Regional airline Rex has grounded an additional five planes as an investigation continues into how a propeller fell off one of its aircraft as it was approaching Sydney Airport late last week.
Regional Express says the crew had shut down the right-hand engine of the Saab 340 before the propeller assembly "was seen by the first officer to separate from its shaft" on Friday when the flight from Albury was 25 kilometres southwest of Sydney.
"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," Rex said in a statement on Monday.
A spokeswoman told AAP five aircraft were grounded in addition to the plane involved in Friday's incident, which has been quarantined.
Two normally operate on Rex's Melbourne network, one is from Sydney and the remaining two are Pel-Air freighters.
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"There will be some minor disruptions for one or two days," the spokeswoman said.
The Saab 340's engine was shut down on Friday following "abnormal indications", with the pilot "feathering" the propeller to reduce drag.
It was at this point that the propeller assembly separated and rotated upwards and to the right of the aircraft, which was carrying 16 passengers and three crew members.
"The propeller was seen rotating in a horizontal position and then moving away without making contact with the aircraft," Rex said on Monday.
"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."
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," he said.
Rex said its propeller sheared off at the shaft and all the fittings at the main assembly were intact.
Mr Howell on Monday praised the crew for showing "enormous composure and discipline under extraordinary circumstances".
The Australian Transport Safety Bureau is investigating Friday's incident, and the search continues for the propeller, which is believed to have fallen off over the Camden area.
Regional Express has a fleet of 55 Saab 340 aircraft and operates about 1500 weekly flights to 58 destinations across Australia.
