The Australian Transport Safety Bureau (ATSB) says a lack of lubrication was the most likely cause of an engine failure involving a Regional Express (Rex) Saab 340B on March 23 this year.
The incident occurred shortly after the turboprop VH-RXS took off from Dubbo bound for Sydney carrying 26 passengers and three crew.
When the aircraft was climbing through 4,300ft, the flightcrew “heard several bangs from the right engine accompanied by jolts through the aircraft”, the ATSB final report published on Monday said.
This was accompanied by a burning smell in the flightdeck alongside cockpit master warnings.
The pilots conducted a shutdown of the right hand engine, declared a PAN to air traffic control and requested emergency services at Dubbo Airport.
They then completed standard failure management procedures before the captain conducted a visual approach back to Dubbo Airport, landing on Runway 05.
There were no injuries, while the aircraft suffered minor damage.
The ATSB report said an initial engineering examination found the number four bearing on the right hand engine failed.
“The bearing failure allowed the high pressure compressor to move off-centreline within the engine. This caused further damage and led to complete failure of the engine,” the ATSB said.
“The damage to the failed bearing was consistent with overheating due to a lack of lubrication. At the time of the release of this report, the reason for the lack of lubrication to the number four bearing had not been determined.”
The ATSB said the engine manufacturer’s engineering examination of the failed engine was not completed at the time its final report into the incident was released.
The Saab 340B is powered by two General Electric CT7-9B turboprop engines.
Meanwhile, the report said comments from the captain indicated emergency procedures and simulator training prepared the flightcrew well for the incident and allowed it to effectively manage the engine failure.
“Faced with an abnormal situation, the training provided to the flightcrew ensured they were able to effectively implement the standard failure procedures, secure the failed engine and return for a safe landing,” the ATSB report said.
“During an emergency, flight crew prioritise the management of the emergency to ensure that the safety of the flight is not compromised. Completing the emergency procedures, along with the coordination of emergency services and communications with supporting agencies may absorb a significant amount of time before the flightcrew are able to provide an update to passengers.”