SYDNEY (AP) -- As many as half of the 80 Rolls-Royce engines that power some of the world's largest jetliners may have to be replaced after an oil leak caused a fire and the partial disintegration of one on a Qantas flight this month, the Australian national airline's chief executive said Thursday.
The 40 potentially faulty engines on the Airbus A380 would need to be replaced with new engines while the fault is fixed, raising the spectre of engine shortages that could delay future deliveries of the 7-story-tall superjumbo.
It was not clear how serious the problem would be, but the comments by Qantas CEO Alan Joyce were the most definite accounting yet of a problem that now appears larger than first imagined when one of his airline's engines came apart over Indonesia, spewing metal shrapnel into a wing and severing vital operating systems.
Qantas has grounded its fleet of six A380s, each powered by four of the giant Rolls-Royce Trent 900 engine. Joyce told reporters that Qantas may have to replace 14 engines, each worth about $10 million.
Rolls-Royce has indicated that the number of engines that needed to be replaced was "40 engines worldwide," he said.
"That's what they think they'll have to change," he said.
Rolls-Royce has remained virtually silent since Nov. 4 as its stock price has dropped. The company was scheduled to hold a news conference at a major biennial air show in the southern Chinese city of Zhuhai in Wednesday, but canceled it, without giving a reason.
An Airbus spokesman couldn't immediately be reached for comment.
Lufthansa said it will only have to change one of the Trent 900 engines on its three A380s. Singapore Airlines, which flies 11 of the superjumbos, declined to comment on whether it may have to change as many as 25 engines.
Aviation regulators have said Rolls-Royce intends to provide new engines to put on planes while the faulty ones are repaired. Airlines typically keep some spares, and Airbus has talked of sending replacement engines from its assembly lines, but the need to replace 40 engines could still cause significant disruption to airline schedules.
"Rolls-Royce are still working through the criteria for which engines need to be changed," Joyce said. "We're hoping to understand precisely which engines need to be replaced and therefore we can have a firm timeline for when they will be back in the air, but we are still a few days away from that."
Rolls-Royce shares were fluctuating on the London Stock Exchange on Thursday. By early afternoon, they were marginally higher -- up 0.1 percent at 600 pence -- erasing small losses in the morning session. The stock has now lost around 8.6 percent since Nov. 4, but it started to make up some ground on Wednesday when it rose 1.8 percent after the company announced a new marine contract and its share of an engine contract to Brazil's TAM Airlines.
Investigators say leaking oil caught fire in the Qantas engine on Nov. 4 and heated metal parts, causing them to disintegrate. Experts say chunks of flying metal cut hydraulics and an engine-control line in the wing of the A380, causing the pilots to lose control of the second engine and some of the brake panels on the damaged wing in a situation far more serious than originally portrayed by Qantas.
The Sydney-bound flight returned to Singapore where it made an emergency landing, safely ending the most serious safety incident for the world's newest and largest passenger plane.
The European air-safety regulator last week issued an urgent order requiring all operators of Trent 900 engines to conduct repeated inspections of several parts, including the oil service tubes, to ensure there was no "abnormal" leakage. If any such leaks are found, the airlines are prohibited from using the engines.
Qantas says three Trent 900 engines have been removed in addition to the one that blew out. Singapore Airlines and Lufthansa briefly grounded some of their planes after the Qantas scare but returned all but one them to service after conducting safety checks.
Singapore Airlines has said it replaced three Trent 900s. Lufthansa replaced one but said the reason was unrelated to the Qantas blowout.
Singapore Airlines hasn't been told how many of its Rolls Royce engines need to be replaced, and is continuing to fly all of its A380s in the meantime, the airline's Vice President for Public Affairs Nicholas Ionides said.
Lufthansa spokesman Thomas Jachnow said the German airline will only have to change one of its Trent 900 engines. "The talks are over now with Rolls Royce and Lufthansa, and the result is that we are lucky -- only one engine neds to be changed," Jachnow said.
Rolls-Royce said Friday that it would be replacing modules, or sections of linked parts, aboard Trent 900 engines that were found to have oil leaks, but provided no other details.
Joyce said Rolls-Royce had ordered modifications on parts of the Trent 900 engines and indicated it had done so before the Nov. 4 incident. But there was no early indication to Qantas that the modification was significant.
"Rolls-Royce have gone and modified certain parts of this engine," he said. "If this was significant and was known to be significant, we would have liked to have known about that ... We and Airbus weren't aware of it.
"But it depends on what the purpose of modifications were for," Joyce added. "It doesn't look like it's a significant modification, but it is a modification that has an impact on how the engines are performing. And it is a modification that indicates whether you are going to have a problem or not with the engine."
Airbus has said new Trent 900s coming off the production line should not have the oil leak problem, but says the changes were ordered after the Qantas incident. It has denied an Australian newspaper's report that an Airbus executive said Rolls-Royce started making changes to some versions of the engine before Nov. 4.
Joyce said the normal procedure for nonurgent modifications ordered by an engine manufacturer is to make the change when the engine is next brought in for routine maintenance.
"If this incident hadn't occurred, eventually all these engines would have had this modification," he said. "Now, because it is an indicator, we are not taking any risks. We're taking the engines off and making sure this modification is in place before the engines are put back on the aircraft."
The other airlines that fly A380s, Dubai's Emirates and Air France, use engines built by Engine Alliance, a 50/50 joint venture between GE Aircraft Engines and Pratt & Whitney.
Airbus has received orders for 234 of its A380s, which sell for list price of $346.3 million. A total of 38 of the aircraft have been delivered. Emirates and Qantas are the biggest customers for the jet, with 58 and 20 total orders so far.
In the first nine months of the year, Airbus delivered 14 A380s and took in 32 new orders.
Associated Press Writers Christopher Bodeen in Zhuhai, China, Rod McGuirk in Canberra, Australia, Alex Kennedy in Singapore and David Rising in Berlin contributed to this report.