A 737 flight crew’s response to an engine failure over the Tasman Sea earlier this year highlights the benefits of effective decision-making and management of an unexpected situation, an Australian Transport Safety Bureau investigation notes.
During a scheduled passenger flight from Auckland to Sydney on 18 January 2023, the left engine of a Qantas-operated Boeing 737-838 shut down uncommanded.
In response, the flight crew declared a MAYDAY to prioritise communications with air traffic control, and to ensure they were cleared for an immediate descent from 36,000 ft to 24,000 ft.
The left engine could not be restarted in-flight, and the flight crew conducted an uneventful single-engine landing at Sydney Airport about an hour later.
“A subsequent engine teardown inspection identified separation of the radial driveshaft in the engine’s inlet gearbox, which resulted in a mechanical discontinuity between the engine core and accessory gearbox,” ATSB Director Transport Safety Kerri Hughes said.
“Loss of drive to the accessory gearbox resulted in a loss of fuel pump pressure and uncommanded shutdown of the engine.”
At the time of the engine failure, the aircraft was around 150 km closer to Norfolk Island than it was to Sydney Airport. However, a diversion to Norfolk Island would have required a deviation from the aircraft’s current track, and Norfolk Island presented changeable weather and operational conditions.
“In contrast, Sydney Airport was on the aircraft’s direct route, had favourable weather conditions forecast, had an extensive emergency response, and a straight-in approach on a very long runway,” Ms Hughes noted.
“The decision to continue to Sydney ensured no additional risk was added to an already high workload situation.”
Separately, the report notes that the aircraft’s cockpit voice recorder was inadvertently overwritten during maintenance activities after the aircraft arrived at Sydney.
Since the occurrence, Qantas has enhanced its procedures to prevent inadvertent overwriting of cockpit voice recorders and flight data recorders.