All Nippon Airways has grounded five Boeing 787s powered by Rolls-Royce Trent 1000 engine. Ground endurance tests by R-R showed the engine could be damaged by crown gears that corroded faster than expected. (Click here to read the full story posted earlier this morning by Flightglobal's Singapore office.)
R-R selected Hamilton Sundstrand nearly eight years ago to provide the Trent 1000 gearbox system, which was the supplier's first such placement on an R-R engine. On the rival General Electric GEnx-1B, which is not affected by the ANA grounding, Italy's Avio supplies the gearbox.
The 787 gearbox is a unique specimen. Boeing chose a "more electric aircraft" architecture, replacing bleed air-sourced pneumatic power for cabin air conditioning and wing de-icing with electric power. The same generator is also integrated with the gearbox and is used to start the engine. A recent Hamilton Sundstrand patent application for an integrated gearbox and air turbine starter illustrates the concept.
The ANA grounding appears to be unrelated to the more-electric aspects of the gearbox that are unique to the 787. R-R has instead pointed the finger at Hamilton Sundstrand's manufacturing process. Hamilton Sundstrand has confirmed it is "of course aware of the issue", and is working with R-R and Boeing to resolve it.