The engines of a doomed plane which killed two people in a crash west of Cairns were reportedly spluttering and emitting smoke.
The crash killed experienced pilot William Scott-Bloxam and passenger Geoff Burry in December.
Witnesses saw the smoke from the engine prior to the first of the plane's two flights, according to an initial report from the nation's transport safety authority.
Following take-off, the Model 44 Angel twin-engine light plane was seen with 'black sooty smoke' coming from the right engine.
The plane was in the air for 10 minutes before touching down.
After taking-off for its second flight witnesses said they heard the engines splutter according the initial report from the Australian Transport Safety Bureau.
The plane was about 100m in the air when the noises were heard by witnesses.
The plane turned sharply before crashing into a corn field near the airfield at Mareeba.
Further investigations are continuing into why the plane crashed, says ATSB's Stuart Godly.
""The ATSB's ongoing investigation will focus on further examination of the recovered engines and propellers, maintenance and operational records, aircraft and site survey data, pilot qualifications, experience and medical history, and regulatory requirements for flight reviews," he said in a statement.
Mr Scott-Bloxam owned Cape Air Transport, an air taxi service for the Torres Straight.
He made headlines in 2008 when he flew to the Papuan town of Merauke, near the border between Indonesia and Papua New Guinea, and was detained as a result.
He was arrested for entering Indonesia without a visa and remained behind bars until 2009.
© AAP 2020