Cracks in an oil feed pipe caused an engine to explode on a Qantas A380 over the Indonesian island of Batam in November 2010, Australia's transport safety watchdog said on Thursday in its final report on the incident.
The airline grounded its entire Airbus A380 fleet after one of the Sydney-bound double-decker super-jumbos was forced to make a dramatic return to Singapore with smoke trailing from its Rolls-Royce Trent 900 engine and damage to its wing.
The mid-air blast sent debris raining down over Batam island in Indonesia, before pilots guided the plane carrying 469 passengers back to Changi Airport.
The Australian Transport Safety Bureau (ATSB) released its third and final report into the accident Thursday, which found that oil feed pipes in the A380's No. 2 engine did not conform to design specifications.
"The ATSB found that the engine failure was the result of a fatigue crack in an oil feed pipe," it said, calling the investigation one of the most complex it had ever undertaken.
"The crack allowed the release of oil that resulted in an internal oil fire. The oil fire led to one of the engine's turbine discs separating from the drive shaft.
"The disc then over-accelerated and broke apart, bursting through the engine casing and releasing other high energy debris."
The ATSB also found that the oil pipe, together with a number of similar pipes in other engines, had been made with a thin wall section and did not comply with design specifications.
"The thin wall substantially increased the likelihood of fatigue cracking," it said.
Since the incident, Rolls-Royce, aviation regulators, and operators of Trent 900-powered A380s have taken a range of steps to ensure that engines with incorrectly manufactured oil feed stub pipes were removed from service or fixed so aircraft could operate safely.
Rolls-Royce also introduced software that would automatically shut down a Trent 900 engine before its turbine disc over-speeds to prevent a similar occurrence, while improving their quality management systems.
The ATSB report absolved the plane's crew of any error, saying they completed the required actions for the multitude of system failures and safely landed.
The root of the problem finally fished out after almost three years. It is heartening to know that a similar incident will not occur again now that a new software has been installed to arrest the problem. Salute to the pilots onboard that plane to bring it back to ground safely when they were so near to total disaster.