Trent 1000 gearbox corrosion traced to manufacturing change

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Seventeen Rolls-Royce Trent 1000 engines have been identified as being susceptible to a potential gearbox corrosion problem which led Japanese carrier All Nippon Airways to ground some of its Boeing 787s temporarily.

Eight engines are with ANA - affecting a total of five of the airline's 787s - while the other nine are with Boeing.

The problem centres on the crown gear in the transfer gearbox and has been traced to a change in the manufacturing process.

Trent 1000 gearboxes are supplied by Hamilton Sundstrand. A source familiar with the situation says that, following the discovery, the manufacturer of the component has reverted to a previous process, and is confident that the problem has been contained.

ANA has already returned two of the five affected aircraft to service.

Boeing says the carrier acted "with an abundance of caution" and "in concert" with the airframer's guidance in withdrawing the twinjets from service until their gearboxes could be replaced.

"The replacement is expected to be complete in the days ahead," it adds. "No airplanes will be delivered with affected parts."

Minor corrosion on the crown gear became apparent during product development testing of the Trent 1000. The issue means that the component has a "reduced service life", says Rolls-Royce.

"As a pro-active measure this component is being replaced in a number of engines," the manufacturer adds, stressing that it has a "rigorous approach to product safety".

"We are working hard to minimise disruptions to customer operations."

None of Rolls-Royce's other powerplants are affected by the gearbox issue and the problem has affected only a particular batch of gearbox components on the Trent 1000.