Regional airline Rex has grounded some of its planes as an investigation continues into how a propeller fell off an aircraft as it approached Sydney Airport on Friday.

"Rex has decided, by abundance of caution, to immediately remove from service and quarantine all propeller gear boxes and shafts of the same series as that of the incident for further inspection and testing if warranted," the airline said in a statement today.

It is not yet known how many aircraft will be impacted.

The airline revealed the crew had shut down the right-hand engine of the Saab 340, after the propeller “separated from its shaft” when the flight from Albury was 25 kilometres south-west of Sydney Airport.

"The propeller was seen rotating in a horizontal position and then moving away without making contact with the aircraft," the airline’s statement read.

"Both passengers and crew reported that the flight thereafter was smooth and the landing was normal in spite of bad weather at Sydney with winds exceeding 35 knots."

A Rex aircraftl landed in Sydney after losing a propeller on Friday. (Image: Supplied)

None of the 16 passengers and three crew members on board Flight ZL768 were injured.

Rex's chief operating officer, Neville Howell, said a propeller falling off was an “extremely rare” event.

"The only other recorded similar event was in 1991 when US carrier Comair's aircraft also landed safely after a separation of its propeller," Mr Howell said.

He praised the crew members for showing "enormous composure and discipline under extraordinary circumstances.”

The Australian Transport Safety Bureau (ATSB) continues to investigate the incident, and the search continues for the propeller, which is believed to have sheared off over the Camden area.