Shortly after a Qantas Airways Ltd. superjumbo jet suffered an engine blowout at 7,000 feet near Singapore last month, the pilots faced initial warnings of potential difficulties with two other engines, multiple electrical failures and problems with various flight-control and fuel systems, according to a report issued by Australian accident investigators.
The preliminary findings announced by the Australian Transport Safety Bureau describe a cockpit drama in which the pilots confronted more serious damage to the double-decker Airbus A380—and scrambled as a team to deal with a wider array of cascading, computerized warnings than previously disclosed.
The report depicts the pilots methodically assessing whether the crippled, four-engine jetliner could be controlled during descent and a heavier-than-normal landing, even with fuel spewing out of the left wing, some control panels possibly damaged on both wings and the crew unable to dump fuel.
The report provides new details about the sequence of events, including the fact that cockpit instruments quickly indicated something was wrong with sensors on two other engines immediately after the failed engine spewed out flames and a stream of metal parts. The pilots decided to circle in a holding pattern for 50 minutes while they figured out an approach and landing strategy. The 53-page description of the incident also indicates, for the first time, that the A380's autopilot system disengaged on its own shortly before touchdown and the captain had to manually land the jet.
Australia's air-safety watchdogs, as expected, identified a problem with oil pipes in the Rolls-Royce Group PLC Trent 900 engines as the most likely cause of an engine explosion that forced the A380 to circle back and make an emergency landing in early November in Singapore. Nobody was hurt, but the high-profile incident attracted global attention and shined the spotlight on issues related to engine reliability and the safety of highly automated aircraft when electrical or computer systems are disrupted.
The bureau's report about the incident, which has prompted widespread disruption of Qantas's flight operations and that of other A380 operators, is preliminary. Since the plane's manufacturer, Airbus, a unit of European Aeronautic Defence & Space Co., Rolls-Royce and European regulators previously unveiled a combination of enhanced inspections and engine replacements, the report wasn't expected to provide new details about how airlines will deal with the issue.
"We're still in the early stages of investigation but significant action has already been taken to minimize the risk of a recurrence," said the bureau's chief commissioner, Martin Dolan.
Qantas, which grounded its fleet of A380s for more than three weeks, has said it would seek compensation from Rolls-Royce for the fallout from the engine malfunction. It announced steps Thursday that are likely to lead to court action if a settlement can't be reached.
Early reports about the Nov. 4 A380 incident stressed that shrapnel exploded from the Rolls-Royce engine, ripping fuel lines and crippling crucial hydraulic-control systems. Aviation safety experts early on talked about the dangers of maneuvering and landing a superjumbo without the ability to transfer or dump fuel.
But the report highlights how all five pilots on the flight deck—believed to have roughly 60,000 hours of combined flight experience—acted in unison to cope with hazards they never expected and never trained to overcome.
"The aircraft wouldn't have arrived safely in Singapore without the focus and effective action of the flight crew," Mr. Dolan told reporters.
The preliminary conclusions underscore how quickly and violently a disc inside the left-side engine closest to the fuselage broke apart, sending three chunks through cables, severing hydraulic lines and blasting through structural parts.
Investigators also described how at the start of the emergency—when the most junior pilot was sent into the cabin to try to visually gauge the extent of damage—the captain apparently didn't realize the seriousness of the fuel leak.
The report indicates that a passenger, who also happened to be a Qantas pilot, was the first to alert the crew by pointing out that a tail-mounted camera showed "some form of fluid leak from the left wing." The pictures were shown on the jet's in-flight entertainment screens.
According to data retrieved by investigators, the first sign of trouble occurred barely four minutes after the plane carrying 469 people lifted off from Singapore's Changi Airport on a clear day. Climbing through 5,300 feet with jets operating at 87% thrust, the No. 2 engine's oil temperature was climbing, but its oil pressure was dropping.
Within 30 seconds, according to the investigators, engine vibrations increased. Roughly 10 seconds after that, sensors showed the engine overheating and the turbine disc failing, immediately touching off multiple "fault indications."
When the jetliner's gear smacked the runway at an unusually high speed, according to the report, the pilots realized they had to deal with degraded braking systems and "limited nose wheel steering." The crew felt that "deceleration appeared to be 'slow' in the initial landing roll," the report states. But manual braking stopped the aircraft about 450 yards from the end of the strip. While circling for the approach, the pilots calculated that if everything went as planned, they would end up with as little as 300 yards to spare.
But that wasn't the end of the drama, or fire dangers, for passengers. The pilots weren't able to shut down the engine next to the one that blew apart because its controls were damaged by flying metal. The engine continued to run despite the crew's use of emergency switches and fire extinguishers, according to the report.
Cockpit displays also showed that the temperature of some brakes on the left-side main landing gear had reached 900 degrees Centigrade, and fuel continued to leak on that side of the aircraft. It took almost an hour before the captain and fire crews decided it was safe to have passengers leave by walking down stairs brought to the other side of the plane.
After landing, the pilots and Qantas engineers struggled for about two hours to shut down the engine. Emergency crews finally succeeded by drowning it with fire-retardant foam.
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