An engine which failed on a Qantas A380 travelling from Los Angeles to Melbourne on May 20 is being sent to manufacturer Rolls-Royce for further investigation. The Australian Transport Safety Bureau has opened an investigation into the incident on QF 94 in which passengers reported hearing a bang, feeling the plane shudder and then saw sparks shooting from the back of the engine. The ATSB said the aircraft was on climb and passing through 33,000ft when the No. 4, engine thrust reduced to about 45 per cent. The crew shut down the engine and returned to Los Angeles, Modern jet engines are extremely reliable but there are rare instances where internal parts fail. The engines are designed to cope with the failure of smaller parts such as compressor blades and the A380, which has four engines, can safely fly on three engines. Qantas said it was working with the ATSB but it believed the Trent 900 engine failed due to a problem with the low-pressure turbine and it was talking with Rolls to understand why this happened. “The engine itself will be sent back to Rolls-Royce to be assessed and a replacement engine will be fitted to the aircraft at our LA hangar and returned to service later this week,’’ the airline said in a statement “In-flight engine shutdowns like this are quite rare, so we can understand why it can be alarming for passengers, but our pilots are trained to deal with these scenarios and modern aircraft have a lot of built-in redundancy to make sure they can still fly and land safely.’’ Passengers, some of whom spent the night in the Los Angeles terminal due to a shortage of nearby hotel rooms, were reaccommodated on another flight and have since returned to Melbourne.