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EASA Adds Trent 1000-TEN IP Turbine to Previous ADs

 - June 17, 2019, 3:11 AM
The Rolls-Royce Trent 1000 TEN offers a 10:1 bypass ratio, the highest of any Trent engine. It first flew on a Boeing 787 in 2016. Boeing also offers the General Electric GEnx on the 787.

A new European Union Aviation Safety Agency (EASA) Airworthiness Directive (AD) covering Rolls-Royce Trent 1000 (T1000) engines expands previous maintenance requirements and, for the first time, draws the T1000-TEN variant into the powerplant's continuing saga of compressor and turbine in-service issues. Taking effect on June 25, EASA AD 2019-0135 covers intermediate-pressure turbine (IPT) blade replacement in more than 30 variants among T1000-series engines (except those modified in production or since entering service).

The AD mandates incorporation of a Rolls-Royce "alert" non-modification Service Bulletin that specifies applicable time limits for removal of each engine from service (including any known to be in workshops), replacement of IPT blades, and IPT-blade cyclic limits (as applicable) after installation of refurbished blades as replacement parts. The T1000 powers the Boeing 787, with the -TEN variant equipping the 787-10, and was also offered for the 747-8.

The development comes two months after Rolls-Royce (Chalet 93) revealed it was introducing inspections and enhanced parts to manage life limits on T1000-TEN high-pressure turbine (HPT) blades.

Since the engine's entry into service in November 2017, the company has told operators that the blades would have a "limited" life cycle. Sampling from some Trent 1000-TENs with "a higher frequency of flights at the upper end of their operating range" has shown "a small number" need to have HPT blades replaced earlier than scheduled.

In anticipation of limited life, Rolls engineers have developed an "enhanced" HPT blade and will "work closely with any impacted customers to deliver an accelerated program to implement [it] and to ensure that we can deliver on our T1000-TEN commitments. We regret any disruption this causes to airline operations."

Last year, Rolls said that the T1000-TEN was not showing any examples of the HPT- and IPT-blade and IP compressor-rotor durability problems that have afflicted earlier variants, initially Performance-improvement Package C engines and, subsequently, Pack B units. Nevertheless, it was taking precautionary action to design a new standard of HTP blade that it then expected to be available in 2019, and which would also be built into Trent 7000 engines that power the Airbus A330neo twin-aisle twinjet.

According to Rolls-Royce, enhanced blades will start to be incorporated into the T1000-TEN fleet "in early 2020." It noted that there are more than 180 examples in service among a 600-strong overall T1000 fleet.

In April, the company reported working closely with regulators to set inspection plans for the T1000-TEN fleet in response to the "earlier-than-anticipated blade deterioration" revealed by the sampling. This "accelerated inspection regime"—designed to permit R-R to confirm the T1000-TEN fleet health "over the next few months"—was communicated to customers two months ago.

“We sincerely regret the disruption this accelerated inspection regime will cause and we are doing everything we can to support our customers," says Rolls-Royce civil aerospace president Chris Cholerton. “These inspections will allow us to confirm T1000-TEN fleet [health] and improve our understanding of the HPT-blade deterioration seen in a small number of engines. This is a known issue, but is occurring faster than we expected in some engines.”

Rolls said the inspections will have no effect on its maintenance programs for Trent 1000 Pack B or Pack C engines.