An alarming incident in which a propeller dropped off a Regional Express (Rex) plane as it approached Sydney was “an extremely rare event” – and that’s official – though most people will agree such a mishap can never be rare enough.
The Australian Transport Safety Bureau (ATSB) yesterday stressed its extreme rarity. Propellers are meant to stay on.
Fortunately, the plane involved, a Saab 340B, has two engines, each with a propeller, so there was one left for the flight crew to use to make a safe landing.
The bizarre incident happened on 17 March 2017 on an otherwise routine Rex passenger flight from Albury, NSW to Sydney. The flight was carrying 16 passengers and three crew.
The ASTB concluded yesterday after a lengthy investigation that the in-flight propeller loss was caused by a fracture of the propeller shaft on the right engine propeller gearbox.
The right propeller separated from the aircraft and plunged to the ground.
The ATSB found the fracture was due to a fatigue crack that originated in a propeller shaft flange dowel hole and spread through the shaft “until it could no longer transmit the loads required to maintain the propeller on the aircraft”.
The pilots were reported at the time to have made a “pan-pan” call as the crisis unfolded. Pan-pan indicates urgency but no immediate threat to life. It is less serious than a Mayday call.
The ATSB issued the following plea at the time: “Important: The ATSB urges anyone who finds a piece of suspected aircraft debris NOT to handle it. Please call the local police or the ATSB.”
The NSW Police Aviation Support Branch began a major operation for the propeller four days later. It was eventually located in dense bushland in the southwest Sydney suburb of Revesby, and airlifted out.
Regional Express grounded five of its 55 SAAB 340B aircraft after the mishap, in addition to the one involved in the incident, ABC News reported.
ATSB senior transport safety investigators Aaron Holman (left) and Max Marton with the SAAB 340 propeller. The propeller assembly detached from the engine on a flight from Albury to Sydney on 17 March 2017
ATSB Chief Commissioner Greg Hood said yesterday the investigation was unable to determine, conclusively, what caused the fatigue crack to occur.
“This was an extremely rare event, and the crew should be commended,” he said.
“The ATSB’s investigation found the crew demonstrated a high level of professionalism in their communication, coordination and application of the safety checklist procedures in their response to the incident, which resulted in an uneventful single-engine landing at the airport.”
Following the incident, the engine manufacturer, General Electric, and the airline, undertook a number of proactive safety actions.
“The airline and the engine’s manufacturer have undertaken a number of proactive safety actions, such as the release of new service bulletins and airworthiness directives, and changes to their maintenance regime, to reduce the risk of this extremely rare event from occurring again,” Hood said.
“Flying remains as one of the safest forms of travel for the public. Here in Australia, we have one of the best aviation safety records in the world.”
Written by Peter Needham
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