A fractured nose landing gear actuator rod has been identified as a key finding in the ATSB's ongoing investigation into the fatal Diamond DA42 accident at Adelaide's Parafield Airport on 29 April.
The preliminary report, released by ATSB Chief Commissioner Angus Mitchell, confirms a pilot under instruction and a flight instructor were on board conducting simulated engine failure circuits when the accident occurred. CCTV footage shows the aircraft deviated left after take-off, was realigned, then veered left again. The main landing gear retracted normally but the nose landing gear remained extended.
About 27 seconds after take-off, at 115 ft above ground level, the instructor made a radio call stating "engine failure." No further radio calls were received. The aircraft then pitched up, banked left and entered a steep descent, colliding with a flying school classroom and hangar facility. Both pilots were fatally injured and nine people on the ground were hospitalised.
Metallurgical analysis of the fractured actuator rod is ongoing, but preliminary examination has identified fatigue cracking prior to complete failure. Diamond Aircraft Industries had previously issued two mandatory service bulletins, in 2013 and 2019, following other occurrences of nose landing gear actuator fractures.
Mitchell noted that in one previously documented case, a fractured actuator moved out of position and interacted with the rudder controls, forcing the rudder into left-hand deflection. In that instance, the pilot regained control by re-extending the landing gear.
"In the DA42, re-extending the landing gear after take-off may not be a usual action considered by pilots, but as noted in the manufacturer's service bulletin explanation of a previous incident, this action allowed the pilot to regain aircraft control," Mitchell said.
The ATSB has issued a safety advisory notice to DA42 operators, noting the increased risk of uncommanded left rudder deflection associated with an actuator fracture. Investigators are also examining the aircraft's engines following the observation that the left engine showed no signs of producing power at impact and the left propeller was in the feathered position.
The operator's procedures stipulated simulated engine failures after take-off were not to be attempted below 400 ft above ground level. The aircraft's maximum recorded height during the accident flight was 161 ft.
A final report will be released at the conclusion of the investigation.