The first findings presented by the Australian Transport Safety Bureau (ATSB) indicate oscillations occurred in propeller speed and load instruments in the cockpit before the instructing pilot took evasive action to land the plane.

The accident occurred at 8.30pm on September 8, 2017 just after the Diamond DA40 NG aircraft, used in training flights operated by the Australian International Aviation College (AIAC), took off from Port Macquarie airport.

AIAC is a member of the Hainan Airlines of China group of companies.

Since 2013, about 150 pilot cadets a year from China were expected to train under the guidance of the Port Macquarie-based aviation college in a step towards becoming pilots with Hainan Airlines. 

Each student spends up to 16 months training in the Hastings.

As it would be the student’s first time conducting night circuits, the instructor was at the controls for the first take-off on the night of the accident, according to ATSB’s executive director of transport safety, Nat Nagy.

“The instructor reported noticing a ‘surging’ sound and feel on initial climb towards the end of the runway and felt as though the engine had lost a significant amount of power,” the preliminary report said.

“The propeller speed and load instruments were showing oscillations. As there was insufficient time for troubleshooting, and no visible forced landing options in the immediate area, the instructor decided to turn left and attempt to land on the reciprocal of the take-off runway, making an immediate radio call to that effect.

“The instructor recalled pushing the power lever to ensure that it was fully forward, and possibly experimenting with power settings to see if the issue improved.”

The aircraft did not maintain height through the turn and it collided with trees about 325 metres from the runway coming to rest in an inverted position. The wings and the tail were structurally detached.

Both occupants were seriously injured and the aircraft was destroyed. There was no fire. The 25-year-old instructor and 25-year-old student were airlifted to hospital for emergency treatment and both now continued to recover from their injuries.

The ATSB said the last maintenance carried out on the aircraft was a 50-hourly engine check, landing gear wheel replacement, and coolant relief valve replacement on 28 August, 2017. The last major inspection was carried out on 8 August, 2017.

Examination of the aircraft wreckage found no pre-existing airframe issues. Previous fuel records and the engine data both indicated that there was sufficient fuel on board the aircraft.

The ATSB findings have revealed the engine manufacturer reported it was aware of 16 other instances involving aircraft fitted with the AE300 engine worldwide experiencing oscillations in propeller speed and load, none of which resulted in an accident. The engine manufacturer reported that in all cases, oscillations ceased with a change in power lever position.

Fifteen of these occurrences were later found to be the result of a fuel pressure issue, propeller imbalance, or faulty electrical connection in the propeller governor. Limited data from one occurrence of each type were provided by the engine manufacturer and exhibited different data signatures than that seen in the VH-YPQ accident.

The other occurrence involved a Diamond DA42, a twin-engine aircraft with a similar engine type to VH-YPQ. The reasons for that oscillation could not be determined from post-event examinations.

“After the accident, the Australian International Aviation College introduced partial engine failure after take-off training into the syllabi for instructors and students, comprising pre-flight planning and self-briefing, ground training, and flight training,” the report said.

“(The school) has performed flight simulator tests for partial engine failure after take-off conditions in each single engine aircraft model operated by the flying school and amended procedures to ensure that pilots keep a hand on the power lever throughout the take-off.”

The training college has also investigated the potential to introduce specific single engine escape procedures for partial and complete power loss situations for each runway regularly used by the flying school.

Mr Nagy said the ATSB investigation is continuing and will include further examination and analysis of recorded data, aircraft maintenance, pilot qualifications and experience and operational procedures.

A final report is expected in 2018.