A Qantas Boeing 737-800, registration VH-VYH performing flight QF-520 from Sydney,NS to Brisbane,QL (Australia) with 175 passengers, 6 crew and dry ice on board, was departing Sydney's runway 34R when the crew declared PAN PAN during initial climb reporting an engine (CFM56) failure. The crew continued the climb to 3000 feet, shut the failed right hand engine down and entered a hold at 4000 feet while emergency services started to battle a fire that had ensued in the grass at the side of the departure runway. The aircraft landed safely on runway 34L about 30 minutes after departure, emergency services were still fighting the grass fire at that time.
The airline reported the engine suffered a contained engine failure and added: "While customers would have heard a loud bang, there was not an explosion."
The flight was cancelled.
On Nov 22nd 2024 the airline reported the engine failure was likely caused by a mechanical failure in the engine's turbine. Following fleetwide examination two more engines were removed from service before scheduled changes.
On Apr 29th 2026 the ATSB released their final report concluding the probable causes of the serious incident were:
Contributing factors
- During take-off, a high-pressure turbine blade failed due to a fatigue crack that had developed prior to the flight, and the blade was liberated from the high-pressure turbine disc. Engine damage from the liberated blade resulted in a contained engine failure.
Other findings
- The flight crew responded quickly and appropriately to an engine failure at V1, a critical time during take-off.
The ATSB analysed:
Engine failure
During the take-off roll, one of the right engines HPT blades was liberated from the HPT disc due to pre-existing fatigue cracks in the blades dovetail. This region was prone to fatigue cracking in the 2403M91P02 blade configuration. The HPT blades had been scheduled to be removed from the engine 13 days later, in accordance with a service bulletin that was intended to reduce instances of such blade liberations. Due to contact with the liberated blade, the adjacent blade 51 failed through the dovetail and was also liberated from the disc.
The 2 liberated blades were thrown into the engine shroud and likely made contact with adjacent HPT blades still fitted in the rotating disc. As a result of this contact, all of the remaining 74 blades experienced overstress failure through their aerofoils, liberating additional blade fragments from the HPT disc.
The liberated blades and other debris then travelled rearward through the low-pressure turbine and were ejected out the rear of the engine. With no torque being produced by the HPT, and debris obstructing and damaging the low-pressure turbine, the right engine failed. The flight crew observed a single loud bang and a shudder, indicating that the liberation of all HPT blades and subsequent engine failure occurred extremely rapidly.
Given the location of the blade failure, it is likely that there was no opportunity to detect the crack during the engines lifespan. The removal thresholds put in place by the engine manufacturer, CFM International, did not completely prevent blade liberation events.
Nevertheless, the manufacturers fleetwide analysis found that the CFM56-7B fleet remained within its defined reliability targets as well as airworthiness guidelines set by relevant regulators.
Flight crew response
The decision speed, V1, is the critical point between a take-off that should be aborted and one that should be continued. This is the worst possible time for a multi-engine aircraft to experience an engine failure during take-off, because safety margins are at a minimum whether the take-off is aborted (minimum remaining runway distance available) or continued (minimum airspeed available). When the engine failure occurred, the aircraft had reached V1, meaning any attempt to abort the take-off would have occurred beyond the point when it was safe to do so.
Confronted with this situation, the flight crew responded quickly and decisively in continuing the take-off, declaring an emergency, identifying the problem and then working through the appropriate procedures. The flight crew, cabin crew, ATC and ARFFS all worked together effectively to enable the aircrafts safe return to Sydney Airport.
View at the engine outlet and turbine blades:
The airline reported the engine suffered a contained engine failure and added: "While customers would have heard a loud bang, there was not an explosion."
The flight was cancelled.
On Nov 22nd 2024 the airline reported the engine failure was likely caused by a mechanical failure in the engine's turbine. Following fleetwide examination two more engines were removed from service before scheduled changes.
On Apr 29th 2026 the ATSB released their final report concluding the probable causes of the serious incident were:
Contributing factors
- During take-off, a high-pressure turbine blade failed due to a fatigue crack that had developed prior to the flight, and the blade was liberated from the high-pressure turbine disc. Engine damage from the liberated blade resulted in a contained engine failure.
Other findings
- The flight crew responded quickly and appropriately to an engine failure at V1, a critical time during take-off.
The ATSB analysed:
Engine failure
During the take-off roll, one of the right engines HPT blades was liberated from the HPT disc due to pre-existing fatigue cracks in the blades dovetail. This region was prone to fatigue cracking in the 2403M91P02 blade configuration. The HPT blades had been scheduled to be removed from the engine 13 days later, in accordance with a service bulletin that was intended to reduce instances of such blade liberations. Due to contact with the liberated blade, the adjacent blade 51 failed through the dovetail and was also liberated from the disc.
The 2 liberated blades were thrown into the engine shroud and likely made contact with adjacent HPT blades still fitted in the rotating disc. As a result of this contact, all of the remaining 74 blades experienced overstress failure through their aerofoils, liberating additional blade fragments from the HPT disc.
The liberated blades and other debris then travelled rearward through the low-pressure turbine and were ejected out the rear of the engine. With no torque being produced by the HPT, and debris obstructing and damaging the low-pressure turbine, the right engine failed. The flight crew observed a single loud bang and a shudder, indicating that the liberation of all HPT blades and subsequent engine failure occurred extremely rapidly.
Given the location of the blade failure, it is likely that there was no opportunity to detect the crack during the engines lifespan. The removal thresholds put in place by the engine manufacturer, CFM International, did not completely prevent blade liberation events.
Nevertheless, the manufacturers fleetwide analysis found that the CFM56-7B fleet remained within its defined reliability targets as well as airworthiness guidelines set by relevant regulators.
Flight crew response
The decision speed, V1, is the critical point between a take-off that should be aborted and one that should be continued. This is the worst possible time for a multi-engine aircraft to experience an engine failure during take-off, because safety margins are at a minimum whether the take-off is aborted (minimum remaining runway distance available) or continued (minimum airspeed available). When the engine failure occurred, the aircraft had reached V1, meaning any attempt to abort the take-off would have occurred beyond the point when it was safe to do so.
Confronted with this situation, the flight crew responded quickly and decisively in continuing the take-off, declaring an emergency, identifying the problem and then working through the appropriate procedures. The flight crew, cabin crew, ATC and ARFFS all worked together effectively to enable the aircrafts safe return to Sydney Airport.
View at the engine outlet and turbine blades:
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