A 100-kilogram propeller retrieved by investigators from Sydney bushland will now be examined to figure out why it fell off a Regional Express plane as it approached the city's airport last week.
The propeller was winched out of a national park in Revesby on Wednesday by a helicopter before being loaded onto a truck and taken away for analysis at an aviation facility in Bankstown.
Australian Transport Safety Bureau investigators will now try to determine exactly what caused it to separate from Rex's Saab 340.
ATSB chief commissioner Greg Hood says getting to the bottom of the separation will help prevent a recurrence.
"We are obviously very interested in both the engine and the propeller and the interconnectivity between the two," he told reporters in Sydney.
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The propeller assembly fell off a Rex flight from Albury to Sydney on Friday - narrowly missing homes - and was spotted in the Georges River National Park in Revesby on Tuesday.
The propeller was located about 18 kilometres from the airport after the ATSB calculated its likely trajectory using data from the aircraft's flight data recorder.
Investigators factored in the plane's height, velocity and the wind speed at the time.
During Friday's flight, the crew shut down the right-hand engine following "abnormal indications" with the pilot "feathering" the propeller to reduce drag.
It was at this point the propeller assembly separated and rotated upwards and to the right of the aircraft - luckily avoiding contact with the plane which was carrying 16 passengers and three crew.
The flight subsequently landed safely at Sydney Airport.
Mr Hood said Australia had not seen anything like it before.
"This is a first - a very rare occurrence."
The only other recorded similar event was in 1991 when US carrier Comair's aircraft also landed safely after losing a propeller.
An investigation into that incident found the likely cause was "a fatigue fracture of the propeller shaft" which originated in the material used to manufacture the shaft.
Regional Express has temporarily grounded five planes "through an abundance of caution" while it replaces gear boxes and shafts from the same series as the propeller that detached.
