SEATTLE -- This week's in-flight failure of a Rolls-Royce engine on a Qantas A380 superjumbo came less than three months after ground testing of a Boeing 787 Dreamliner engine from the same Rolls product family also resulted in a serious failure.
Are the failures linked? There are similarities between the engines, but also big differences.
It's too early to know what happened. Rolls-Royce refuses to answer questions not only about the latest incident, but even about the Dreamliner one last August.
Phil Abbott, editor of Aircraft Engines, a United Kingdom-based analytical industry report, said a flaw in the A380's Trent 900 wouldn't necessarily imply that the Dreamliner's Trent 1000 is also flawed.
"Although the technology and design are very similar, they don't share much in the way of major components," he said.
The Dreamliner engine failed during a ground test in Derby, England.
Like the Trent 900 on Thursday's Qantas flight, the incident was an "uncontained failure." That means that parts of the engine's innards broke apart and flew out of the engine.
Photos of the Qantas jet after it landed show that flying parts penetrated the reinforced engine casing and punctured the wing. If the pieces had taken slightly different paths, they could have ignited the fuel tanks or blown holes in the fuselage.
On Friday, another engine failed on a Qantas jet -- a 747-400 powered by Rolls-Royce's RB21 engines, a generation that preceded the manufacturer's Trent series. No injuries were reported.
All airliner engines are designed to be able to contain a relatively rare event, such as a fan blade breaking off.
This was typically accomplished by wrapping the casing in bulletproof Kevlar. That's the system used on the Trent 800 that powers some Boeing 777-200s. But it is not the case on the Trent 900. That engine's fan-containment system is "the first to be manufactured from titanium and does not need the additional Kevlar wrap, making it a lighter and smaller system," according to the Rolls-Royce website.
It seems likely that the Trent 1000, developed after the 900, also has the titanium casing and no Kevlar.
The A380's Trent 900 operates at much higher power -- 70,000 to 80,000 pounds of thrust--compared with 53,000 to 75,000 pounds of thrust for the Dreamliner's Trent 1000.
The engine that failed on the Qantas flight was likely at full throttle, generating maximum power shortly after takeoff. One question to be answered by the investigation is whether some design flaw manifests itself at high power settings.
Alternatively, was it a faulty component that failed, one that could be beefed up to avoid a repetition?
"If it is a component fault, like a fan blade or such, that would be very worrying but at least something could be done about it," said Abbott. "If it's a design fault, that's seriously serious."
Dreamliner customers choose between GE and Rolls for their engines when they order the planes. The two engines are different and require different attachments to the wing. A plane built for one cannot easily switch to the other.
Most early Dreamliners, including all those going to launch customer ANA of Japan, will have the Rolls engines.
Of the 847 Dreamliners on firm order, 253 will have the Rolls-Royce Trent 1000. An additional 381 are destined to have the GEnx engine, made by GE. The remaining 213 aircraft don't have an engine selection yet.
Since August, Rolls-Royce has repeatedly declined to comment publicly on the Trent 1000 failure. But Rolls has briefed Boeing on its investigation and on a fix that Boeing said involves hardware and software changes.
Boeing Chief Executive Jim McNerney and commercial-division head Jim Albaugh have expressed confidence that Rolls will resolve the problem.
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