17th of March 2017
Updated: Mar 18, 2022
A Saab 340B was operating a scheduled passenger flight between Albury and Sydney (both in New South Wales Australia) on this day in aviation history, in 2017. Onboard a crew off three and 16 passengers.
The aircraft at Sydney Airport, showing the missing right-hand propellor, with a close up showing the fractured propellor shaft (Source & © ATSB)
After a smooth flight and about 100 km (55 nautical miles) south-west from their destination Sydney, the crew became aware of a slight fluctuation in the torque indication for the right engine. By altering the power lever and condition lever setting the crew attempted to stabilise the condition. When this did not have the desired effect the c4ew initiated the checklist for "uncommanded engine operation". While progressing through this checklist the crew noticed and felt slight vibrations, which appeared to originate from the right engine. As the crew worked through the checklist the vibration level kept on increasing. It then reached a point where the crew decided to shut down the engine. While actioning the shutdown checklist, at 11.49 local time, the propellor separated from the aircraft. The crew contacted ATC, making a 'PAN PAN" call. The engine shutdown checklist was completed and the aircraft continued for a safe landing at Sydney Airport.
The left picture shows the propellor as found in the forest, the right picture shows the propellor hub (which holds the propellor and is the "end" of the propellor shaft. (Source and © ATSB)
4 days after the incident the propellor was found in a dense forest, 19 kilometres (10 Nautical Miles) from Sydney Airport. The Australian Transportation Safety Board investigated the incident and issued a full report on the event (available by clicking here).
They listed the following contributing factors and findings;
The propeller shaft failed as a result of a fatigue crack that had initiated at the dowel pin hole and propagated through the shaft until it could no longer transmit the required loads.
The engine manufacturer did not have specific inspection procedures in the maintenance documents of the propeller shaft to detect a fatigue crack originating from the dowel pinhole.
The ATSB and the engine manufacturer, General Electric, were unable to determine conclusively the reason for the fatigue crack initiation and propagation.