Rolls-Royce will replac all Trent 1000 intermediate pressure turbine blades with a new design over a period of three years to address fatigue cracking resulting from sulfidation corrosion, the engine maker acknowledged Wednesday. The program covers 169 Boeing 787s powered by Rolls-Royce engines.
The decision comes after consultations with Japan's All Nippon Airways, which experienced such “engine related irregularities” with three Trent 1000-powered Boeing 787s since February. The most recent case, on an August 20 domestic flight from Tokyo Haneda to Miyazaki, forced ANA to extend a Rolls-designed program to replac the blades on its internationally operated 787-8s to the Dreamliners it uses for domestic operations, forcing the cancellation of some 20 flights since last Friday.

The first two instances of what ANA termed engine irregularities—one on February 22 and the other on March 3–forced the return of two international flights to their departure airports. Those incidents prompted Rolls-Royce to recommend replacing the engines operating on international flights earlier than indicated in their design specifications. Because international operations involve flight through airspace with higher atmospheric concentrations of certain corrosion-producing chemical compounds and the airplanes’ engines run hotter due to higher power output, those engines would more likely generate fatigue cracks, the thinking went. Boeing has delivered 169 Boeing 787s powered by Rolls-Royce engines

However, the same engine “irregularities” found on the airplanes that returned to their departure airports earlier in the year also developed during the August 20 domestic flight between Haneda and Miyazaki. As a result, ANA also decided to apply the early replacement program to its domestically operated 787s. ANA flies 50 Boeing 787s in all.

Until Rolls-Royce replaces new engines with improved, corrosion-resistant blades as a permanent solution, ANA will fit engines removed from existing aircraft with brand new or “minimally used” turbine blades now in use. “We would like to emphasize that this current type of turbine blade does not pose any safety concerns when in brand new or minimally used condition,” said ANA in a statement.

Rolls-Royce, meanwhile, said it would continue to “manage the situation” with all operators through an ongoing service maintenance program involving like-for-like replacements. “We are producing blades now for like-for-like replacement to support the ongoing service maintenance plan for the fleet,” it added. “We will introduce a new improved blade design by the end of the year.”

While Rolls-Royce said it agreed with ANA’s decision to extend its replacement program to airplanes operating domestic flights, the airline’s accelerated service management program “does not change [its] assumptions with regards to the rest of the Trent 1000s in operation.”

Although ANA’s program will take about three years to complete, Rolls stressed that airlines with smaller fleets will not take as long, and that it will work with every customer to speed the process.