Parafield crash plane’s nose gear failed to retract, says ATSB

“The failure of a nose landing gear actuator rod, as was found in this accident, is known to have caused in-flight controllability issues with this aircraft type in the past, and is one of a number of scenarios, including loss of engine power in one of the aircraft’s engines, that the ATSB investigation is examining,” said ATSB chief commissioner Angus Mitchell.

“ATSB transport safety investigators’ examination of the aircraft wreckage identified that the nose landing gear actuator rod had fractured.

“While our metallurgical analysis of the broken rod is ongoing, preliminary examination of the rod end has identified indications of fatigue cracking prior to a complete failure of the component.”

The student and instructor were simulating an engine failure as part of training when the crash happened, according to the ATSB, with CCTV footage showing the aircraft veering left as it departed the runway, with the main landing gear retracting but the nose gear remaining down.

“About 27 seconds after take-off and at 115 ft above ground level, the instructor made a radio call stating ‘engine failure’. No further radio calls were heard from either pilot,” said Mitchell.

The plane then pitched up, banked left, entered a steep descent and crashed into a hangar and flight school facility, fatally injuring both on board; nine more injured people were taken to hospital.

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The ATSB’s report noted that manufacturer Diamond Aircraft Industries had issued two mandatory service bulletins, in 2013 and 2019, following “other occurrences of fractures in the nose landing gear actuator”.

“One of these bulletins described an occurrence where a nose landing gear actuator fractured in flight and, as it was no longer attached to the gear leg, it moved out of position and ‘interacted with the rudder and nose landing gear controls in such a way that the rudder was forced into left hand deflection’,” said Mitchell, though noted that in that instance, the pilot had regained rudder control after re-extending the gear.

The ATSB is also planning to tear down the aircraft engines for inspection as part of its investigation, with Mitchell stressing that the safety watchdog is “considering a range of scenarios to explain the entire accident sequence”.

“We are very much in the early stages of this investigation, and while we have determined the existence of a fatigue crack leading to a failure of the rod, and its potential impact with the rudder controls, we need to follow our evidence examination and analysis processes to determine all of the factors that contributed to this tragic accident,” he said.

“Importantly, our onsite examination identified the left engine was not showing signs of producing power on impact, and that the left propeller was in the ‘feathered’ position,” he noted.

“While the left engine post-impact observation may be consistent with an actual engine failure, it may equally be indicative of an assumed or simulated engine failure.”

According to the report, the operator’s procedures stipulated that “simulated engine failures after take-off are not to be attempted until the aircraft has reached a minimum of 400 ft above ground level”, while the aircraft’s maximum height above the ground during the accident flight was 161 ft.

“While we continue to establish the contributing factors to this accident, we felt it important to raise awareness with operators of the DA42 of the actuator fracture and the increased risk of an uncommanded left rudder control deflection with the release of a safety advisory notice,” said Mitchell.

“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.”

The ATSB also said there are “many reasons why pilots may experience difficulty with directional control on take-off, in addition to an engine failure, such as flight control mechanism interference”.

It will release a final report, detailing findings and the analysis to support those findings, at the conclusion of the investigation.