Report Due On Qantas A380 Incident

The Australian Transport Safety Bureau (ATSB) this week will issue a preliminary report that is likely to confirm investigators’ suspicions that oil pipe leaks led to the uncontained failure of a Trent 900 engine during a Qantas Airbus A380 flight Nov. 4. Meanwhile, the carrier plans to resume limited operations of some A380s, although the investigation will remain open. Flawed welding led to the oil pipe leaks, which caused a fire and the failure of the turbine disk in the intermediate-pressure turbine, industry officials close to the investigation tell Aviation Week. Rolls-Royce declined to confirm the information, but a new airworthiness directive (AD) issued by the European Aviation Safety Agency (EASA) on Nov. 22 appears to confirm it. The AD calls for more detailed inspections of the Rolls-Royce turbofan. The investigation previously identified an oil fire in the high-pressure/intermediate-pressure structure cavity as a possible cause of the failure. EASA notes that “the incident investigation has progressed, and inspection data from in-service engines have been gathered and analyzed.” The agency adds that “the results of this analysis show the need to amend the inspection procedure, retaining the inspection of the air buffer cavity and focusing on the oil service tubes within the [high-pressure/intermediate pressure] structure.” Such a procedure remains an “interim action,” and further updates are possible as new information is developed, EASA says. In the Nov. 4 inflight emergency on Flight QF32, the No. 2 engine failed about 4 min. after takeoff from Singapore en route to Sydney. The aircraft returned to Singapore after 110 min. in the air, during which the pilots dumped fuel and tried to determine what had happened. The A380 suffered major damage to engines, important aircraft systems and the fuselage skin at Frames 46/47 in Section 15/21, according to an Airbus overview documentation of major damages obtained by Aviation Week. All six Qantas A380s have remained grounded since the incident and are only now being phased back into scheduled services. Lufthansa and Singapore Airlines are continuing to operate their Trent 900-powered A380s but have had to change engines on several aircraft. Following initial findings, EASA ordered frequent checks for the in-service fleet in an AD published Nov. 10. That airworthiness directive is “consistent with the maintenance program we described on Nov. 12,” the engine manufacturer says. “Rolls-Royce has worked closely with Airbus, the airlines and regulators to agree to a regime that will ensure a safe operation.” While the investigation remains open, conflicting information has emerged about whether Rolls-Royce knew before Nov. 4 about mechanical defects that are suspected to have caused the oil fire. Questions have also been raised about the speed of the manufacturer’s response to the problem. An industry executive close to the investigation says Rolls-Royce is adamant in its claim that it had no idea about potential oil leaks, even though it had introduced numerous modifications to the engine in the past. The executive points out that Rolls-Royce would have been required to tell the airworthiness authorities of any safety-related findings. The executive further indicates that Rolls-Royce started developing a fix only after the investigation into the Nov. 4 incident yielded preliminary results. The company has no comment on these points. However, others in the industry say Rolls-Royce was aware of potential problems before Nov. 4, and that it was in the process of implementing a modification to correct the oil leak but had not informed operators. Lufthansa states that 15 of its 16 Trent 900s were delivered with engine upgrades and have not had any oil leak issues. So far, however, it has not been verifiable if the modifications solved the oil leakage issues on the new engines and if they were done specifically because of that problem. Lufthansa’s aircraft have flown many fewer hours and cycles than those of other carriers, though, since they were just delivered in May. Lufthansa also uses them at a 70,000-lb.-thrust rating, while the Qantas engines have been taken up to 72,000 lb. thrust—a difference that has considerable implications for internal temperature levels. Rolls-Royce has also pulled some engines that had been delivered to the Airbus final assembly line to replace older standard motors, particularly on Qantas aircraft. For that reason, Airbus confirmed it will claim damages from the engine maker for any financial impact. Airbus does not rule out that future A380 deliveries this year and in 2011 could be delayed for lack of engines. Rolls-Royce is not commenting on why it pulled these engines. Qantas CEO Alan Joyce reportedly said at a Sydney press conference that Rolls-Royce “has modified certain parts of that engine.” He was quoted by the Associated Press as saying that “if this was significant and was known to be significant, we would have liked to have known about it . . . . [But] we and Airbus were not aware of it.” According to the Associated Press, Joyce also said that “it is a modification that indicates whether or not you are going to have a problem with the engine.” Qantas has a power-by-the-hour arrangement with Rolls-Royce for overhaul and maintenance to be performed by the manufacturer. While much public attention has focused on the engine problems, the Nov. 4 incident also raises some serious questions about the airframe and systems. Among other things, the aircraft lost one of its two hydraulic systems, potentially signaling problems with routing and segregation, since pipes of the two are closely collocated in the wing area. Also, pilots were unable to pump fuel from the aft tanks forward, which could have led to serious center of gravity implications in a longer flight when fuel transfer is required for stability. But redesigns could turn out to be highly expensive or even impossible when it comes to basic changes such as introducing additional back-up hydraulic and electrical systems. Meanwhile, Qantas has decided to resume flying some A380s on its London routes, but it is still not putting the aircraft back on its longer Los Angeles flights due to concerns over operating the Trent 900s at maximum thrust. One of the airline’s A380s was due to begin flying the Sydney-Singapore-London route on Nov. 27, and another was expected to follow soon after on either the Sydney or Melbourne flights to London. There is no timetable yet for the return to service of the other four Qantas A380s. As more aircraft come online, the emphasis will be on increasing A380 frequency on the London routes, a Qantas spokesman says. The airline will not be operating A380s on its Los Angeles routes until it has performed sufficient inflight analysis on the London flights. It stresses that this is an operational decision in line with its conservative approach to safety, not a manufacturer’s directive. Qantas is “being very circumspect about transpacific flying,” says the spokesman. Qantas says it is not yet prepared to put the A380s on the routes to the U.S. West Coast because these flights “regularly require” maximum certified thrust due to factors including higher fuel loads and the shorter runway at Los Angeles International Airport. The airline says the suspension will continue “until further operational experience is gained or possible additional changes are made to engines.” The first aircraft to return to service—VH-OQF—was ferried back to Sydney from Los Angeles after two of its Trent 900 engines were replaced. One is an overhauled engine from Rolls-Royce, and the second is from another of the carrier’s A380s. The second aircraft to return to the air is VH-OQE. Australia’s Civil Aviation Safety Authority (CASA) says it has “given a green light to [the] plan developed by Qantas to return its A380 aircraft to service.” This plan describes how the A380s will be operated, together with “additional safety measures and required inspections.” “Qantas has devoted considerable resources to making sure the return to service of the A380 will meet all relevant safety requirements,” says John McCormick, CASA’s director of aviation safety. The agency will continue to monitor A380 operations, using data supplied by Qantas. The airline has confirmed that it will still take delivery of two new A380s before the end of this year and another two in early 2011. This means that by the end of December, it should have at least four A380s in service.