New restrictions on a subset of Rolls-Royce Trent 1000s that power Boeing 787-8s are not expected to be as disruptive as similar limitations on Package C engines, but add more headaches for affected operators ahead of permanent fixes that the OEM is introducing.
The new mandate, issued by FAA with a Feb. 4 effective date and expected to be adopted globally, limits extended range (ETOPS) operations for "Package B" Trent 1000s with more than 1,000 cycles on its intermediate pressure compressor (IPC) blades to 180 min. from the nearest suitable airport. The restrictions are a safeguard against IPC blades failing during a diversion due to low-cycle fatigue cracking.
The fatigue-cracking issue was discovered on newer-standard Package C-configured engines, leading to inspection mandates and a 140-min. ETOPS limitation on certain engines, and subsequent disruptions at more than a dozen carriers due to the need to perform the checks and replace affected aircraft. Rolls in October introduced a new Package C blade and is rolling it out to affected operators.
"A similar intermediate compressor durability issue has also been identified on a small number of high life Package B engines and we have therefore agreed with Boeing and the relevant regulatory authorities to introduce a similar inspection regime as for the Package C," Rolls explained. The Package B issue is "less severe," FAA noted, and unlike with the Package C fleet, has not led to any in-service disruptions.
The Package B standard, in service since 2012 and limited to 787-8s, accounts for 166 of the 600-engine Trent 1000 fleet. The new inspections and ETOPS restrictions are not expected to lead to the same level of disruption as the Package C requirements, which at one point last year had about 50 787s out of service. One of the reasons: the 180-min. ETOPS allowance covers more of the affected missions than the 140-min. Package C restriction, which applied to both 787-8s and longer-range 787-9s. The engine versions can be inter-mixed on a single 787-8. In such cases, the more restrictive ETOPS limits apply.
Rolls plans to introduce a new blade for the Package B engines this year. It says it is also developing a new blade for the Trent 1000 TEN, the engine's current standard, as a "precautionary action."
There are 292 Trent 1000-powered 787s in service, Aviation Week's Fleet Discovery shows.