Saab 340 REX aircraft endured a nightmare flight after one of its propellers sheared off in mid-flight. Picture: Grahame Hutchison.

The Regional Express Saab 340 — carrying 23 passengers — made a safe emergency landing about 10am on Thursday.

Civil Aviation Safety Authority spokesman Peter Gibson told AAP the right-hand engine issue was “totally unrelated” to the plane’s propeller assembly. The right-hand propeller of a similar aircraft fell off Regional Express’s Albury to Sydney flight last week after the engine was shut down following “abnormal indications”.

Rex flight made emergency landing in Dubbo.Source:Supplied

Mr Gibson said the crew on Thursday’s flight “had an indication of high engine temperature on the right-hand engine so it was shut down and they returned to Dubbo”.

A Rex flight bound for Griffith was forced to return to Sydney Airport on Tuesday afternoon with cabin pressure problems.

Regional Express has a fleet of 55 Saab 340 aircraft, and operates about 1500 weekly flights to 58 destinations across Australia.

The regional airline grounded some of its planes as it investigated how to propeller fell off an aircraft as it approached Sydney on March 17.

A propeller has been found in bushland off River Road in Revesby Heights NSW Australia.Source:News Corp Australia

Regional Express revealed 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” 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.

Rex’s chief operating officer, Neville Howell, says a propeller falling off is an extremely rare event. Earlier this week, the missing propeller was found in Revesby, 22km south-west of Sydney.