A 100-kilogram propeller that fell off a Regional Express flight bound for Sydney has been found in bushland close to a built-up residential area in the city's south-west.

The 34-seat plane, carrying 16 passengers and three crew, was about 19 kilometres from Sydney Airport when its right-hand propeller flew off last Friday, narrowly avoiding hitting the wing and tail.

The two pilots on board flight ZL-768 from Albury were forced to declare a PAN, which is one step down from a full-scale Mayday, before safely landing at the airport.

On Tuesday, a NSW Police helicopter patrolling Sydney's south-west spotted the propeller in bushland at Revesby.