An ATSB investigation has revealed a botched simulated engine failure was behind an Angel 44 utility aircraft crashing into a cornfield and killing two onboard.
The report said neither the pilot, William Scott-Bloxam, 73, nor instructor, Geoff Burry, 63, had any recent experience in the aircraft, which was likely a contributing factor in the incident in far north Queensland on 14 December 2019.
In particular, the ATSB found the instructor was “likely unfamiliar” with the long time necessary for the landing gear and flaps to retract and that there was also no evidence of a complete engine power loss.
The twin piston-engined Angel 44, VH-IAZ, took off from Mareeba Airport at 11am, after which witnesses reported hearing one of the engines hesitating and backfiring, accompanied by a sooty smoke trail from the right engine.
The aircraft operated in the training area until returning to the airport circuit area at 11:12am. Witnesses observed the aircraft touch down on the runway, accelerate and take off again.
After take-off, the aircraft climbed to about 100-150 feet above ground level before entering a right descending turn.
The aircraft was airborne for about 20 seconds before witnesses observed it rolling rapidly to the right and crashing into a cornfield 475 metres north of the runway.
The pilots sustained fatal injuries and the aircraft was destroyed.
“The ATSB found that shortly after take-off, the flight instructor very likely conducted a simulated failure of the right engine on a warm, humid day at a high aerodrome elevation in a configuration in which the aircraft was unable to maintain altitude with one engine inoperative,” said ATSB director transport safety Dr Stuart Godley.
“Power was not immediately restored to the right engine to discontinue the exercise and the pilots were unable to maintain altitude or heading, particularly with the aircraft banked towards the inoperative engine.
“The pilots did not reduce power and land ahead, as required by the aircraft’s flight manual, resulting in a loss of directional control and the aircraft rolling to the right. The loss of control occurred at a height too low to recover and the aircraft impacted terrain in a cornfield 475 metres north of the runway.”
The ATSB found that neither the pilot nor the instructor had any recent experience in the aircraft, which had not been flown regularly for more than two years.
In addition, the pilot had not flown for three years before the accident, which likely resulted in a “decay of skills” at managing tasks such as an engine failure after take-off, while the instructor had limited experience in multi-engine aeroplanes with retractable landing gear, and had only once before flown the Angel 44 aircraft, several years earlier.
As a consequence, the investigation concluded that the instructor was likely unfamiliar with the time necessary for the landing gear and flaps to retract – approximately 14 seconds, significantly longer than other aircraft the instructor had flown – and the associated detrimental effect that extended flaps and landing gear had on the aircraft’s single-engine climb performance.
“In light twin-engine aeroplanes, loss of power on one engine shortly after take-off poses a high risk due to low height above ground, low airspeed and generally limited single-engine climb performance,” Dr Godley said.
“When conducting simulated engine failures, it is essential that pilots understand the risks and ensure effective controls are in place to prevent the simulation turning into a loss of control at low level, where recovery will probably not be possible.
“Attempting to continue flight with one engine inoperative in a multi-engine aeroplane when directional control cannot be maintained, carries a high risk of an accident and fatal injuries.”
Dr Godley also said the ATSB found no evidence of a complete power loss, with both engines producing power at the time of impact, and with the ‘splutter’ heard by witnesses consistent with simulation of an engine failure by rapidly retarding the throttle.
Nonetheless, investigators established that two of the fuel injectors in the right engine showed evidence of partial blockage by corrosion particles. That would have resulted in the over-fuelling of the other injectors and the engine running overly rich, backfiring, and reducing the maximum power available.
In the two years the aircraft had not been flown, its engines had not been preserved in accordance with the manufacturer’s procedures, the investigation notes.
“If an aircraft is not flown regularly, the airframe and engine/s need to be preserved in accordance with the manufacturer’s procedures,” Dr Godley noted.