Investigators have discovered that the cockpit-voice recording of the Qantas Airbus A380 engine failure was overwritten because the adjacent engine could not be shut down after the aircraft landed in Singapore.
The inboard left-hand Rolls-Royce Trent 900 engine, which suffered the in-flight uncontained failure, has been removed from the aircraft and is being transported to an engineering facility for technical inspection.
"Removal of the engine will also facilitate closer examination of the damage to the surrounding wing and other structures and systems," says the Australian Transport Safety Bureau.
The extent of this damage to the A380's airframe has yet to be detailed but images have shown evidence of shrapnel puncture to the wing, loss of hydraulic functions to the control surfaces and landing-gear, and loss of fuel or other fluid from the aircraft while airborne.
ATSB investigators have retrieved information on the powerplant's performance from the flight-data recorder, and this has been distributed to the aircraft and engine manufacturers in order to understand the event fully.
But while the flight-data recorder stored parameters from the entire flight, the ATSB states that its team in Canberra have only retrieved part of the cockpit-voice recorder audio.
It says that the failure of the adjacent outboard left-hand engine to shut down, after the stricken A380 landed in Singapore, meant it continued to supply power to the recorder.
Audio from the time of the in-flight engine failure - some two hours beforehand - was "overwritten", the ATSB adds: "That said, elements of the available audio are expected to be of assistance to the investigation."
Indonesian search personnel are continuing to scour the island of Batam for debris from the destroyed engine, and the ATSB has released images showing the flight path of the A380 as it departed, and then returned to, Singapore, and the areas of interest for the recovery effort.
"After initial success, the search is becoming increasingly difficult as a result of the local terrain, which includes virgin jungle," it says.
Rolls-Royce engineers are examining the fractured turbine disc whose ejection is considered by investigators to have been responsible for the destruction of the engine. The manufacturer has already stated that it believes a component failure led to an oil fire which resulted in the loss of the disc.