Close to 40 Rolls-Royce Trent 900 engines will have to be replaced on Airbus A380 super jumbos worldwide, according to Qantas chief executive Alan Joyce.

Qantas has grounded its six A380s since the midair explosion of a Trent 900 engine on an Airbus A380 on 4 November. The airline is conducting safety checks on its aircraft with Trent 900 engines.

Between Qantas, Lufthansa and Singapore Airlines, 20 A380 planes are currently in operation, each of which have four Rolls-Royce engines.

"We've been talking to Airbus and Rolls-Royce and we understand that the number [of engine replacements] is around 40," said Joyce, speaking to reporters at the Sydney airport.

He added, "We'll have a daily dialogue with Rolls-Royce to determine which engines actually need to be taken off."

Investigations are pointing towards an oil leak that could have instigated the fire on the Qantas carrier flying from Singapore to Sydney.