly before 4 pm, with the helicopter’s last recorded automatic dependent surveillance broadcast (ADS-B) detecting it descending into a valley in the Morton National Park at 4.11 pm. An aerial search was launched when the helicopter failed to return to Goulburn as expected, with the wreckage located in a valley approximately 4 km north-west of the last ADS-B transmission.
The report notes that the accident helicopter had been manufactured in May 2020 and at the time of the accident had an estimated 150 hours total time in service. During a periodic maintenance inspection in November 2020, and in line with a safety alert from the manufacturer, the engine’s intake valves were inspected and reinstalled with new gaskets.
“To date the ATSB has attended the accident site twice for examination and evidence collection, examined the helicopter’s engine and tail rotor driveshaft and interviewed relevant parties,” said Mr Macleod.
“As well as analysing weather conditions at the time of the accident, the ATSB will continue our detailed technical examination of the engine and other recovered components, including electronic devices.”
The preliminary report notes that the two closest automatic weather stations to the accident site showed significantly different weather from one another—both 1 hour prior to, and at the time of the accident. At Goulburn, 31 km to the west, recorded conditions were winds from a north-westerly direction, up to 9 kt, visibility greater than 10 km, and the temperature was 25°C. There was no other significant weather observed, while at Moss Vale, 43 km to the north-east, a special weather report was first issued at 1538, due to a significant deterioration of weather conditions in the area. These conditions continued for several hours, with a layer of broken cloud descending to 1,100 ft above sea level, with a second layer of overcast cloud descending to 1,600 ft.
Mr Macleod explained that the preliminary report does not include any safety findings or analysis, which will be detailed in the investigation’s final report.
“However, should a critical safety issue be identified during the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken,” he said.Last update 01 March 2021